TS-808 Voltage divider not dividing

Danny G · March 29, 2005, 07:53:21 PM

Gah!

A long time ago I built a GGG TS-808 that never worked coz the voltage divider wouldn't divide the voltage. Never figured it out after many weeks consulting you guys here--had to just rebuild the damn thing from scratch to finally get it to work. And it worked for a few months. I put it away for a few months while I tried other pedals.

Now I'd like to try it out again and it's not working. What's wrong? Voltage divider not dividing! WTF? Is this some flaw in the GGG layout? Why would I have the identical problem on two versions of the same thing, one of which WORKED FINE FOR A FEW MONTHS?!?

At first I realized something was wrong because the gain knob wasn't working. Figured I'd come back to it. When I did, it's completely dead. Checked the voltages and immediately knew what the problem was (8+ on all the IC pins, just like last time).

What could cause the voltage divider to just stop working? Any theories would be much appreciated.

scottosan · March 29, 2005, 09:24:43 PM

Quote from: Danny GGah!

A long time ago I built a GGG TS-808 that never worked coz the voltage divider wouldn't divide the voltage. Never figured it out after many weeks consulting you guys here--had to just rebuild the damn thing from scratch to finally get it to work. And it worked for a few months. I put it away for a few months while I tried other pedals.

Now I'd like to try it out again and it's not working. What's wrong? Voltage divider not dividing! WTF? Is this some flaw in the GGG layout? Why would I have the identical problem on two versions of the same thing, one of which WORKED FINE FOR A FEW MONTHS?!?

At first I realized something was wrong because the gain knob wasn't working. Figured I'd come back to it. When I did, it's completely dead. Checked the voltages and immediately knew what the problem was (8+ on all the IC pins, just like last time).

What could cause the voltage divider to just stop working? Any theories would be much appreciated.

I made a GGG 808 and have had no issues with 25 plus hours of play

george · March 29, 2005, 09:49:07 PM

sounds like there is no connection to ground somewhere in the 2 resistors making up the voltage divider. Either a cold solder joint or (unlikely) one of the resisitors is faulty

Check the continuity with your DMM on resistance setting (you don't need it to be powered up), set one terminal on the positive rail then work your way down the resistors making up the voltage divider.

Also check the sticky at the top of the forum

ninoman123 · March 29, 2005, 09:51:35 PM

Yah its possible that you had a cold solder or a bad one and moving your box around finally broke the connection. Its happened to me, everything works and then one day nothing. Too much stomping breaks connections.

Danny G · March 29, 2005, 10:17:26 PM

What about first the volume (or drive, can't remember now) pot not working, initially indicating something is amiss? Related or no?

mojotron · March 29, 2005, 10:31:34 PM

I must have built at least 20 of those, well with a lot of mods, for others - there is no issue with the schematic or the layout. Now, voltage measurements are going to be wierd if you don't have the input plugged in... So, plug in the input and retake the voltages.... Without a path to the - side of the battery, it could apear that things are not right, when in reality the volt meter (which is a very high resistance for voltage readings) is the only path to the neg side of the battery because the input is not in the jack - at that point all of the voltage is dropped across the meter (being that it is a very high voltage...) and you get a reading that is like 9v when it should be someting like half that.... just a thought...

Also, make sure you have all of the connections for ground and 9V to the opamp - those are just wires laid on the top side of the board...

By the way, I used to live in Houston... Until about a year ago... Man I really miss going to Austin on the weekends..... Do you spend any time at Joe's Generic Bar? I used to see Alan Haynes play there, or Redd Volkert at the Continental Club every chance I could.... Seattle's live music is pretty dead! :cry: :cry: :cry:

Daniel · April 02, 2005, 05:57:02 PM

I've built the ts-808 from tonepad.com but its not working =\ ne1 know what the voltages that i should be reading on the ic? i'm getting like 4.5v on all of them (besides v+ and v-). btw.. i had a problem with the pcb layout.. the ic pins wasnt right for the pcb (i've flipped it horizontally =\ )
so to fix that i've put the ic upside down on the ic socket... now the pins are right.. is that ok?

btw... i'm using 2x 0.22 film caps besides de 0.22 tant ones and the pots arent exactly the right ones =\ but i think i still should get some sound.. shouldn't i?

Daniel · April 02, 2005, 06:18:04 PM

btw... for simply check the circuit (without using a switch) i can just connect the input jack to the input in the board and to the ground and the output jack the board output and ground right? and the battery snap to 9+ and ground.

Danny G · April 05, 2005, 08:38:03 PM

FIXED IT

Turns out lug 1 of the Volume knob was tounching the side of the box. I re-positioned it and VOILA!!! It fired right up.

Damn, these things cause alot of headaches. But when they work, BOO-YAA!!!

ninoman123 · April 06, 2005, 03:33:08 PM

Thats why I use plastic boxes. :wink:

george · April 06, 2005, 11:21:53 PM

Quote from: Danny GFIXED IT

awesome!

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TS-808 Voltage divider not dividing