84 GE 25PM-C Color console problem
 

You guys helped me so much with the Sylvania set now I have another problem. I just got this set and the first day it played beautifully. It is a 1984 GE color console with stereo and a bilingual adapter. It is using the same 25PM-C Chassis as another set I have.



https://lh5.googleusercontent.com/-_...9I_600x450.jpg

I turned it on the next day and it clicked a few times and smoked. I found that it was a 5.6 uH choke coil or maybe its called an inductor I've heard it called both.

https://lh6.googleusercontent.com/-S...6-10-56_82.jpg

Here's the full schematic on the sweep board that has the problem.

I tried swapping the entire chassis with the other tv but it had the same problem and the same inductor started getting hot . I turned it off and put the chassis back in the other set. Fortunately it didn't hurt it. I'm thinking something in the stereo adapter or the connections for the bilingual adapter could be causing the problem.

https://lh6.googleusercontent.com/-F...-09-30_473.jpg



https://lh5.googleusercontent.com/-X...-56-02_804.jpg

I'm going to get the replacement part but I figured something caused this and I was wondering what to look for. The bilingual adapter on the back of the set was unplugged. Any suggestions is greatly appreciated.

Jeff

Not sure what the +36 feeds but prob vert or tuning voltage.
Most likely Y932 shorted, note there is not the usual low ohm
resistor used as a fuse. Also the 2 'lytics possible also.
I got the training manual at least & will pull it tomorrow
& have a look what it feeds.

73 Zeno:smoke:

Yeah, My gut feeling is it's something in the tuner module. I swapped the entire chassis from the other TV. I used the same stereo board and tuner module. The problem was the same and the same part got really hot.
What about the relay driver in the tuner module?


Thanks

Jeff

The 36V source feeds the tuner and the audio output. Your problem probably lies in one of three things - a shorted device at the powers supply, or a short in the tuner or audio amp. Very few components to check - I'd start with Y932, C937-939, and then pull the audio output to see if the audio is pulling the 36V down if not, it is most certainly the tuner.

Cheers,

thanks
I checked c937-939, all good. I will go back and check y932 , and then go from there.

Jeff

If its the diode use the right one. ECG552 IIRC the regular
diodes overheat & short at 15khz.
For the tuner there will be a resistor then a 32V zener to ground.
Suspect that. If audio the output IC almost a sure thing.
I will pull the manual later..

73 Zeno:smoke:

OK, it looks like it the audio amp. I hooked everything back up and it did the same thing, I unplugged the amp and it came up with a perfect picture. Here is the pic of it unplugged.

https://lh5.googleusercontent.com/-B...o/DSCN1371.JPG


from the schematic ic200 and ic201 is EP84X109. that crosses to NTE1376. if you guys know of something that will replace it that may be a little easier to find that would be great. How would you go about testing these to see if they are shorted?



https://lh3.googleusercontent.com/-C...o/DSCN1372.JPG

Thanks for all of the help

Jeff

If shorted they usually read real low ohms ( pin5 -pin 3 )
or 5-4 etc. the zeners on the output (pin 4 ) could do it also.
If one is gone I would change both. ECG is same as NTE &
maybe easier to find. Also could back cross it to an
origional number ( not GE ) but dont know where to do it.
Any markings on them ???

73 Zeno:smoke:

There are 2 numbers on it 143530-1
underneath is 88419 and a logo of SGS.
I tested them and one did have resistance of .5 ohms between 5 and 4 and 11 M- ohms between 5 and 3 the other had of 11M-ohms reading on either points. I ordered a lot of 3 NTE1376 new unopened from eBay for $12.99. That was the cheapest I could find. While I have it out I'm going to check all the caps too.
Thanks for all the info I will update you when I get the parts in.

Jeff

The Audio ICs are LM1875T - GE used them in the PM/PC chassis. Digi-Key and others stock them. We sold the GE ones for ~12 bucks, the LM1875T was cheaper to source, and we sold lots of them.

CHeers,

The Digi-Key part number LM1875T/NOPB-ND is now a lead-free (RoHS) part with the NOPB suffix (no lead), and works fine. Make sure you use some heat sink compound when you remount the new ones.

Cheers,

I had printed a data sheet on that part number and was wondering if it would work. It's good to know. I tested all the capacitors on the audio board and found one 2200 uf 35V cap was reading only 1 uf. I will get it and the other parts in a few days. I hope to get it back going soon. The other GE set has the same chassis but it is mono. This has the stereo amplifier and the bilingual decoder on the back of the set. I like the fact that is has several antenna hookups as well has several rca inputs. That's kind of rare for this old of a set. I know after 1986 a lot of the sets had stereo as a standard feature.

I replaced the 5.6uh inductor that was burned out in the chassis. I replaced both of the audio IC's and one 2200uf 35V cap on the audio board. It's back working great again. Its the TV on the right. the other set has a weak picture tube.

https://lh6.googleusercontent.com/-y...3_09-36-22_940

This TV will be replacing the set on the left to be used in the living room.

Thanks again everyone for your guidance.

Glad to see it running again. I always like the PM & PC
GE chassii, otherwise I dont miss GE.

73 Zeno:smoke:

Is that one of those Zinwell DTV adaptors. I picked one up at the G/W for 5 bucks. Brand new, in the box. I don't think it's very hot.
I'm 41 miles from the transmitter, using an amplified set-top antenna.:yes:

Glad you got it going and those are both nice looking TV's. With a good CRT tester, you could probably jolt that weak CRT back to life.

Yeah, its the Zinwell. I don't really like it. I have two Magnavox DTV adapters and they are much better. We bought the Mohu Sky HDTV antenna and installed it in the attic. it came with a booster and we wired it into our existing cable which had another booster in the basement. It works on all the tv's and picks up 27 channels. No more Times Warner Cable for us. It's the first time I have been cable and satellite free since the 80's.

Yeah I need to get another tester. I have a Sencore CR-125 and it doesn't have the adapters for this set. Unless there is a way to hook this up and try it. I would definitely needs some advice on how to do that. I appreciate all of advice on these projects. You guys have helped me out several times.

https://lh3.googleusercontent.com/-G...-22-39_345.jpg

Yeah, it seems to play good. I was having a little trouble with the stereo sound but found the the coil in the right speaker was a little sticky. I took the speaker out and played around with it until if started working better and now the stereo is back. I will look around for a little 8ohm 15 watt replacement speaker. I thought I would give it another day or two of playing in the basement before I lug it back upstairs to the living room.

My next project will be to see if I can get the color to straighten up on the 85 Zenith Advanced System 3. It's not really bad to watch but its as if the tint is a little off and it won't adjust out like the green color driver is turned up too high. I will get some pictures of what I'm facing. It could be a simple adjustment.
Thanks again

Jeff

That older CRT tester is an "atomic blast" model and wouldn't be the best one for the job, even if you had an adapter. I'd highly recommend getting a newer B&K 467, 470, 480, 490, or a Sencore CR70. These have a more advanced rejuvenate function and will come closer to giving you some more life out of that tube, instead of blowing it up. On the B&K models, you'll need adapter #CR23 to test that tube.

Thanks for the heads up on that tester. I had a feeling it was too old for the job. I found a bk 490 on eBay and it comes with the cr23 adapter. I also want to thank you for your youtube videos on unfreezing a bsr turntable. I had one that was very sluggish and was never able to remove the gear from under the turntable. Your advice with the soldering gun loosened it right up. I took it off, cleaned and regreased it and now it works like new.

I moved to Albany NY from Mississippi 4 years ago. These little projects keep me busy during the cold winter months. LOL.

Jeff

Try this on your sticking speaker. Sometimes over the years the cone absorbs moisture from the air and sags making the voice coil drag on the pole piece. Take the speaker out and put it on the table facing upwards. Get a little water in a cup and use your finger to carefully dampen the cone entirely. Keep water out of the voice coil area. The moisture allows the cone to move back to its original shape. Let it dry overnight sitting with the cone facing upwards. It might just get back into alignment. Have done this many times.

Thanks for the info. That is exactly what it was doing. I will take it out in the morning and do that.

I took your advice and took the speaker out last night and followed your instructions. It worked like a charm. The set it back to crisp, clear sound. Thanks for your advice

Jeff

Adaptor problems ?? You can make a universal adaptor for any
checker that will do any tube except some RCA & Zenith jugs that use
spring contacts. ( & those to if you pull the plastic key ).
You need a socket for the cable,some wire, manual of checker & a bunch of
small hook type clips. Hard to put in words but think about it
& it will come to you. If not will help. Setting are pretty much
universal except very small odd ball CRT's. The GE with the
soft tube is still pretty bright so it will probably take a shot
nicely.
Now lets get that Zenith on the bench & work on it !!!

73 Zeno:smoke:

I have several Magnavox DTV adaptors. Once in a while, you can buy them at
the thrifts, very cheap, as they're totally dead in the water without the remote.
Also, who was the brilliant one that designed the OEM remote?
The channel up-down buttons are tiny and poorly located. Older people have a hard time using it, as some just like to step up or down, to find their favorite channel. :sigh:

Yeah the remote is a little weird but it have a better guide than the Zinwell. I was thinking about trying another one that I found on amazon. It has a pvr function, just plug in a usb drive. I'm curious about the reception and display quality.

http://www.amazon.com/HomeWorx-HW-15...+converter+box