Redesign.IT – Spinfire Flame Bearing and Bearing Housing

Back in June 2013, I bought a new racquet stringing machine. It was a Spinfire Flame with a Wise 2086 Electronic Tension Head. It happened to have a special price on it, so eventually cost me $1250 at the time.  These are still being sold now albeit at a slightly higher price – $1799.

https://www.tenniswarehouse.com.au/spinfire-flame-with-wise-tension-head.html

When I had received it, and was using it for the first time, I noticed that the turntable wasn’t spinning very well. Actually, it was a little notchy, in that it would turn but seem to settle in certain positions. I didn’t worry about it at the time as I had a few badminton racquets to string, but several weeks later, I decided to investigate the problem. I found that one of the bearing races was cracked.

I checked and found a local supplier, ABC Bearings, that had this in stock and got a price. I also notified Tennis Warehouse in Melbourne about the problem, and they were happy to reimburse me for the cost of the bearing – since that was easier than getting a bearing and sending it to me.

I replaced the bearing and found that it had to be done up very tight in order for the turntable not to feel sloppy. The design of this bearing housing was two bearings kept together with a 8mm diameter bolt.  Here is a photo of the bearing mount, upside down showing the relative positions of the parts. I had made a plastic sleeve for the bolt some time ago, to make improvements to reduce the sloppy fit.

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Sometime later, I also made a spacer to raise the turntable a bit higher. The photo below shows what it looks like when assembled and with the spacer that I had made.

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This housing is mounted to the base, and the turntable sits on top. Tennis racquets can be strung at up to 60lbs, so there is considerable side force on this housing, and to stop the turntable from tipping or showing considerable slop, the bolt has to be tightened so much, that the bearing can break.

Fast forward many years to about six months ago – I was thinking about how I would redesign this housing. I looked up stub axle designs, like trailer wheel mounts – but nothing appeared to be easy to make with my lathe and milling machine. So I decided to design it from scratch, knowing what sort of loads I would need to handle.

Instead of the existing ball bearings which are compression types, I went for ball roller bearings that would handle the side loads better than the original. Also the axle would be minimum 12mm, not 8mm – so would be stronger. Another larger bearing for the top, then a needle roller bearing to allow the turntable to spin easily even when tightened.

Then ordering the bearings, and working out how to machine the parts out of aluminium, and the axle out of mild steel – it was time to make a prototype. I did have photos of the machining process, but won’t bore you with them here.

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My design is shown here with the top part removed, showing the axle with the slight taper. The needle roller bearing is visible in the bottom housing to handle the vertical load, then the other bearing with the rubber seal.

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Here you see the assembly shown upside down with the smaller bearing, then the tensioning screw to the side. Unfortunately, when I had this bottom piece in and out of the lathe, it sort of dropped onto the concrete floor, so it shows some slight dents and marring on the edges – only cosmetic though.

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This is the completed assembly – with some slight markings on the surfaces due putting it in and out of the lathe. The earlier photos showed that the bottom piece had four tapped holes. There are also four tapped holes in the top piece that the turntable is screwed onto.

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Finally a look at where this goes when mounted to the stringing machine base with four bolts underneath. My design was to be a drop-in replacement, i.e. remove the old bearing assembly, and drop mine in place and screw it together. Well almost! I had to use bolts of slightly different length. The only thing I am missing is the locking screw that locks it from rotating – but that is a feature that is only used for a couple of special tennis racquets, and I don’t anticipate having to string any of those ever.

Does it work, you ask? Yes, actually the turntable turns very freely now – although I can hear the roller bearing noise and with none of the original slop that could be felt.

Repair.IT – Benq GL2250 LED Monitor, Part 3

I should have known that there would be a part 3 in this monitor repair.  After thinking about this I thought I would see if I can verify a hypothesis.  Scientists are always testing hypotheses in order to explain things that happen based on limited evidence.

I was thinking that whenever I turn on the monitor, the Benq display comes up – with no backlight issues.  Thinking back, I seem to remember that the backlight problem comes up after some time, particularly when the monitor has gone to standby – or the computer has turned off monitor output to conserve power.

My hypothesis is that perhaps the backlight problem will not occur if I do not let the monitor go to standby.  So I decided to test it.  As I had a number of these monitors, I decided to test each one.  I connected it to a laptop, and turned off all power saving features to do with the laptop going to sleep, and those settings affecting the display timeout.  By using a laptop – it uses less power than a regular desktop and I want it turned on for a long time.  I thought that one day each would be sufficient.

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So, it went on – I connected one monitor to the laptop and left it – I also put a test pattern on it, courtesy of PassMark evaluation software.  Each day I would confirm that the backlight was fine and that all sections of the screen were lit properly – then the next morning, I would swap the monitor with another one.  Eventually I got back to my repaired monitor – for that one, I swapped the power supply from a previously tested monitor.  This was to check whether the backlight leds were having a problem.  Then the next day, I put the repaired power supply in for the testing.

After a number of days, almost a week – what was the result of my testing?  I.e. is my hypothesis confirmed?  Yes, in all of this testing, day and night – whenever I walk into the room where the monitor was testing – no backlight issues found at all.  A search of google also showed a number of issues that people had raised and it all seems to be that the backlight partially fails after the monitor has gone to sleep and is woken up.

Further examination of the MP3394 integrated circuit shows that it has two inputs, an enable input and a dimming input.  Both of these inputs are driven from a separate circuit board – the one that the DVI or VGA cable goes to.  So it seems that the power supply was not at fault, and I removed a perfectly good MP3394 and replaced it with another new MP3394 – which was why the problem wasn’t fixed with that replacement.

Now however, I know how to mitigate the problem – just leave the monitor turned on, without going to standby.  That would be the workaround to the backlight problem, albeit using a little more power – which could be solved by just turning off the monitor when I don’t need it.  Now, would that also work?  Let me test it – since this is another hypothesis – that instead of letting the monitor go to standby, turn it off when not using it.

Perhaps there is a part 4 in the future for this monitor fault – we will see.

Repair.IT – Benq GL2250 LED Monitor, Part 2

Well I should have known that perhaps it wouldn’t be that simple.

I reassembled the monitor last night and this morning connected it to my laptop for testing.  It powered up perfectly and appeared to be working fine.  I left it and came back after a while – the displays were off, due to power saving settings, pressed a key on the keyboard and…

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Ok, so the problem wasn’t fixed – looks like two sections on the bottom right were not lighting up.  Power off and back on, then it was fine again.  The MP3394 drives 4 LED lines – the IC had been replaced, so it is very unlikely to be faulty – therefore, the fault must not lie in the MP3394 – ok, that is now settled.

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After some time, I woke up the monitor again – this time, the bottom left was also out, in additional to the bottom right hand two.  If a LED line was out, then the entire section should be out, not one of two – so it looks like possibly, that the LED backlights are at fault.

One thing that doesn’t make sense is that if the LED’s were overheating and then failing, the fault should be permanent, but it seems to get better after a power off and on, but not always it looks like.  I also don’t know how the LED strings are attached to the LCD panel.  I am expecting that they would be in a row, so likely two strings for the top, two strings for the bottom.

So for now, the repair hasn’t been successful, but that is the name of the game.  I will test the others until I end up with a panel where the LED backlight is off permanently – then can take the panel apart to see if the LED itself has failed.  I might also check the input voltage to the MP3394 to see if that is acting up.  Let’s leave it at that, and I will update with a Part 3 if I make any further progress.

P.S. Why am I writing these articles so quickly – I picked up another 6 month contract job, part-time that starts next week.  Life happens, lol.

Repair.IT – Generic brand CD Boombox

Back in March, a neighbour brought over a CD Boombox – that was its name.  No brand names visible – so it is one of the generic products that are manufactured in China.  It would play CD’s or cassette and had AM/FM radio as well.  It came with a plug in power cord, and it also had provision for having 8 D cell batteries.

The problem was that it would not turn on.  I verified that if I supplied 12V from a small lead-acid battery that I could get it to turn on and play a CD, so it looks like the internal non-power sections are working.  In due course I opened it up, removing about 8 screws then the case opened up, revealing a lot of cables to be disconnected before the two halves come apart completely.

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The photo shows the insides of the boombox, upside down.  The CD mechanism is seen at the lower middle of the picture with the cassette mechanism at the upper middle.  Four speakers were visible as you can see.  After some checking, I noted that one of the diodes – those black bits on the lower left of the printed circuit board, was shorted – which could well cause the problem.

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I removed the failed diode – a 1N5393, which I didn’t have a good replacement for so found a supplier on eBay and ordered some.  It arrived after a couple of weeks, then I soldered it in and tried it out, still no go.  Ok, so what else is the problem?

One the other half of the case, there is a transformer, and from the secondary windings,  a cable plugs into the board.  I connected the power cord, then measured the output of the transformer – nothing.  I then measured the input to the transformer, i.e. the power cord, and got no resistance.  After some further investigation, it appears that this transformer has an integrated thermal fuse and that this fuse has failed.  I cannot get to the fuse without disassembling the transformer, and I could not get replacements of this transformer either.

In order to not have this sitting around for a long time, I found one of those adjustable power packs – a Dick Smith one that had a switch for choosing the voltage.  It had been sitting around in my spares box for years, so decided to repurpose it.  I drilled a small hole in the case and fed the cable from the power pack through, then connected it to the battery box terminals through a diode to protect it if batteries were inserted.

Then powering up, it played CD’s – great.  Just a matter of putting the Boombox together and get it back to its owner.  Since the cost of parts was quite minimal – the two diodes ended up costing 40 cents and the power pack had been around for probably 30 years – it was just another charity repair job.  To now, I understand that it is still performing well.

Resolder.IT – DC-DC Converter from eBay

While I had the soldering iron out for the Benq GL2250 monitor power supply repair, I thought I should fix up this pending job.

I had bought some DC-DC converters from eBay in the past.  Some were buck converters which meant that the output voltage could higher than the input voltage.  Others were standard down converters so will produce a lower voltage.  This can be ideal if you want to power 5V devices like a Raspberry Pi from a car battery at 12V.

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One of those that I had bought had a three digit meter that could display the input or the output voltage measurement depending on which button was pressed.  I had ordered two of them, and when they arrived, I noticed that something wasn’t right about one of them.  Sure enough when I opened the sealed packet, the converter came out and a loose capacitor as well.  I contacted the vendor, and they were kind enough to come to an arrangement with me.

Anyway, this had been put aside since I only needed to use one of them.  But since the soldering iron was out, I thought – why not resolder the capacitor.  The capacitor is a surface mount type, and it looked like it had not be flow soldered properly.  I used the soldering iron tip to wipe both contacts, so that it flowed the solder on the pads.  Then put a drop of flux on each pad, set the capacitor in place – then while holding it down, I touched one pin with the soldering iron tip that was wetted with solder.

Then turn around the board, and do the same with the other pin.  Of course making sure that the capacitor was oriented the correct way.  After using the 9x magnifier again to visually check it, I decided to wet each pin with the soldering iron again, just to make sure.

Anyway, I was happy with the results and I can put this DC-DC converter away until I need it for some project.  Another quick repair – that had been sitting around for a while.

P.S. The black bar or stripe on the capacitor designates the negative electrode.

Repair.IT – Benq GL2250 LED Monitor, Part 1

Sometimes for some reason or other, repair jobs may sit around for a while – here is one of those.  I had been given a number of these monitors by my brother.  They had been found thrown out in a loading dock in the city, probably from an office cleanup.  The Benq GL2250 is a full HD monitor that is LED backlit and when I had the time to test them – I found that the reason these had been disposed of, was that part of the screen would go dim.  It appeared to be part of the LED backlight that was going out, and turning the monitor off and on again, would often restore operation for a time.

Since a 22″ monitor is still a reasonable size to use in the home office, and there were several of these with the same problem – I thought it would be good to repair them and get them working consistently.  Certainly it would be worth a blog article.  After disassembly, I was able to get to the power supply board, and on that board I found a MP3394 4-string White Led Driver integrated circuit.

I could access the cable from the power supply to the LED backlight – so decided to do some measurements, in the sense of leaving a voltmeter connected to one of the lines – to see what happened when parts of the screen dimmed out.  After some of these measurements – which took time, due to the intermittent nature of the fault – I concluded that either the driver was at fault or maybe a faulty LED in the backlight.

Replacing the led in a backlight is not a simple operation, so I elected to try replacing the driver IC.  On eBay, I found a vendor selling 5 pieces of these MP3394 devices for US$6.99 + US$1.00 for delivery – a reasonable price, so I ordered them.  In time, the parts arrived and I put the parts together with the first printed page of the MP3394 datasheet.  Then life happened – as it does.  Just like that?  Well, the reason was that a couple of weeks earlier, I was asked to go in for an interview for a challenging job, and was offered a full-time contract job that was for 6 months, but actually turned out to be nearly 3 years.

I could have come back to this repair job, couldn’t I?  The new job was interesting, challenging and much of my time was spent working, so after getting home – I was tired, and didn’t feel like doing anything other than relaxing.

It isn’t really an excuse, but when I say life happens – it certainly does.  I went on to do some studying in Cyber Security which I had been planning to do for over 10 years.  This time I committed to do the training, CompTIA Security+, then CompTIA Cyber Security Analyst+ (CySA+), and only a couple of weeks ago, I completed CompTIA PenTest+.  By completing, I mean studying for and passing the exams.

I also studied CCNA CyberSecurity Operations at TAFE, and since I did well in the final exam, I received a discount voucher for the actual Cisco exams.  I then eventually sat for and passed both Cisco exams achieving the Cisco Certified CyberOps Associate certification.  But I digress – I really wanted to talk about the repair of this BenQ monitor, but now you understand by what I mean that life happens.

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The MP3394 is a chip in a 16pin SOIC package.  It is a surface mount chip, so I masked out the area around the chip with heat resistant tape – to protect the other parts nearby.  After brushing some flux onto the pins, I applied the hot air gun onto the chip, and moved it around and around to get the chip and pins hot enough that it would then come off.

Actually it took a few minutes – I had the hot air gun set to 300 Celsius and airflow around 80%, which might have been too high – but it worked.  After a bit of time, I could see and feel that the solder was molten, but the chip would not come off – and after another minute – it then came off.  I was grabbing the chip with curved tweezers.  When the chip was off, I found that there was three spots of glue under the chip, which is often used to keep the chip in place during flow soldering.

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Then a quick cleanup using soldering wick, flux and the soldering iron to remove the left over solder, and leave a clean flat surface on all of the solder pads.  Next step is to get the new chip in place, tack a couple of corners with solder to keep it in place, then solder each side of the chip.  Soldering each side is done by putting more solder on the soldering iron tip, then wiping the tip down each row while holding the iron at an angle, so that the pins and pads are heated together and the flux allows the solder to flow and make a good join.  With practice, you can get very good results.

I had a problem in that one of the pins on the IC was bent up, and I didn’t notice it when I was placing the IC – so good idea to double check before soldering.  Since it was a single pin, I just pressed down with the soldering iron tip until it made contact with the pad.  Then I visually inspected each joint with a 9x magnifier.  To verify, I used a multimeter in the resistance measuring mode, and checked each pin was connecting to the solder pad test points, which were conveniently placed near each pin.

Next step will be to reassemble the monitor and check that the backlight fault is resolved, but the results of that will be in Part 2.  To be continued…

Repair.IT, again – Samsung CLX-3305FW Colour Multifunction Laser Printer

Recap: Back in October 2018, I wrote about the repair of this Samsung CLX-3305FW printer.  Fast forward about a year – I was printing a long document that I needed for studying my CompTIA Security+ course, and partway through, the printer stopped feeding paper.

I went and checked the paper feed roller – just like last time – but this time, it didn’t work. In the meantime, I needed to finish the printing, so bought a reasonably inexpensive Brother MFC-L2730DW Mono Laser Multi-Function printer, which could also do automatic double sided printing, which meant that I could save on paper as well.

The Samsung was relegated to the garage where it was stored, until fast forward to Feb 2020. Just a week ago, I decided that I found a requirement to print something in colour. So, then the Samsung came out of the garage, and I decided to do further troubleshooting to see if I might be able to repair it this time.

This meant removing the paper tray, so that I could see the paper feed roller in action. There is an interlock switch, so I opened the rear cover door, put something into the tray sensing switch to indicate that the paper tray was installed, then another to set another switch to think that the rear cover door was closed.

After powering on, I selected the menu to perform a network configuration report, which should print out the network settings. By using a torch shining into the area that the paper tray would normally sit, I waited for the paper feed roller to rotate – after a number of clicks and attempts to feed paper, the printer stopped with an error – Paper Jam, and of course, no movement of the paper feed roller.

This would explain why adjusting the paper feed roller did not work this time. After an extensive google search, where 95% of the responses was to replace the paper feed roller, I found an article that mentioned something about a paper feed solenoid. A check of the service manual, showed that this device actually did exist, buried in the internals of the frame base-paper path mechanism. But no troubleshooting diagrams in the manual involved the solenoid.

After finding a Youtube video from someone cutting a piece of foam rubber, and attaching to the solenoid – I thought, why not. I had nothing to lose by trying this. So the steps I followed was:

  • Remove all the toner cartridges and place them somewhere safe
  • Open the rear cover door
  • Remove 4 screws and remove the rear cover
  • Release and remove the right cover
  • Release and remove the left cover
  • Remove 4 screws that secure a printed circuit board, and partially remove the connectors and the board

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  • Remove some screws and remove a gear assembly – actually this might not have been necessary, because maybe only one or two screws were needed, but I had done this anyway.

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  • 6 screws removed, and then the frame base-paper path assembly could almost be removed.
  • 3 cable connectors on the left, when viewed from the back and 1 connector on the right needed to be released so that they could be threaded through the metal chassis, before the aforementioned assembly could be completely removed.

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The picture above is viewing the side of the assembly that has the solenoid on it – as pictured in the service manual. After removing the gears as needed, the solenoid was released and could be looked at. Sure enough, there was a black pad, that seems to have compressed almost completely over time.  The printer was bought mid-2014 so after 5 years of only moderate use, this black pad had deteriorated.

The reasoning behind this is that the pad should have been probably 1.2mm thick, so that the clapper plate would be within range of the solenoid operation.  But being further away, meant that the solenoid wasn’t strong enough to pull this plate in, which would then release the gear that allowed the paper feed roller to rotate.

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I remembered that I had some natural rubber sheet, previously bought to repair a vacuum pump, so got a piece of it out and cut it to similar size and after scraping off the original black foam, it had some sticky stuff left on the plate that my replacement appeared to fasten firmly.

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I added a dab of plastic glue, just in case, but normally the solenoid retainer would keep this in place.  Next is a photo of the solenoid re-installed, but without the gears.

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Then finally, all the gears back on, together with the paper feed motor.

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You can just see that solenoid buried inside. Then the chore of re-installing everything back in, keeping to the order that things were removed, then putting the covers back on and count how many screws remain – none, great, so everything is back in place.

Occasionally during repairs like this, there is the extra screw left over, which had been removed at one stage, and when memory doesn’t work to put it back, so taking lots of photos before and during disassembly helps, to see if there is a missing screw.  My extra screw collection is quite small – I have heard of engineers accumulating large numbers of these extra screws, but that is another story.

So did the printer work, I can see you asking. Yes, definitely. On power-up, a page was fed and ejected, due to the paper feed gears being in a position to rotate. Next up, print the network configuration report – the output was very crisp, meaning that the printer was working properly.  Yes, I did also remember to install the toner cartridges before powering up.

The big test was printing a colour certificate. I had only recently in the past week passed my 210-255 exam for the Cisco CCNA CyberOps certification, so just wanted to print the certificate while the original was being processed for shipping. Success again, the certificate printed out with only a slight discolourationin the pale blue background – but hopefully that should clear up once the printer gets a few more printing jobs done.

Now since I have also passed my CompTIA Security+ and CompTIA CySA+ certifications, I should try printing the CompTIA Security Analytics Professional certificate which I get by completing those two CompTIA certifications.  Now I will concentrate on studying for the CompTIA PenTest+ certification.

Repair.IT – Vertical Blinds broken or detached cord

I was asked to look at some vertical blinds at my sister’s apartment where the cord had either broken or detached, such that the blinds could not be opened or closed. This was after my nephew had moved out of it. It turns out that two bedrooms, and the balcony blinds were in this state. The information I got is that something broke off some time ago, and it had been left like this until I was told about it.

Since I am the handyman of my house, and especially for things that others are unlikely to know about – I had first look at the problem. The ends of the loose cords were blackened, very likely from using a cigarette lighter to seal the ends – so that meant that the cords were not broken as such, so should be relatively easy to fix.

After working out how the system works, I managed to thread the cord ends back to where they should go.

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Here in this photo – it would seem that both cords should be fastened to this white plastic bit, that should have a metal clamp on it that had broken off.

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The intact metal piece on a working blind. So how do I join this? After some considering, I remembered that I had some crimp eyelets from a miscellaneous small size nut and bolt set that I had bought back in 1977. I found some of these.

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I only had five of these, so also decided to use a slightly larger eyelet. The idea being that I would drill the white piece with a 2mm drill, then use a self tapping screw to anchor the eyelets after crimping.

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Here I have crimped the eyelets to the ends of the cords. You can see the blackened ends sticking through the crimped area. Next I drilled the small hole, to enlarge the existing hole in the white plastic, then screwed it in place. As I was doing this, I heard a cracking sound – uh oh, the white plastic is too brittle with age.

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Ok, so the white piece had split but was still connected to the clear plastic piece. Back to the drawing board – how do I make sure that the ends will stay connected to the white piece?

Why not use some cable ties? After checking some dimensions, I realized that I could use a wide cable tie to go around the white plastic, then a small cable tie to go through the eyelets and through the larger cable tie – well, this is where this article is IT related.

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After doing this, and trying it out, it seemed to be satisfactory.  So I cut the cable tie ends off as shown here.

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Then to look at the other one on the balcony.

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This white piece is a bit more broken, but the cable tie method should still work. Well it was done, then finally, the second bedroom was done the same way. The blinds will open and close properly and the materials used were 6 irreplaceable crimp eyelets, and 6 cable ties of two sizes. Time-wise, about 1-2 hrs in total, the slow bit was figuring out what to do, then threading the cords back to where it needs to be connected.

That beats the cost of replacing the vertical blinds since the broken part is likely not to be available, or needs the track to be disassembled completely in order to replace it – which would be a lot more labour. Now, I wonder what that white plastic piece is called…

Recalibrate.IT – Eagnas Plus 8000 Electronic Tension Head

In the past months, I have been receiving some comments about the calibration of the Eagnas Plus 8000 Electronic Tension Head, and I realize that I may not have given any details about this procedure since it is documented in the user manual.  It appears that many users do not have the user manual, so when I mention the calibration, the users are still in the dark.

To help out, I have found my photocopy of the instructions and referred to section 7 which details the steps for calibration and will describe them here.  The content is straight from the instructions with slight grammar changes and I have added a couple of notes in blue.

7 – Calibration

  1. Calibrate the Eagnas electronic tension head when the Eagnas Plus 8000 stringing machine does not perform properly.  NOTE: It is recommended to wear safety glasses during the calibration.
  2. Unplug the power cord from the wall outlet. eagnas1
  3. If your model has the VR1 and VR2 on the back panel, please skip steps 4 through 11.  [My note: The earlier models had the two potentiometers mounted on a circuit board inside the machine.  If you are lucky enough to have a newer version, then they are mounted on a small board that is accessible via the back panel.]
  4. Use a screwdriver to loosen two screws that hold the side cover to the string gripper.eagnas2
  5. Remove the side cover from the string gripper.
  6. Place a small stick against the dowel pin and use a hammer to apply a light force to the dowel pin as shown.  Push the dowel pin out of the string gripper housing.
  7. Carefully lift up the string gripper from the string gripper housing.
  8. Use the 5mm Allen wrench to loosen two screws that hold the string gripper housing to the electronic tension head.
  9. Carefully lift up the string gripper housing from the electronic tension head.  [My note: most of them have a pair of wires that attach to the switch using a small connector.  This usually has glue on it, and it needs to be disconnected before the cover can come off.  During final re-assembly, if you have a hot melt glue gun, use some glue to ensure that the connectors don’t come loose.]
  10. Use a screwdriver to loosen four screws that hold the cover to the electronic tension head.  Carefully lift up the cover from the electronic tension head and put it on the side of the electronic tension head.  Make sure the cables are still connected to the tension controller printed circuit board.
  11. Re-assemble the string gripper housing back to the electronic tension head.  [My note: don’t forget to plug the connector back in for this step, otherwise the electronic tension head may give an error on the display.]
  12. Plug the power cord into a properly grounded wall outlet.  Turn the power on.
  13. Set the tension setting to 60-pound position. eagnas3
  14. Use the Eagnas string clamp to secure the string on one end of the Eagnas TCG-100 tension calibrator and place the string that is attached to the other end of the Eagnas TCG-100 tension calibrator into the string gripper.
  15. Press the pushbutton tension switch to activate the tension pulling.  Check whether the tension indicated by the Eagnas TCG-100 tension calibrator is the same as the tension setting of the electronic tension head.
  16. Press the pushbutton tension switch again to release the tension pulling.
  17. Repeat steps 15 through 16 four or five times to have the correct tension indication on the Eagnas TCG-100 tension calibrator to avoid poor calibration due to string stretch.
  18. If the tension indicated by the calibrator does not match the tension setting of the electronic tension head, adjust the potentiometers “VR1” and “VR2” on the back panel slightly.  Or adjust the potentiometers “VR1” and “VR2” on the tension controller printed circuit board slightly.  NOTE: There will be a range of tension from the maximum tension at which the electronic tension head stops pulling, to the minimum tension at which the electronic tension head starts pulling again.  The difference between the minimum and maximum could vary 2 – 4 pounds depending on the string and the tension calibrator used to calibrate the electronic tension head.  Therefore, it is recommended that the tension setting of the electronic tension head should be calibrated on the maximum reading to ensure the consistency in the calibration procedure. eagnas4
  19. Turn off the power.  Press the “+10” key and hold down.  Then turn the power on.  The display should read in between 34 – 39.  If it does not, then turn the potentiometer VR1 to increase or reduce the number into the correct range.
  20. Use a small screwdriver to adjust the potentiometer “VR1” slightly.  To achieve a higher number, turn this potentiometer “VR1” clockwise.  To reduce the number, turn it counterclockwise.  NOTE: Do not apply excessive force; this will damage the potentiometer.
  21. After making the adjustment, press the “+” key and the machine will run the normal program.
  22. Set the tension setting to the 60-pound position.
  23. Press the pushbutton tension switch to activate the tension pulling.  Check whether the tension indicated by the Eagnas TCG-100 tension calibrator is the same as the tension setting of the electronic tension head.  If not, press the pushbutton tension switch again to release the tension pulling.
  24. Use a small screwdriver to adjust the potentiometer “VR2” slightly.  To achieve a higher tension, turn this potentiometer “VR2” clockwise.  To reduce the number, turn it counterclockwise.  NOTE: Do not apply excessive force; this will damage the potentiometer.
  25. Repeat steps 23 through 24 until the tension calibrator reaches the 60-pound position.
  26. Repeat steps 19 through 25 four or five times to reach the right tension.
  27. After calibration, turn off the power.  Unplug the power cord from the wall outlet.
  28. If your model has the VR1 and VR2 on the back panel, please skip step 29.
  29. Disassemble the string gripper from the electronic tension head.  Carefully install the cover back to the electronic tension head.  Use a screwdriver to tighten four screws to hold the cover to the electronic tension head.  Re-assemble the string gripper back to the Eagnas Plus 8000 electronic tension head.

Ok, so there you have it, or is that it?

As you can see, it is an iterative process to do the calibration.  VR1 and VR2 obviously affect each other.  The aim is to have VR2 set so that the tension will be pulled correctly while VR1 keeps the zero balance to read between 34 and 39 – does this make sense?

Another comment I would make is that you should calibrate it so that it is correct for the maximum tension that you would ever use.  I.e. if you only ever string at 50-55 lbs, then calibrate it at 55 lbs.  If you are stringing badminton racquets, then I would suggest calibrating at 26 to 30 lbs, whatever the maximum your clients ask for.

The tensioning is non-linear, so ideally, you would create a calibration chart.  What do I mean by this?  Make a chart of set tensions and read what the calibrator shows the actual tension to be.  45 lbs on the tension head gives ?? lbs on the calibrator, do this every 3 or 5 lbs up to the maximum that you string at.  Then you can extrapolate so that if you actually want 50 lbs, you can set the correct number on the tension head to get the 50 lbs.

Next question is that the Eagnas TCG-100 tension calibrator is a spring calibrator which itself might need also need calibrating so what should we use?  Ever see those electronic or digital luggage scales?  Those are quite handy and they are available to read in both lbs and kgs.multi-purpose-pocket-weighing-scale-smiley-500x500

I bought a couple of different ones, so that I could use them to compare each other – if they both read the same, then generally that is the right tension.  I use it check the calibration on my Wise 2086 tension head – and I found that these luggage scales are quite good.  I prefer the ones like the one above which has a ring which is handy to attach string to.

So there you go, the calibration procedure, if you don’t have your instructions.

 

Repair.IT – Kleenmaid TO500X Oven door hinges replacement

The other day, my son heard a cracking sound when he opened the oven door, and it wouldn’t close properly anymore.  It seems that the oven door hinges spring wasn’t working to hold the weight of the door and when closed, the door would sit ajar.

On further inspection, the pin that would connect to the springs was broken, so there was no choice except to remove the door from the oven so that I could have a better look at the problem.  Fortunately the manual showed how to remove the door, which in this case was very easy, lift it, and then pull outwards while tilting back towards the oven.  If the springs were working, we would have to normally open the door, then engage the hinge latch which would allow the door hinge to stay in the open position for the door to be removed.

I found that the part number was GN166667 and after a quick check on eBay found a supplier that had a pair of these original hinges for around AU$64 after an eBay discount was applied.  If I order this from the spare parts warehouse, I would be paying AU$55 plus delivery for each hinge, so I ordered from eBay and saved a bit of money.

On my Kleenmaid oven door, there are two screws that hold the inner door from the outer glass door.  Also around the top and sides of the inner door is a sealant that has also deteriorated.  I found by at Bunnings, a Sika 300g Black Sikaseal Appliance Sealant for AU$14.78 that has a high temperature resistance, up to 250°C which appears to be the right sealant for the job.

Next step was scraping off as much of the old sealant as I could – a razor blade would have been handy, but who has one of these nowadays with electric shavers.

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A few days after I had ordered the hinges, they arrived.  The hinges are held to the inner door by three screws, two on the base, and one screw that is at the top of the hinge, only accessible when the inner door has been separated from the outer door.

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The inner door, by the way had two sheets of glass – one that is facing the inside of the oven.  This means that the door assembly has three sheets of glass, so good insulation of preventing the heat from radiating through the door.

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Here is a picture of the two hinges after removing from the door.  The top one should not be able to stay like that since the spring should be pulling back, except of course it is broken.  From recollection, a while ago, the door didn’t seem to be closing properly which could mean that one hinge had already failed at that time.  Also I didn’t find any broken bits of the pin, so no idea how it broke unless it had just kept wearing away, due to the door being opened and eventually there was not much left of it.  The oven is 12 years old – and I have worked on this in the past, with various electrical issues, but this was the first mechanical issue.

After the replacement hinges were installed, I then applied the sealant – it was difficult to squeeze the trigger and move the tip at the same time, to get the sealant into a good straight line with the correct thickness.  Of course, if I did this over and over again, like the appliance repairers do, I could then do a good job each time, but for my first, I did an adequate job.  Once the sealant was on, the inner door was mounted and screwed up.

I did have a bit of sealant squeeze out, so used a cloth to wipe around the edge of the inner door, and got most of the excess sealant off and cleaned up well enough.  The sealant generally takes 24 hours to cure, so it was left in the garage to do this (also the sealant smells, and wife doesn’t take kindly to stinky things in the kitchen).

The next day, I wipe the door over, since the garage is dusty – then needed to extend the hinges and lock them in the open position.  I used an adjustable spanner, to hold the tip of the hinge, then cranked it open – then moved the latch, and released the hinge.  Both hinges were done eventually.  I did slip with the spanner a couple of times, without breaking my fingers, but one was a little sore afterwards.

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This picture shows the door removal and installation process – showing the movable lock that I call the latch.

Then it was a matter of getting the hinges into the slots in the oven frame, then letting it settle downwards and latch, then open the door fully, release the latches then the door can close – actually they closed very well – looked better than new, no gaps at all.

Now I have most of a tube of appliance sealant left over, who needs some?  By the way, if I got an appliance repairer to do this job, I wouldn’t need the sealant since they would have it, but it would cost AU$250 for the callout, and then plus parts and whatever additional labour is needed – so likely to be around AU$400 or so, but this has cost me AU$75 to do it myself.  There it is – another repair done, and the wife is happy!