Stk3082

[Burnedfingers]

I found some NOS modules in my parts bin. Can I make anything usable out of the module? If my memory is correct they were used in integrated amplifiers in the 80's. Anyone remember?
What would it take to make an amplifier out of one of these?

 

[guitar_joe]

a datasheet perhaps

 

[east electronics]

if i remember

well this should be a driver stk ic mostly used as a driver for a couple of transitors for sansui amplifiers .....

nice circuit ...produces a lot of power but SOA of the all device is way overestimated resulting this b1000 amps to fail quiet easy .....

i have a broken one ,,,,,, never bother to fix it ....if i ever do i will replace trafo to something lower for more safety ....

regards sakis

 

[djk]

A stereo driver IC rated at 4W (max) ±57V (max). Single ended diff input, Vas, and CCS.

Intended to drive high-gain double EF output modules with bias circuits (STK 0050) and triple EF (STK 1050).

 

[guitar_joe]

data sheet is here

 

[Burnedfingers]

Received a PM inquiring about my stash of STK3082's. Upon looking I see they are STK3082II's are they interchangeable? A few years back I seem to remember a site that had all the information about STK packs. I lost this with a hard drive failure. Does anyone remember the link?

 

[Kaplaars]

Received your PM, thanks But, aye, I unfortunatelly need the STK3082 (I). The latter versions lack internal compensation caps and resistors. Chances of oscillation arise when using a newer version, than the original one which your amplifier once had. So they are not fully backwards compatible.

It is possible to add the compensation caps and resistors externally. I already am using a STK3082 III this way, but it is not ideal, so I was searching for a previous version instead .

Here is some more info about the different versions:

http://www.diyaudio.com/forums/chip-amps/170525-sanyo-chip-amps-v-ii-xi-differences.html

 

[djk]

The 3082 has four internal compensation caps in the module, between pins 3-4 (12-13) and between pins 4-6 (10-12).

The 3082 II has only two internal compensation caps between pins 4-6 (10-12).

The 3082 III has no compensation.

The 3-4 (12-13 cap is about 68pF with 470Ω in series with it, the 4-6 (10-12) cap is about 15pF.

It's not that hard to add the compensation your circuit needs.

 

[sregor]

Also - adding a heat sink to the driver chip usually helps. They tend to run hot and that contributes to there failures.

 

[Kaplaars]

Yup, it is pretty common that STK's will fail. They cause a lot of trouble in many amplifiers after a few years. It is not that the STK's are bad by design, but unfortunatelly many STK's are pushed to their limits which will cause them to fail after a while. More cooling is for most of them necessairy. Additionally here in Holland mains voltage has been raised from 220VAC to 230 / 240VAC. This will cause a STK to degrade even earlier due to an higher applied voltage and thus higher dissipation.

I've added extra cooling and changed the transformer to 240V setting, so I hope the new STK will last longer. But for me adding the compensation circuits externally is not a very professional solution (messy setup, I am a bit of a perfectionist about layout ), although it seems to work fine right now. Also leads in the compensation circuits for version one are much shorter (because this circuit is mounted inside), which will result in less chance of oscillation. Although I think this chance will be negligible, since some amplifier use version III with the compensation circuits mounted on PCB.

 

[dragonweed]

Just a quiet warning.... lots of the recently available STK-s are fakes. Had a bad experience with the 3082-II, the original one in the amp worked until warmed up, then started to make terrible cracking noise (specially when gently knocking on them) activating the protection. The new ones I purchased from a local store (2 of them) refused to work, protection remained on, no sound, no bias voltage for the output stage, nothing... Finally I glued a large heatsink on the original, now it seems to work well. So be careful....

 

[djk]

The Crest solution to NLA STK voltage amplifiers.

 

[Kaplaars]

Ai dragonsweed, that does not sound pretty. Do you have a picture of your fake STK's? Maybe there are some differences from the original ones to spot? I was able to obtain one original STK3082 from the USA. Well, it seems original, because the amp rocks again without any flaws and I can't spot differences from the original

 

[Burnedfingers]

The Crest solution to NLA STK voltage amplifiers.

The Crest solution is the far better one.

I have on hand a number of STK 3082 II that are NOT fake. They were for a project that never got made.

 

[Kaplaars]

I have actually never heard of the crest ones. Do they offer 1:1 copies, or are it mere substitutes?

What concerns me when looking at the crest ones is again cooling, or is a heatsink attached at the rear of them?

 

[dragonweed]

Unfortunately I threw the "fake" ones out, so I cannot post pictures of them. But as far as I remember, the bogus ones have a 3 letter/number code printed on the lower right corner, something like P3T, while the originals have either a four number, or three number/one letter code printed (like 8719, or 1H30). Also the
bad ones have no printing on the metal back plate, while the originals do have a rather long code printed on them.