Op-amps are here and installed....I have +15v and -15v as it should be on every one.   :tu:

The replacement for the TL604 wont be here for another few days.

That said, if I jumper for the channel switch temporarily, which pins would I use?

It looks to me like I can use pins 3 and 4 jumpered to either pin 6 or pin 7 if I understand the schematic correctly.

Can someone confirm this for me so that I dont break something?  :dbtu:

Well no delivery of my replacement op-amps today....so much for any more progress tonight. 

Thanks for letting me know that the Peavy part works Enzo, its on order.  :dbtu:

I can add one more to the list. I reconnected P2 and tested for voltages, IC10, another op-amp, is dead as well.

Glad I ordered plenty of them.

Peavy has a replacment circuit that plugs into the TL604CP socket since it looks like this IC is out of production, has anyone tried it?  Its cheaper than buying the IC and I wouldnt have to wait for it to ship in from China. http://shop.magicparts.com/PV99598160

So I have two bad op-amps, and have also found that IC6 is bad, I lose the -15v if it is on the board.

With IC6, IC1, and IC2 out I have +15v and -15v as it should be and R85 and R86 stay cool.

Its a TL604CP, not able to find much on this except for bulk order or ebay from China....I skimmed some posts on the search that looks like this chip is an issue regularly.

I am hoping that my new op-amps show up tomorrow.

I removed all of the IC's and installed sockets for them.

I can only get +15v on pin 8 of 1,2,3,5,7 if IC1 and IC2 are not in the sockets, this drops pin4 to -.06v.

R85 and R86 still heat up.

I rearranged a couple of the IC's to check if they gave similar readings in different sockets, IC1 is definately bad as it tanks the voltage readings in any socket.  IC2 installed in any other socket gives the same +15v on pin8 and -.06 on pin 4 no matter what socket it is in, so it seams IC1 has failed.

On the 24v supply if I am measuring in the right spot (C52, R85 and C53, R86) I have +16 and -16. Strange as I thought earlier on I had +19 and -19?

Q-2 and Q3 are good.

IC1 pin4 -1.8v  pin8 +2.3
IC2 pin4 -1.8v  pin8 +2.3
IC3 pin4 -1.8v  pin8 +2.3
IC4 pin7 -1.8v  pin14  0
IC5 pin4 -1.8v  pin8 +2.3
IC6 pin4 -1.4v  pin8 +2.3
IC7 pin4 -1.8v  pin8 +2.3

I am going to start pulling IC's now.

I replaced all of the electrolytics, C49, C51, C25, C47, C48, C52, C53, C54, C55 polarity is correct on the board.

I have gone over the board for hours on several occasions with a bright light and magnifier and havent found any solder crosses.

With D1, D2, D9, and D11, pulled they test good on my meter. With a standard diode is this an okay test? Or is it not very valuable like the zeners?  They are 1n4448's. I dont have any of these on hand some 1N1419's that look similar in specs.

Is it worth pulling some ICs and pull some voltage tests even though they didnt get warm?

R83 and R84 and brand new, 1/2 watt and 10 ohms. 
R85 and R86 are also new, 1 watt flame proofs as that is what I had here, right at 150ohms.

I dont know if I should have done this or not but with D1, D2, D9, and D11 removed I get +3.2 and-.5 on the zeners still, would this point to the IC's even when they dont get warm?

I went ahead and ordered some 4558's so I will have them on hand. If I dont need them I will have them for something else in the future.

Again I truly appreciate all of the help on this thing, I am completely lost on it without the assistance.

:dbtu:

Sorry, results are the same for the 15 volt supply with R83 and R84 connected.

The zener voltage dropped to +3.2, and -.5 again.

removed one leg of R83 and R84 and the zener voltage was restored to +15 and -15.

I have not removed any of the op amps at this point because none of them felt warm.

The 15v zeners arrived, got a pack of 100.

Fitted a pair in, have +15 and -15 as it should be with R83 and R84 disconnected.

C49 and C51 both have -.6v on them.

IC1, 2, 3, 5, and 7 are all MC4558CP

IC4 is a CD4007UBE

IC6 is a TL604CP

I went ahead and reconnected R83 and R84 and could not detect any of the IC's getting warm at all.

Should I order up some of the IC's in case they are needed?

The IC's are soldered in, I have sockets I can install if needed.

reinstalled the old Zeners.

R83 and R84 disconnected
Zeners are +1.5v and -.07v
R85 and R86 are cool

R83 and R84 connected
Zeners are +3.2 and -.5
R85 and R86 get hot

I am in Vancouver, Washington.

I dont have any local suppliers, Radio Shack is the only one in town and they dont have much to speak of anymore. They did have some 12v zeners. The 15v Zeners should be here tomorrow or Thursday.

Probably shouldnt have but I popped the 12v zeners in because I couldnt stand not knowing. With one end of R83 and R84 pulled I got +12v and -12v on the Zeners, R85 and R86 did not heat up. I resinstalled the ends of R83 and R84 and +12v and -12v goes away on the Zeners and R85 and R86 heat back up.

Pulling the 12v zeners and will put the 15v in as soon as I get them.

Maybe its time I throw the towel in on this one.

I pulled on end of R83 and R84, no change on the zeners, I actually could not get a stable reading without them, the reading bounced all over.

Is there a way that I can test them since it sounds like the diode check on my meter wont do this properly?

I have ordered replacements but wont have them for a few more days.

I miss posted the hot resistor, it is R85 and R86 that are getting very hot.

I meant I cant visibly see an issue, apparently I cannot spell tonight.

I have ordered the zeners.