The community repair thread

Kittyfrisk

I meant to mention this earlier but forgot (it's airing now).
It relates to repairability... or not.
https://www.bbc.co.uk/programmes/m000vgh8

Danny1969

So been a while since i've put anything on here. I have a few interesting jobs on the go that are awaiting parts to turn up amid all the boring tablet repairs. Here's a couple of recent fixes that might be of use to people, maybe inspire people to at least have a go at repair before it becomes landfill. 

So first of the bat here's a very old special radio. Owned by an old lady who doesn't want a new one. She and her ;late husband have been half way around the world with this radio over the last 30 years and she wants it fixed. i don't know much about what makes this one special but it certainly has a lot of stuff on it you don't get on normal radios. The fault is there's no volume, banging it can introduce some crackling but other than that it turns on but no volume. Another repair place has decreed this BER which in our game means Beyond economic repair ..... which can sometimes also mean I can't be arsed to do it. 



Now straight away I'm thinking bad volume pot or some switch inline with the audio has failed. Headphone jack etc. But first I want to look inside just to see the build. 



Ah, this is the kind of stuff i tinkered with as a kid and learnt about electronics. As I couldn't afford to buy new components I would spend hours pulling the resistors and caps off old PCB's ... the leaded solder was easy to melt and I could strip a board within a hour, harvesting hundreds of useful components which I built other stuff with. 

However a bad joint causing the fault is unlikely, leaded solder on components that don't get hot is very good in general. So I power it up and prod about, obviously this is a mains powered device as well as battery so have to be careful while I running it off the mains. The board tests good on the old prod test so I go looking for something that breaks audio for whatever reason. 

And then I find it. On the side of the radio there's a little switch which switches between it's own internal radio and an external record player. Over the years the switch doesn't get used and a non conductive (semi conductive) layer forms and breaks the contacts. This leads to a break in the audio path. This fault is also very common on guitar amps with serial effects loops. They don't get used so go faulty. When you tell the customer that they always say " can't be that, I never use the effects loop"



So spray some switch cleaner, give it a few on / off jiggles and all is well and returned to happy customer fully working. 

Danny1969

So these repairs are an economical challenge. Because I want my musician stepson to have a reasonable portable recording setup but being tight I don't want to spend a lot of money. So I have a budget of £100 for his birthday and I have brought a faulty 2012 Macbook pro  which doesn't post for £70 and (from this very forum) a faulty Scarlett 2i2 audio interface for £20
. 



So first up the Macbook Pro. Here I have an advantage, having had repaired a lot of Macbooks in my time. Basically when you turn it on it beeps. The guy I brought it off has changed the ram but to no avail. I have a good idea what this fault is though. Basically the ram slots are doubled up and one hangs on longer legs. What happens with unleaded solder and possible movement ? well the joints crack. So board out and here I'm pointing to what is what needs to be resoldered ... with leaded solder so it doesn't happen again. I wish I had taken a pic of the other slots legs as they are worse. 




So, back together and it boots into OSX. I have an old 128Gb SSD so I clone a clean load of HS to it and install the SSD. That quickens things up and I also nick 4Gb sticks of Apple ram out of a dead Imac so it now has an i5, 8Gb ram and a 128Gb SSD. 

Now the audio interface. This is punt, these things are complicated, not so much on the analog audio side but defo on the digital side. Luckily It's detected and presumed working by the computer, the fault is no audio gets through it, even to the headphones so either the opamps are dead, their rails are dead or something is muting the audio. Now my money is on something muting the audio because even a dead opamp with no rail with often pass some tiny audio because it's negative feedback loop is a path for audio to jump across the in to the out. So lets get it in bits. 




So in rush to crack on I didn't document how to take it apart which I wish I had done because unscrewing every screw removes the back panel but the front one with the board attached still won't slide out. Look at those clips on the top of the plastic panel though, once you have the screws out you need to insert a flat blade screwdriver into the enclosure and hook those clips off .. then that whole piece will slide out of the enclosure and you can get the boards out. 

Now what do you do before you start attacking it .... you google it because the net is full of clever people and I had linked to a reddit page to help the previous owner of this where a guy described a faulty quad analog switch IC. So sure enough I find this and remove it with some hot air 



Here's the link I used to buy a replacement ... well pack of 5 actually for £1.65 

https://www.ebay.co.uk/itm/260930300136

The new chip is slightly wider than the old one but there's enough width in the pads for me to get it on there 



And boom, inputs are no longer muted and we have audio. So test both channels in Reaper and all is well. 



So I'm pleased, 2 devices saved from the dump and a lot of money saved for me. 

ICBM

Today I accidentally fixed the dishwasher... it had stopped working mid cycle.

An error code had come on which indicates "water leak" - but there was no sign of one, it was dry as a bone all around the bottom of the machine. A bit of online research revealed that what it actually means is that it thinks there's water in a trap in the bottom of the casing, which it detects by means of a polystyrene float and a microswitch... but that they can be prone to triggering falsely, sometimes if something as small as an insect/woodlouse gets under the float and pushes it up slightly. The error code can't be reset without getting the float to go back down.

Getting at it isn't too easy of course, you have to take the front of the door off in order to get at the panel that covers where it is, and this also means lifting it up so you can remove a trim strip first etc, and then reach right into the bottom of the casing. The machine is quite a tight fit in its recess and in particular I've got to lift the front edge slightly to clear the ceramic floor tiles, in a very narrow gap where it's easy to trap your fingers. Much cursing and swearing ensues and I still can't get the damned thing out. Finally it nips me quite badly, I let go and it falls back behind the step where it started. Grrrr!!

But then I remember that the online tutorial man said that some people have managed to free the float just by tilting the machine back and forth, so - not expecting anything to have changed - I plug the machine in again and power up... and the fault code is gone . The impact of it falling back down must have freed it.

So at least I now know for certain that it was the float sticking that was the problem, I'm going to leave taking the machine out and cleaning under it until next time .

Moral of the story - doing a little research and understanding the likely cause of the fault can make a huge difference to how difficult something can be to fix, even if it hadn't actually done it unintentionally - I at least knew exactly what I was looking for.

boogieman

ICBM said:

Today I accidentally fixed the dishwasher... it had stopped working mid cycle.

An error code had come on which indicates "water leak" - but there was no sign of one, it was dry as a bone all around the bottom of the machine. A bit of online research revealed that what it actually means is that it thinks there's water in a trap in the bottom of the casing, which it detects by means of a polystyrene float and a microswitch... but that they can be prone to triggering falsely, sometimes if something as small as an insect/woodlouse gets under the float and pushes it up slightly. The error code can't be reset without getting the float to go back down.

Getting at it isn't too easy of course, you have to take the front of the door off in order to get at the panel that covers where it is, and this also means lifting it up so you can remove a trim strip first etc, and then reach right into the bottom of the casing. The machine is quite a tight fit in its recess and in particular I've got to lift the front edge slightly to clear the ceramic floor tiles, in a very narrow gap where it's easy to trap your fingers. Much cursing and swearing ensues and I still can't get the damned thing out. Finally it nips me quite badly, I let go and it falls back behind the step where it started. Grrrr!!

But then I remember that the online tutorial man said that some people have managed to free the float just by tilting the machine back and forth, so - not expecting anything to have changed - I plug the machine in again and power up... and the fault code is gone . The impact of it falling back down must have freed it.

So at least I now know for certain that it was the float sticking that was the problem, I'm going to leave taking the machine out and cleaning under it until next time .

Moral of the story - doing a little research and understanding the likely cause of the fault can make a huge difference to how difficult something can be to fix, even if it hadn't actually done it unintentionally - I at least knew exactly what I was looking for.

I found an simpler way of getting built-under appliances out. I’ve got a nail bar, basically a flat piece of metal with a hooked-up end to lever out old nails. Put the short end under the front edge of the dishwasher/washing machine/whatever and push down...it gives you enough lift to pull it forward over the edge of the flooring. (I did it with a sack truck first but then figured out the nail bar would do the job). Also if you spray the floor with furniture polish in front of the appliance it makes it easier to slide the whole thing forward. 

We had an error code on a dishwasher a while back for pump not draining. I ferreted around in the sump and discovered a small piece of glass had stopped the pump rotor turning. You can usually see the pump rotor at the edge of the sump, it looks like a small plastic gear wheel. 
 

Kittyfrisk

@ICBM ;  Very similar to what I experienced. The dishwasher would either carry on trying to drain even though the bottom was empty or it wouldn’t drain properly.

I rocked it as you did & that worked briefly, then it happened again.

So, I took the back off & took a look inside.

There was a plastic tube hanging down that had some water at the bottom, so I uncorked it to clear it & then tried again. Bingo, worked fine for some months until it happened again. Repeated the draining & this sorted it

Carried on like this for several years until a major failure finally forced a new machine.

Turns out that the pressure switch that controls the filling & draining is pressure actuated. It has the small thin plastic tube attached to the switch. Water collected in the pipe over time, forcing the air up the pipe until it was compressed enough for it to operate the pressure switch. Thus causing the machine to get confused. Clear it & it’s good to go again.

ICBM

boogieman said:

I found an simpler way of getting built-under appliances out. I’ve got a nail bar, basically a flat piece of metal with a hooked-up end to lever out old nails. Put the short end under the front edge of the dishwasher/washing machine/whatever and push down...it gives you enough lift to pull it forward over the edge of the flooring. (I did it with a sack truck first but then figured out the nail bar would do the job).

Can't do that, because the trim strip along the front - which is the bit that has to come off, but can't be done with the machine in place behind the edge of the tiles - is too fragile to lift the machine up with, even if I could tilt it back far enough to get anything on top of the tiles and under the edge of it, which I can't - it's about 1mm less tall than the gap between the tiles and the worktop. It does definitely go through the gap, because I fitted it! But I seem to remember that at the time, I hoped I wasn't going to have to get it out again any time soon...

crunchman

My dishwasher has adjustable feet.  You need to lower it to make room to get it out, and then raise it again when you put it back.  I had to take it apart a few years ago when it wasn't working.  Found a broken bit of crockery obstructing things.

boogieman

ICBM said:

boogieman said:

I found an simpler way of getting built-under appliances out. I’ve got a nail bar, basically a flat piece of metal with a hooked-up end to lever out old nails. Put the short end under the front edge of the dishwasher/washing machine/whatever and push down...it gives you enough lift to pull it forward over the edge of the flooring. (I did it with a sack truck first but then figured out the nail bar would do the job).

Can't do that, because the trim strip along the front - which is the bit that has to come off, but can't be done with the machine in place behind the edge of the tiles - is too fragile to lift the machine up with, even if I could tilt it back far enough to get anything on top of the tiles and under the edge of it, which I can't - it's about 1mm less tall than the gap between the tiles and the worktop. It does definitely go through the gap, because I fitted it! But I seem to remember that at the time, I hoped I wasn't going to have to get it out again any time soon...

Ah ok. We have the opposite problem... a reasonable sized gap between the top of the appliance and the underside of the worktop. Too small to be of any use but big enough to lose stuff in. 

thermionic

Well, after months on my bench and procrastinating about swapping all the old electrolytics in my Cambridge Audio A4, I took the main circuit board out to investigate. Lo and behold, I found a broken solder joint on a capacitor near the speaker outs - the symptoms were a horrible crackling and loud pops on power on.

https://i.imgur.com/q3cEJ3n.jpg

Ten seconds with the Hakko and then the worst part - working out where exactly the 20+ tiny screws went to put it all back together!

https://i.imgur.com/IawXyjz.jpg

Now working fine as part of a small bedroom system. There is still the slight issue of some crackling on the volume knob as I turn it - I suspected a cap leaking dc to the wiper but I couldn’t find one that was connected to the pot. Anyway, that’s always been there and seems unrelated to the more serious issue.

menamestom

After some advice, my grinder is tripping the 16a mcb.
I’ve not used it for ages and come to use it today.

Plug looks okay.  Motor looks okay and measures just less than 5 ohm.  Cable looks okay.  All dry.  Brushes fine.

Now there’s a big juicy capacitor plugged in a slot by the switch, I assume that’s to aid startup.  If it has become faulty, would that mean the motor pulls more current in startup thus tripping the fuse?

2nd question, will the grinder sound better if I replace with orange drop?  

Danny1969

@thermionic ;
Nice work on the amp. If you can measure DC on the pot then it shouldn't be too hard to trace back, looks a well built amp

@menamestom things that use motors often have a start cap to create a field to get it going .... if it is that cap that's gone then disconnecting it and  spinning the wheel then turning it on quickly might well start it. Other caps are used for run and for power factoring. 

menamestom

Danny1969 said:

@menamestom things that use motors often have a start cap to create a field to get it going .... if it is that cap that's gone then disconnecting it and  spinning the wheel then turning it on quickly might well start it. Other caps are used for run and for power factoring. 

Thanks, after reading about it a bit more, I think it is a suppression cap, to limit RF interference from the tool.  It’s across the main switch so if it has failed perhaps causing short circuit.  I’ll try without, If I’m grinding I’m not recording so can live with some electromagnetic pollution!

thermionic

Danny1969 said:

@thermionic ;
Nice work on the amp. If you can measure DC on the pot then it shouldn't be too hard to trace back, looks a well built amp

I did try and trace the wiper but it took me to a pin on the opamp of this smaller board, which is related to one of the outputs (not part of the power amp section):

https://i.imgur.com/nw3KFp3.jpg

I emailed Cambridge Audio but they said they didn’t have the schematics for the A4 but sent me some for an earlier/later version. Apart from trying to work out what had or hadn’t changed between models, I couldn’t find an obvious suspect. This crackle has been there for years although I can’t remember if it was happening from new. Googling suggests it may be related to the phenomenon of the left/right channels being unequal at the very quietest part of the travel (which I’ve read is a desigh choice related to speaker protection somehow.)

Anyway, I’m quite pleased I fixed the main fault.

Danny1969

So been really busy for weeks now, trying to run my Dr Watson business, running my mates shop and fix a whole bunch of stuff for various people. Most of the stuff has been boring but here's a few things that might be useful as reference. 

First up is replacing Macbook Pro battery the easiest was. This is a 2013 model 15", for 2016 models upwards the bottom cover has clips to hold the middle  so they need to be slid and lifted once unscrewed . Changing the battery is much the same though in terms of how it's held in place. 




So ten Pentalobe screws and remove the bottom cover and there's the battery at the front. First job disconnect the battery before you touch anything else. You can recognise the battery connector because it's the only thing in the computer that has a high ampage connector ... on these models it's the big black block connector ... (on touchbar models it's a large copper pad on a fex cable  system).  Then unscrew both speakers each side. There's 3 torx screws in each and they slide out from under the brackets

Then put the straw in the hole on a can of CPC label remover   CPC part no SA01889  .... and spray a small amount down the edge of first pouch on the left. Within 40 seconds it will disable the adhesive and you can lift that pouch and spray a little it down the next one and so on until the whole battery just lifts out with no effort at all. 




Then just rub the leftover non sticky adhesive with you thumb and it will roll right off leaving a clean surface for the new battery. 



Fitting is just the opposite but make sure you have it in the correct position before you press it down otherwise you won't have room to fit the speaker on one side. It needs to be bang on centralised . Then once reassembled reset the SMC using Shift - CTL - Opt  and power on to wipe out settings of old battery otherwise it won't show the correct percentage of the new one. 

Expect to pay around £50 for a quality battery. They normally come with the Penalobe and Torx driver  you need to do the job but check with supplier first. 

Danny1969

Here's a repair of a trusted companion of 20 odd years. I know people are all about the young sexy Hako's these days but I honestly doubt a Hako will get near the duty cycle of this Weller ..... I have had this for 22 years, used virtually ever day for hours at a time and only now has it gone wrong. I know what the fault is, it's failure of the actual mulitcore wire where it bends the most ... near the iron. Even though the Germans designed and built it using the best cable 22 years of constant bending movement have broken one core ... the one that reads the temperature. 



So 3 screws and carefully slide off the body to reveal the design and routing of the wires. 



Then make a note of which colour wire goes where and then chop out a few inches of cable 





Then strip back the good wire to expose the cores, cut to correct length, solder to correct position and my trusted friend is back in the game. Luckily as you can see from my bench pics I have 2 Wellers and luckily so

Danny1969

Well here's familar thing, a Line 6 Relay 10 wireless thing, same as the one this thread started with and surprise surprise the micro USB port is broke. Belongs to same guy as the last one I fixed, one does acoustic the other electric. This time I'm gonna mod it though as I am sick of repairing things with micro USB ports. 

So it needs to run on pedal power. That means 9V neg centre Boss type connector. Internally it needs 5V. So I drill a hole, fit a Boss type power connector. I wire a diode in series with the earth pin (+V on boss adapter) and take that to a 5V linear regulator. As these G10 things have a lump of metal in the bottom to help it stay upright there's a perfect place to screw down a TO-220 package. I use heatshrink to prevent any short of the regulators legs to the metal block and use some thread lock on the screw. 



So a linear regulator has 3 legs, in, common and out. For 5V choose a 7805, for 12V choose a 7812 for example. So for this application power comes in, goes through the diode to protect against reverse polarity and onto the in leg of the regulator which is pin 1. Then the regulated 5V leaves from pin 3 and I've soldered it onto the bulk cap on the top left which is the main supply cap for the unit. The earth or neg wire simply comes in on  pin 2 of the regulator which is the common pin and then leaves and is connected to the other side of the bulk cap. 

Then I spend ages playing guitar running down the battery in the transmitter because I need to measure the charge current when it's charging a flat battery. Linear regulators basically operate like potential deviders and loss is converted to heat. They don't modulate switching duty cycle like a high efficiency regulator so you need to know the power you are drawing at the required voltage drop is within the safe operating margin of the device.  Bolting it's tab to a lump of metal increases it's rated current output without overheating but in this application it's not a problem anyway, the unit doesn't draw much at all. Normally when using these devices to get a good regulated output from a rectified AC supply I would use a couple of 100N caps between in, common and out but as I'm only using it to drop an already regulated DC supply I haven't bothered. 

So back together and looks more or less right I think and more suited to living on a pedal board in a giging situation 

TTony

I made a fix!

Not too hard really, but I'll share it here in case anyone else has a similar worry.

I've been through a LOT of mp3 players through the years.  I've still got my original Gen2 iPod (on perhaps its 5th battery by now), a few newer ones, and then some other makes/models too.  One of my favourites was a FIIO X5 II.  Not hugely expensive, but I just liked the way it worked and sounded.

Maybe 4-5 years ago, it overheated when charging.  The battery expanded and distorted the rear of the case.  I thought that was probably a bad (dangerous) thing, so put it away in a drawer and bought a nice new Sony player instead.

Occasionally I thought about trying to fix it, but I couldn't find any info about battery specs (etc) and no obvious source for a replacement, so I never did anything with it.

I eventually found something that said it'd work on AliExpress, but would take ~3mths to arrive.  It was less than £20 delivered, so I took a punt.

Taking the FIIO apart was iPod standard (gently pry the case apart with something thin, strong and plastic).  Only the FIIO has a couple of tiny-tiny screws too.  Found those before I forced it too far.  Straightened the back out just by clamping it to a workbench overnight.

Battery arrived in <2 weeks rather than the promised ~3mths, apparently from a UK source.  All fitted fine, put the player back together, and it seems to run for around 30hrs now rather than the 10-12hrs life that I remember previously.

Moral of the story ... it's worth a gamble on AliExpress!

Danny1969

@TTony ;

Nice fix, do you recall the supplier of the battery on Ali  ? chances are if they had one for that they probably do a lot of other less common ones too. 

TTony

@Danny1969 ;

Yes, lots of batteries here
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