ge 802

[Phil Nelson]

Well, your sweep circuits and video output are working, which is a fine thing. Power supplies, too, at least enough to make a raster appear.

Before looking for more exotic things, I'd check very basic stuff. Did all of the tubes in the RF and IF and audio sections get put back into the right sockets? Even if they tested OK before, are they still lighting up? One of them might have decided to croak since you began. Are their pins clean and are they well seated in the sockets?

What about the mode switch (whatever switches between TV mode and radio, phono, etc.)? Contacts clean? Not burned up?

If you have a no-signal condition that affects both video & audio, possibly the problem's located somewhere between the antenna and the point where the audio signal is picked off. You could test voltages on those tubes (V1, V2, V3) and look for an obvious discrepancy like the one you found before. Sometimes those things jump out at you.

A couple of simple ideas to start, anyhow . . . .

Phil Nelson

[old_coot88]

Originally Posted by stusnyder

I tried every channel that was on it....nothing. So then I hooked up a vcr that has the channel 3 - 4 switch on it, again nothing....no sound or picture. If I turn the fine tuner I get some whine out of the speaker...At least some progress has been made on it.

Just for the heck of it, check to verify you've got B+ on the plates (pin 8) of all the 6AC7s. They're fed from the same point that was losing B+ to the vert.out stage, so there `might` still be a little booboo there somewhere.

[stusnyder]

Hi old coot88,
Seems like you know your way around this set. Here are my findings tonight:
tube 6au6 tested good, but the short light was flickering on my tester, so replaced the tube.
voltage readings on the 6ac7's
v13 pin 8 160 should be 115
v12 pin 8 140 " " 155
v3 pin 8 180 " " 137
----------------------------------------------------------------------------------

v13 pin 6 156 should be 170
v12 pin 6 143 " " 158
v3 pin 6 187 " " 157

I also found resister r7 crispy - crittered this is on v3 pin 6. It's suppose to be 3900 ohm reads 1.048 ohms. I also get humming thru the speaker when I start the vcr, it goes away when I stop the tape. I ordered resister kits thru justradios, should have them early next week.

[leadlike]

Oh, don't let voltages on the 6ac7 plates throw you off-when you turn the contrast control up and down, it changes them.

[stusnyder]

riders said test voltages at contrast min and brightness max.

[stusnyder]

ok I confirmed the b&k 1077 works by hooking it up to a known good tv.
What I did was inputted the video signal on the grid of v14 which is the video amp. I still get no pic on the screen. So then I put the video source right to the crt, and I get the black blanking bars. The only thing in between the two is v15b which is the dc restorer. I checked components in between and everything seems ok. Anybody got any ideas?

[noah300g]

I have been working on an 802 as well. I have good sound on Broadcast, FM, and TV sound (using a dvd player and RF modulator set to channel 3).
I have raster, but no video. I replaced 7F8 converter tube as it was shorted. All other IF and detector tubes test fine. I also have brightness and contrast, however the contrast control seems to also effect volume a bit on TV, which is strange.
Also, the entire picture area is a little bit smaller than the CRT. I kind of expected it to fill the whole area. is this a yoke position issue?
What else can I check for lack of video?
All Electrolytics and paper caps have been replaced.
I'm so close I can taste it, but just not quite there.

[noah300g]

I like the idea of applying video directly to the proper point in the video amplifier chain. It's easy to apply the audio to the volume control. If I could learn how to restore these sets to have just a video input and audio input from a dvd player and not worry about all the tuner RF and IF alignment, that would be great! Has anyone ever done this?
Thanks,

[Phil Nelson]

Yes, I just wrote an article about building an A/V adapter for my Admiral 24C15:

http://www.antiqueradio.org/A-V_Adap...VintageTVs.htm

That approach has some pros and cons, as discussed in the article.

The contrast control may affect audio because they're indirectly related through a bias circuit. This paragraph is from the end of the audio description in the Rider's manual:

"A low negative voltage derived from the output damping tube (V23) grid circuit is applied to the contrast control R108A and then to the grids of the i-f amplifier tubes V3 and V12. This is used to change bias on these tubes and therefore the video i-f gain."

The audio is picked off following V3, so the stronger the signal there, the stronger your audio.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html