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 Missing valve in an STC Radiogram
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 Return to top of page · Post #: 1 · Written at 5:23:33 PM on 20 May 2019.
Sundries's Gravatar
 Location: Nagambie, VIC
 Member since 20 May 2019
 Member #: 2353
 Postcount: 5

Hi guys,
I'm brand new to this forum and keen to learn all about vintage tvs & radios!
I have recently acquired an old STC radiogram with a Garrard turntable. The turntable seems to work mechanically and the radio lights up, but no sound at all! Upon checking the "guts" - it seems a valve is missing!
Can anyone clue me in on what type of valve would suit the vacant spot?

A long shot maybe - but I'm sure you guys are collectively very clever! Smile

Cheers,
Chris

STC Radiogram
STC Radiogram


 
 Return to top of page · Post #: 2 · Written at 6:07:58 PM on 20 May 2019.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 5500

G'day Chris and welcome to the VR forums.

Some photos of the radiogram would help with ID. If you can manage it, include a shot of the front, the back of the chassis and any identifying marks such as model numbers, etc.

Email them to me and I will see they are attached to your comment. You can click on my username to access the e-mail address.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 3 · Written at 6:21:15 PM on 20 May 2019.
Sundries's Gravatar
 Location: Nagambie, VIC
 Member since 20 May 2019
 Member #: 2353
 Postcount: 5

Thanks Brad,
I did browse the forum for clues on adding pics before I posted! I found the guidelines and have already emailed you Smile
I only have the two pics at the moment - can add more if required.
Cheers,
Chris


 
 Return to top of page · Post #: 4 · Written at 8:53:34 PM on 20 May 2019.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5262

Meanwhile, if you let us know the valves that are still in it, we can possible identify the chassis involved.


 
 Return to top of page · Post #: 5 · Written at 5:06:57 AM on 21 May 2019.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1403

It's a 5y3gt that's missing


 
 Return to top of page · Post #: 6 · Written at 9:51:58 AM on 21 May 2019.
Sundries's Gravatar
 Location: Nagambie, VIC
 Member since 20 May 2019
 Member #: 2353
 Postcount: 5

Thanks guys for your comments.
Yep, it seems a 5y3gt is required (I received some help from a facebook group).

Cheers,
Chris


 
 Return to top of page · Post #: 7 · Written at 10:15:20 AM on 21 May 2019.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 570

Chris, careful, don't just plug in a valve and fire it up!
The 5Y3 missing may be the thing that last stopped the unit, because it failed, because of something else failing! (bad English).
Possibly a dud filter cap.
Fred.


 
 Return to top of page · Post #: 8 · Written at 11:28:02 AM on 21 May 2019.
Sundries's Gravatar
 Location: Nagambie, VIC
 Member since 20 May 2019
 Member #: 2353
 Postcount: 5

Thanks Fred, and in the past that's exactly what I would have done!
But after getting some great feedback from those in the know, I now want to learn how to do things properly and understand the complete restoration process and the order in which things should be done.
So, I've decided to sell this beast 'as is' rather than clutter my shed with large future projects. Just last week I picked up a nice bakelite Peter pan radio from an old guy's shed clean-out and the case is in great condition but the unit doesn't work. At least I have room to store this one until I learn enough to make a start restoring it. Smile
Cheers,
Chris


 
 Return to top of page · Post #: 9 · Written at 3:20:23 PM on 21 May 2019.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1403

Replace the electrolytic capacitors first. I can supply you with all you need. Email me if you like


 
 Return to top of page · Post #: 10 · Written at 8:09:18 PM on 21 May 2019.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 5500

Photos uploaded.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 11 · Written at 8:37:08 PM on 21 May 2019.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1043

Yes, I definitely wouldn't be plugging in a 5Y3GT. More likely to be a 5Z4G, which was a commonly used rectifier in STC's of that vintage.

The large output bottle - is that a Brimar 6L6G?


 
 Return to top of page · Post #: 12 · Written at 12:10:40 AM on 22 May 2019.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 3698

The top of the OP transformer seems to have 2800 more likely 2500 on it? The 236 here has a similar stamping on its OP transformer but its definitely 6V6 as it's stenciled on the chassis.

2500 Ohms would be consistent with a 6L6 a 250V Peak would be about 85mA through a 170 Ohm self bias cathode resistor.


 
 Return to top of page · Post #: 13 · Written at 8:21:50 AM on 22 May 2019.
Sundries's Gravatar
 Location: Nagambie, VIC
 Member since 20 May 2019
 Member #: 2353
 Postcount: 5

Thanks again to everyone, and to Brad for getting the pics up.

I've now reassembled the radiogram and it's in my shop tagged as a "project" for $50! I don't have time (or the space) to keep this unit and even in restored condition, these large consoles have very little resale value!

So - things I've learned in the few days since joining this forum (and joining a facebook group)..

- Don't just plug an old radio in and 'see what happens'!
- Don't assume that a missing or obviously burnt-out part is the problem and replacing that will make the world rosy again..
- Electrolytic caps replacement is pretty much the first port of call when starting a restoration.
- Joining this forum was a good idea!
- Valve radio fanatics are a very helpful bunch!

Once I get my workshop up and running, I'll probably be a regular pest on here! ;)

Cheers,
Chris


 
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