Re: JU570-2 caps and fix

From: Julian Perry <jp_at_digitaltapestries.com>
Date: Tue, 21 Jul 2015 16:55:37 +1000
Message-ID: <1174161082.20150721165537@digitaltapestries.com>
I can't see any reason why using a ceramic capacitor WOULDN'T work
just fine (if not better - but one wonders why that wasn't done in the
first place)

Alternatively wiring 2 identical electrolytic cpacitors anode<>anode (or Cathode<>Cathode -
it doesn't matter which) creates a bipolar capacitor with 1/2 the
capacitance of one of the capacitors. (IE: you'd need 2x20μF
capacitors to create a 10μF bipolar). It's often done in speaker
crossovers, I believe.

Rated voltage of each capacitor would need to be the same, I would
imagine (25V in this instance). Depending on the location in the
drive, you might start having challenges fitting them in.

Julian

> Hi!,


> I'm about to fix a 8296D. The internal 8250LP has a pair of JU570-2 
> drives with pretty obvious traces of capacitor leak... they definitely
> need a good cleaning and recapping. In this thread (already mentioned on
> this list about half a year ago, 
> http://forum.classic-computing.de/index.php?page=Thread&threadID=7382 )
> there is a precise list of the used caps.

> I've already recapped some of my vintage machines in the past and used
> ceramic and tantalum caps as replacements whenever possible, so that 
> they won't need to be fixed again (and the implied salvaging could be 
> avoided...) at some unpredictable time in the future.

> The JU570-2 seems to be a simple case, except for the three bipolar 
> electrolytic capacitors (10uF 25V), which just can't be replaced by 
> simple tantalums.

> I'm asking your opinions. What, if I simply replace these caps by todays
> cheap 10uF ceramics?


> Thanks,


> Levente

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-- 
Best regards,
 Julian                            mailto:jp@digitaltapestries.com


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Received on 2015-07-21 07:00:07

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