Strange GGG reverb problems

[El Heisenberg]

« Reply #129 on: Today at 08:08:39 AM »

The thing broke again!
This time it worked fine unless i played any pedal through it. Turn on rangemaster or orange squeezer and it gets loud like a distortion pedal. Turn on the big muff and the thing goes totally quiet! I had problems with static and white noise with it after i fixed it the first time. It would start and id have to jiggle the input cord or turn it off an on again and it would function. But suddenly, again for seemingly no reason it starts acting strange again.

After desoldering the second op amp which, after probing and measuring, i assumed, was again what broke, i put in a tl082 since im outta tl072s. The thing still didnt work. And after desoldering the brick and the ic twice already, thr pcb is destroyed! Its not made like most of GGGs PCBs. After it got bad i got strange readings from the op amp that wasnt affected and from the 5v regulator which measured 7v! It looks like I have to rebuild the circuit on perf board. Desolder the surface mount regulator and use it on perf board. I cant afford another kit.

What the heck is wrong with my unit?!? Please trust me, ive checked connections, wires, resistor and cap values and orientations, solder bridges, and its not a metal box problem. Its plastic.

Only thing is i just measured the voltage from the adapter i used for it, it was putting out 12v instead of 9 like it says! In fact All my adapters that say 9v put out 12 except for the one spot. Which is unusably noisy, even with my commercial pedals.

I need my reverb back! That was all i had and it sounds like crap without an atmosphere! I just spent 4 or more hours trying to fix this! Im not gunna be able to sleep. This is the only DIY pedal i really paid for. I ordered the kit sans enclosure, and its given methe most problems! Strange unseeable voodoo problems! 

[biggy boy]

Sorry to hear of your problems!
When I built mine I used sockets for the IC, in case I had to ever pull them out.
When I was having problems with mine and checked the voltages coming out of the surface mount reg I got odd voltages. But that was because I had no load on it. I had the reverb brick/ module unplugged from the board at the time, I used SIP sockets to connect the reverb brick.

My problem was from running the 9 volt batteries down, now I know I need to replace my batteries more often.

I'm not sure what you can do at this point with your board.
I really like my GGG pedal and enjoy using it.

[R O Tiree]

The problem with the adaptor is probably because it is un-regulated and you're drawing less current for the pedal than the PSU was designed to supply, so the voltage goes up a bit. Get a decent, regulated adaptor and it will put out a reliable, smooth 9VDC for you.

[El Heisenberg]

Well one things for sure, if i ever get this thin going again ill never use an adapter

but this reverb eats batteries faster than anything i have

[El Heisenberg]

Actually it just doesnt work with around 8v. Needs
more than 8 or it just squeels.

Could i have damaged op amps by using a bad adapter?

[Paul Marossy]

Actually it just doesnt work with around 8v. Needs
more than 8 or it just squeels.

Could i have damaged op amps by using a bad adapter?

Not a "bad adapter", but possibly by using one that is supplying too high of an operating voltage. In other words, unless it's a regulated 9V power supply, it might be putting out 12, 18 maybe even 20 volts depending on what the current rating is on it.

For example, if you use an unregulated 9V power supply that can supply say 1500mV (1.5 amps) and your only load on it is 100mA (1/10 of an amp), then it will be supplying far more than 9V - maybe 24V or more. That can fry your opamps. Your reverb module is protected by the 5V voltage regulator, although that also (the voltage regulator) could get fried by giving it too high of a supply voltage.

That's why when I built mine, I used an LM317 adjustable voltage regulator set to 9.5 volts at the power supply input, which is what a new 9V battery will typically measure. It's protected from any overvoltage condition caused by using an unregulated wall wart (or small power transformer in my case) and I don't have to rely on batteries. Batteries are expensive and end up in landfills. I wouldn't think of using the GGG reverb pedal without a wall wart.

[Paul Marossy]

Here is a page on the LM317: http://www.national.com/mpf/LM/LM317.html

It's very, very easy to use one of these. I omit C1 & C2 because they are not required in my typical scenario. I use the "thru-hole" kind (TO-220), not the surface mount ones. You can get them at RadioShack.

You need a multi-meter in order to set the output voltage, or to make any measurements on voltages. Hopefully you have one...

[El Heisenberg]

I have a buncha rechargable batteries. But id still prefer wall wart too.

I tried breadboarding the circuit. Had to put the 5v surface mount regulator on a little peice of perf board. I couldnt get the circuit to work right. There was no reverb and it added gain. Pin voltages were outta wack. Couldnt get 4.5 from the voltage dividing portion when it was connected to the circuit. It read like 1.5v.

Then i tried to measure the V from the regulator and there was none. I touched it and it was hot. I think i fried it.

Is there a replacement i could use?? I hope i havent damaged the reverb brick!!

And paul, did you build yours into an amp or something? You used the LM317 for the main supply and used the same 5v regulator, eh?

[Paul Marossy]

And paul, did you build yours into an amp or something? You used the LM317 for the main supply and used the same 5v regulator, eh?

Yep, mine is "built into" an amp. I am using the same little power transformer that powers the DC cooling fan that I added to it. I used an LM317 to regulate the voltage supplied to the whole circuit. The 5V regulator on the PCB supplies a steady 5V to the reverb brick and also serves to protect it from any overvoltage (it sounds like that Belton reverb brick is designed around a 5V power supply).

[El Heisenberg]

Eeh. The 5v regulator works fine.

On the breadboard, the digital reverb doesnt work. And there is distortion. Is there a way to test my brick? I cant figure out what else could be wrong. I shoulda just bought a reverb pedal or got the other reverb kit.

[Paul Marossy]

Eeh. The 5v regulator works fine.

On the breadboard, the digital reverb doesnt work. And there is distortion. Is there a way to test my brick? I cant figure out what else could be wrong. I shoulda just bought a reverb pedal or got the other reverb kit.

If you have soldered/desoldered the reverb brick a lot, you might have damaged it due to it being exposed to excessive heat for too long.