SOLVED Madbean total recall

[Phil hodson]

Morning all.

It pains me to post this here as I took my time on this one as I knew it’s a complex built. I was hoping to beat @MichaelW to a build report but we both hit problems at the same time. He got a new board and got it working. I’m persevering with mine thought as I want to know what I have done or not done!

So before I loose my patience and or my mind and start ripping things off the board I thought I would ask around on here. I know there are some very accomplished builders and some total recall experts here!

Firstly I have checked values. Cleaned the board. And started an audio probe.

Going from the main audio schematic it’s all good. I get a squeal on pin 3 of IC3 not sure if that’s an issue.

Audio stopped at C14 so I replaced that and it’s fine now. All the way to D in. After that nothing.

I her audio on pin 3 and 4 of IC6 but no delay at all.

Looking at my voltages everything looks good apart from IC4. I get nothing at all ok the right hand side.

I also get no voltage at pin 7 of IC7. Could this be related to the issue at IC4?

My thoughts is a bridge or issue in the socket for IC4. Before I take it off does this sound like it might be the issue?

Any thoughts and suggestions very very very welcome!

See attached pics. Can take more as required.

Phil

 

[Phil hodson]

Ok

So I put a new R57 in measured at 238.3 ohms so close enough!

With NO voltage reg in place (I removed the old one earlier!)

I get -31.45 at the input jack.
I get -31.45 at both sides of R57 (and no heat)
I get -30.02 at voltage reg pin in (middle one)
I get 0V at the reg output (top one)
I get -30.0 at D1
I get -30.04 at negative side of C42
I get -30.03 at C43

On the three points you marked R60, R45 and Bias 2 leg 3 I get 0V.

These are all with no voltage reg in place.

 

[Guardians of the analog]

could the trimmer be bad?

 

[Phil hodson]

could the trimmer be bad?

Could be. I have others so no big issue to change it.

 

[music6000]

Ok

So I put a new R57 in measured at 238.3 ohms so close enough!

With NO voltage reg in place (I removed the old one earlier!)

I get -31.45 at the input jack.
I get -31.45 at both sides of R57 (and no heat)
I get -30.02 at voltage reg pin in (middle one)
I get 0V at the reg output (top one)
I get -30.0 at D1
I get -30.04 at negative side of C42
I get -30.03 at C43

On the three points you marked R60, R45 and Bias 2 leg 3 I get 0V.

These are all with no voltage reg in place.

1. Important, Are you getting Continuity at the top Regulator OUT pin itself & coloured Circle on top of R60???
2. Replace Regulator & confirm Voltages on the R60, R45 & Bias 2 Leg 3 Circles.

 

[Phil hodson]

Before I go on, I just want to say a massive thanks to you all. You are all being so helpful!

@music6000

1) Yes I have continuity between reg out and R60

I replaced the voltage reg.

I now have -29.6V at DC jack.

2) Into Voltage reg 28.3V
Out of voltage reg -15.3V
R60 -15.3V
R45 -15.3V
Bias 2 leg 3 -14.32V

R57 not hot to the touch!

 

[music6000]

Before I go on, I just want to say a massive thanks to you all. You are all being so helpful!

@music6000

1) Yes I have continuity between reg out and R60

I replaced the voltage reg.

I now have -29.6V at DC jack.

2) Into Voltage reg 28.3V
Out of voltage reg -15.3V
R60 -15.3V
R45 -15.3V
Bias 2 leg 3 -14.32V

R57 not hot to the touch!

Great!, Adjust Bias 2 & see if you can get 7.5v at IC4 PIN 5
If that Works?
Then check Voltages at IC4 Pin 6 & 7
Then Check IC7 Pin 7

I have to Go to Sleep now, It's 12:45am, if you have an issue It might be the BIAS 2 trimmer?

 

[Phil hodson]

Thanks @music6000 for your help so far!

I could adjust bias 2 to get 7.5 V on pin 5 IC4

I got no voltage at all on IC4 pin 6 and 7 though.

I changed the 100K bias 2 trim pot. New one measuring around 98K.

Still the same voltages.

IC4
1 0
2 0
3 -7.6
4 - 15.3
5 - 7.5
6 0
7 0
8 0

I had no chips in at all though. Let me know if I need to put them back in and take them again.

 

[Phil hodson]

Right then!! Think we are getting somewhere.
I replaced all the chips and took readings again.
And now I have voltages on the right hand side of IC4!! Finally.

They are all close enough to the voltages on the build doc.

Unfortunately life has got in the way and I can’t bloody test it right now. Hopefully I can tonight. If not will have to wait until tomorrow.

So I changed the R57, voltage reg
And the bias 2 trimmer. Hopefully one or all of those would have made the difference.

I will keep you all posted and to when I can do my audio tests.

Thanks again for all your help so far.

 

[Fuzzonaut]

What a cliffhanger ....

Good luck! I'll see myself out ...

 

[Phil hodson]

Haha I known tell me about it.
I was in the situation where I just about had time to either check the voltages or run some audio through it.
My sensible head said check the voltages incase I f@&k something else up. I don’t want to continue trouble shooting this one anymore. Now matter how much I wanted to play through it!!
Should get on with it soon!!!

 

[Fuzzonaut]

Don't give up, you'll get there! We all want a happy end.

I'm usually no help in trouble shouting threads, but I like to read them for educational purposes. And I admire people like @music6000 for their knowledge and especially for the effort they put into helping others out.

 

[Phil hodson]

Well there you go!!! I finally got round to testing it and calibrating it this morning and al I can say is IT WORKS!! finally.

Firstly I would not have ever got his far in both building this and trouble shooting it with out help from the forum. Shouts out to..
@Guardians of the analog, @music6000, @jimilee, @MichaelW and everyone else who contributed. I massive thanks to you all.

I never thought I would make a 4 page trouble shooting page but I did! not sure if thats a record, or if it is, im not sure its one I want ;-) But at least in the end I get to mark it Solved. I still have a couple of other boards to trouble shoot and this has helped a lot with my learning so I feel more confident going into those too.

I think we can put this down to a faulty Voltage regulator. Not sure how or why it was faulty but the hot R57 lead towards this. I changed the reg and R57 just in case and also the Bias 2 trimmer as that might have been an issue too.

Now its singing loud and proud. Some amazing tones and noises coming out of it just like everyone has mentioned before me.

This has been a great win for me and Im so happy. Build report to follow once I stop playing through it.

Thanks again to everyone who helped. I could not have done it with out you!

Phil

 

[MichaelW]

Well there you go!!! I finally got round to testing it and calibrating it this morning and al I can say is IT WORKS!! finally.

Firstly I would not have ever got his far in both building this and trouble shooting it with out help from the forum. Shouts out to..
@Guardians of the analog, @music6000, @jimilee, @MichaelW and everyone else who contributed. I massive thanks to you all.

I never thought I would make a 4 page trouble shooting page but I did! not sure if thats a record, or if it is, im not sure its one I want ;-) But at least in the end I get to mark it Solved. I still have a couple of other boards to trouble shoot and this has helped a lot with my learning so I feel more confident going into those too.

I think we can put this down to a faulty Voltage regulator. Not sure how or why it was faulty but the hot R57 lead towards this. I changed the reg and R57 just in case and also the Bias 2 trimmer as that might have been an issue too.

Now its singing loud and proud. Some amazing tones and noises coming out of it just like everyone has mentioned before me.

This has been a great win for me and Im so happy. Build report to follow once I stop playing through it.

Thanks again to everyone who helped. I could not have done it with out you!

Phil

AWESOME that you got it working! Way to hang in there and persist! You're a better man than me......

 

[music6000]

Well there you go!!! I finally got round to testing it and calibrating it this morning and al I can say is IT WORKS!! finally.

Firstly I would not have ever got his far in both building this and trouble shooting it with out help from the forum. Shouts out to..
@Guardians of the analog, @music6000, @jimilee, @MichaelW and everyone else who contributed. I massive thanks to you all.

I never thought I would make a 4 page trouble shooting page but I did! not sure if thats a record, or if it is, im not sure its one I want ;-) But at least in the end I get to mark it Solved. I still have a couple of other boards to trouble shoot and this has helped a lot with my learning so I feel more confident going into those too.

I think we can put this down to a faulty Voltage regulator. Not sure how or why it was faulty but the hot R57 lead towards this. I changed the reg and R57 just in case and also the Bias 2 trimmer as that might have been an issue too.

Now its singing loud and proud. Some amazing tones and noises coming out of it just like everyone has mentioned before me.

This has been a great win for me and Im so happy. Build report to follow once I stop playing through it.

Thanks again to everyone who helped. I could not have done it with out you!

Phil

Celebration Time!!!!

 

[jimilee]

Celebration Time!!!!

View attachment 44120

I’m super happy you got it going. I had a bitch of a time the first one I built, too.

 

[Harry Klippton]

Good job @Phil hodson I was hoping you'd get this sorted. And it's nothing close to that cobalt troubleshooting thread from last year

 

[ICTRock]

Good job @Phil hodson I was hoping you'd get this sorted. And it's nothing close to that cobalt troubleshooting thread from last year

there was a pcbguitarmania one where I showed up like 7 pages in, pointed out that even if they get the pedal working the design was flawed, then left ... I think about that one often

 

[Harry Klippton]

there was a pcbguitarmania one where I showed up like 7 pages in, pointed out that even if they get the pedal working the design was flawed, then left ... I think about that one often

Was that the rockerverb preamp one? I think that's where I first found out that pcbguitarmania was not to be trusted

 

[ICTRock]

Was that the rockerverb preamp one? I think that's where I first found out that pcbguitarmania was not to be trusted

I think so. it was some sort of attempt at an amp in a box using jfets where they went from TMB tone stack to volume control to out with nothing in there to address signal loss, DC blocking/coupling, or output impedance.

 

[JamieJ]

I still have a couple of other boards to trouble shoot and this has helped a lot with my learning so I feel more confident going into those too.

Fantastic that you got it working @Phil hodson. Well done for persevering.

Your statement above is what it’s all about! So many people just want answers and quick fixes when it comes to trouble shooting but the best way is to learn and progress as you go.

That’s why I love reading troubleshooting posts so that you can build experience of the common faults that happen.