Hello everyone:
With great effort I ended to build such a complex PCB. After months of personal problems that made me stay away from my soldering bank, today I connected it to a Boss 9V power supply and...... NOTHING. Well, in bypass mode the audio signal goes thru, and with the pedal engaged no sound at all. Already checked posible cold joints, apparently everything is OK. Curiosly the LED does not go on when required. My first attempt to debug the pedal was with an audio probe, and I lose signal in a very early stage (Q1 MPSA 18 to be exact). But I cannot realize whether a failure in the power section or a damaged component. I guess I must upload some pictures, and I still did not have time to check the voltages -in case there is any-. I will appreciate any kind of advice/help. Thanks a lot.
Ariosto
Are you getting any dry signal through the circuit or nothing?
If nothing it's probably the first transistor or opamp that the signal goes through or surrounding component. I don't have the schematic in front of me and I cant remember it off the top of my head
THANKS FOR THE QUICK REPLY!
As before mentioned, the audio signal comes through 100% when the effect is off. When on -and this is somehow striking- the LED does not light. The power supply works OK, and I still did not check the voltages. With the audio probe the signla comes upt to the central pin of Q1. I attached here two pages of the official PDF document.
And the other "relevant" page:
PICTURES
Can anybody say me if the voltafe regulator is soldered in the correct position?
MORE PICTURES:
AND STILL MORE:
That MN3101 looks suspect, I've never seen one with that bold writing on it. Did you purchase it from a reputable source?
Is the LED oriented correctly?
You should still get dry audio signal at the output when the footswitch is in bypass mode. Do you have the "tails" switch wired up?
Regulator looks to be in correctly
I think I have somewhere some other MN3001. I can look for it and replace to see what happens. About the LED, I tried in both positions without results. I soldered both switchs to the PCB, Tomorrow with a freh head I will check the wiring.
Well, I changed the MN 3001 and nothing changed........... Any other ideas out there?
So, are you saying that there's no power? Is it possible to measure voltages?
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HELP! I tried to measure voltages in the ICs and I don´t become any ! What could be wrong? The voltage regulator maybe? Up to the contact of the jack with the PCB I have 9 Volts.
Get any voltage at the regulator?
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Well, I am a noob, but I put the negative (black) tip of the tester to the ground and with the red tip I touched eah of the three tips, and there was no signal at all.
Then the board isn't getting power, that's why the LED won't light.
Figure out why power isn't getting through to the regulator
Which problems are common in such cases? The diode perhaps? How can I follow the elctric signal? Tester or audio probe?
Quote from: danfrank on October 10, 2020, 11:08:09 PM
Then the board isn't getting power, that's why the LED won't light.
Figure out why power isn't getting through to the regulator
Which problems are common in such cases? The diode perhaps? How can I follow the elctric signal? Tester or audio probe?
I´m back. I checked the 9v input from thesocket until Q4 and it was everything OK, then I went to the D1 and D2 and there is no more voltage. Do you think I must replace them?
You mean you're getting voltage on Q5? Q5 is the BS250 transistor, it should be passing voltage. If you're not getting voltage on pin 8 of the LT1054, then your BS250 is probably not working
Quote from: danfrank on October 12, 2020, 04:42:00 PM
You mean you're getting voltage on Q4? Q4 is the BS250 transistor, it should be passing voltage. If you're not getting voltage on pin 8 of the LT1054, then your BS250 is probably not working
Sorry, my mistake. I mean, Q5 and not Q4. Noob question again, must I have voltage in D1 and D2 as well? Because I don´t have any.
See above
Quote from: danfrank on October 12, 2020, 11:40:47 PM
See above
Well, I checked the voltages in Q4 and pin8 of IC 7. Both are 9.12 volt.
Well that's good!
What I would do is pull out IC7 and then check the diodes with your multimeter.
Even with IC7 out of circuit, you should get around 8 volts around pin 1 of the regulator
Quote from: danfrank on October 13, 2020, 12:37:46 PM
Well that's good!
What I would do is pull out IC7 and then check the diodes with your multimeter.
Even with IC7 out of circuit, you should get around 8 volts around pin 1 of the regulator
Well, I pulled off the IC7 as you recommended and the diodes measures 9.15V more or less. But something suspicious happen when I check the voltage in the regulator, because I become again 9 volt IN ALL THREE PINS...... Is that normal?
The center pin of the regulator should be ground... 0 volts. You either have a solder bridge or that regulator is bad
Quote from: danfrank on October 13, 2020, 11:24:52 PM
The center pin of the regulator should be ground... 0 volts. You either have a solder bridge or that regulator is bad
I ´ve already checked and there is any solder bridge. I can only guess that the regulator is bad like you said. I hate desoldering because the risk of damaging the PCB rings is always present. What do you mean? If I make a last test with an audio probe before desoldering could be an option? Is the absence of signal when the pedal is engaged a clear sign that the regulator is the problem?
Well, I received 5 new voltage regulators today and gave them a try, but apparently that´s not the problem because I still don´t have voltage in the PCB......