ge 802

[stusnyder]

Just got done recapping my ge 802 AM FM TV Phono, radio works fine, TV has a raster. Next step is to try to get a pic on it. Was thinking about trying to hook up a vcr to it. Are all vcr's analog?
I have a leader lcg-388 color bar pattern generator I picked up years ago, but could never figure out how to use it. Anybody know if this can be used on a b/w tv?

[bandersen]

You need a device that can output RF modulated video on channels 2-13.
Most VCRs can do 3 or 4. The LCG-388 should be usable too.

You may also need a 75-300 balun to convert from a 75 ohm coax type connector to the 300 ohm antenna spade terminals on the 802.

[stusnyder]

I tried hooking up the leader lgc-388 and got nothing. Before I recapped this set, all I would get on this set is a 3/4 inch wide band across the pic tube. Since recapping, nothing changed in the tv dept.
So from reading on here, it's something with the vertical. Any suggestions where to start or what to look for? This is the first vintage tv I have worked on. Got radio experience, but not tv.

[Phil Nelson]

The white band across the screen usually means that you have insufficient vertical deflection.

You are using a schematic, right? The problem is in the circuits labeled vertical.

It sounds like you recapped the TV, so the first thing I'd do is re-check your work in the vertical circuits. You may have miswired a cap or installed one of the wrong value or pushed aside some other component so that it makes a short circuit or left behind a solder blob that makes a short circuit.

If the schematic has voltage and resistance charts, you can check the voltages and resistances on the vertical tubes. If anything is way off, you may have found the trouble spot.

If the schematic includes oscilloscope waveforms, you can hook up an oscilloscope and compare the waveforms that your TV is generating at the designed test points. If the ideal waveform is a sawtooth and your TV is making a flat line or some mutant shape, not a good sign.

You can check the values of the resistors in those circuits. The best way is to unsolder one leg of the resistor so there is nothing else connected in parallel with it.

If you don't disconnect the resistor for testing, then measuring a value significantly more than 20% above the listed value is often grounds for replacing it. However, if it tests below the listed value, then you are just measuring its resistance reduced by whatever other things are wired in parallel with it, so the test doesn't tell you much.

If the vertical circuits have any mica caps, those are worth checking. Micas are usually more reliable than paper caps, but they can go bad.

This is just general advice. Someone with the schematic could be more specific, perhaps.

Don't run the TV for long periods when it's showing a bright band across the screen. It may burn a band in the picture tube.

I have a Leader pattern generator that gives output on either channel 5 or 6. There's a switch on the front labeled RF Channel, 5, 6.

Phil Nelson

[stusnyder]

Well I figured out the leader...tried it on a old tv that I had that that still works.
Anyway I did check for stuff touching, shorts, ect. Since it does the same thing as before the recap, that tells me other components. I guess checking resistors are next, although there are a number of "domino dot" caps in the unit. Found a weak 1b3 tube and put in a good one, but same results

[stusnyder]

Found like 5 resistors that are off spec in the vertical section, going to replace them and see what happens.

[bandersen]

Here's a schematic and socket voltage chart I scanned: http://www.bobandersen.com/images/schematics/ge/802/

Does adjusting the height control (R49) have any effect ? There are 3 electrolytics (C27B, C27C & C27D) around V19 and V20. I'd double check the polarity on the replacements you put in. Also try swapping V20 with another 6V6 like V8.

[stusnyder]

Hi Bob,
the height goes from a thin line to about 3/4 inch wide using said control. I can clearly see lines in that band.
All the e caps have been replaced, and I checked polarity.
I will check out the tubes, but I should replace those off resistors first.

[stusnyder]

Ok I replaced some off spec resistors, measured the voltages at the vertical tubes, here are the results:

v19 6sn7gt

pin 2 21.6v should be 14v
5 2.7 " " 7
4 -6.9 " " -1.05
3 0 " " 0
6 0 " " 0
1 -192 " " -.45
---------------------------------------------------
v20 6v6
pin 3 11.6 should be 200

4 56.7 " " 215
8 5.9 " " 24
5 2.7 " " 7
---------------------------------------------------
v18 6sl7gt
pin 2 117 should be .18
5 115 " " 108
3 3.2 " " 7
6 10.3 " " 9.2
1 119 .18
4 8.5 " " 3
---------------------------------------------------
v17 6sl7gt
pin 2 -3.4 should be -6.4
5 53.3 " " 40.7
3 120 " " .15
6 .62 " " .68
4 117 " " .15
1 -3.4 " " .18
---------------------------------------------------
All above tubes test to at least 80%
I got this data from riders...no idea where to go from here...this thing is kicking my ass.....any suggestions?

[old_coot88]

Hokay, now we're cookin'. It looks like the plate and screen voltages on your 6V6 (pins 3 and 4) are 'waaay low. Check voltage at the red lead of the vert.out transformer. It should be over 200V. If it's low, check the 680 ohm resistor R51, and keep tracing back through choke L21.
Bill(oc)

[leadlike]

On the 802 I worked on, it was tough to get good vertical deflection. Most of the components in that section were toast, and even then, the picture only filled 75% of the screen, and would shrink a little as the set warmed up. I tried a couple of different 6V6s (all tested as good, including the one original to the set), and a new one filled the screen right up.

[old_coot88]

Originally Posted by leadlike

On the 802 I worked on, it was tough to get good vertical deflection. Most of the components in that section were toast, and even then, the picture only filled 75% of the screen, and would shrink a little as the set warmed up.

Whenever there's an electrolytic on the cathode of the v.out stage (which there is in the set under discussion), if the cap goes wonky it will cause insufficient sweep, usually accompanied by bad linearity.

Also (worth bookmarking), a very common problem is the plate load resistor of the v.oscillator which goes high in value over time. That's because it's constantly being hammered by a high level pulse.
Bill(oc)

[stusnyder]

I found it with your help. Stupid me forgot to move the transformer wire off the old can e cap to the new lead. I got over 300 volts coming out of the transformer.I got a full screen now, and stability, but still not getting a signal from my leader pattern generator.
I had it hooked up to a old portable, so I know it works. Maybe it won't work on a set this old?

[Phil Nelson]

If the pattern generator worked with a new TV connected to the antenna terminals, it should work with this one and the same hookup.

Is this TV tuned to the correct channel?

Phil

[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.