4-pin suitcase 73 Filter Capacitor Bridging

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4-pin suitcase 73 Filter Capacitor Bridging

Postby pjmusic on Sun May 17, 2009 9:06 pm

Hi there,

I have a '75 (week 18) suitcase 73 Rhodes that has some buzzing issues. I recently purchased a set of the power supply filter capacitors, as well as the 4 pin PSU repair video.
However, I'm having a bit of trouble determining which terminals are positive and negative. There was a segment where this is explained, but my filter caps appear to be different that the ones in the video. I have one of the non-metal kind (paper, I think, shown below), and it's explained in the video that the polarity of these terminals may be different. There seems to be a few terminals, and I'm not sure which ones to bridge the new caps too.
Also, just to be clear, I don't actually need to replace the large caps, just bridge them with new caps, right?

Thanks so much! Love the site and the videos!!!

Cap1.jpg


Cap2.jpg
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Re: 4-pin suitcase 73 Filter Capacitor Bridging

Postby chriscarroll on Fri May 29, 2009 10:16 am

Capacitors are usually marked or if they have leads, the black one is negative. It is usually OK to put a new capacitor in parallel with the old unless the old one is shorted.
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Re: 4-pin suitcase 73 Filter Capacitor Bridging

Postby chriscarroll on Fri May 29, 2009 8:53 pm

first pic

Silver can shows electrolytic to chassis , this can is negative Wire in center is positive.

second pic

Shows can covered with Black card board. This can is positive

Wire from 1.5K 1w resistor goes to positive can. Inner wire is negative
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Re: 4-pin suitcase 73 Filter Capacitor Bridging

Postby chriscarroll on Fri May 29, 2009 8:55 pm

Yes, you just need to bridge them and not replace them. Unless one is shorted, then you would have to replace them.
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Re: 4-pin suitcase 73 Filter Capacitor Bridging

Postby chriscarroll on Mon Jun 01, 2009 6:05 pm

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Re: 4-pin suitcase 73 Filter Capacitor Bridging

Postby pjmusic on Mon Jun 01, 2009 11:59 pm

Wow! thanks! I really appreciate you taking the time to do all that. Great video too.

I'm having a problem with my supply voltages now, though. I tried to do the caps thing earlier and may have messed something up. The circuit breaker tripped, and things have i'm getting no +35 or -35 volts DC, and the +25DC volt in the middle is reading at +15. I've replaced the old caps and the zener diode on the pcb, and resoldered some sketchy looking connections, but I can't think of anything else. the pilot light comes on as normal now that i've properly done the caps as per the video, but I'm stumped as to what could be the problem.

Any ideas would, of course, be wonderful.

Thanks again for the great video and info.
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