I have a Pioneer SPEC 2 amplifier on the bench with a capacitor and transistor on the modules thats not been documented in the service manual. Anyone aware of this?
I have to map it out but I am curious if anyone else has encountered this.
I have to map it out but I am curious if anyone else has encountered this.
Well that is news, better said that was news in 1980 🙂 That is one of the later produced versions. If it works OK just leave it like that, those guys at Pioneer then were pretty smart.
Better worry about recapping it as those electrolytic caps won't measure that well. Some don't recap as they worry about resales value and such. They probably don't use stuff but look at money. If you have it to playback music then maybe it is better to focus on having the device in nominal state and then simply enjoy it.
Make sure to use a film cap 5 mm for input caps and a bipolar like MUSE ES for the feedback loop. I think your SPEC 2 has a larger value than the schematic says for that capacitor too. I remember 100 µF for the later versions but I may be wrong.
Better worry about recapping it as those electrolytic caps won't measure that well. Some don't recap as they worry about resales value and such. They probably don't use stuff but look at money. If you have it to playback music then maybe it is better to focus on having the device in nominal state and then simply enjoy it.
Make sure to use a film cap 5 mm for input caps and a bipolar like MUSE ES for the feedback loop. I think your SPEC 2 has a larger value than the schematic says for that capacitor too. I remember 100 µF for the later versions but I may be wrong.
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You say it’s on the bench but for what reason?
I agree with JP but do not think that leaving original ecaps installed makes it more valuable maybe the other way around esp if you follow his recommendations.
If you are doing service or retrofit you might consider clean up or refresh of thermal compound, touching up solder joints on those devices running hot.
As for those comps on the pcb that do not match the docs, obviously leave them as they are
Some folks like to change semis but imo leave them alone as long as they are functioning properly.
I agree with JP but do not think that leaving original ecaps installed makes it more valuable maybe the other way around esp if you follow his recommendations.
If you are doing service or retrofit you might consider clean up or refresh of thermal compound, touching up solder joints on those devices running hot.
As for those comps on the pcb that do not match the docs, obviously leave them as they are
Some folks like to change semis but imo leave them alone as long as they are functioning properly.
Thank you for your concern with the capacitors. I have 21 years of service work behind my back and capacitors and all their antics I am well acquainted with.
The Pioneer is on my bench because of one channel that failed spectacularly. It was previously repaired but with inferior parts and it took out a lot of components. The only thing that stumps me is the undocumented mod on this unit's PCB. It seems to be some kind of clamp that sits on the emitters of the output devices but I have to sit down and draw it out on the original schematic to make sense of it.
The Pioneer is on my bench because of one channel that failed spectacularly. It was previously repaired but with inferior parts and it took out a lot of components. The only thing that stumps me is the undocumented mod on this unit's PCB. It seems to be some kind of clamp that sits on the emitters of the output devices but I have to sit down and draw it out on the original schematic to make sense of it.
Not a biggy, sounds like an I/V limiter ckt mod, supposedly in order to prevent amp blow ups 🙂 that seem to happen anyways, like blowing your speakers first and then the amp shortly after 🙂
Sounds to me like the std order of parts are in need, mj2119x, mje1503x, ksa1381/ksc3503, ksa992/ksc1845, maybe ksa1013, ksc2383, emitter and base drive resistors, almost a complete rebuild.
I was asked the other day if I have power supply pcbs for spec2 for sale. I do not have them designed, first time i was asked for that design, it’s so low volume uneconomical to invest the time plus I need one in hand to measure it out.
Sounds to me like the std order of parts are in need, mj2119x, mje1503x, ksa1381/ksc3503, ksa992/ksc1845, maybe ksa1013, ksc2383, emitter and base drive resistors, almost a complete rebuild.
I was asked the other day if I have power supply pcbs for spec2 for sale. I do not have them designed, first time i was asked for that design, it’s so low volume uneconomical to invest the time plus I need one in hand to measure it out.
Rsavas - it is maybe worthwhile to make a couple of board sets with the appropriate markup of course.
I am not sure why you would think it would be a worth while effort considering the very low demand for these rare items
I have seen that oddities like these and their related parts do sell incredibly well.
I have been focusing on the high failure items such as Pioneer power supplies as needed and requested. If someone asks for a new one to be designed, I ask them send me the old one to measure up, then I design, build, test, send them the new assembled and old design, asking them to pay for parts. imo it’s a good relationship to have with folks in need. It started with that sx-1980 ps that blew up in my face one day when it was in for service.