I've got an old russian sovtek big muff circuit i tried to "modify" and in the process managed to get it to stop working. Does anyone offer a service where they fix stuff incompetent people like me screwed up??
I was originally trying to make it true bypass, run off a 9v adapter, and improve the tone, more distortion/sustain etc. Now all I have is the circuit board and a mess!
whenever you understake a project like that, you should break down each part and test each part as you go... that way you can pinpoint when and where the problem started
I think the problem is a combination of me and general stupidity/over confidence.
I'm sure alot of people here would enjoy doing it for free, but if you cant find any, I could repair it for a small fee.
As you sure you don't want to get it working yourself? I can assure you, you WILL get it working with step-by-step help from people here, and if you've already had some experience (good or bad!) working with the circuit that is a huge advantage.
Then again, I know the feeling of just wanting something fixed and being willing to pay someone else to do it. :(
Mike
I had trouble wiht one of those old Sovtek muffs (it was creased across the from\nt panel like it was hit by an axe, no joke!). THe trouble was, the switch pinout was non-standard! like, what you would expect ot be the "middle" pins were at one end!! didn't expect that!
I'd like to be able to say I could fix it myself but to be honest I'm struggling with the beginner project!
I have hooked everything up on the old muff circuit, I labelled all the wires, hooked them back up the way I thought they should be and now I'm not getting anything, the led doesnt even light up (which is becoming a constant problem for me!).
If its the same one i modded i might be able to take a few pics of mine on the inside if thatll help.. Mine is the black BMP everything inside is russian..It made it tricky when i modded it..Even the transistors were labeled in russian! PITA! But i got it from help from the forum.
Quote from: jimbobIf its the same one i modded i might be able to take a few pics of mine on the inside if thatll help.. Mine is the black BMP everything inside is russian..It made it tricky when i modded it..Even the transistors were labeled in russian! PITA! But i got it from help from the forum.
Yep, mines the black russian one. It's a total pain, when I opened it up there was actually rust inside (and I'd bought it 'new'). I guess quality control wasn't a major issue.
here are a couple of pics if anyone can shed any light on it. Its pretty messy looking.
http://www.geocities.com/eyecandy5296/scan0006.jpg
http://www.geocities.com/eyecandy5296/scan0007.jpg
do the pics shed any light on the problem?
Just lookin it seem's you did a nice job, I see only 1 place on the back side of the board that look's like you may have scrimped on the solder, right hand side, mid board over pin 9 i see a place that you need to make sure the trace is still good, and how hot was your soldering iron when you nailed the transistor's in, I've been soldering for 40 year's and i guess i'm just a Wuss, LOL, I still use socket's for those lil darlin's, and i alway's get fire in the hole, no blowed transistor's from me overheating them,
Maybe 1 of the guy's that have built this will see a wireing mistake, but it still look's good to the eye, keep a truckin, you'll get it.
Johnny
Hey TG,
beautiful pics!!!
i've slightly rotated each jpg.
then clipped an pasted both into one jpg.
that way can compare the traces front/back.
what equipment do U have to test?
can U make 555 generator?
can U make audio prober?
do U have digital voltmeter?
what about a power supply--regulater 9V?
PM me if U want the new jpg.
afn
tone
I see you cut a trace at the bottom left corner of the pcb. I'm not familiar with the Russian BMP layout, what was that for?
Quote from: tonemanHey TG,
beautiful pics!!!
i've slightly rotated each jpg.
then clipped an pasted both into one jpg.
that way can compare the traces front/back.
what equipment do U have to test?
can U make 555 generator?
can U make audio prober?
do U have digital voltmeter?
what about a power supply--regulater 9V?
PM me if U want the new jpg.
afn
tone
I have an audio probe I put together, although Im not that confident using it.
I have a digital multimeter.
I have regulated 9v adapter.
I'm not sure what a 555 generator is sorry.
Quote from: Fret WireI see you cut a trace at the bottom left corner of the pcb. I'm not familiar with the Russian BMP layout, what was that for?
There was a trace running from a 2.2K resistor that connected to the led. I connected the resistor straight to the led wire to save space so I could remove that part of the board (to fit it into a new box). I cut the trace to make sure nothing was going to short. If you look at the pic from the top you might be able to see where the resistor goes.
upon further looking....
looks like there a mess of badlooking solder joints.
lots of pads are gone 2.
in this case, i would label the transistors as to orentation
and part number and remove each and test.
Test for polarity AND operation. write down info.
once U R sure trannys R OK, put them back in
and shoot a signal in.
Straighten out the wires 2 the pots so U can follow them.
The input (stereo) jack turns 9V power on.
The footswitch is a "true bypass" i think. Hard 2 tell.
The 555 is a timer IC that uses minimal parts and
can run on practacally any voltage.
lots of websites have NFO on the 555---do a google.
The 555 is your (cheap&dirty) signal source, since it's a steady,
constant tone out. Adj 2 around 800HZ.
555 usually has only a squarewave out.
If set at a constant freq, U can run it thru a LowPassFilter
and turn it into a fairly decent sine wave.
Sine is the best for troubleshooting.
"Troubleshooting" with text, remotely is difficult.
afn
tone