Tonepad Ross compressor debug

Plinky · July 29, 2007, 06:49:50 PM

QuoteYou bought FIVE?! Just pop a fresh one in there then!... what are you waiting for?

Just tried all I had (4) - no change in voltage.

This reminds me of some cars I've worked on. After throwing about 3 parts at it, chances are that won't fix it.

I'm off to see Andy Timmons at the Granada tonight. If I can get my camera to agree with me, I'll take some pics front and back of the pcb and wiring.

oskar · July 29, 2007, 07:12:58 PM

I have no more ideas for the moment...

I dropped a message to effectsconnection to see if someone else had complained...

Plinky · July 30, 2007, 04:05:50 PM

Alright. Got some fresh batteries in my camera, although I wish that would help me take a better picture (photography is my brother-in-law's dept.).

Disregard the yellow lead (it broke from the switch while taking these pictures

)

This is the first Tonepad layout I've used, so let me know if something appears wrong with the offboard wiring.
On a side note, the LED isn't working. I looked at the circuit and it appears to be wired correct but I haven't checked the LED yet.

oskar · July 30, 2007, 04:13:33 PM

You did have a cable in the input jack when you probed the pcb did you? DID YOU?

It is easy to forget and would make the 3080 appear to be ungrounded...

oskar

Plinky · July 30, 2007, 04:14:41 PM

Quote from: oskar on July 30, 2007, 04:13:33 PM
You did have a cable in the input jack when you probed the pcb did you? DID YOU?
It is easy to forget and would make the 3080 appear to be ungrounded...

oskar

Yup, I did. Made it real fun to keep the pcb from falling off the bench.

oskar · July 30, 2007, 04:25:31 PM

It isn't really a closeup... but this looks like a bad solderjoint.

oskar · July 30, 2007, 04:27:46 PM

Maybe you should call Ross customer service?!

Plinky · July 30, 2007, 04:29:05 PM

Yeah, I noticed that after I took the pic. I sucked all the solder out to make sure there was nothing shorted underneath, and resoldered it.

Plinky · July 30, 2007, 04:35:26 PM

Quote from: oskar on July 30, 2007, 04:27:46 PM
Maybe you should call Ross customer service?!

Was that really necessary???

oskar · July 30, 2007, 04:42:24 PM

4 uggly little arrows... this looks like traces of copper that should have been etched... can't really see.

Plinky · July 30, 2007, 05:01:14 PM

That's probably just the light. There's no short in any of those spots.

Plinky · July 31, 2007, 12:56:16 PM

Anybody else care to chime in??? I've checked all the solder joints and all are clean and not shorted.

oskar · July 31, 2007, 01:30:29 PM

yeah, I'll help you bump this... Help over here!
Honestly I'm clueless...

--- But brother, I checked your link and you shure can play...

Plinky · July 31, 2007, 03:47:01 PM

Quote from: oskar on July 31, 2007, 01:30:29 PM
yeah, I'll help you bump this... Help over here!
Honestly I'm clueless... --- But brother, I checked your link and you shure can play...

lol!!
At least I have something going for me.

Is it possible from the pics to determine if I have the offboard wiring correct?? Like I said before, this is the first Tonepad layout I've done so the offboard wiring is completely different. I need to debug the LED. At least maybe I can get it to work.

Mark Hammer is floating around the forums at the moment. Maybe I can channel out and get his input.

oskar · July 31, 2007, 04:00:02 PM

I only glanced at the wiring...
The problem is that it doesn't explain the voltages at the input of the OTA. If I can find time and
components and if, if , if... I could breadboard the OTA part of the machine and try to duplicate
this particular error but... I don't have time. At least not tonight.

Plinky · July 31, 2007, 04:27:52 PM

Well, I have enough spare parts, so I may just do the same myself. Lord knows I need to brush up on my schematic reading skills.

oskar · August 01, 2007, 11:45:37 AM

EDIT --- This post censored!

--- due to violations of fundamental laws of physics!

oskar · August 01, 2007, 04:44:35 PM

OTA CA3080 test

I tried to replicate your problems with the circuit above, but only with DC levels as I don't have a scope...

( - ) indicates I forgot to measure this one...
All measures was taken while sweping the pot (470k) and in the instances where the value changed it has been
given as an interval.

V+/pin7 removed

pin	V
2	2.3
3	2.3
4	0.0
5	6.0-8.5
6	0.0
7	0.0

Ground pin removed

pin	V
2	4.6
3	4.6
4	-
5	4.7-6.7
6	1.4
7	9.2

Both V+ and ground pins removed

pin	V
2	4.6
3	4.6
4	-
5	4.6-6.6
6	0.5
7	0.0

Also, shorting pin6 to ground didn't make any difference on the other pins as expected.
I didn't manage to replicate your problems, sorry. I even turned the chip around (with a 100R resistor on V+) but
it didn't come close to reasonable.
I have no clue to why this can be. If there where any problems with HF instability ringing I would most surely have missed this but
oscillations reads out on a DMM in DC mode as a voltage so it probably would have shoved up somehow (and perhaps did...)
The transistor you traded for have more than two times Hfe than the 3094's but I don't see what difference it would make in
this case.
I don't want any more nightmares and I want the voices to stop too.

----moahahahahahaha!

Jackie Treehorn · August 03, 2007, 07:14:22 PM

Hello,

I ordered 3 Harris CA3080E's from Effects Connection for a 1980 Dynacomp I acquired without the chip.

I am having the exact same problem!

I have tried, literally everything (desoldering all the legs of components to b+ which could be causing signal drain, desoldering all the other ground connections). The voltages are fine without the chip in place, once I place the chip in, I get around .6 volts. I even made a little bridge with another socket so I could just connect pins 2&3 to the chip. Voltages are good until I connect pin 4, at which point they all drop to .6. I tried lowering the 470k to 100k and it raised one pin to .9 with the other still at .6.

All three chips the same. Given the original poster's experience and my own, I really think that the batch of CA3080e's at effects connection is bad.

I have no idea how to get this thing to work at the moment....

PS I also get .6 volts on pin 1 which is supposed to have no connection.

oskar · August 04, 2007, 06:50:40 AM

It's another chip marked wrong?! ...or the bonding machine is set up with the wrong program...

maybee you can save them and sell them as relics to IC-collectors years from now?
I measured pin 1 and 8 on my 3080's and they're unconnected allright.

skar

EDIT

Quote from: Jackie Treehorn on August 03, 2007, 07:14:22 PM
All three chips the same. Given the original poster's experience and my own, I really think that the batch of CA3080e's at effects connection is bad.

If this is so at least the error is spotted. It's a bad case considering the chip is obsolete.

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Tonepad Ross compressor debug