Peavey Classic 50 head no reverb

[jupiter235]

Hello I am new to the forum and this is my first post, this is a great community and glad I found it.
OK, so i read a few posts here on the classic 50 combo with dead reverb, I have the same problem with the classic 50 head, no reverb. I checked all the wires in the pan and they appear to be fine, someone mentioned the 4558 op amp and in the schematics I see 2 of them, does anyone know the spec's on it or a part order number from digi-key ? Sorry if this sounds like a dumb question I never ordered from them and i am lost on the part.
http://search.digikey.com/scripts/Dk...ll?Cat=2556125
I would be happy to send someone the schematics if that helps...
Any help would be greatly appreciated.

[tubeswell]

The 4558 is a 8-pin op amp in a DIP package. It just plugs into the 8-pin socket on the pc board (i.e.; no soldering needed). Why not do both of those 4558s at the same time? (They are cheap enough)

http://www.alldatasheet.com/datashee.../ETC/4558.html

As a direct plug-in replacement you can substitute a TL072 (same sorta thing but a weeny bit quieter) if you like, or a NE5532. Don't get the miniature version - get the normal size.

However it might not be the IC - it might be that the pan is at fault (one of the transducers might be open/haddit), or one of the jumper wires/pan leads. Test everything for continuity with your R-meter.

[olddawg]

A 4558 is just a dual 741 opamp and about as ubiquitous as it gets in old gear. You might want to check the power supply rails for ripple and semetry. Your's probably a have +15v and -15v supply. Get the pinout from a TCG reference or whatever.

[Enzo]

There is just one 4558 in the amp. 4558 is a dual op amp. What you see on the schematic is the two halves of it - note both of them are called U1.

4558 is about the most common op amp, though in recent years 4560 and 4580 are taking its place. Just a general purpose op amp-, nothing special. Peavey would sell you one, but you can get them from any electronics supplier.

Digikey? Enter 4558 in the search. Comes up with tons, so scroll down to integrated circuits and click on amplifiers, op amps, etc.

There are still tons. The differences in them all are the physical shape, and you need an 8-pin DIP. SO look in the filters and select DIP8, then APPLY FILTERS. You wind up with two.

NJM4558D, they want 42 cents.

Mouser, do the same thing. You find the same NJM4558D for 32 cents, and they also sell the Rohm brand for 55 cents. That is BA4558

Some suppliers might also have RC4558. They are all the same.


But I agree it is more likely something else is bad first. Take the reverb pan out and look inside it. Any of the tiny wires broke free from the jacks? Pull ther cables from the jacks - note which one where - and measure resistance across each jack. Neither should read as open.

With the amp on, turn the reverb up some and touch the tips of hte reverb cable plugs with a finger. One should make hum. That is a test.

[jupiter235]

I really appreciate the response, I checked the tank out and ran some tests, it seems to be ok, checked out the wiring and all contacts are good, just ordered the part from digi-key today and hoping that is it.
Thx again, I'll post what I find .