Heatsink grease - I'm confused ;-) ?

[Netlist]

Hi!

That very much indicates broken ICs, as well, doesn't it? So bying that one wouldn't help me, or could that also be another fault?

Arndt

Unless you can bye it for a very low price, I wouldn't do it.
If both STK's are broken, you wasted you money..

/Hugo - Thinks Haldor's probes look very nice - Is going to bye a set of those - and never! drinks tea while working.

 

[dwjj]

If the STK080G is no longer available, there may be something you can substitute to make it work. I've managed to use slightly different STK's and they worked fine. Besides substituting a higher number like stk0050 for stk0040, whcih should just be a rating increase, so works fine, I've substituted stk0039 for stk1039-the difference is output pins and emitter resistors.

Even though they are obsolete, sometimes there are places that still carry stock. Here in US www.matelectronics.com and www.fistells.com both carry STK080, which would function, wouldn't it? Or perhaps STK082G or STK083G would function. www.i-mcm.com also carries stk084 (which is odd, since I can only find stk084g datasheet, so perhaps it's an stk084g).

Personally, I'd find a substitute rather than attempting to buy one and hope to salvage the old ones. That way if you kill it again you can get another one.

 

[RemoGaggi]

Question for Cradle22 re Marantz

Hi Cradle22,

I am currently working on replacing the two STK080g modules with STK084g on my Marantz SR3100. I am expecting the STK084g's to arrive in a few days. I know a lot of time has passed, but I was wondering if you ever got your Marantz running and how it performed with the replacement STK's.

Also, if you have any installation tips or suggestions for me on my project, it would be much appreciated.

Thank you!

 

[unclejed613]

that thread's been dormant for a long time....... one thing i can tell you about STK packs, is that they are usually pre-trimmed for bias at the factory. if you had one you could open up, you would see a print resistor at about the middle of the circuit that has a laser etched line running part way through it. i don't know the exact test conditions for setting the bias at the factory, but my guess would be to run the chip at 95% max voltage, and laser etch the bias resistor for a pre-determined bias current (probably between 15 and 20mA). that's one reason not to run it at or above the listed max voltage. before you put everything back together, check the emitter resistors. those would be the white ceramic bricks. they are usually between 0.2 and 0.5 ohms. be absolutely certain your replacements are pin-compatible!!! also be careful that you get genuine STK packs..... STK packs are actually counterfeited more often than transistors (both for audio, and TV convergence amps). one good test is to wipe acetone on the lettering. if the ink dissolves it is definitely fake. other things are quality of construction and stiffness of pins, and printed fonts and spacing and layout of part numbers and date codes. if any of these things are much different from the originals, suspect a counterfeit.

after the unit is back together, connect a 100 watt bulb in series with the amp's AC power line. if the bulb gets bright and then goes dim, everything's ok. if it stays bright, you have a short somewhere. the OP in this thread made the mistake of not protecting his amp while testing. i suspect that his "naked" amp was oscillating, being outside of it's chassis, and with different ground paths, it's probably what caused the oscillation. i never measure directly on the pins of any chip, since any slip of the hand is instant disaster. i usually test on traces or component leads in less densely populated parts of the board.