Help identifying Amp Module

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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
 
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/semi/dis_pdf_j/STK083G.pdf

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

SVI2004A said:
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.
 
Bill Fitzpatrick said:


If image file size keeps pace with bandwidth increases then the whole point of greater bandwidth goes into the toilet.

Anyway, I like to complain.

you should get uorself back into school inthat case, a 10Mbit connection here is costing me a whole £60 a year and I have to say I didn't even notice the images were any larger than normal in terms of loading times.

Anyway, in terms of the chips, they do indeed look like hybrid modules, and there are one or two people on the forum her who know a lot about where they came from and how they work, try a quick search for the STK chips if you missed that already.
 
Hi Tom,

Those modules are thick film hybrids containing discrete transistor chips directly mounted on an aluminium substrate. Topology is straightforward with a pnp diff. input stage, Vas and output stage. They came as modules for single and dual power supply some with output current limiting and some without. The 10 pin modules are without output current limiting.

Have some sheets here dating from 1975, but the STK089 is not listed yet.

However if it is some help to you here is some data for the STK086:

Max. psu voltage + and – 55V
Recommended psu voltage + and – 42V
Pmax at 0.2% THD @ 8 ohms 70W
Max. collector current 7A
Pmax @ 4 ohms (0.2% THD) 100W

Pinout:

1/ plus in (non inverting in)
2/ substrate
3/ minus in (inverting in)
4/ driver stage V-
5/ Vas out lo, compensation.
6/ power stage V-
7/ output
8/ power stage V+
9/ Vas out hi, not used
10/ driver stage V+

Cheers ;)
 
Cheers, I was hoping to build a 12v amp with anyway so looks like it might not be as appropriate as I though.

I'd also like to apologise to Fitzpatrick, if you look at the second set of images they're actually quite usable and another 20% compression wouldn't have hurt their usability at all.
 
You wont get much output power from 12V.

Two suitable candidates I can think of are National LM1877, or LM4950. If you want higher output power think about a higher supply. If it's for a car you're getting into switchmode supply territory (all the big car amps have one built in for exactly this purpose)
 
There is an online shop that stock a fairly extesive range of STK chips & has the Specification manual downloadable in PDF format for each chip.

Try visiting www.ampslab.com/components_stk.htm

I just found out an interesting fact that has no bearing on the subject.
The STK084 is a 50W Amp chip but my local electronics store web site is selling it (or at least has it listed as) a 70W Amp Chip which is actualy the STK086. :smash:
 
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