Hey everyone. I haven't posted in a while and during that time I forgot my old user name, so I had to create a new one.

Anyway, to fill you in, I've been restoring a 1955 Zenith Flash-Matic television.

I'm pretty new to the whole tv restoration and many of you veterans told me not to undertake the flash-matic until I've got my bearings. But like an unruly kid, I do it anyway...

I've done a complete re-cap. After the recap, I got a grey screen, but no sound. I double checked my connections and found a wire wrapped resistor that had a broken lead. I soldered that back and tested again. This time, I got sound but the CRT was dead. I checked all of my connections again and double checked the Electrolytics as well to make sure I did those right.

The last time I left here, you guys were mentioning that I need to check to see if it's getting high voltage. Well, long story short, I had to put the tv away while I focused on some other things. I got the itch again and now it's back out. I tested it once again and have the same result. A dead CRT with sound.

I proceeded to test for high voltage. I loosened the cap on the high voltage tube inside the cage and powered up the tv. I touched a screwdriver tip to the exposed part and got nothing. No spark. So now that tells me I'm not getting any high voltage from this tube.

So, I am now asking for you guys to help me troubleshoot what the possible causes and possible fixes may be.

Thanks!

Tim J.

No high voltage can be caused by many things. You need to test all DC voltages in the high voltage and horizontal circuits.

It seems to me that there is a bad connection somewhere, because you had high voltage, then it went away. I suggest you pull the chassis and check.

Most TV sets had a B+ fuse in the damper or horizontal output circuit; check that first. Also, Zenith used sand-covered wirewound resistors back then, which had a tendency to corrode and open up. If your set uses them, check them all.

Horizontal output tubes and damper tubes can develop shorts under load, often intermittent. If you do find a fuse that is blown and the set works after replacing it, you may have an intermittent short. With the set running, gently tap the damper and horizontal output tube with something like a piece of wood. It the tube flashes when you do that, you need to replace the tube.

Tim, which tube did you do this to?

You can test at the cap of the Horizontal Output tube, and the cap of the 1B3 but they are different.

For the HO tube you have to leave it connected, touch the tube connector with an ungrounded (but insulated handle) screwdriver, you should get a small arc from it.

For the 1B3 you can check it with it disconnected but you check for the arc at the wire from the Flyback, not at the tube.
You can also check it while connected however if the 1B3 or anything after it is shorted it could kill the voltage.

By the way, if you get nothing from the top of the HO tube then your Horiz Oscillator is likely not running.

Thanks everyone for your kindly assistance.

I'm sorry I haven't been able to give an update, but here goes.

I was wondering if the fuse might be at fault even though it appeared normal. So I went and bought some replacements. I installed one and turned on the set.

It warmed up as usual, except for a few distinct differences this time. One, the Horizonal Oscillator tube (the one outside the cage) had a lit filament that it did not before. And two, I heard the CRT 'ignite' or power on. The soft static sizzle that it makes when it comes on. A new fuse seems to have cured the high voltage issue, but I still have a dead screen. No grey no snow no nothing. So now, I'm asking for opinions on what I should troubleshoot next.

Thanks for everyone's input. I appreciate it!

Tim J.

Turn the lights out and see if the CRT filament is lit.

What model is this TV?

The CRT filament does glow. If I'm right, the filament is at the base of the CRT. If so, it does glow.

The tv is a 1955 Zenith model X2365RQ with the 22X20Q chassis. This is the 'Flash-Matic'.

Thanks

Tim J.

If you have high voltage and the CRT is good, and the screen does not light, then you have a video problem. You need to have about 75 volts on the cathode of the CRT, which is pin 11.

Can you test high voltage? Do you have an oscilloscope?

I'm certain the CRT is good as I had a grey screen at one time.

I do not have a high voltage tester or an oscilloscope. All I have is your standard multi-meter.

Thanks!

Tim J.

You can do this as a very general test: Power up the TV, then shut it off, then slip a grounded screwdriver under the anode cap. You should get an arc. It won't be very large, but should be there.

Next, get a long non-metallic screwdriver or wooden dowel and tape a neon lamp to the end (like a ne-2). When the TV is operating hold the neon lamp near the flyback in different locations. You should see it glow at different points. If not, the flyback is not working.

You can also, carefully, hold a metallic screwdriver near the metal plate cap of the horizontal output tube. DON'T have your hand near the metal. You should see some arcing. If there is no arcing, the horizontal output stage is not working; you have no horizontal drive or no B+. Note: you may have a plastic cap on the horizontal plate and may not get any arcing.

If the horizontal circuit seems to be working, but there seems to be no high voltage, you might check the 3.3 ohm resistor at the filament of the 1B3.

Hey everyone,

Well I tried one of the tests mentioned above. I turned the set on for a minute, then off. I stuck my grounded screwdriver under the anode cap and got a spark! I would assume that's a good thing.

I haven't tried the neon bulb thing yet as I don't have any bulbs but I will be getting some so I'll try that.

Thanks and keep 'em coming! I truly appreciate it!

Tim Jones

The test with the neon bulb will tell you if you have high voltage AC at the plate of the high voltage rectifier. That test is most useful if you either do not have high voltage DC at the CRT or don't know if you do (sometimes the anode cap is hard to get to and sometimes it will self discharge faster than you can get a grounded screwdriver near it). Since you did get an arc you have to have at least some high voltage AC, so the neon bulb test is somewhat redundant.

I assume that your CRT is new enough to not need an ion trap, so a mis-adjusted ion trap would not be the problem.

Try measuring the voltages at the CRT socket and compare them to the values given in the Sams. If you do not have the Sams, take the readings and post them here. In general you need several hundred volts on the second grid of the CRT and the cathode needs to be less than something like 30 volts positive relative to the first grid.

I have an update.

My chassis does indeed have an ion trap. I powered up the set, and slowly adjusted the magnet and EUREKA! A nice bright screen!

It's just a grey screen as it was before, but I think it's a big step!

For a SPLIT SECOND while I was adjusting the vertical and horizontal knobs, I had snow for the first time since I've been repairing the set. I was unable to get it back.

As far as sound, I hooked it up to the speakers and I get white noise prior to the CRT 'igniting'. Once it comes on with a grey screen, no sound.

I hooked up a VCR to test this, and no sound. I had sound before the dead CRT issue.

I cycled through the channel selector and would get some white noise intermittently between a couple of channels but that is all.

So I guess this is the next step.

Thanks for your continuing help! I appreciate it!

Tim J.

You need to clean the tuner thoroughly. Don't adjust anything in the IF or tuner (except the fine tuning). Tuner and IF tubes need to test good or you can have a serious degradation of the picture. Test your tuner B+ voltages.

All of the tubes in the IF section and tuner test good.

Is there a specific product you recommend cleaning the tuner with? Or is there a specific way I should go about it?

There doesn't seem to be any easy access to the inner workings of this tuner, so I'll have to see how I can open it up and get a good look.

Thanks

Tim J.

I use Deoxit for tuners. The tuner will have a shield that comes off; some have screws, some don't. I think your tuner is mounted above the chassis; you may want to pull the tuner assembly from the cabinet to work on it. You will be able to clean the other controls then.

The tuner assembly is separate and I have everything out of the cabinet and on the table for easy access.

I will be checking this out soon.

Thanks

Tim J.

You may also have some tube sockets that need to be cleaned. You mentioned a tube that was not lit until you changed the fuse. A bad fuse hardly ever will cause the filament to not light. Quite possibly you slightly bumped the tube and shifted it enough to cause it to now make contact.

Along those lines, you could try gently wiggling the tubes in the tuner and IF strip and see if wiggling any makes any difference. If you wiggle one and get the snow back, that is at least one socket that needs to be cleaned.

And here is another vote for Deoxit. It is made by Caig laboratories.