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Vintage capacitor

Mandrake

Oct 11, 2011
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Need help identifing the value of a capacitor from a vintage Rotel RA1412 stereo amplifier.
It is brown 16x11x6mm and is marked:
.01K DT or D7
630 ST.S

It looks like a large orange drop capacitor.
Any help would be greatly appreciated.
 

Resqueline

Jul 31, 2009
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I figure it's 10nF 630V. Is it connected across the mains, or where?
 

Mandrake

Oct 11, 2011
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Oct 11, 2011
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It is on the power PCB for the left channel between the fuses and diodes connected to the main 22,000uf 63v capacitors for the left channel. The 2 fuses for the left channel are blown and the schematic trouble shooting guide says to replace these capacitors first. There are 3 of them in similar locations on the PCB. Trying to read the capacitor I could not tell if it was .01uf or .01pf. I suspected the 630 was for volts. I bought this amplifier new in 1976 and this is the first problem I've had with it. It's an old friend and I want to bring it back to life. Thanks.
 

Resqueline

Jul 31, 2009
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Ok. You could measure (Ohm) the capacitors, but also the rectifier bridge, for shorts.
0.01pF doesn't exist so that one's easy, it's 0.01uF - and the size of it also corresponds with what I'd expect from 10nF 630V.
K is a tolerance symbol btw.
 

alfa88

Dec 1, 2010
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.01uF

My vote goes for .01uF, 10 nF, 103 (same value - different name). I think your old friend is hinting that it wants new capacitors all around. Most notably the electrolytics. By the way .01pf would be an unlikely value since I don't think you can easily find one much lower than 1pf.
 

Mandrake

Oct 11, 2011
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Oct 11, 2011
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Thanks for everyone's replies. I will post a reply when I correct the fuse blowing problem. Then I will start replacing the electrolytics which are not easy to find in sizes (physical) similar to the originals. Thanks again.
 

nepow

Jul 18, 2011
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Jul 18, 2011
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Unless the capacitors show any signs of stress i.e. a pimple bulge and leaking gunge they're probably ok. Check out the power stages for shorts...namely the output transistors ( all transistor design) or maybe the power amp output module!! if this is at fault you may strugle to obtain a replacement. If you do manage to repair it after finding the fault within the output stage, make sure your speaker connections are good and not shorted!! Early amplifier designs often died as a result of shorting speaker leads.
 
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