Found a Sylvania SS/Tube hybrid

[Jon A.]

Originally Posted by Electronic M

Honestly, if you are wearing rubber soled shoes and not touching any metal that leads back to the chassis you could touch the HV lead with the set off and it would not be much worse than a static shock from shuffling your feet across the carpet and grabbing a door knob.....

Sounds like what happened to me after I aired a bad CRT in a console that had been running shortly before. Back then I had no HV probe. I got a small bite when reaching for a piece of glass dangling from the remains of the evac stem.

Anyway, no pain, no gain.

[MRX37]

Originally Posted by Electronic M

You should get an HV probe to use it to discharge the CRT, and confirm HV reg is adjusted properly once you get it going. If you use an HV probe, the CRT second anode should not 'recover' any voltage, and you get to see that it has discharged to a safe voltage. Just clip the ground lead of the probe to the chassis, hold probe by user handle stick the tip on it's far end under the HV suction cup or to the plate at the base of the HV rect tube if more convenient, and watch the needle jump and fade back to zero.

I might pick one up, when I can afford to do so. Right now I can't even afford a thermistor much less an HV probe.

And the rest of your post was unnecessary. You're talking to a guy who recently wrestled with the exhaust system on his truck for 12 hours before the damn parts would line up. I'm no stranger to working on vehicles, or the various injuries resulting from it. Any stripes that I needed to earn, buddy I earned them years ago and there's nothing cowardly about not wanting to risk 15 KV traveling through your body.

[Electronic M]

Originally Posted by MRX37

there's nothing cowardly about not wanting to risk 15 KV traveling through your body.

In my book there is, especially given the method your scarred of. The screw driver method was a safe and common technique among service techs for decades....I've even seen SS sets that have warnings not to use that method because the SS HV system was not built to take it. I've done the screw driver bit dozens upon dozens of times before and after I got an HV probe (surprisingly easy to miss-place for a 1' long stick). I've never been shocked doing it, even when the ground clip lead has slipped off the driver mid way through....Hell I've even used wood handled drivers once or twice. Only jolts I've taken are from anode recovery when reassembling (eventually realized that leaving the jug clipped to ground prevents even that), and once or twice forgetting to discharge the HV before removing the suction cup....That don't feel good, but I've gotten bit MUCH worse by 120VAC.

If you work on CRT TVs as a habit you WILL get bit by the HV or MEANER voltages/waveforms eventually, just a matter of time. And it's only spooky until it stops being an unknown experience.....Then it becomes more of a minor nuisance....Like dropping a heavy set on your foot or stubbing your toe (only the pain don't last nearly as long...5sec to 5 min tops), you cuss a bit and move on unphased.

[MRX37]

Let's agree to disagree then.

Anyway I'm hoping I'll get lucky and the set stopped being used early on because the diodes shorted. I see Sylvania tubes in the chassis, suggesting they're original and the set might be a low hour set.

My theory is somebody's grandmother bought it 40+ years ago, and they paid good money for it so they weren't about to throw it out, so it probably became a table to set knickknakks on until it was tossed.

[MRX37]

Thanks to a generous donation from Findem-Keepem, I received the diodes I needed. So now to replace them. Hmm... how to get at them without fully removing the chassis? That's a problem.

Fortunately I'm good at finding solutions to problems:



So here's my, er, less then elegant repair:


Not pretty but if it works that's all that matters.

So now to power it on, but first I need to do the following ritual, what I do every time before I plug in a TV that I've been working on. I connect it to my power strip with the kill switch ready, then I put my hands together and say the following:

"Please Lord, don't let this thing blow up!"

Here we go... the big moment. Shall I be joyous? or shall I be damned?

It's alive!..... barely.



So the HV comes up after about a minute or so and I see what looks like a very faint, very out of focus image. I noticed the brightness knob was maxed out, suggesting the previous owner had this issue as well.

My guess is the HV is very weak. I'll need an HV meter to be sure though. Wish I also had a CRT tester so I could see if the tube is shot.

EDIT: connected a DTV box. Tuner seems to be working. knobs are scratchy, to be expected. No horizontal hold, though I think vertical is stable... hard to tell with such a dim, out of focus image.

[MRX37]

So I was thinking... When I fixed that Motorola tube TV I had to clean the tube pins. So I just finished removing and cleaning each of the tubes in this TV... except the tube that that ceramic cup attaches to. I can't pull that one out.

Ran into a headscratcher looking for a tube that was labeled as being for HV regulation. diagram said it was locared where the flyback is... wait... what's that above the fly-- there it is!

So I pulled it out and saw that like the other tube, the connector on top was corroded. Might explain the faint blurry image. So I cleaned it up and put it back in. Let's see what happens.

Well, it helped slightly. Picture's a bit brighter. Still extremely blurry. Very low contrast.

[Marco-nix]

The CRT on a Sylvania are not tough !... i had 2 Sylvanias , both had a weak CRT and one of the 2 was shot.. i had them 10 years ago. Good luck with yours.

[Electronic M]

If there is a HV regulation control, note position so it can be returned then, and then try adjusting it for more brightness. If the HV reg heater is glowing rather bright then it is probably not working right and dragging down the HV....unplugging the top cap is an option to deal with that.

The cabinet is French Provincial style. It was a popular style in the 60's....I have an example and have seen many sets in that style.

[MRX37]

Could a weak video output tube also be causing the picture issue?

I had a look at it last night with the lights out, and far as I can tell, all the tubes glow, however the tube labeled as being for video output was glowing the weakest.

That tube appears to be original, or at least a very old Sylvania tube. I wonder if that can be used to provide a rough figure of the set's hours.

Some of the other tubes, including the one above the flyback are RCA branded.

[old_coot88]

Did you DeOxit those slide switches on the rear apron of the chassis?

BTW, there's usually a "one-way jaws" hold-down clamp preventing the HV regulator tube from being pulled out. To release it, you have to push down on both sides of the clamp while pulling the tube.

[MRX37]

Oh, no, I should probably try that.

And the HV regulator tube didn't have any jaws holding it in place.

[zeno]

From the pix the focus itself seems to be good.
There is a focus coil. You can adjust it to see if
it focuses best in range. If it goes to either end &
focus getting better but not good may be a bad
focus rectifier.
Seems to have good width so if its HV related its
probably the 6BK4 or 3CU3. If you pull the 3CU3
grab it at the cap end, you may get bit near the socket.
Also the big plate cap for the 6BK4 has HV on it until
discharged.
If HV is OK brite prob. could be adjustments, video problem,
boost problem or CRT.

73 Zeno

[MRX37]

I just had the set on, lifted the flyback cage door and did not see a glow from the tube that it plugs into.

Also cleaned all the switches, no effect.

[zeno]

HV rectifiers often dont light. they just need a little heat
to emit. Usually a weak rectifier causes "blooming".
As you turn up the brightness the pix expands like zooming,
the brite drops & the focus gets worse. HV regulation can do it to but not
as bad. For now try this.
Turn up the R, G, & B screen ( G-2 ) controls one at a time then
return them to where they were. You should get a brite pix
from each one. The CRT is magnetized so the colors will be blotchy.

73 Zeno

Originally Posted by MRX37

I just had the set on, lifted the flyback cage door and did not see a glow from the tube that it plugs into.

Also cleaned all the switches, no effect.

[MRX37]

All three screen controls were turned fully clockwise. Whoever worked on this set before me must have tried this.

Setting them to about the halfway point produced no change in the image. Turning one fully up or down produced no change in the image. The screen controls do nothing noticeable.