Audiobahn A16000V amp in Protection

[adelphia83]

Thanks a bunch for that advice. Is there any certain size or shape tip I'm looking for for this type of electronics repair if I used the Tenma station?

You mentioned the desoldering braid as being expensive. Price is not a concern for this. Could you explain further on the desoldering pump? I've never seen or used such a thing. How does it work?

I hope to have the cap dimensions for you in the AM. Again, I appreciate all the help.

[Perry Babin]

I don't know what's available for the Tenma. These are the dimensions of the tip I generally use:
0.02" T x 0.093" W x 0.625" L


The desoldering pump is a spring loaded plunger. When you press the release, the plunger is pulled up by the spring and the vacuum it creates pulls up the molten solder with it. Don't by a cheap or small desoldering pump. Only buy the DS017 or the static dissipative version of it.

If you do a lot of work, desoldering braid gets expensive. The desoldering pump uses nice cheap air to do the job.

[adelphia83]

Perry- Could you explain the expected temperature of an amp to get? Should it be too hot to touch, or should I be able to rest my hand on it? When I play for 20+ minutes at high volumes the amp gets (what I consider) dangerously hot to where I cannot hold it for more than a second or two.

The amp does have a protection circuit, using a thermistor underneath the board sandwiched to the heatsink. The only problem I see with this design is that it is on the power supply side of the board, which does not get as hot as the audio output side. This was typical even when the original audio components (output transistors) were installed.

I measured voltage at the emitter resistors when the amp reaches this temperature and none read > 0.001V.

I'm still debating using thermal epoxy to mount CPU heatsinks to the base of the amp. I'm just leery of the replacement output transistors going bad due to excess heat, which I assume killed the originals. This amp seems to have a faulty protection circuit because I've never seen it once go into thermal protection.

Other than it pounds away with a single sign of any problems.

[Perry Babin]

It's normal for the amplifier to get hot. If the voltage across the emitter resistors remains low, I believe it's simply getting hot due to normal power dissipation.

Most amps shut off at 180-200°F. That's far too hot to hold your hand on.

Did you try lifting it up off of the mounting surface and using a second fan to force air under the heatsink?

You could extend the wires on the thermistor and move it to the sink next to the output transistors.

[adelphia83]

Amp is working great. I installed the correct cap in the meantime. I've been using it non-stop on a 60 minute drive to and from work and it really shines. I'm more than content with the output, and even though the amp does get hot after 30+ minutes, it has never entered protection.

Now I have a new problem in that the subwoofer has split one of the enclosure joints.. But that's a topic for another thread..

Again, many thanks Perry and others for the generous help provided!