Short question:
I need to replace 2SC5200/2SA1943 outputs in PG amp, is it possible to replace them with something better, or is it a bad idea?
Longer story:
This is Titanium amp I repaired previously for different problem. First sunny spring days it was slightly too much abused by me 😱, worked great... Today on cold start it just shorted one of the outputs immediately 🙁 I remember when I tested this amp on bench without heatsink, one output transistor was getting hotter then others, so I guess this is it.
Thanks!!!
I need to replace 2SC5200/2SA1943 outputs in PG amp, is it possible to replace them with something better, or is it a bad idea?
Longer story:
This is Titanium amp I repaired previously for different problem. First sunny spring days it was slightly too much abused by me 😱, worked great... Today on cold start it just shorted one of the outputs immediately 🙁 I remember when I tested this amp on bench without heatsink, one output transistor was getting hotter then others, so I guess this is it.
Thanks!!!
Actually, there is.
Even Elektor mag once did a 200W car amp with big Sanken devices.
Curious me, which series Phoenix Gold is it ?
Even Elektor mag once did a 200W car amp with big Sanken devices.
Curious me, which series Phoenix Gold is it ?
The Motorola MJL3281A and MJL1302A may be suitable replacements. They are rated higher (200W vs 150W) but the SOA curves are not quite as good as the originals.
I'd suggest using the originals unless they're not available. At this time, mcminone.com has them.
If one transistor is running hotter than the others, and there are parallel sets of output transistors, it's possible that one or more of the parallel transistors isn't sharing the current load. It could be due to an emitter resistor being out of tolerance or a problem with the drive circuit (open base resistor).
I'd suggest using the originals unless they're not available. At this time, mcminone.com has them.
If one transistor is running hotter than the others, and there are parallel sets of output transistors, it's possible that one or more of the parallel transistors isn't sharing the current load. It could be due to an emitter resistor being out of tolerance or a problem with the drive circuit (open base resistor).
Both parts are available on e-bay from several different suppliers all of which are reputable dealers.
I just had to replace a whole channel in a Ti-1000.2 three days ago. They are good transistors.
I'll bet your blown transistor were located on the inside sink plate and it was probably located just under the fan wasn't it?
I have never seen a failure any where else in these amps. Always the inside plate and just under the fan where the short fins are located.
Seems to be a common failure spot in the design, and bigger outputs might not help, as it might be a thermal design issue. Maybe 🙂
Perry's correct check all your resistors, the Green and Grey FUSE types should be replaced with the same for safety reasons. You should re-install the sinks while looking for leaky outputs as these amps can be bias'ed fairly high and they might go into thermal runaway without there sink plates installed. PG can and will sell you fuse resistors if you can't find them on the net.
I just had to replace a whole channel in a Ti-1000.2 three days ago. They are good transistors.
I'll bet your blown transistor were located on the inside sink plate and it was probably located just under the fan wasn't it?
I have never seen a failure any where else in these amps. Always the inside plate and just under the fan where the short fins are located.
Seems to be a common failure spot in the design, and bigger outputs might not help, as it might be a thermal design issue. Maybe 🙂
Perry's correct check all your resistors, the Green and Grey FUSE types should be replaced with the same for safety reasons. You should re-install the sinks while looking for leaky outputs as these amps can be bias'ed fairly high and they might go into thermal runaway without there sink plates installed. PG can and will sell you fuse resistors if you can't find them on the net.
Thanks a lot! I'll recheck all resistors + replace all parallel transistors. Then rewire my subs to 4 ohms 😀
Be very careful when buying 2SC5200 and 2SA1943 because there are really a lot of fakes out there. Fortunately there are some very good threads discussing fake transistors, so you may want to use the search engine.
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