Vintage GE clock radio will not Power on fully

[lexmarks567]

Hello new here.

I have a Vintage GE AM/FM clock radio. Can't find a model number but the date code is 2643M. The only thing that works is the 2 dots in the middle of the display that act like a second hand and the alarm on dot. Nothing else lights up. None of the digits light up,the radio doesn't work in either mode. I pulled 2 caps and 3 transistors from the board in the picture. One cap is rated at 1000uf 16v and it's reading about 880-870uf 0v. Another cap is rated at 470uf 16v and I either can't get a reading or the meter will show 0.03. So both caps needs replacing but what about the transistors? I cannot get a ohms reading no matter how I test them none will give me a reading. Are they bad also? the Info on the 3 transistors are 6002-012 t 639. I can't find any replacements online.

 

[Bluejets]

Do you have the meter on diode test to test the transistors?
They need a certain amount of voltage/ current to turn on and give a reading which in most cases, the normal ohm scale will not provide.
BTW, that board below looks all burnt up...

 

[73's de Edd]

.

lSir lexmarks567 . . . . .


.I also have one of those older . . . Gently Electrified . . . clock radios.
Further check the very front's top corners . . . . and possibly expect a model number of 7-2643 in your case,any very final Alfa suffix is usually related to the colorization or "stimulated" wood type aspects of the case.
Next chance, is to inspect all of these photos of your 1987 vintage of unit.

Check out:
https://www.google.com/search?newwindow=1&biw=1920&bih=950&tbm=isch&sa=1&q="+General+Electric+"+1987++clock+RADIOs&oq="+General+Electric+"+1987++clock+RADIOs&gs_l=img.12...25432.44891.0.47524.22.22.0.0.0.0.139.2390.2j20.22.0....0...1c.1.64.img..0.0.0.Yb2Hihxvb0I#imgrc=_

Also . . . these units for sale . . .relate photos to models:

http://www.ebay.com/sch/i.html?_fro...987+General+Electric+clock+radio&_sacat=50608

I think that your 3 transistors on the power supply board will be GE's proprietary numbered SE6002's which are being NPN silicon 500 MW units .

Pull out your DVM again and place in DIODE test function.
Viewing the BOTTOM of a transistor, with its cases flat index at the top position, the lead are E-B-C.
Your conducting Vf spec from B-E and B-C will be in millivolts and could be any where from he 500's on up to the 600's of millivolts.. Finally confirm no C-E short /or / leakage, in testing with both test lead polarities reversed. .
I would expect them to test good.

As you describe it,it sounds like one electrolytic has just open circuited on you. Try another unit in circuit in place of the ? one, just to confirm.
That looks like a dual level supply, maybe, initially developing up in he 12VDC region and a drop to ~ 9VDC for the second level.

BTW, that board below looks all burnt up

If seeing the same that I am seeing, that is being the two terminal break out from the delicate Litz wires of the ferri-loop antenna. Being somewhat delicate they may have put a mechanico-buffering coating of "black pookie" on them.



Zero in on a model . . . .and then maybe more help than was found at the the dood-its-yerselfs forum will be forthcoming.


73's de Edd

.

 

[lexmarks567]

OK via the link that 73's posted it's model 7-4620.Ok found diode mode, One transistor reads 713. Another reads 698 and another reads 714. That's with the NEG lead on the Base or middle prong and with the POS lead on the collector. With the POS on the collector I get the same reading with the NEG touching the Base and the emitter but no reading the other way around and no reading with the POS on the Base and the NEG on either the collector or emitter.

 

[73's de Edd]

.

Sir lexmarks567 . . . . .

GR---eeeeeeeee-at ! . . . . it looks like those 3 transistors are O.K then..
Next test is in a no power applied situation where you see the three electrolytics on that board.
Note their ground hash markings on the side . . .I am mostly curious about the very physically smallest one.
Place metering in OHMS mode to its lowest range . . .short probes together to confirm a shorts response on your meter . . .as I'm blind here, since I can't see a thing . . . .
Confirm that ALL 3 of those ground band associated caps leads are directly interconnected.

I'm suspecting so . . .just wanna be sure..

I can see at least 3 diodes on the board, most that I see, have been assigned a "D" plus part number..
We are curious, as if any of them have a "Z" as their designation.

Back to the electrolytics, go to ohms metering mode and see if any of the 3 lytics are reading as having a low ohmage reading between their + & - leads.
Matter of fact . . . . post them.

Giving you time to do that . . . . . then we can proceed on to measuring some voltages-es-es.


BTW . . . . .
After thought, your model number was molded into the back of the cabinet.

73's de Edd

.

 

[lexmarks567]

The 470UF cap reads 00.4 the 1000UF one won't give me a reading no matter what the ohms setting. Those 2 where pulled from the board. The small black one I had pulled earlier and it was rated at 10UF 35v and read 7.80UF and I put it back in. With it on the board no ohms reading. The diodes do not have a Z anywhere on the board. as far and interconnected here are pics of the underside of the board.

 

[lexmarks567]

It works again. I replaced the 3 bad capacitors and it fully works again. So far is holding the time.

 

[73's de Edd]

.


Sir lexmarks567 . . . . .

The 470UF cap reads 00.4 the 1000UF one won't give me a reading no matter what the ohms setting.

I was just about to query . . . . to be for sure . ... if you were reading as ohms.
Possibly, with you having a cap meter and expressing it as cap values .
Seems that the 1000 ufd unit is the principal filter cap, its being initially connected to the units power rectifier diode which I marked within a YELLOW circle .
Then . . . . the 470 was providing filtering for a secondary supply fed from the first. so a .4 ohm reading would not be correct on a 470 unit !
It should have tested as a slowly transitioning voltage as the unit took on a slight charge.

I had pieced together your one skewed and the two part photos . . . I will post now, just in case they are needed in the future or used for others referencing.
One hidden thing to remember, just in case the unit completely goes dead.
Note on the first photo, at the right bottom corner that the line cord LOW comes in as a WHITE lead and connects to the common ground plane of the chassis foil patterns. The line cord HOT BLACK lead comes in and connects to a line inductor (in ORANGE square) with a somewhat frail winding. If you ever get a totally dead unit check out that coil . . .it is hidden within a black heat shrink wrap cover.
Well . . .that GE started in 1987 . . . .maybe it will make it on . . . . . to 2047.


ENHANCED CHASSIS REFERENCING:

73's de Edd