Boss GT-100 that has choked op-amps. The audio input op-amp is supposed to run on +/-12V. It's receiving upwards of +/-14V. If I put my finger on the pin to soak up a little bit of voltage, the audio starts to crackle through. The snapshot shows the +-14V line coming into the 2 transistors, but I'm high on the output side of them. What could be keeping the transistors from reducing the output voltage down to the required 12V?

I followed this exact schematic directly with these exceptions/options:

I omitted the relay section completely for a normal modern 3PDT bypass (so the following components are unused: LED1, R11, R12, Q1, R13, C8, Rel1)

I used a 1watt 220E resistor and an 8V2 zener diode for the power bit (which I think it calls for)

I used TL071 for the opamp, and 50k linear for the PRESENCE pot

triple quadruple checked everything about it

SYMPTOMS:

overall shrill sound and horrible...

I unearthed this ME5 I bought broken years ago and decided to see if I can get it working again. The person I bought it from said that the tech at BOSS told hm the transformer is bad and a replacement is no longer available. What would be the best way to replace this? The original transformer is flat and I'm having no luck finding a suitable replacement. I'm not against using an external power supply which would likely require an artificial center tap. I'm assuming something like 9VAC, 2A would...

I've been battling this pedal for a little bit and the effect is working, however when I increase the knobs, and put the pcb in darkness, I get this ugly buzzing that I would assume is the LDR's fault. I tried a few different IC's on each one and they all sounded the same so I know it's not that. First time I've tried a build with one in it so I'm not familiar with them, and I don't know what the first thing I should try is. This is the photoresistor I'm using in the circuit . I believe I saw a...

This is an interesting old phaser that i'd like to fix up.
It has a couple of different settings; Pedal On and Off (front toe footswitch) and Wah-controlled sweep or automatic sweep (back heel footswitch).

The problem is that the phase does not activate all the time. This makes the heel footswitch pretty much useless.

BUT about 5-10% of the time that the pedal is activated it works and sounds good.
As a side note, when the pedal is not phasing the sound is quite good a la echoplex preamp -...

Hi all.
I’m looking for some troubleshooting assistance to help me fix an old 1982/3 Stereo Memory Man. It’s the one with the LED, board code is EH7811B.
I bought it as not working and found a few faults immediately (replacement Echo/Chorus switch wired up incorrectly, broken tracks around the Blend pot). After fixing them, all is still not working as it should. I’ll do my best to describe the current state of play.
In Bypass mode:
The effect is not properly switched off. The Blend pot acts...

Trying to repair this old baby.

Power supply is good
Opamps fine.
No oscillations from the 4047, so I replaced it and have a strong oscillator signal at pin 13, but none at pins 10 and 11 which drive the SAD1024 chips.

I pulled all three of the delay chips, but still nothing from 10 and 11, there should be a clock there, right?

Hi Guys,
I aquired a T-REX Reptile pedal, with a problem that i'm now trying to solve.
Basicaly on the output signal we can ear like a click song, that seems to me that is the clock signal.
I opened the pedal and start probing, when i realized that someone was troubleshooting the pedal before me.
In the back side of the board, there's a chip covered with epoxy, that someone tryed to remove the resin, and i suspect that on the process they ripped the little resistor on the right.

Now two...

Anybody have any information or a schematic of the power circuit of this pedal? The negative side is not being created properly. I'm getting .89V being fed into the voltage regulator, when I'm guessing it would be around -24V. I have removed various capacitors to see if I can narrow down the issue. The right side of the inductor is short to ground which I assume is normal. The LM2574 has been replaced. At one point I had R104 removed and the inductor. When plugged in, the voltage was only .89V,...

(Edit) Sorted it now.

But maybe you could help me overcome something else?
In my bio I mention turning a 1960s 3 watt Elizabethan reel-to-reel recorder into a guitar amp by putting it in an Eminence 2x12 amp-less amp. I added on board effects, bass and treble pots, and a master volume using an attenuator between amp and speaker. For five minutes the amp runs fine, then a deep continuous buzz starts. I switch it off and back on again and it's fine for another five minutes before doing it again....

Got this in for repair. Main complaint: The Howling Adjust control doesn't do anything, whether with the fuzz, the wah or both engaged.

Very cool pedal - nice smooth wah, and a really nice octave-fuzz. The tone control blends in the octave very nicely. Even better, the fuzz and wah work really well together. But turning the Howling Adjust control has no effect.

I have uploaded the schematic (it is inside the bottom plate). Clearly a shortened Super-Fuzz like effect. The Howling control is the...

Hey - I have built these before, but it has been awhile. Got it all together and it sounds great, except when the Depth control goes past the 2 o'clock position it starts to thump, getting quite dramatic as the depth increases.

Voltages seem perfect - 9.2v in all the A voltage spots, and 4.6v at all the B voltage spots. Tried different chips, even a TL022 in place of the 062 with no change at all.

Checked for solder bridges and correct parts. Even moved the wires away from the 022 chip....

I bought this PCB years ago, but I don't remember what it was for. Anybody recognize it? I'm guessing it was probably a fuzz circuit? Thanks for looking!

unknown_pcb.jpeg

Hi,
Just got one of these Gibson Maestro W3 boxes. It's working when let on for a half hour /45mins but needs some recapping etc. for any reliability but nice fuzz/octave - ok tremolo.
Works best with a slight boost pedal going in (with guitar) as these were to be used with woodwind mics at hi impedance.
Many Thanks in advance.
Satch

Recently I built an MXR GT-OD.

W20K is recommended for the tone pot, but I didn't have it in stock, so I made it with B25K.
I know that it is used as a replacement for the W20K in many TS pedals, and I also have a few TS pedals made with the B25K.

However, make my GT-OD with B25K, the tone was too dark when the tone pot was set to 12 o'clock.
I looked for other errors, but there were no special problems, so I purchased a W20K and replaced it.

There has been a big change. It gave me a...

I got said pedal in not working condition for a good price.
Signal doesn't go through in standby or on mode. I found the input op amp was not letting the signal through so I exchanged it. But still no sound.
A schematic would be very helpful. I guess since it's all digital any soundblox pro schematic would be sufficient.

Or if someone fixed said issue.

Thanks in advance

Cheers Gregor

Thought I'd pick up one of these to see what it's like.
I was hoping I'd be lucky and it would be a take on the Moen Shaky Jimi/Jimi Nova, which are based on the EasyVibe.
Here's links to the Moen Shaky Jimi and Moen Jimi Nova threads.
And I'd like to thank John Hollis for his lovely EasyVibe circuit. :thumbsup

What's inside then? The highlights:
1 x ST 064C
3 x TI TL062C
4 x LED/LDR pairs

It does indeed look to be generally based on the Moen/EasyVibe circuit although I haven't checked the...

Hi everybody !
I have a Danelectro Cool Cat Vibe with a problem :
it worked great for a few years, but suddently, the speed knob is acting strange : It's like if the speed is now a lot more fast than before. At minimum it's the same speed at, say in the middle when it worked normally, and then goes really fast, so fast that when I reach the middle of the pot travel, the speed is so fast that you can't hear any modulation.

I built a few kits and stripboard, but I consider myself still a newb...

Hi there, I need a little help to check if my test station noise is at a normal level, taking into account the exposed wires - ill leave photos here. The thing is that there is always a little noise just with my guitar going through a switch and the effect send / return wires. Even with the switch bypass theres some noise.

The audio connection is input jack to dpdt toggle switch and then it either goes through the send / return wires or goes to output jack. The ground connections are a wire...

Good morning everyone, I would like to ask for help regarding the chain of effects that I would like to use for my setup.
For obvious reasons, I need to have the Treble Booster on a dedicated line and the rest of the effects on the other.
To do this I built the Passive A B Y box and the micro mixer by General Guitar Gadget.
All good, except for the fact that the sound becomes incredibly trebly.
Initially I had thought of adding a dual buffer to the A B Y box but it would have created problems...

Hi i'm needing some help with this.
I bought an MZ-2 on reverb with the mode knob not working properly.
The MZ-2 is an analog pcb which is the drive circuit sandwiched to a digital pcb which is the chorus/doubler circuit.
The issue being the Mode knob stays in drive mode no matter where i set it. I poked every solder joint with a chopstick and could barely get a whisper of the chorus/doubler signal. I even flowed some solder to the obvious connections to the mode knob and checked the...

Hey Guys, new to the Board, been searching for a few days on how to hook up this Foxrox mod on this Wah Pedal. Foxrox has no info on this pedal. I emailed them but never got a response. The Mod has a Red, Black ( 9v power) and a White ( input) and Blue ( Output).

I have been playing around with it today, I took the Blue wire off the wah Pot, and connected white lead from the mod, to the pot, and connected to the Blue wire back to the blue wire. And connected the power.

Result was Pedal did...

Hi, can anyone share what C16 on the older Keeley Compressor Tantalum value is please. Is it 1uf? I have an older gifted unit with a burned out Tantalum. Also will this pedal run on 12V?

Thanks

Hi, yesterday I've found the R.G. Keen layout, and I gave it a shot. Basically it works: rate and speed knob does works, switch does work, ldr/led does work, I got output signal with vibrato but, the output is completely distorted (like a fuzz, but in a bad unusable way).
I tried a lot of IC (all get from Mouser) but nothing has changed.

I took readings of the ICs and they are numbered from left to right if you have the layout (I think I can't post it here) on hand.
Where there are 2 values...