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In Reply to: RE: Recapping receiver - slow progress and and couple questions. posted by DRam on January 31, 2017 at 21:02:42
Slanted slash marks can also mean optional. Meaning the capacitor may or may not be present/needed in the circuit. This occurs for example with crystal oscillator capacitors.
I may be way off on this, but reading between the lines, you may be considering replacing more capacitors than you need to. Typically what people replace when updating audio equipment are the power supply electrolytics and coupling capacitors to improve/change the sound and/or they are or may become leaky. There are also some capacitor types that from experience, are knows to have high failure rates. For example Hunts PIO's, and I wish I could recall the name of the silver coloured foil type capacitors they used in the 60's that had a high failure rate. And any electrolytic cardboard exterior or that are bulging.
Follow Ups:
Several capacitors indicated on the schematic and block diagrams are not present in the receiver.
As for replacing more than needed, I was going on advice to replace all electrolytic capacitors. If that isn't necessary - well, what a time and work saver.
I was thinking you were changing a lot more caps than just electrolytics. Some equipment it does make sense to change all of them, but that is usually when there aren't that many of them. What is the receiver you are working on?
It is a Denon DRA-1025-R receiver, a late seventies surround sound item. Only electrolytics are being considered for replacement. There are 56 caps in the amp / phono input / power sections. I'm not messing with the tuner section.
Change the 4 large capacitors in the power supply. On the amplifier board you could change the 5 physically larger electrolytics, and any larger electrolytics in the phono section and then see how it sounds.
I did something similar with a Sony surround that was about 10 years younger, but it was left on for all that time. I changed the large electrolytics in the power supply and one that had failed in the amplifier, and it has been fine.
The large power capacitors are #1 on the list. Coupling caps are also a prime target. I suspect one or more are not good as my tweeters keep frying. If my skills were good enough I could pinpoint the high frequency area of the circuit, but about all I can do is figure out which are coupling caps that might be letting DC into the circuit.
Thanks for your advice. The number to be replaced has been dramatically reduced.
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