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 – 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.

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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.

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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.

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

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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.

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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.

 

Recharge.IT – Samsung phone batteries

What happens when you are trying to fix a Samsung phone but the battery is flat, and won’t charge in the phone – for various reasons? Of course, find an identical working phone – put the battery in and charge it on that phone.

A while ago, my brother gave me a Samsung Galaxy S2 to look at. The touch-screen wasn’t working, and also the battery was flat. I also have a S2 but his battery also wouldn’t charge in my phone, so I put that aside. I opened up his S2 and was able to locate the display cable, which I think also included the touch-screen – so when I removed that connector and plugged it back in, the touch-screen started working again, so he got the phone back minus the battery.

Some time later, he gave me a Samsung Galaxy S3 to look at. This one had just stopped and would not boot up. It powers up but then stays at the Samsung Galaxy SIII GT-I9300 screen. I wrote about it here.

https://j0hn88.wordpress.com/2015/05/16/research-it-samsung-galaxy-s-iii-gt-i9300-not-booting/

I have the battery for the S3 here still, so I thought about charging it. If the phone doesn’t boot up, then it will not charge the battery – very unlike a laptop. While doing a few Google searches, I came across mention of a TP4056 chip that would charge Lithium batteries. On eBay, these are very cheap – so cheap, that I ordered a few, as in five. I have this idea of getting those Lithium cells, like the 16550’s and converting everything to use Lithium instead of NiCad etc.

Of course, not everything works from 3.7 Volts, so I also ordered a few DC-DC boost converters, which will take the 3.7V and get 9V or even 12V etc. Again, not everything wants 5V, so for some things, it might like 3.3V so I also got some DC-DC buck converters. Oh, wouldn’t it be nice to have boost-buck converters?

In converter nomenclature, boost means to get higher voltage, and buck is to get lower voltage – from the input voltage – got? A boost-buck converter would be able to take any input, within reason and produce any output – within certain limits of course. They are available, but not as cheap as the boost or buck converters. Anyway, I am getting off topic.

So, these TP4056 chargers came in eventually. They can take an input voltage and produce up to 4.2V to charge a lithium cell. The charger also has a mini-USB connector on it, so I plugged in my GPS charger that can output 5V at 1A and tried it out.

I made a little jig to fit the battery and some copper wire, sort-of spring loaded to connect to the battery terminals, then used a couple of jury-rig wire clips to connect the battery to the charger. The TP4056 is set to charge at 1A which should be fine, since most phone batteries are more than 1Ah in size.

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Jury rigged lithium battery charging system

The S3 battery charged ok, even though it is a 3.8V Lithium-Ion battery. Now I have a fully charged S3 battery – what do I do with it, ok – later. I thought I would try the dead S2 battery, so I connected that one, and to my surprise – it started charging. I had previously tried to charge that battery with a specialized battery charger that could handle lithium batteries, but it had failed to charge.

Now, those of you who are know something about lithium batteries will say that this won’t fully charge a 3.8V battery. Of course, the end-point full charge of a 3.8V lithium battery will be about 4.35V whereas the 4.2V is for a 3.7V lithium battery – I certainly agree, however the difference in charge level is only small – perhaps 90+% of charge, and not 100%.

Let me tell you a little secret, which most of you know anyway. A lithium battery has a certain lifetime – defined as the number of full charge cycles. Let us say, for instance that it is 1000. Most of us, will need to charge the phone almost daily – which means that in about 3 years, if we left it to charge overnight, and in the morning – the phone was fully charged, that is a charge cycle. I didn’t finish, in about 3 years or so, the capacity of the battery will be diminished – it may start to happen in 2 years, and if you are lucky, in 3 years or so. By then of course, most people have already upgraded the phone.

So if everyone knows this, how is it a secret? The secret is – what if we don’t fully charge the battery? I.e. for a 3.7V battery that has a full charge voltage at 4.2V – what if we charged it only to 4.1V – and similarly for a 3.8V battery that has a full charge voltage at 4.35V, what if we only charged it to 4.2V? We actually wouldn’t be using up charge cycles – it’s like driving without the odometer clicking over. Theoretically, that battery would still be in top condition even after 10 years! The reason is business – we want you to replace the battery, so that we can sell batteries. We want you to replace the phone since it is getting old, and the new phone can run a lot more apps than the old one. It is just that simple.

Research.IT – Samsung Galaxy S III GT-I9300 not booting

My brother sent me his Samsung Galaxy S III, a 16GB GT-I9300 android phone – it wasn’t booting. Based on his report of the symptoms, I did some research on the internet and concluded that it was most likely a eMMC failure.

When I got the phone, the first thing I did was to plug in my charger. As expected a battery symbol comes up – not expected is that it doesn’t change, normally it will show a battery level going up as it indicates that it is charging.

I tried turning it on, the Samsung screen comes up, then stays there – doesn’t go away.

Ok, that isn’t good. Next I try to go to the Recovery Settings – press and hold volume up, menu and power. The screen will eventually go off, then the Samsung screen comes up then let go.




Now this seems to indicate that the phone is unable to access partitions in its memory.

/efs, /system, /cache, /data are separate partitions in its memory which is laid out as disk storage – if these are not accessible, the phone cannot boot and is essentially now just a brick. Further research on the internet shows up a lot of information that is contradictory in both nature and content. The only promising thing about the research is that I learnt more about this android smartphone environment. There were a few references to try to correct this by erasing the Nand flash memory, however doing so will require access to a pit file, a partition information table which is similar to a MBR in disk terms.

Even finding a pit file was difficult. I was able to find a zip file on the internet that contained not one, but three pit files. Trawling through more forums, I was able to find out some critical information – the pit files are for 16GB, 32GB and 64GB phone versions, so now I was able to identify the correct one to use, the 16GB one – of course.

Another forum page suggested that we try Nand erase then Re-partition, others say never do this. Other pages suggested that it was possible to fix it by doing this and then installing the stock firmware. In preparation, I downloaded both the android 4.1.2 and 4.3 stock firmwares for this phone which was from HK. I also downloaded Odin 3.07 and 3.09 – some sites say to use 3.07, others to use the later one – I also got 3.10 just in case.

Ok, now to put the phone into downloading mode.

Now we press and hold volume down, menu and power.

Then connect the phone to the computer after making sure that the Samsung USB drivers had been installed.

Now run Odin 3.07, load the pit file, select Re-Partition and Nand Erase All, load the PDA firmware which is the phone firmware for 4.1.2

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Now the time to click Start… and… Fail – ok, not unexpected.

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What it means is that the Nand flash memory is basically not accessible, cannot be erased, or written which means that my original conclusion was valid – the eMMC is dead. The only way to fix this is to replace the memory chip.

I also did try with different Odin versions, as other forum pages suggest, but the result was still the same. One possibility is that the memory chip being a bga chip might have suffered a fate similar to graphics chips in laptops – perhaps one thing that I could do is to heat it up with my smd rework station, the same way that I did on the Dell laptop – maybe that might fix it if the memory chip hasn’t actually failed, so something to try…

Retell.IT – 2011 – Samsung HT-TZ315 Home Theatre System

Going through my repair books, I came across an interesting repair that I did in June 2011. It is now time to “retell.it“. I had purchased a Samsung HT-TZ315 Home Theatre System a few years earlier – it was a good price, and performed well, however I noted at the time that the display was a little dim. I didn’t think much of it at the time since everything was working fine. Fast forward to June 2011 – one day, we went to use the home theatre and the blue power light came on, but nothing from the display. The display just would not light up – but we managed to use the remote control shortcut buttons to prove that the home theatre system was indeed working – just nothing being displayed.

Ok, most faults like this are usually power supply related – I thought. The display panel uses a VFD, a Vacuum Fluorescent Display, so most likely the power to the VFD on the front panel must not be working. I removed the home theatre from the tv cabinet, disconnecting all five speaker cables, plus the optical and hdmi cable etc. After opening the box, I looked at the power supply and fortunately, the voltages are screen printed on the pcb – fantastic.

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I used my multimeter to check the voltages on each pin concentrating on the vfd power – and all pins had voltage on them. Although the vfd pins were not quite +4.3V and -4.3V but were +3.2V and -30.1V – I thought that it might be fine.

I also checked the ESR of the capacitors and mostly were ok, with a few that I consider a little borderline. I proceeded to obtain replacements for those that I did not have in stock, then replaced them. After doing this, I retest the home theatre and still no display – sound was working, volume was working, just no display. From a search on the internet, it seems that problems like this require replacing the front panel pcb – AH41-01100A. From what I could find, the only replacements at a reasonable price was from the UK at around 40 pounds, ouch – not cheap when converted to AUD.

Ok, why not check the front panel pcb, maybe there is a broken track somewhere – a long shot because a broken track usually means something burning out, which is usually accompanied by other problems that would be visible. Anyway, removing the front panel pcb was eventually accomplished – need to remove a few other cables in order to get it out.

Tracing the power connections around, I eventually got to the VFD and interestingly, could not measure the VFD voltage – so there was a broken track or a dry joint.  I used a 10x magnifier and went through all of the pins attached to the power connector and where they go to, no dry joints seen. Turning it over, I could trace connectivity from the power sockets to all of the pins – what gives. After scratching my head a while, and turning the board over and over, I eventually noticed something that was slightly unusual. Two pins on the VFD were a little bent – ok, most pins should be straight since these are inserted in the factory during manufacture, but two pins, which coincidentally were connecting to one of the power circuits – the -VFD pin. When I put the multimeter probe on the pin, of course I push down, and it makes contact.

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What seems to have happened is that because the pins were slightly bent when the VFD was inserted during manufacture, over time, together with transport, the solder pads on these two pins had lifted from the circuit board. Looking from the bottom, all the joints look fine, but using a 10x magnifier, I could see a gap between the soldered pin and the circuit board. I took a photo of it to show that I was not dreaming.

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Here is a magnified image, you can see the right two pins have a slight dark area under the solder, this is the gap – compare with the other pins on the left where the solder pad merges well with the board. Resoldering the two pins, and reconnecting the front panel pcb – and voila! I get a display and had saved ordering a replacement board from the UK. It is also brighter than it had been originally.  The lifting solder pad had produced a dry joint that was high in resistance, but enough so that it would pass inspection since it was lit, but eventually the resistance increased due to the pad continuing to lift, until it went open circuit.

Now, three and a half years later, this same home theatre system is still working well.  You may also think, how could this happen.  These home theatre system can get reasonably hot when driving all the speakers.  This heating and cooling cycling will cause metals and plastics to expand and contract at different rates – because the pins were bent, it acts like a little spring that pushes and pulls each time the system in on and off, eventually the solder pad lifted enough that no power was going to the VFD.  The forces involved are very small, but over a period of time, like 2-3 years, it all adds up.  In addition, with a sub-woofer in close proximity, this may also cause the display to vibrate, and this would just make it worse.