The community repair thread

thermionic

I built a Fuzzdog Big Muff variant and it didn’t work; the blend control seemed to be working but I wasn’t getting a fuzz sound out of it all. I checked any solder joints I could, but the rear-mounted pots makes access to most very difficult. I was stumped for a good few days. Late last night I stumbled across a YouTube video where someone had constructed an audio probe to fault-find broken pedals - great idea!

https://i.imgur.com/M15DSIO.jpeg

I sacrificied a crappy guitar cable and a couple of test leads - a probe soldered to the signal wire and a croc clip soldeed to the shield. Plug a convenient audio source (I used an FM radio) into the pedal input and plug the audio probe into an amplifier (my toy AC30). The croc clip goes to a convenient ground and then you can probe various points in the circuit, monitoring the sound through the amp. In this case I found the signal was fine going into the first transistor stage but it was very weak going into the second stage. I checked a few component values, probed voltages at a few points… sure enough, I found a bad solder joint at the input to the second transistor stage and now it works.

 I’m so glad I fixed it - I worked in the microelectronics industry for ten years and although most of that was simulating silicon layouts on computers, a Fluke multimeter and a Weller iron were never far away. I though I’d lost my electronics mojo after changing career! Great to do some proper engineering.

BillDL

Nothing worse than loosing your mojo 

SteveRobinson

I lost the clasp from the back of a pin so replaced it with what I hope will be more secure.

I took a piece of aluminium bar, drilled through using a 1mm drill then at rightangles with a 2.5mm drill and tapped M3. Inserted a grub screw and voila.



I'll remove the Allen key before wearing.

BillDL

You had me totally baffled there before I scrolled down below the photo and saw your Allen key sentence.  I imagined you walking around wearing a flag pin on your lapel that had a long Allen key poking out to one side.

Danny1969

thermionic said:

I built a Fuzzdog Big Muff variant and it didn’t work; the blend control seemed to be working but I wasn’t getting a fuzz sound out of it all. I checked any solder joints I could, but the rear-mounted pots makes access to most very difficult. I was stumped for a good few days. Late last night I stumbled across a YouTube video where someone had constructed an audio probe to fault-find broken pedals - great idea!

https://i.imgur.com/M15DSIO.jpeg

I sacrificied a crappy guitar cable and a couple of test leads - a probe soldered to the signal wire and a croc clip soldeed to the shield. Plug a convenient audio source (I used an FM radio) into the pedal input and plug the audio probe into an amplifier (my toy AC30). The croc clip goes to a convenient ground and then you can probe various points in the circuit, monitoring the sound through the amp. In this case I found the signal was fine going into the first transistor stage but it was very weak going into the second stage. I checked a few component values, probed voltages at a few points… sure enough, I found a bad solder joint at the input to the second transistor stage and now it works.

 I’m so glad I fixed it - I worked in the microelectronics industry for ten years and although most of that was simulating silicon layouts on computers, a Fluke multimeter and a Weller iron were never far away. I though I’d lost my electronics mojo after changing career! Great to do some proper engineering.

thermionic said:

I built a Fuzzdog Big Muff variant and it didn’t work; the blend control seemed to be working but I wasn’t getting a fuzz sound out of it all. I checked any solder joints I could, but the rear-mounted pots makes access to most very difficult. I was stumped for a good few days. Late last night I stumbled across a YouTube video where someone had constructed an audio probe to fault-find broken pedals - great idea!

https://i.imgur.com/M15DSIO.jpeg

I sacrificied a crappy guitar cable and a couple of test leads - a probe soldered to the signal wire and a croc clip soldeed to the shield. Plug a convenient audio source (I used an FM radio) into the pedal input and plug the audio probe into an amplifier (my toy AC30). The croc clip goes to a convenient ground and then you can probe various points in the circuit, monitoring the sound through the amp. In this case I found the signal was fine going into the first transistor stage but it was very weak going into the second stage. I checked a few component values, probed voltages at a few points… sure enough, I found a bad solder joint at the input to the second transistor stage and now it works.

 I’m so glad I fixed it - I worked in the microelectronics industry for ten years and although most of that was simulating silicon layouts on computers, a Fluke multimeter and a Weller iron were never far away. I though I’d lost my electronics mojo after changing career! Great to do some proper engineering.

An audio probe is a handy tool. This is one I built, the large box just contains a high voltage non polarised capacitor which blocks the DC from getting to the output. As this is used to test valve amp stages amongst other things it has a 600V cap. It also has pad to pad down the level if necessary. 

I would use a cap to block DC even on probes only used for low voltage stuff feeding into an amp or little mixer etc as some opamps will latch up if the input signal is higher than it's supply rail and there's always a chance you could reverse bias something as well. 

thermionic

Interesting idea about the dc blocking cap. In my case it didn’t matter much because I probing capacitor coupled single transistor stages, but I build a better one the next time I get round to building a valve amp…

roundthebend

OMG I did a repair. My gravel/commuter bike has mechanical disc brakes. The rear was getting stuck on a while back then I stopped using it. Put some air in the tyres at the weekend and then discovered that it's completely seized. Wouldn't pull at all. 

The caliper would move freely by hand so I deduced that the cable was rusty inside the housing, right at the lowest point where moisture would gather. You could actually feel it. 

So I ordered a Shimano kit and watched some Park Tools tutorials. They make it look easy. I've never even swapped bar tape on a bike, so I had to learn to do that too - well, unravel enough to get the old cable out from underneath. 

First hitch - with the cable seized I couldn't fish it back out of the lever cos it wouldn't slack off. So I had to cut it above the rusty section. Didn't want to because i wanted the old housing to measure against. But.... that worked.

I measured up the new housing against the pieces of old housing. Then chopped that with my cutters.

The new cable has an MTB lug on one end, and a road lug on the other. I snipped off the MTB one.

Second hitch - my cable cutters are a bit naff so they caused a slight fray to the cable. Pushing it through the new housing room me a frustrating few minutes. It also got stuck at the chopped end of the housing because it had slightly crimped. A tiny crosshead screwdriver fixed that. 

Threaded all the bits together and temporarily secured the cable in the caliper. Tested it and all seemed good. Taped the gear and brake cables onto the bars then re-wound the bar tape and fixed that. Very neat considering my usual amateur efforts.

Then finished it all off with some fresh cable ties to secure the housing on the down tube, bottom bracket and chain stay. Everything still working so tightened up the clamp on the cable and tested it. 

Bingo. Lots of words. No pictures. Just a proud DIYer. I also learned to adjust disc brakes so they work nicely and don't rub when moving.

roundthebend

Slight lie. It's not a finished job. I've yet to snip the cable and crimp the end ferrule on.

drofluf

Well done @roundthebend changing bike cables is one of my least favourite jobs. A couple of tips for next time if I may?

Invest in some decent cutters to avoid the wire fraying. 

Cut the outer with some of the excess cable in it, that way it won’t get crushed and if the cable does fry you won’t have to push a frayed cable all the way through the outer. Bit trick to measure but once you’ve worked it out it makes the job easier. 

Danny1969

Nice job @roundthebend ; ... I leave my bike outside all year, nothing can rust on it due to materials used except the bloody brake cables. So I'm having to do a bit of this myself. Turning the bike over and letting oil run down the cables tends to free my off. 

Danny1969

Another keyboard job .. Don't get many so I thought I would post this repair. I suppose this is a vintage synth now, a Korg M1



The owner brought it at a decent price but there's no sounds in it. Scrolling through the patch list I can see all the preset names have gone, must be memory battery gone. This is a pain because just replacing the battery won't achieve much, the original presets will need to be found and dumped in again via MIDI  SysEx

Bottom off. I love working on old stuff like this. It reminds me of teaching myself electronics in the eighties when all components were massive and easy to identify. 



I found the memory battery, a standard 2032 on the main PCB so that's one job done 



Now comes what I thought would be the tricky bit but I found the original presets on Korgs site straight away here 

https://www.korg.com/us/support/download/software/1/139/3374/

Now I need to find some software and something with a normal Midi DIN connector and cable, as an old synth like this has no USB for a virtual midi connection.  Firstly the software, everyone else seems to like Midi-ox so fine let's go with that. Only drawback is it's Windows only, so I prod my only remaining Windows machine in the house awake and download it from here 

http://www.midiox.com/

I find my old USB to Midi DIN box that I used to use in the noughties and connect it to Windows. Don't know what that is says Windows, best disable it !  ... brilliant, so Win 10 doesn't recognize something 98 and 7 had no problem recognising. I try to manually  ram a generic driver up it's arse via the add new hardware routine but it's adamant,  so I come up with another plan.  

I dig out some old audio interfaces .. a MOTU from the late 90's .. that's got MIDI but it's firewire and the PC has no firewire. Then I look at an old Mbox Pro ... that has USB so I plug that it. Unsurprisingly Windows again is a little uncooperative .. Nah, don't know what that is . FFS .. I track down a modded driver on someones google drive and manually install it. Now Windows can see the Mbox and it's midi ports. 

So then you basically extract the presets from Korg to a folder. Then start the Midi-0X software and look at the options menu. Make sure it can see the midi ports. Select the port you are going to be using. Before you try sending make sure the keyboard is ok to recieve .. go to global and make sure the writes are enabled and it's set to receive on Ch1 as that tends to be a default. 

Then load the sys.ex file into the Midi-OX software and send it. Just when it looked like it was getting to the end it crapped out. I try again and it does the same thing with an error about buffers. I fuck about in the settings increasing the amount of buffers. Still craps out. I find another page with some guff about "delay if necessary"  I figure a keyboard this old probably does need this info sent a little slower so I check that. Then the file goes over ok. Nothing appears to tell me all is well so after a while I turn the M1 off, turn it on again and all the presets are now there. Hooray !

That should have been it but plugging in headphones for a trip down 80's memory lane reveals another problem. The headphones keep cutting in and out on one side. The customer never mentioned that but I guess he wouldn't have known really,  being the keyboard was lobotomised by the dead memory battery. Not one to leave it there at this stage I put the thing back on the operating table (dinner table) 

I knew what the fault would be. All 80's / early nineties use these crap jack sockets that have little to no support to stop them moving. So unsurprisingly the solder joints crack. Sure enough that's exactly what I find on the headphone socket 




And that was that. All back working again. I have to say it's impressive how long stuff like this is capable of lasting and how easy it is to repair when it does go wrong. The sounds haven't really dated either. Sure the piano sounds aren't like the  modern multi sampled pristine patches but they are still solid and the strings and pads are awesome. So I had a happy half hour testing it. 

Chris.B

@Danny1969 that's a first class repair and a good save from landfill for the old keyboard.

I had no idea you could "force-feed" midi data to reinstall presets, something useful to remember. 

It's surprising how long those CR2032 batteries can last, the one in my PC recently failed after 14 years. 

TTony

Danny1969 said:

And that was that. All back working again. I have to say it's impressive how long stuff like this is capable of lasting and how easy it is to repair when it does go wrong.

As long as you manage to find other old tech to be able to communicate with it!

The old tech is fine - it’s the new tech that turns old tech into landfill

normula1

Bome Send SX is good for MIDI dumps too. Not all interfaces are good with Sysex. I got lucky with the cheap and cheerful class compliant one from the evil penis rocket tat purveyor, but M-Audio Midisport 2 is the one I use most.

roundthebend

Danny1969 said:

Another keyboard job .. Don't get many so I thought I would post this repair. I suppose this is a vintage synth now, a Korg M1



The owner brought it at a decent price but there's no sounds in it. Scrolling through the patch list I can see all the preset names have gone, must be memory battery gone. This is a pain because just replacing the battery won't achieve much, the original presets will need to be found and dumped in again via MIDI  SysEx

Bottom off. I love working on old stuff like this. It reminds me of teaching myself electronics in the eighties when all components were massive and easy to identify. 



I found the memory battery, a standard 2032 on the main PCB so that's one job done 



Now comes what I thought would be the tricky bit but I found the original presets on Korgs site straight away here 

https://www.korg.com/us/support/download/software/1/139/3374/

Now I need to find some software and something with a normal Midi DIN connector and cable, as an old synth like this has no USB for a virtual midi connection.  Firstly the software, everyone else seems to like Midi-ox so fine let's go with that. Only drawback is it's Windows only, so I prod my only remaining Windows machine in the house awake and download it from here 

http://www.midiox.com/

I find my old USB to Midi DIN box that I used to use in the noughties and connect it to Windows. Don't know what that is says Windows, best disable it !  ... brilliant, so Win 10 doesn't recognize something 98 and 7 had no problem recognising. I try to manually  ram a generic driver up it's arse via the add new hardware routine but it's adamant,  so I come up with another plan.  

I dig out some old audio interfaces .. a MOTU from the late 90's .. that's got MIDI but it's firewire and the PC has no firewire. Then I look at an old Mbox Pro ... that has USB so I plug that it. Unsurprisingly Windows again is a little uncooperative .. Nah, don't know what that is . FFS .. I track down a modded driver on someones google drive and manually install it. Now Windows can see the Mbox and it's midi ports. 

So then you basically extract the presets from Korg to a folder. Then start the Midi-0X software and look at the options menu. Make sure it can see the midi ports. Select the port you are going to be using. Before you try sending make sure the keyboard is ok to recieve .. go to global and make sure the writes are enabled and it's set to receive on Ch1 as that tends to be a default. 

Then load the sys.ex file into the Midi-OX software and send it. Just when it looked like it was getting to the end it crapped out. I try again and it does the same thing with an error about buffers. I fuck about in the settings increasing the amount of buffers. Still craps out. I find another page with some guff about "delay if necessary"  I figure a keyboard this old probably does need this info sent a little slower so I check that. Then the file goes over ok. Nothing appears to tell me all is well so after a while I turn the M1 off, turn it on again and all the presets are now there. Hooray !

That should have been it but plugging in headphones for a trip down 80's memory lane reveals another problem. The headphones keep cutting in and out on one side. The customer never mentioned that but I guess he wouldn't have known really,  being the keyboard was lobotomised by the dead memory battery. Not one to leave it there at this stage I put the thing back on the operating table (dinner table) 

I knew what the fault would be. All 80's / early nineties use these crap jack sockets that have little to no support to stop them moving. So unsurprisingly the solder joints crack. Sure enough that's exactly what I find on the headphone socket 




And that was that. All back working again. I have to say it's impressive how long stuff like this is capable of lasting and how easy it is to repair when it does go wrong. The sounds haven't really dated either. Sure the piano sounds aren't like the  modern multi sampled pristine patches but they are still solid and the strings and pads are awesome. So I had a happy half hour testing it. 

@Danny1969 this makes my brake cable replacement look very Mickey Mouse. Great work.

I know we all have a level, but I find it very inspiring to read the stuff that people get up to. My bike repairs actually took a confidence boost at the weekend when I asked a mate to re-seat the tubeless tyres on my bike. He did it while I waited and it was a joy to watch for so many reasons - the tools used, the tips and tricks, the mindset and process, the fallback options, the mistakes which the novice often assumes don't happen (imposter syndrome).

I'm not ready to fix PCB mounted micro electronics yet but I'm going to have a go at putting a kit guitar together which has been gathering dust for 5 years.

roundthebend

drofluf said:

Well done @roundthebend changing bike cables is one of my least favourite jobs. A couple of tips for next time if I may?

Invest in some decent cutters to avoid the wire fraying. 

Cut the outer with some of the excess cable in it, that way it won’t get crushed and if the cable does fry you won’t have to push a frayed cable all the way through the outer. Bit trick to measure but once you’ve worked it out it makes the job easier. 

That's a great tip @drofluf ;
about using a piece of excess cable when snipping the housing. Only works if you have a piece long enough to reach the snipping location. I suppose I could have pulled some of the new cable back through and make sure I've measured enough excess for the lever and caliper ends. Risky!

drofluf

Usually the cables and outers are way too long but it's also easy to get wrong....

ElectricXII

@Danny1969 That's great work on the synth. My sister-in-law's husband specialises in resurrecting old synths, and he makes and sells loads of useful MIDI devices too, as well as creating his own synth wave music. Here's his website:

https://www.mindburner.co.uk/

Emp_Fab

My new shed's floor is nice and stable all around the edges but due to the slightly uneven concrete base it's on, the middle dips about an inch. Trying to push spacers under the middle bearers from the outside of the shed is close to impossible - so I decided one of the planks had to come up inside so I could gain access that way. However, the planks are nail-gunned to the bearers and the flat heads are just below the surface, so trying to pull the nails out with a claw-hammer is out too. Trying to pull the plank up by getting something down the side of it and yanking upwards is guaranteed to split the wood. 

So.... I originally was going to try drilling the nails out - or at least take the heads off then try pulling the plank upwards, but then I had an idea....

I bought a cheap set of plug cutters for cutting out plugs of wood to hide screws under....



I used the second-smallest one to cut around the nails and picked out the bits of wood around them.  I was then left with a plank with 8 nails that had no wood around them.  I lifted the plank and sorted out the gaps under the bearers with plastic spacers, so the floor is rock-solid all over now. 

I then used the next size up cutter to make 8 plugs from some treated wood I have and glued them into the holes in the plank. 

When that's all dry tomorrow, I'll trim the excess off the plugs and refit the plank.  Then I'm going to drill small pilot holes into the plugs and countersink them, then screw the plank back down so I can easily remove it in future if needed.

Danny1969

ElectricXII said:

@Danny1969 That's great work on the synth. My sister-in-law's husband specialises in resurrecting old synths, and he makes and sells loads of useful MIDI devices too, as well as creating his own synth wave music. Here's his website:

https://www.mindburner.co.uk/

Nice site, he's my kinda bloke