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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Dec Tue 22, 2020 7:16 am 
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First order of business with these half century or more old sets is to replace the Electrolytic's. Doing so eliminates them as being troublemakers. Once you have finished recapping, then advise how the set operates.

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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Dec Mon 28, 2020 7:31 pm 
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Location: Costa Mesa CALIF 92626
Thanks fifties!
I made a small donation to the site. I'm a volunteer on another forum and I realize that these don't just operate for free! I hope it helps a little. I'm unemployed right now due to COVID and major surgery. Hoping I will be working soon though.

I got to the radio last night, finally. I found a 80uf 3v cap that was bulging: a good sign of a bad cap.
I know you mentioned earlier that up to a 20uf difference wouldn't matter. The closest I have in my stock is a 100uf. The other problem is I don't know where this cap is, in the schematic - which is for a different model. It looks nearly identical to me (SR-G900L, schematic here in the downloads area). Nothing in the parts list shows an 80uf and this looks absolutely stock to me. Should I just stick the 100uf in?


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Dec Mon 28, 2020 9:31 pm 
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Location: SoCal, 91387
Yes, replace the 80 with a 100 uF. The circuit won't know the difference, and don't worry at all about the component not being listed for a similar model.

The largest difference however would be in replacing the small value Electrolytic cap coming off the volume control center wiper.

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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Feb Mon 01, 2021 6:05 pm 
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Location: Costa Mesa CALIF 92626
Sorry for all my delays here, to those helping me out.
I had an accident about three weeks ago... crashed into the ground at 17mph on inline speed skates. Wasn't a smart thing to do although I'm a good skater. It was just a stupid accident though. Luckily I didn't seem to mess up my recent neck surgery even thought I went face first in the ground.

The radio - I again got back to it the other night but now there's no reception whatsoever. Just hiss on both bands. I've done NOTHING since the last two caps I replaced.
It's getting increasingly frustrating for me to work on the radio just due to my lack of experience in something like this. I feel like I'm just shotgunning caps that are good.
Plus, some are so squeezed in, along with factory jumper wires on one side, that I'm afraid to unsolder them without losing my place, so to speak. I've tried to make drawings and take photos but it's not doing me any good.
I've repaired old telephones, antique and newer slot machines (computerized) but this dang thing is mystifying me.

Is there ANYONE out there willing to do the repairs for me, at a reasonable cost? And, of course, give me a "briefing" on how it was troubleshooted. I feel like if I go on, I'm going to make it worse.
Let me know.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Feb Mon 01, 2021 10:53 pm 
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Location: Mountains of Mourne. Ireland.
Mark, place your City or Zip in your profile.
via... User Control Panel.

...there may be someone nearby, though it wouldn't be too difficult to ship it out.
Not everyone reads these forums daily, so be patient, someone may step up to the plate.

Bummer about your Slam. I no longer skate, too many knee operations.
:) Greg.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Feb Tue 02, 2021 1:30 am 
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I'll add it to my profile. I'm in Costa Mesa Ca. It's a pocket radio so cheap to ship. I can pack it and add a return label too.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Mar Wed 10, 2021 4:47 pm 
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egg wrote:
Mark, place your City or Zip in your profile.
via... User Control Panel.

...there may be someone nearby, though it wouldn't be too difficult to ship it out.
Not everyone reads these forums daily, so be patient, someone may step up to the plate.

Bummer about your Slam. I no longer skate, too many knee operations.
:) Greg.


Hey Greg ... late response to your last sentence! Did you speed skate on ice or inline skates? Hockey?


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Mar Fri 12, 2021 3:34 am 
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Location: Mountains of Mourne. Ireland.
There's only one kind of skating. lol
Image
Greg.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Mar Fri 12, 2021 6:22 pm 
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Awwww I wish I could do that! I think I could learn to skate board, but maybe cruising at a speedy pace on a long board?
I'm back to short track on ice after nearly 7 years off. A small group managed to get ice time but I literally know no one other than one adult!
The problem is that I'm "too fast" for the old guys my age so with the kids! I'm the old dude in the middle with the Italy suit.
I live one minute from a skate park like that one too. I'd crash in the bowl!!


Attachments:
155147428_10165250466390171_1262209556464162086_o.jpg
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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Aug Sun 29, 2021 11:38 pm 
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Ok 5 months later... I think I'll attempt to work on this radio again. I'm just blindly changing electrolytic caps. So far no change at all.
Should I just replace them all out?
I feel like I'm making it a lot "less original" if most of the caps are actually good.
I almost want to solder them back in! This is a very difficult radio to work on... it's quite tight in there and there's numerous factory jumpers.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Aug Mon 30, 2021 12:16 am 
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I would just replace them all out, I just recapped a customer's radio today and the last cap was the one that got it working. Check your work after each cap.

I just skimmed over the previous posts does the set not work at all right now?


Henry


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Aug Mon 30, 2021 5:20 am 
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Location: Sunnyvale CA
shortrackskater wrote:
Ok 5 months later... I think I'll attempt to work on this radio again. I'm just blindly changing electrolytic caps. So far no change at all.
Should I just replace them all out?
I feel like I'm making it a lot "less original" if most of the caps are actually good.
I almost want to solder them back in! This is a very difficult radio to work on... it's quite tight in there and there's numerous factory jumpers.


You should just replace them all, if you want it to work. This is not some rare collector radio where "original" matters very much.

Typically, it's the small capacitors that fail first, coupling the audio and/or controlling the response of the AGC. The usual failure mode is that the electrolyte dries out and they lose capacity. There may be something else wrong, but you really need to start with the most likely failures, and the most obvious (like a short, bad solder joints, or obvious damage).

Brett


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Aug Mon 30, 2021 6:11 am 
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In your OP you said that the radio did receive stations, but at low volume. In a later post you said that it no longer received anything.

Forget further recapping until you get it working again, and verify that what caps you did change were installed with their polarities correct.

Try this next, and advise.


Attachments:
Second Radio Test.Jpeg
Second Radio Test.Jpeg [ 110.74 KiB | Viewed 639 times ]

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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Aug Mon 30, 2021 11:47 pm 
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fifties wrote:
In your OP you said that the radio did receive stations, but at low volume. In a later post you said that it no longer received anything.

Forget further recapping until you get it working again, and verify that what caps you did change were installed with their polarities correct.

Try this next, and advise.


Thanks everyone!
Fifties: It's not working at all now. I got so frustrated months ago that I just left it siting there, apart. I'm very sure the caps are in the correct position with regards to polarity. However I'm not sure if I screwed up a jumper. This is the most difficult thing I've ever worked on. This shouldn't be that hard. Still I"ll look at all my caps just in case I had a brain fart and go from there.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Aug Tue 31, 2021 12:00 am 
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Do the second radio test in order to eliminate the converter as the trouble maker (or identify it, if it is), and advise.

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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Sep Fri 10, 2021 7:52 pm 
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Ok I reassembled the radio partly, powered up and did the test.
I do hear the sound on the other radio, in both places.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Sep Fri 10, 2021 10:21 pm 
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shortrackskater wrote:
I'm not sure if I screwed up a jumper.

OK, I think we can be confident that the problem is downstream from the converter. You are going to have to trace against the print every connection, starting with the input to the first IF. Believe me, all it takes is one off or missing.

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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Sep Mon 13, 2021 10:44 pm 
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Thank you!
After some thinking ... I'm 99.9% sure I got that jumper in the right spot. There were two but I'll check both and hope they're in the schematic. I don't have the exact one for my radio but the one I found here (shows the circuit board as well) looks identical.


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 Post subject: Re: Standard SR-G901 7 transistor radio - low volume
PostPosted: Oct Mon 25, 2021 5:06 pm 
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Sorry all, that it takes me a month to get back to this. I appreciate all the help but I'm having some health issues from a "bad" neck surgery.
I've ended up sending the radio to a friend who is very experienced with this and was willing to have a look at it for me. I hate giving up, but I feel like I was more likely to create additional problems rather than fix them, in this case.
Still I'll post back with an update when he gets to it.
I did find a couple radios on eBay that were easy fixes, including one from Kmart, with the original box and instruction manual. I'll make a post for that one soon.
mark


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