Repair.IT – New Year’s resolutions

Happy New Year! to all readers. This Christmas and New Year period has been very hot in the Sydney area, so what resolutions have you made this time?  One of mine was not to leave things too long that need repairing, and also to write about it, if it is worth writing about – not to leave that too long either.  I remember a saying that if you thought of something (or an idea) and didn’t write it down, it is as if you had never thought of it.  How many times has someone come up with a new product or service, and you said “I thought of that a long time ago!”

To come to today’s subject, is not really IT related but here goes.  We have a built-in wardrobe in our main bedroom where the doors would not shut properly, would blow open on a whim – you know the ones, you close one door and another one opens.  I had already repaired one door a year ago (or was it two) by replacing the hinge.  At the time, I had noticed that the wooden frame to which the hinge attached, had a crack in it.

After a number of windy (read “stormy”) days recently, this particularly door was blown open which was causing the crack to get larger.  I could wait until the door fell off, but that would be a bigger job to fix.  Also my dear wife had something to say about that the night before, however on New Year day, I decided to remove both doors attached to that frame to fix the crack.

I did this by using a small screwdriver to open up the crack, then squeezed PVA glue into the crack and helped it by using a knife to coat the glue onto the inside surfaces.  Once that was done, I used a number of clamps to close the crack and left it to set overnight.  Of course, I did have to use a soft cloth and wipe up the excess glue that squeezed out.

You can see from the photo above that it is quite a long crack.  So what does this have to do with IT or recycling – it does have repair though, but here it comes.

While removing the door on the side that the photo shows, I noticed that each hinge was held by two bolts with a nut on the other side, which had embedded into the wooden frame by tightening each time the previous owner noticed that the door was loose.  The wood is quite soft, so I can’t keep doing this so decided to come up with a proper solution.

After scratching my head a little bit, I came up with an idea – I needed something with a screw thread, like a nut but with a flange on the other side, that would not dig into the frame like the nut did.  I quickly did a few measurements and drew up something on a small piece of paper.  The original screws were 3/16″, but I decided to use M4 screws since I had almost a box full of M4 x 25mm stainless steel countersunk screws left over from another repair.

As the photo shows, a metric 4mm internal thread, so making the outside about 5.2mm diameter would give a wall thickness of 0.6mm which should quite sufficient.  The flange could be about 18mm in diameter with a thickness similar to the hinge on the other side, so about 1.5mm.  So this is where my metal working equipment came into play.

I had some 20mm mild steel bar left over from another repair job – almost 2m of it, so cut off about 12cm with a hacksaw.  I could have used the bandsaw, and on hindsight should have, but what are muscles for if you used them from time to time.  The inside bore of my lathe is 20mm so this means that I could put longer pieces into the lathe chuck, but cutting a smaller piece means that the lathe has less work to do.

I made the first part with about 1cm of thread – cutting metal can be fun, but since my lathe is a small one, I had to take a number of small cuts – like 0.5mm at a time.  I see some Youtuber’s taking 2-3mm cuts of steel at a time, but that would be using a more powerful or larger lathe.  Some of you may be wondering about the process of doing this?

1. Mount the mild steel bar in the lathe chuck, enough for the machining needs – around 2cm.
2. Take 1mm or so off the bar diameter, for the total length of the part, plus 3mm for the parting off and a bit more.  This meant about 18mm.
3. Spot drill the center hole with a center drill first, then with a 3.3mm drillbit to full depth.  For the next piece, I won’t need the center drill which is used to start the hole.
4. Turn off the lathe (and unplug the power) and attach my homemade hand crank/turner for the spindle, to tap the M4 thread by hand.  Using some cutting fluid /lubricant on the tap, use the starter/taper tap, then the intermediate tap, and finally the bottoming/plug tap.  Remove the spindle crank.
5. Power up again, and turn the shaft to the right length and diameter of about 5.2mm – I made the first one 10mm long, but decided to do the remaining pieces shorter – around 5-6mm, less work involved.
6. Use a parting tool to cut the piece off the bar leaving a flange of about 1.5mm thick.  When it is almost cut through, I used a plastic pipe held next to the parting tool so that the part falls inside when it gets cut through.  This avoids the part spinning around at 900 rpm falling and running off somewhere off the lathe.
7. Repeat the process another three times.

My wife asked – couldn’t I have just gone out and bought something like this?  Yes, if I knew who might have it but on January 1, 2019 – Bunnings was open, but I had the tools and the material.  How much was this worth?  I used about $3000 of equipment to make these four parts.  When getting into metal turning and milling, it doesn’t look expensive, but once you get a few upgrades like quick change tool post, 12mm turning tool sets, etc – it all adds up.

As an example, the parting tool, is from Hare & Forbes, and buying one now as a kit would be https://www.machineryhouse.com.au/L464 for $198.  The quick change tool post that I have is  https://www.machineryhouse.com.au/L280 – another $198.

Once the glue was set, I used a 50mm long wood screw, after drilling a pilot hole, to screw into the frame – this should help keep the crack from opening up again, since just relying on the glue is not a good idea.  Then it was a matter of cutting the M4 screws to be a little shorter, like 17mm in length overall – then placing the wardrobe door on some spacers to get the height correct – then fastening it.

The photo shows where the old hinge on the next door was replaced with a proper door hinge a bit lower down – that door was next on the list to remount.

Some of you might comment on the finish of the part – I can see turning marks/grooves on the part.  This is due to the material of the mild steel bar that I used.  It is not a free machining steel, so it doesn’t cut cleaning in the lathe – it feels a little gummy.  But then carbide tools are not very sharp, so using high speed steel cutting tools should improve the finish – but nobody is really going to look at it since it spends most of its time covered by the doors – so here this is, my first repair job of 2019.

I did actually work on a second repair, but that one was machining a piece of nylon with a 4.5mm spigot sticking out and then riveting it to a piece of plastic that is part of a paper towel holder but I didn’t take any photos of it.

 

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Repair.IT – Sony RM-GD001 Remote Control for Sony Bravia KDL46X2000 LCD Digital Colour TV

Here is another job that was sitting there for some time, having put up with the inconvenience patiently until it was time to look at it.  This remote control for a Sony colour TV had been playing up – first it was unable to turn on the TV – but that was ok, since we use the side power button anyway.  Then we couldn’t adjust the volume, again the side buttons still worked.  How tolerant we are?

Then the input source selector stopped working, so we had to use the side buttons again, to access the menu so that we could choose a different HDMI input when we wanted to play Blu-ray movies.  We went through the same hassle to switch back to the Google Chromecast, etc, until it happened that it was time to do something about.  Maybe the wife complaining also helped to bump up the priority.

This remote control RM-GD001 was relatively easy to open up.  By opening the battery compartment, I could see two screws that needed removing – this is usually a sign that the job will not be difficult.  The ones where there are no visible means of fastening are usually the harder ones.

I needed the smallest precision Philips screwdriver since the screw slots were so small and thin.  After removing the screws and the battery, I turned my attention to the bottom where there were two visible holes.  By inserting an angled pair of tweezers into the two holes and pulling upwards, the bottom started to come apart.

Then once the opening was sufficient, I then use an old plastic card to slide into the opening then around the corner and with a click, the housing started to unlatch.  You could use an old credit card, or used gift card (flybuys etc), since they are all a similar size and great for this purpose.

Once the two pieces of the housing were separated

This it was a matter of cleaning the contacts.  I used an alcohol wipe that I had previously bought from Officeworks.  Similar products are available from chemists, pharmacies, computer stores etc.  You have seen them before – nurses use them to clean the skin before giving you a needle.  The good thing is that when it dries there is no residue, unlike methylated spirits.

If you are quick, you can use the same wipe to clean both the black circuit board contacts and wipe down the black rubber buttons which press down onto the circuit board.  Once these were clean, I was able to put the batteries in, lay the rubber button overlay onto the board and try pressing some buttons and confirm that they do work.

Now was also a good time to clean the top surface of the remote control as the buttons are not going to get in the way.

Now that this is relatively clean, I clipped the two housings back together, put the screws back in, and I have a functional remote control again.  Another successful repair.

[Note 1]  It can happen that with use, the conductive coating on the buttons are worn out.  We can get a conductive paint and just paint onto the buttons again.  This is available as a remote control repair kit, that I have seen on eBay but not used.  Others have reported gluing thin pieces of aluminium foil onto the buttons.

[Note 2]  What if you want to test the buttons, but the appliance is not available?  I will explain how to do this with a common webcam attached to a computer.  I have this webcam that I put onto the table, and aimed it where I was working.  With the display on the monitor, I could press a button and confirm that the infrared led lights up.  This is possible because unlike the human eye, webcams can still see infrared light even though they may have infrared blocking filters in place.  I could also use a multimeter set to the current range, and activate the remote by putting the probes on either side of the black contacts – I did this to verify that the microcontroller was sensing the contacts currently.

Now this reminds me, the Samsung TV remote control in the lounge room was also playing up.  I had a universal remote control lying around that I reprogrammed for the Samsung TV, maybe I should look at the failing remote control!  Oh well, I will leave it for another rainy day.

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

Actually, as a species, human beings are quite tolerant.  What do I mean by this?  You print something and go to the printer and it isn’t there.  You look at the screen and you see the dreaded “Paper Jam”.  So the process is pull out the paper tray, no stuck paper – put it back in.  The message is still there.  So open the front of the printer where the toner cartridges are, pull out the cartridges one at a time – no paper stuck behind, so replace the cartridges, and close the front panel.

The message goes away, and the printer starts humming and the printout comes out.  Now this can happen for a while, until such time that even doing this doesn’t help.  Oh, there is another door at the back of the printer, so open and close this one, and sometimes this helps and the printout comes out.  Eventually, it gets to the stage where the paper jam happens almost every time you try to print.

We could have lived with this problem for months, because once we get our printout, we forget about the problem.  This is what was happening to my Samsung CLX-3305FW Colour Multifunction Laser Printer.  It hasn’t had a lot of use, from memory it is still on the second box of paper, so what could be wrong with it?

After a bit of googleing – (or is it googling?) it seems that the culprit is the paper pickup roller – which with printing and/or age, gets a bit smooth from the paper dust and other environmental issues.  Fortunately, I was able to find a service manual for this printer, and the diagnosis also appears to be the pickup roller.

Hence, two days ago, I decided that it was time to have a look at the culprit.  I removed the toner cartridges and stacked them neatly with a piece of newspaper on top to stop dust from getting onto them.  This was a precaution since it is easy to take things apart and then it sits there for days, weeks,…  Continuing, with the paper tray removed, I put the printer on its back – and just managed to stop the scanner lid from crashing down onto the toner cartridges.

With the printer in this position, I could see and reach the pickup roller quite easily.  The roller is locked in place by a white piece of plastic, which is held by another black bit of plastic.

Here is a closeup of the pickup roller.  By unhooking a tab on the black bit (where the dark line is), I could slide the white bit to the right, thereby giving some room for the roller to disengage, then spin it around 180 degrees and it comes out.

You can even see some paper dust.  Then the pickup roller comes apart, by unlatching the two black bits.

I brushed the rubber tube, then decided to turn it around by 180 degrees and use the surface which was not exposed as the new pickup surface, then put it back together.  Replacing it was just the reverse, put it back onto the shaft, spin it around, then lock it in place by moving the white and black bits to the left until it locks.

So, there it is, another repair done.  Ok, so did it work?  It did say paper jam on the first page I tried to print, but then did the rest of the pages ok.  So time will tell if this is a permanent fix, or if I need to do more.

 

Regrease.IT – Losmandy GM-8 Equatorial Mount

The other day – actually around the middle of July 2018 I was talking to friends about Mars being visible.  Then there was shortly going to be a lunar eclipse.  In preparation of viewing the much anticipated lunar eclipse that was going to be the longest duration event for a long time, I dusted off my telescopes to see which one would be suitable to use for the viewing.

I went through some of my telescopes, one of them was a computerized Meade LXD-55 with a 6-inch Schmidt-Newtonian, but the view of Saturn was a bit small, so eventually settled on the big monster.  Some years ago, before I started travelling, I had purchased a Losmandy GM-8 equatorial mount, together with a Meade 10-inch Schmidt Cassegrain optical tube assembly.  Due to my travelling, and subsequent house move, this combination had very little use and was mostly in storage.  The mount had been sitting in a corner for quite some time, and the optical tube assembly was inside its original box.  I thought it would be a good time to let it see the light of day (or night) again.

A few days earlier, I had set up a measuring stick so that I could mark the Sun’s shadow at solar noon, which happened to be at 12:01 PM on those days.  Knowing which direction the Sun’s shadow pointed to, at solar noon, meant that I could accurately know the direction to the South Celestial Pole (SCP).

One leg of the Losmandy tripod was set in the direction of the SCP, then the mount was installed on top, so that the Right Ascension axis would point towards the SCP.  The idea of this is that the RA axis, being parallel to the direction of the SCP would be in line with the rotation of the Earth.  The motors driving the RA axis would counteract the rotation of the Earth so that the stars, planets, moon etc would appear to be stationary.

Of course the slightest misalignment would mean that some adjustment would still be needed, but having it close would mean that it would be small adjustments.  I am digressing I think – just setting the scene to what I had in mind.

So during a nights viewing of the Moon, Mars and of course Saturn – I noticed that when slewing the telescope in the RA direction, the view would move then when I stopped slewing, the view would come back a bit, which in some ways is like backlash in gears – but this was enormous.  I had noticed that the RA axis was a bit stiff, since I usually balance the telescope – and had a lot of trouble doing so, but since it was still usable, I ignored it at the time.

As it turns out, we were very clouded out on that Saturday, so there was little viewing of the lunar eclipse.  In the following days when the clouds cleared up, there was some viewing, and then the rain came.  Of course, I didn’t leave the optical tube outside, but did leave the mount there, covered with a plastic bag.  During a violent wind storm, I came home, and the bag had been blown off, never to be seen again.  I decided it was time to bring the mount inside.

When inside, I was then able to have a much closer look at the stiffness of the RA axis, in fact – it was so tight that I could feel some cogging, which meant to me, that the bearings had stopped working.  After some thought, I decided it was time to see about getting to the bearings.  On Google I found a number of people had seen this problem, especially when the mount was in storage for some time.  This mount is about 20 years old, spending much of its time in a corner as I had no permanent place for it to live, like an observatory.

I removed the Declination axis, which was bolted onto the RA axis with two bolts.  Then removing the various bits, left me with the RA axis tube sitting inside the RA assembly.  After careful consideration, I used my rubber mallet to knock the tube loose.  I had already loosed the main gear and worm drive, removing the motor – and as it turns out, I could have left those intact.  After some effort, the tube came out and I could see that the tube showed the signs of frozen bearings.

Then after moving the RA assembly to a horizontal position, here is a picture of the lower bearing.

And of course a shot of some of the bits that came off the mount.

I could feel that the needle bearings were not spinning, which is a bad sign.  After rubbing it, I sprayed the bearings with WD-40.  One of the bearings is not visible, being set inside the assembly.  The WD-40 can had a long nozzle which I used to get the liquid inside.  Using a cotton cloth, I could move my fingers around and around the bearings – and they seemed to move a bit.  Some of the old caked grease was starting to come off.

I got as much of the old grease off as I could, then sprayed more WD-40 and left it overnight.

The next day, I then used a cloth to clean the WD-40 out of the bearings and the bearings seemed to be working – with the needles spinning somewhat.  More spinning of the bearings and another application of WD-40 and it seemed to be clean enough – at least the rag I was using was not coming out with a brown coloured gunk, but was coming out clean.  More work with the rag, until it was coming out dry.

Leaving overnight again, for any further WD-40 to evaporate, then clean again with lint-free tissues, before regreasing the bearings.  Before regreasing the bearings, I tested them by inserting the RA tube, then rotation the tube, which went well.  I then used a white lithium grease that is in a spray can, typically available from most places like Bunnings, SuperCheap Auto, etc.

I sprayed the grease onto a piece of cardboard, then used my finger to scoop some grease and work it into the bearings.  After further applications and doing the upper bearing that was inside the RA assembly, I was satisfied that I had sufficient grease on the bearings.

Then it was time to reassemble the RA axis, effectively – install the main thrust bearing, then the main gear that has the RA setting circle mounted on it.  Install the worm drive, making sure that it meshes with the main gear, then mount the motor drive, and then worm drive cover, and finally insert the RA axis tube.  At the lower end of the axis, install another main thrust bearing, then the clutch knob spacer, the clutch knob spring washer, then the clutch knob and tighten it up.

Almost done, now – what am I missing.  Ah yes, the Declination assembly – this bolts on to the 2 holes in the RA axis tube.

Ok, finished – regreasing it.  Well, almost!  I still have to adjust the worm drive since there is still some play in it – I need to adjust the meshing of the worm drive with the main gear so that it is tight enough that it will rotate well but loose enough that it doesn’t bind or have any tight spots.  I adjusted it as best as I could, but I would have to revisit this again next time I use the mount.  All of this was done over several days and apparently, this regreasing may need to be done on a regular basis in the future, maybe every year or two.

I did mention that the RA axis tube is hollow, right?  That is so that the polar scope can be mounted into it, so that we could adjust the axis to point directly at the South Celestial Pole, which is located somewhere in Octans, but I am digressing again…

Repair.IT – Highgate wall light with PIR motion detector

Here is something that was on my bench for repair. A Highgate OL7664BK outdoor wall light with PIR motion detector. It is a nice light made from black metal housing with glass pieces which had been installed at a sister’s place during a small renovation, and then failed to turn on, a few months later.

After making contact with the supplier, a replacement light was sent out. In due course, the light was then replaced, and I was given the faulty unit – perhaps I could Repair.IT and get it working again.

After opening the light housing where the sensor is located, I found that the sensor unit is a small black box with the PIR on the outside and three wires going into it. Brown, Blue and Red – guess what these would be? Fortunately, they also went to a terminal block which was marked. Brown and Blue are standard colours for Active and Neutral, but Red’s marking was an X – ok, meaning switch.

Sure enough X went to the Active of the light socket, with Neutral being the common for the light socket. Also I noted that there was also a ground wire terminating onto a stud on the metal housing – that is very good indeed. Now, the light is still usable if we wish to use it just as a standard light fitting, without the PIR sensor by just wiring the input wires to the active and neutral of the light socket.  However, I am interested in how to fix it.

The small black box was sealed, but nothing a rubber mallet couldn’t solve, so eventually the seal where it was either glued or plastic welded – came apart and I could get to the interior.

Inside was a small board that was connected to the separate PIR sensor board. Often the question I get asked, is how do we determine what the fault it.  Generally we will know something about the device, in this case – it is a switch that turns on or off the light.  The PIR sensor board does the sensing, so it must then use the small board to switch the light.

Usually this involves an optical isolator which is usually in a small 4-pin or 6-pin package.  This optical isolator, or opto isolator will then somehow connect to a switching device, which is usually a triac.  This small board contained a MOC3023 which is a known optocoupler with a triac driver output.  From this chip, it connected to a triac via a small limiting resistor.

I examined and determined that a Triac had failed. In additional the small limiting resistor of value 200 ohms had also gone open circuit.

Likely what had happened was that the Triac had failed, and the ensuring high voltage caused excess current to flow through the tiny resistor which then failed. Or it could have been the other way around, but the resistor is slightly discoloured which meant that it had gotten way too hot.  In this photo, the resistor is the one near the top left.  The marking shows 201 but the 0 is a bit marred.

The marking on the Triac was a BT136-600E. My local Element14 supplier had these in stock, for around $1.26 but then ordering this by itself  plus the resistor would incur a delivery fee much larger than the total.  Since this was a charity repair, I elected to buy these parts on eBay.  10x BT136-600E’s were $1.86 delivered, so this was a good deal.

The resistor was a 200ohm surface mount version in a 1206 package – I managed to find a good supplier that would give me 100 pieces for $1.34 delivered.  In the case of eBay, why buy 1 when you can get more for a similar price.  It leaves me with lots of spares for future repairs.

The BT136 was easy to remove, just using my desoldering station – it was a matter of minutes to desolder each pin and remove it from the board.  Similarly, but using a SMD tweezer soldering station, the resistor came off in a few seconds after heating.

Once the parts came in, which was a few weeks in most cases – I soldered the replacements into place.  Here I am showing the replacement resistor with a good 201 marking.

Here is a view of the top of the board, showing the bad triac on the board mounting.

In case you are wondering how small a 1206 resistor package is, it is 3.2mm long and 1.6mm wide, just don’t drop it on the carpet, since you may not find it again.

Oh, by the way, once assembled and wired up on the bench – it does work.  The light would light up when I walked near it.  Another successful Repair.IT

Reply.IT – Reply to comments

Hi, first of all, I would like to apologise for being slow at responding to replies.  So today, I got onto another computer, logged on to WordPress.com and went through the comments and replied to them.

I switched computers because my main desktop was getting old, and on the new computer, I was playing a number of online games.  I also built a number of new cryptocurrency mining PC’s of which I may document at a later time.

Also with internet issues, I found that I could not even approve comments and write new articles.  Anyway, I managed to get the WordPress app onto my Android phone and was able to approve the comments a couple of days ago.

Now I have replied to most of the comments and will endeavour to respond in a more timely fashion in the future. I also have some articles lined up which I will upload soon.

Repair.IT – Kleenmaid TO500X Electric Oven – again

This is a followup to the previous article on the Kleenmaid TO500X Designer Multi Function Electronic Timer Oven.  Remember that after the repair, it was working, but after baking a set of frozen pies on one weekend, the next weekend – it stopped working again.  The symptoms were different this time.  The oven lights inside will work, but no heating or fans would operate.  I thought at first that it was the thermostat, since this controlled the power to the heating elements in order to turn them off to maintain a set temperature.

I switched off the power, and checked that the thermostat was in fact … working, just like last time I checked.  Ok, so scratch that idea – what else could be wrong.  Eventually after some thought and research, I was reading the oven operation manual, which suggested that on some models, there was an oven door switch which would cut the heating if the door was opened.  Yes, this oven did have a door switch, which used to cut off the heating when the door opened, but I remember that recently it had not been stopping the heating.  There is a red indicator light that shows when the heating elements are on, and in the past – this went out when the door was opened, but in the last few months, it seemed to not go out.  Maybe this could be the reason.

So, open up the housing and locate the door switch that was on the left side, check for continuity, and nothing – even when the button was pressed all the way.  This had failed so checking for a replacement – Metalflex MS-385 seems a common part, but this one was shaped differently.  The local oven parts stores didn’t seem to show this as a spare part – so maybe I can just bypass it, like I did with the relay.

After I had written the previous article on this oven, I remembered reading that this particular model would disable the power if the clock was not set – as a fail-safe.  By applying the power and setting the clock, I could hear a click from the clock area.  Perhaps the relay was now being turned on.  But then – how to explain the previous problem?  Unless the door switch had decided to become intermittent, and sort of arc’ed over – maybe the timer electronics detected this as a fault and cut the relay.

I had tested the clock board and controller out of the housing and had not been setting the clock, so the relay would not have been turned on.  Bypassing the relay would allow the power to be available independently, so maybe the relay is working again, after a power reset.  To test this hypothesis, I decided to remove the bypass on the relay and just have a bypass on the door switch.

I reassembled the door switch mechanism and then closed up the oven, and went and replaced the fuse that I had pulled out in order to remove power to the oven.  The oven clock was now blinking and after setting the time – a couple of seconds later, I heard a click which could have been the relay turning on.  I used the control to turn on the light, and the light came on – fantastic.  Selecting the fan, and yes – the fan would spin up.  Next, turn the thermostat, and the thermostat indicator light came on – meaning that power was being applied through the thermostat.

Well that is good, I have a working oven again – except that the door switch is no longer operational – but it was an optional feature anyway, which helped for safety – but most of these ovens don’t have one.  It looks like this oven is now repaired, again – and hopefully for good.  In the meantime, I will see whether I can locate a suitable replacement switch to restore its full function.