Help identifying Amp Module

[tom daghdha]

Hi

does anyone recognise this amplifier module? I found it in a Stadium PA amp i picked up, someone'd obviously had a go at it themselves.

It would probably be of use, but i can't find diagrams or any amps that use this end module.

I preume the shielded cable in is audio input, there's also two wires that are fairly obviously audio output, (two cut off are bridged with the two remaining) but which two voltages it needs are a mystery. I'll try +5 and +12 as a kill-or-cure, but it's not going to do it any good if i get it wrong.

The pcb is marked as Yamaha, but i haven't seen it in any yamaha amps.

if anyone recognises it please help me out.

Pic1
Pic2
Pic3
Pic4 (with annotation)

cheers, tom d

[SVI2004A]

note them 2 63V cappies in series?
center of them of them is gnd, hook the - side of the cap (63V 220uf nearest the IC) to -30V betewwn the caps to gnd, the +side of the 2nd cap (furthest from ic to +30v) test circuit
post reply.

regards Baily

[Bill Fitzpatrick]

Great, 2 Megs worth of images. Is adding to Internet constriction one of your job titles?

[lubbie]

I have a Yamaha pro amp model P2050 that uses chip transistors but don't remember what the chip #'s were.

The Yamaha Japan site has alot of schmatics and manuals.. give them a shot.

[jaycee]

STK084 is a hybrid IC power amplifier made by SANYO, a fairly popular range during the 1980's, and still available today in various incarnations (although most of them including STK084 are long discontinued). It will be running off about 30-35v symmetric (ie +35v and -35v)

I found on Sanyo's website the datasheet for the STK083G, the pinout seems to be the same. It's in Japanese but it should give you some clues:

http://service.semic.sanyo.co.jp/sem..._j/STK083G.pdf

I have a Fisher amplifier from about 1986 that uses 2x STK4028X modules at 38V. They deliver pretty good sound considering.

[tom daghdha]

Fitzpatrick, here's a set of images that might suit your bandwidth..

Pic1
Pic2
Pic3
Pic4 (with annotation)

but then, considering these might be slightly hard to draw any detail from, perhaps the first ones were more use.

But cheers for the rest of your help, i'll have to find a +-30v supply. Could anyone guess what kind of power it'd be? I'd say about 40w but i could be wrong.

[Bill Fitzpatrick]

Originally posted by tom daghdha
Fitzpatrick, here's a set of images that might suit your bandwidth..

You're a funny guy.

[SVI2004A]

i would use a 30V CT 100VA or higher - this may be adequate or underrated, i am currently trying to acquire info on your specific STK (power output, supply requirements etc)

- stay tuned...

- Baily

[paulb]

Originally posted by Bill Fitzpatrick
Great, 2 Megs worth of images. Is adding to Internet constriction one of your job titles?

Get used to it. Time to upgrade your dialup, or go back to printed text. Either way, stop wasting space here griping about it.

[jaycee]

Originally posted by SVI2004A
i would use a 30V CT 100VA or higher - this may be adequate or underrated, i am currently trying to acquire info on your specific STK (power output, supply requirements etc)

That'd produce 42V when rectified and smoothed and that would be right on the edge of the maximum voltage for the hybrid, I reckon.

I'd recommend a 25-0-25 transformer, say 160VA, which would give about 35V rectified. The 1986 Fisher Amp using 2xSTK4028X i mentioned has a 120VA transformer that produces about 32V per rail rectified. It is smoothed by 2x7000uF capacitors.

As you're in the UK, i'll venture to suggest some Maplin parts codes. Thier VS33L toroidal transformer, an AR87U bridge rectifier, 2xTX85G capacitors should run the unit. You may also want to fuse both +ve and -ve supplies at about 3A to be safe.

I take no responsibility however if you blow yourself up !
This article from Rod Elliot should give you an idea of how to wire up the PSU.