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 Post subject: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Thu 01, 2018 6:26 pm 
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Joined: Aug Mon 21, 2017 11:08 pm
Posts: 8
Hi gang -

My friend's Sky Buddy II is in need of some electronic TLC. Upon power-up and tube warm-up, I get a loud hum with no reception. The hum is independent of volume control and band switch position.

My thought is that it is the electrolytic can cap (C9A,B,C), and it appears to be the only "one" electrolytic (actually, three). All the rest of the caps are ceramic or Duramica types.

Knowing the history of this receiver, it appears to be a time-related issue. He hasn't used it in years, and I personally remember this set working at one point. Hence, I suspect it's a capacitor decay issue, and not a blown tube(s). I'll test the tube voltages against the S-119 manual values, before recapping.

Any ideas regarding this hum? The set looks easy enough to troubleshoot, even for me...

Thanks,
Bob T.


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Thu 01, 2018 6:49 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 3839
Location: Near Brandon, Iowa
Replace the dry electrolytic multi-cap.


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Thu 01, 2018 10:10 pm 
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Joined: Aug Mon 21, 2017 11:08 pm
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Indeed - the trick is finding the right metal can (here, it's a 60/60/20 mfd with 175/150/25 V rating, respectively). Otherwise, I'll have to build one out of discreet parts.

-Bob T


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Thu 01, 2018 10:14 pm 
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Posts: 11791
Location: S. Dartmouth MA 02748-1225 USA
https://hayseedhamfest.com/collections/ ... ers?page=2


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Fri 02, 2018 4:06 am 
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Joined: Dec Sun 14, 2008 3:33 pm
Posts: 649
Location: Tokyo
Why not disconnect the three electrolytic cap sections and temporarily wire in three caps, ballpark close in value, from your parts bin? If the radio works, then you can order a proper replacement part.

On mine, I confess I just snipped the leads from the original cap but left it in place on top of the chassis. Underneath, I used new individual caps from my collection. I also replaced the three audio coupling caps and the AVC line cap at that time; nothing seemed wrong with them, but at 60 years old, their time on earth is coming to an end.

Rob


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Sat 03, 2018 7:52 pm 
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Joined: Aug Mon 21, 2017 11:08 pm
Posts: 8
I checked the hayseedhamfest.com site, and they don't have an S-119 recap kit. I checked all the other models for a 60/60/20 mfd, but no luck. I will, however, drop them a line regarding my needs/wish list.

As for using discreet caps from the workbench, modern electrolytics usually have only certain values available. So, would a 68/68/22 mfd work in place without compromising (original) performance?

Thanks,
Bob T.


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Sat 03, 2018 8:48 pm 
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Joined: Sep Wed 10, 2014 2:01 am
Posts: 1594
Location: Costa Mesa, California
Your 68 and 22 MFD are fine for replacements.

Norm

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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Sat 03, 2018 11:36 pm 
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Joined: Aug Mon 21, 2017 11:08 pm
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Thanks, Norm (et al). That's good to hear.

I put a quote request in at hayseedhamfest.com. We'll see later. Now I have to find some metal mesh to replace the front speaker grill...

-Bob T.


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Sun 04, 2018 6:19 am 
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Joined: Sep Thu 01, 2016 3:56 am
Posts: 155
Location: San Jose, Ca.
Bob, The loud hum does sound like the power supply electrolytics are bad, but could also be something else. It's probably a good idea to power it up using a variac so as not to load down or stress other components in the power supply until you're sure other components won't be damaged. If you don't have one, try to borrow one. Have fun.

Regards, Larry


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Mon 05, 2018 6:12 pm 
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Joined: Aug Mon 21, 2017 11:08 pm
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How critical are the voltage ratings for electrolytics? Exact matches seem tough to find. The 60/60/20 mfd I need is rated 175/150/25 V. Is it better to get higher rated voltages?


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 Post subject: Re: Hallicraters S-119 Sky Buddy II hum
PostPosted: Feb Mon 05, 2018 8:17 pm 
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Posts: 1594
Location: Costa Mesa, California
Get higher voltage rated capacitors. They are small and inexpensive as long as you just go a step higher in voltage--50V for 25V rated, 250V for the 68 MFd's.

Norm

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