Hi All
Last night my prologue 5 decided to stop working properly i was using it in the evening for a few hours, i stopped playing music but left the amp on for another hour or so.
When i went to play some music nothing happened, no output at low volume, i had to raise the volume on my preamp to almost 90% which gave me output but it was distorted.
Now i thought thats not good a proceeded to switch it off, now this is the strange bit, when i switched it off the music played come on really loud and clear for like a second before it fully switched off?
So i thought lets open it up and see whats going on, now i was actually impressed with the build, what i wasnt happy about was the lack of thought on resistor placement! Look at those large solen capacitors just being burnt by the heat (i always thought there was a strange smell when it was on).
Even the 100uf electrolytics look bad and they are only 85 degrees, surely they need to be high temp and better brand.
Now check out the auto bias board, those mkp caps look like they need changing.
I clearly need to do a recap on this thing, do you think this will help the issue i currently have?
Anyone on here got a schematic?
Thanks
Last night my prologue 5 decided to stop working properly i was using it in the evening for a few hours, i stopped playing music but left the amp on for another hour or so.
When i went to play some music nothing happened, no output at low volume, i had to raise the volume on my preamp to almost 90% which gave me output but it was distorted.
Now i thought thats not good a proceeded to switch it off, now this is the strange bit, when i switched it off the music played come on really loud and clear for like a second before it fully switched off?
So i thought lets open it up and see whats going on, now i was actually impressed with the build, what i wasnt happy about was the lack of thought on resistor placement! Look at those large solen capacitors just being burnt by the heat (i always thought there was a strange smell when it was on).
Even the 100uf electrolytics look bad and they are only 85 degrees, surely they need to be high temp and better brand.
Now check out the auto bias board, those mkp caps look like they need changing.
I clearly need to do a recap on this thing, do you think this will help the issue i currently have?
Anyone on here got a schematic?
Thanks
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Is there a relay in the circuit? Sounds like a relay (or its supporting circuitry) is not operating properly.
An 85C capacitor is fine, they just won't last as long as a 105C part of otherwise similar ratings.
An 85C capacitor is fine, they just won't last as long as a 105C part of otherwise similar ratings.
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Well primaluna won't give me a schematic, rayma they should be fitted as standard with 105c capacitors so they do last long.
I think perhaps the auto bias maybe the issue or one of the capacitors have failed.
I'm going to recap it all and see if that solves the issue. If not then I'll have to send it to get repaired.
I think perhaps the auto bias maybe the issue or one of the capacitors have failed.
I'm going to recap it all and see if that solves the issue. If not then I'll have to send it to get repaired.
You should troubleshoot first, at least with a DVM. If the sound comes back on at power off, it's probably not a capacitor, certainly not a coupling capacitor. If both channels are bad, it's likely to be either a relay or the power supply, either of which would be common to both channels.
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It feels a little dangerous to perform an improvement involving multiple changes before identifying the root cause of this issue. Once you have recorded all the voltages on all pins of all the valves, then chances are you will have a better clue.
Of course I'll start trouble shooting, only thing is i wouldnt know what to look for in terms of voltages.
My thoughts were a psu issue aswell, If I had a schematic I could work my way through it all.
My thoughts were a psu issue aswell, If I had a schematic I could work my way through it all.
Some of their amplifiers have a HV kill circuit that protects against a bad output tube.
I would look for a bad output tube first, then if the tubes are ok, look at that circuit itself.
So it is mravimsky! It looks exactly the same under the hood, well you learn something new everyday.
So perhaps I can find schematics for the cayin which will help.
So perhaps I can find schematics for the cayin which will help.
I tried different power tubes which were new and working and it was still the same issue rayma, even tried a different preamp and preamp tubes.
Ok, see if it has that HV protection circuit, that sounds more likely to be the problem.
@ rayma - In case it's relevant, there is a plate fuse situated on top of the Adaptive Autobias board.
The manual gives instructions on how to locate and replace it:
http://www.absolutesounds.com/pdf/main/brochures/PL5.pdf
Forgive me if this is too obvious a cause.
The manual gives instructions on how to locate and replace it:
http://www.absolutesounds.com/pdf/main/brochures/PL5.pdf
Forgive me if this is too obvious a cause.
One should let primaluna keep their amps if they refuse the customer essential
documentation ! Shame on them ! They gain nothing on hiding the design,
competitors will reconstruct the schematics the only loser is those
poor customers that hve bought the stuff and encounters problems.
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I don't know anything about these amps, but if there's a fuse, it shouldn't turn on and off like he says it does,
when powered off.
I completely agree peter useless service, i even explained the issue and that i would appreciate a schematic.
