I have a Denon PMA 900v that sat for awhile unused. I opened the unit up and inspected it before trying to power it up. It immediately blew the main fuse (appears to be original) and the was a spark around main capacitors. I pulled the power supply capacitors to check them. 4 of the 6 capacitors read within spec ( I am going to replace them anyways) and 2 read dead short. The capacitors are 8200uf 72v (35mm x 70mm) electrolytics. I considered replacing them with 10000uf 100v capacitors but read somewhere about there being a concern that these amps do not have in rush control. Any advice, recommendations on suitable replacements. I plan to recap the entire amp as well while in the process; which brings me to my second question. I am considering replacing the ceramic capacitors in the signal path. What would be best in their place? Thanks.
New 10,000uF 100V capacitors won't be a problem.
Are you sure the others are ceramic and not film? That would be unusual.
Suggest you only replace a few capacitors at a time, and then make sure it still works before going further.
Are you sure the others are ceramic and not film? That would be unusual.
Suggest you only replace a few capacitors at a time, and then make sure it still works before going further.
There is ceramic caps in the audio path. This amp is from the mid 80s. I am planning to recap the entire amp. I bought a Denon PMA 700v along with the 900v and the 700v has low sound on one channel, which sounds like a bad capacitor. I would like to replace the ceramics with something better as I read that they are not the best for audio.
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I would hesitate to modify a Denon set, those small caps rarely go bad.
8200 uF caps should be available, it is a fairly common value.
Use a proper meter or scope to check, replace only if faulty.
And like above, go step by step, those sets are difficult to repair, technicians hesitate when they see most Denon sets, some of the circuits are quite complex.
If all else fails, consider getting a new plate amplifier from the usual sources, just flip it out, it may be less effort and expense in the long run.
And please think of using a series lamp when switching on again, very useful.
8200 uF caps should be available, it is a fairly common value.
Use a proper meter or scope to check, replace only if faulty.
And like above, go step by step, those sets are difficult to repair, technicians hesitate when they see most Denon sets, some of the circuits are quite complex.
If all else fails, consider getting a new plate amplifier from the usual sources, just flip it out, it may be less effort and expense in the long run.
And please think of using a series lamp when switching on again, very useful.