1971 Philco color Tube Hybrid - Page 2 - Videokarma.org TV - Video

Lain94 · #1 08-17-2022, 03:03 PM

Quote:

Originally Posted by Electronic M

Clean it with rubbing alcohol or goof off, file or scrape off any remaining carbonization of the material, apply some silicone over the arc point and let it cure.

It sounds like a good plan. I also am getting a product called "Super Corona Dope" apparantly it is a product meant for very high voltage stuff like what I am working with.

Lain94 · #2 09-04-2022, 03:47 PM

Ok well, I cleaned up the connector, the plastic nipple cup for the HV tube, applied the corona dope generously ect. But still having the same issue of arcing in the HV metal box. To be fair I did not directly witness it, only saw the flashing coming out from the translucent plastic tube holder for the HV rect tube 3DC3 which hangs upside down weirdly.

Flyback physically looks fine but I am starting to wonder if the damper and/or the hv rect tube are bad as well. I read the damper tube if bad can actually kill the horizontal output tube too. The first tube that was arcing internally was the horizonal output tube which i replaced with a NOS one and that issue had went away which is when this new issue has started.

Any overt signs to look for with a bad damper or HV rect. It is just weird to me why it is arcing still. Would it be worth getting a known good damper and HV rect. tube and swapping just to see what happens?

The arcing seems to happen within seconds of the tv being turned on. All tubes do glow.

old_tv_nut · #3 09-04-2022, 04:22 PM

Apparently you cleaned and insulated to cap connector, but didn't do anything around the base of the tube? If that's correct, do an inspection of the base for problems.

zeno · #4 09-04-2022, 05:37 PM

Take the whole thing apart. Clean the cup, socket, wires with 91% alky.
Look for pin holes & carbon traces on the cup. Check the filament
winding also. It is at full HV potential & a common place to arc.
Last be sure the HV is in spec. If it runs high it will start arcing
soon again & cause other headaches.

73 Zeno

LFOD !

Lain94 · #5 09-05-2022, 01:32 AM

Quote:

Originally Posted by zeno

Take the whole thing apart. Clean the cup, socket, wires with 91% alky.
Look for pin holes & carbon traces on the cup. Check the filament
winding also. It is at full HV potential & a common place to arc.
Last be sure the HV is in spec. If it runs high it will start arcing
soon again & cause other headaches.

73 Zeno

LFOD !

I think the arcing is actually happening where the wires go into the plastic tube socket as shown in a screen shot of the issue occurring. Any tips on how to open it up? The plastic base is riveted onto the metal cage and the top cover of the plastic socket might be glued in. Not sure how to get it off.

Also what in the heck is this bare copper wire that is dangling from the side of the HV box?

https://imgur.com/a/aD58QCV

zeno · #6 09-05-2022, 07:49 AM

Wire looks like its to dress the wire bundle, yoke wires ?
Top cap should pop off.
Cup would need to be drilled off. Do last if needed.
Try removing the cover & running it in a blacked out room to see arc.
Set has a focus divider, white block behind the cage. Those can
crack & arc.

Zeno

Lain94 · #7 09-08-2022, 10:34 PM

Quote:

Originally Posted by zeno

Wire looks like its to dress the wire bundle, yoke wires ?
Top cap should pop off.
Cup would need to be drilled off. Do last if needed.
Try removing the cover & running it in a blacked out room to see arc.
Set has a focus divider, white block behind the cage. Those can
crack & arc.

Zeno

I removed the top plastic cap to see the pins where the red and white wires go. First I hear the high pitched CRT whine seconds after powering it on. Then the arcing starts. The arcing is still happening and clearly is jumping between the red and wires across the pins they connect to. Also there appears to be a second spark happening right after the first bright one which is seen flying off bottom part of the metal chassis (near the HV metal box perhaps)

https://imgur.com/a/UgnZ2GO

Electronic M · #8 12-15-2022, 10:58 AM

I can't really tell what it is. If you think it's metal then it probably is a danger. If it looks like glass or mica wafer (insulator materials) I usually keep running the tube...A chunck of insulator won't hurt anything, but a conductor can short things.

Lain94 · #9 12-27-2022, 10:45 AM

A bit of a minor update but it is good news in regards to the CRT. I recently acquired my first CRT tester. It is a Sencore CR 161. From what I have heard online, Sencore is a trustworthy brand. After reading the instructions and manual, I quickly learned how to use the tester.

I tested the Ford Philco tv's picture tube at the normal 6.3 volts and all three color gun's emissions were GOOD! Also no shorts in the CRT were detected by the tester which rules out the CRT being the cause of the arcing I had been seeing in the HV cup area.

So it appears that I have a picture tube that is in great shape and with plenty of life left.

Electronic M · #10 12-27-2022, 01:02 PM

That's good. I would check other tubes of known working and non-working status to make sure the tester is telling you the truth. I've bought sets at the ETF where someone tested the tube good and it was very bad and tubes where they tested the tube bad and it was good.
It probably is good, but testers can lie to you so get a feel of it on multiple tubes of known performance to be completely sure, and get a better feel for your new tester.

Lain94 · #11 02-05-2023, 11:18 PM

I finally got around to taking the whole chassis and tuner out of the tv. Cleaned up the wooden cabinet. Checked all the diodes on the tv, all diodes tested good. I am now recapping all the capacitors that are known to be bad. Mostly the bad ones were small low value electrolytic ones on the pcb board. A bit annoying to get into the tight spaces on the board. I much prefer working with point to point wiring.

Flyback seems to test ok based on measured ohm values via a multimeter and comparing to the schematic. Will be cleaning up the high voltage cup more thoroughly this time to make sure no carbon tracing happens, if necessary a Dremel will be used.

Replacing a burnt out 6.3Volt incandescent bulb that illuminates the tuner.

In summary:
Flyback good, capacitors that tested bad are being recapped to rule those out, diodes all tested good, CRT is in great shape, and cleaning the HV cup again in hopes of stopping the arcing that keeps happening within seconds of powering on the tv.

Replacing a burnt out 6.3Volt incandescent bulb that illuminates the tuner.

Also, I now have a NOS vintage RCA high voltage probe, so I can now test what actual voltage is coming to the CRT. A bit nervous using this as I have never done so before.

Question:
Is it possible that the sole/original cause of the arcing was a bad doubler or tripler? There is a white box on the back of the high voltage cage that is believe is a doubler or tripler. Also perhaps the voltage is set too high on the potentiometer that sets it?

A theory I had was that as the emissions performance from the old Horizontal tube had declined, the knob that upped the voltage output was turned up to compensate...until the horizontal tube finally had failed and went to air. Now with the new horizontal tube in it the voltage is too high at current setting.

https://imgur.com/a/Wqq1s8l

zeno · #12 02-06-2023, 09:34 AM

Most likely the box is a focus divider. They can arc. Its a like 300 meg resistor
that drops the HV to abt 6 HV for focus.
Never trust testers 100%. Most common mistake they make is it can
read bad but still be a good pix.
With HV probe just be sure you have a solid ground & touch the probe
right to the button. Sometimes when you lift the rubber you will get
an arc & hissing. Not to worry.

Zeno

Electronic M · #13 02-06-2023, 12:33 PM

If it uses a 6BK4 shunt regulator tube then turning the HV up actually reduces load/strain on the H output tube...A 6BK4 acts like a CRT but essentially conducts harder when the CRT goes dark to try and keep the load relatively constant.

Pulse regulator tubes 6HV5 work the opposite way... Instead of loading down the flyback output they modulate the bias of the output tube so the input sent to the flyback matches the power level it needs to maintain stable output.

Both circuits monitor the B+ Boost line as boost voltage is a good indicator of the load demands on the flyback/the sweep width and HV level...So if you hold boost constant you should get constant HV and deflection levels.

Lain94 · #14 06-01-2023, 12:02 PM

Any idea what type of diode this is? I am having trouble identifying it. I have to replace it because the leads are too short to solder it back in safely.

https://imgur.com/a/nCO9EfE

Electronic M · #15 06-01-2023, 12:23 PM

Looks like a silicone diode. If it's one of the power supply rectifier diodes that are fed 60Hz from the transformer then you really only need to know 2 specifications of the original to replace it with a modern part. Those specifications are PIV (peak inverse voltage) and current rating, and make sure the new part has those numbers as high or higher.
For power supply rectifiers I stock 2 types that can handle everything....1N4007 (1A, 1KV PIV) and a 1N51?? that's rated for 3A 1KV PIV....The higher current part is pretty much never necessary, but anything over .75A I try to use it for so I'm not running the 1A part too close to it's rating.

In convergence and detector diode applications switching time, junction drop, and capacitance become more important.

Boost and focus/HV applications are pretty much the same as B+ rects but with faster switching time requirements.