[Hallicrafters] MOD. S-38A Recap Issue - Help!

[David C. Hallam]

I don't have a schematic for a S-38A but don't get too hung up on the
capacitance of old electrolytics.  The tolerance for them is VERY wide; -20%
+80 or 100% is common.  Some were even rated at +250%.  If you look in the
old radio parts catalogs, you will see.

David
KC2JD

> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Mac McAtee
> Sent: Thursday, October 19, 2006 5:33 PM
> To: hallicrafters at mailman.qth.net
> Subject: [Hallicrafters] MOD. S-38A Recap Issue - Help!
>
>
> I just got the radio in today's mail.
>
> I have plugged it in and it works, picks up AM and broadcasts on the SW
> bands.
>
> I started recapping it.  I have replaced all the paper/foil caps except
> on .25 MFD that I don't have and will order shortly.
>
> Then I get to the electrolytic and that is where the problem lies.
>
> I have the schematic that apparently has been with the unit since it was
> new.  On the parts list there is the following:
>
> "C-29 40-30-30 mfd 150V, 20 mfd 25V electrolytic"
>
> In the chassis is the following:
>
> 1 ea. multi part 150V cap with 80, 40, 20mfd taps
> 1 ea. multi part 150V cap with 50, 30 mfd taps
>
> The two part cap has the two positive leads joined together on pin 4 of
> the 50L6GT tube base.  If I understand correctly, when you run caps
> parallel you add the two ratings together.  If that is correct that
> makes that connection 80 mfd. This cap does not look like original work,
> the solder connections look like they are different from the rest.
>
> The three part cap is hooked up with positive leads as follows.  80 mfd
> to pin 4 on the 35Z5GT tube base.  40 mfd to pin 6 on the 50L6GT tube
> base.  20 mfd to pin 8 on the 50L6GT tube base.
>
> I am not the best at reading schematics but it looks to me like the two
> part cap with the joined leads is installed where cap C29D goes.  Cap
> C29D is supposed to be 30 mfd.
>
> Pin 4 of tube 50L6 has the joined two part cap connected, a 220,000 ohm
> resistor that goes to pin 6 on 12SQ7.  From that pin a wire that goes to
> what I think is terminal 21 on the T3 Osc. Transformer.
>
> Does anyone have this model and can tell me the proper electrolytic caps
> and the proper connection of them.
>
> I don't know if the higher value caps are factory or changed at some
> point.  I also don't know why they are so much higher than what is
> specified.
>
> If I need to look at anything else, let me know.  Thanks for any help
> that is forthcoming.
>
> Regards,
> Mac
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