1971 Philco color Tube Hybrid - Page 4 - Videokarma.org TV - Video

Lain94 · #1 08-02-2023, 09:46 PM

I looked over all the connections and sure enough one of the wire going to the flyback from the chassis was on post X when it should have been on post 9. I am not entirely surprised that I made the mistake though since I was probably tired when I was working on it. All the other wires though are as they should be. I did another inspection of the whole chassis to look for any other potential issues. I noticed the socket where the thermistor and degaussing coil plug into the chassis is VERY loose and questionable. The pins were basically floating up and down and had way too much give making a possible connection issue where one or two of the four pins may not have been making good contact if any at all.

I was not always turning the tv on with the degausser plugged in (usually not) The last time I know I didn't because I did not want the degausser to be a potential issue at this time. Aside from that I saw no apparent connection issues, but I find it concerning how Ford Philco had sloppily wound wires onto posts and how easily bent many posts also were. It is not a surprise to me that this tv has numerous electrical problem despite being low hours for its age.

I corrected the wiring mistake I made on the flyback and will be conducting another test soon to observe cautiously for any other signs of trouble. Any recommendations on where to set horizontal bias control or any of the other controls for initial setup? Service mode vs normal? ect. I have a HV probe to check HV but a bit nervous about doing it and getting zapped. Can I use the oldschool RCA HV probe I have with a standard multimeter safely?

Lain94 · #2 08-03-2023, 12:20 PM

Good/Better news: Circuit breaker had tripped for the low voltage circuit protection I realized when I tried turning the tv on again, which mean the breaker did its job correctly! I reset it and after testing the tv again I for the first time ever was able to get as as far as seeing ANYTHING on the screen including vertical deflection with no trouble. Solid state audio circuit still working fine as well. However a few moments after vertical deflection was achieved the CRT seemed VERY bright almost like HV was way too high, and elecricity was going all over the inside of the CRT and (possibly outside and arcing over to one of the terminals of the focus divider before a surge of electricity or current made it way from the flyback to the 6KD6 horizonal output tube tip which was very visible and a bright brief glow happened before going back to looking normal. Nonetheless I quickly turned the tv off as soon as I heard the audible arcing. I was stunned at how bright the CRT was, I knew it was good on emissions and lowish hour but that was the brightest CRT in a hybrid or full tube set I have encountered so far.

My possible suspects of this issue are: The HV anode was somehow not on firmly enough, carbon tracing around the HV anode due to dirt or dust? Bad Focus divider? Yoke seems to be ok. I did not smell or see anything that was suggesting any shorts. I did not screw in the chasses to the wooden cabinet as I had grown tired of doing that only to have to take it out over and over so the focus divider may have been too close to the CRT aquadag and encourage an arc that way?

While I am not out of the woods yet with this tv's troubles, I am able to run the tv to the point now where I get visible static on the tv, sounds of static, a raster line and then vertical deflection! A good morale boost for me considering how much I have had to fight this tv.

Pics of this issue and situation: https://imgur.com/a/2ccF0ux

Electronic M · #3 08-04-2023, 01:42 PM

A few things. Did you connect the CRT day grounding to the chassis? In most sets there's either cabinet provisions to do that whe the chassis is bolted in or a separate wire....If the chassis is out and you don't run your own wire the CRT day ground can arc to the chassis and or yoke.

If your HV isn't too high (measure it to confirm) it could be your screens (G2) are too high...I've seen those set ridiculously high by previous owner morons before.

Lain94 · #4 08-05-2023, 11:39 PM

Issue resolved, It appears the aquadag of the CRT was not making good contact with chasiss which is ground. Also set horizontal bias to roughly mid position. TV is now working with no apparent arcing, sound is solid state on this tv and functions as it should, tuning also seems ok although I kind of dislike AFT this tv has, there is a way to disable it which I may end up doing.

There seems to be some sort of issue with the color not syncing up, is it almost like it is out of phase. Barber poll pattern of colors. Also need to adjust vertical linearity and horizontal size a bit.

I had the tv on for an hour when I was testing it and seeing what controls were responsive. Tint and color killer all seem to do little to nothing. Color intensity works but only makes the barber poll pattern of colors become more intense.

https://imgur.com/a/KUJj5Fy

Electronic M · #5 08-06-2023, 07:44 PM

If the chroma osc is not in sync and the set is barber-poling then tint won't do anything noticable.

Color killer is basically a unimportant nicety....It suppresses color in snow when no signal is applied. It used to mute color on monochrome shows improving the viewing experience by sensing the absence of color burst, but since the 80s or 90s virtually all TV stations and signal sources run the color burst constantly even if the show is monochrome...So in essence unless the color killer is preventing a color show from displaying color it's the appendix circuit of the TV.

There should be a color osc/AFC adjustment procedure in Sam's...Follow it and your tint should work and good color should be achievable.

Lain94 · #6 09-04-2023, 08:18 PM

Update: I am still having the same issue with the color being out of sync and causing a barber poll pattern. I measured the base of Q95 Burst Amp Transistor in circuit with an oscilloscope. Should be 7V along with a certain waveform pattern but is measuring way higher like closer to 45v or so and the waveform also dose not match up. I am beginning to wonder if the transistor is leaky or some other transistor or IC is causing issues.

https://imgur.com/a/3nX50qh

old_tv_nut · #7 09-04-2023, 10:18 PM

Posting a schematic would help. Since you changed the flyback, there's a possibility you have a wrong/bad connection for a burst gate pulse from the flyback causing your lack of color sync.

Lain94 · #8 09-17-2023, 10:57 AM

Here are some photos of the schematic, I have used my oscilloscope to check various points, so far I have concluded the burst amp transistor is ok as well as the 3.58mhz oscillator IC based on the waveforms I got. I am suspecting a bad or out of tolerance crystal at this point and already ordered a replacement one of the appropriate case size and power rating. We will see if that resolves this color being out of sync.

https://imgur.com/a/ZgjkHZm

old_tv_nut · #9 09-17-2023, 11:41 AM

If the oscillator is running but won't sync, I suspect the crystal is OK and something else is wrong. It appears that D98 (or D96, hard to read) (between R124 and the IC) is a varactor diode used to control the oscillator frequency. I would check it out.

old_tv_nut · #10 09-22-2023, 02:17 PM

Have you checked the diode? I'd like to know if my guess was wrong or not.

Lain94 · #11 10-03-2023, 04:59 PM

Diode will be checked next, crystal replaced and issue persists albeit not as severe. I am thinking this could be simply a matter of adjusting the 3.58mhz oscillator inductor.

old_tv_nut · #12 10-03-2023, 05:09 PM

Quote:

Originally Posted by Lain94

Diode will be checked next, crystal replaced and issue persists albeit not as severe. I am thinking this could be simply a matter of adjusting the 3.58mhz oscillator inductor.

You mean you haven't tried adjusting it yet?

Lain94 · #13 03-21-2024, 02:28 PM

Quote:

Originally Posted by old_tv_nut

You mean you haven't tried adjusting it yet?

I later ended up trying to adjust it but to no avail, all it seems to change is whether or not the rainbow barber polls pattern is in motion or not. I will be revisiting this project soon as I had to put a lot of things on hiatus last year but will be going on a marathon of sorts later this summer and I am aiming to get the Ford Philco color sync issue resolved hopefully soon.

old_tv_nut · #14 10-03-2023, 05:20 PM

Does the service info give an adjustment procedure? It looks to me like there is a tuned output transformer that may or may not have much effect on the oscillator frequency depending on wha the internal IC output circuit is. Is that coil mentioned in the procedure?

Lain94 · #15 03-21-2024, 02:29 PM

Quote:

Originally Posted by old_tv_nut

Does the service info give an adjustment procedure? It looks to me like there is a tuned output transformer that may or may not have much effect on the oscillator frequency depending on wha the internal IC output circuit is. Is that coil mentioned in the procedure?

From what I have been able to deduce there is a varactor that is controlling and automatically adjusting the oscillator frequency in parallel with the oscillator itself.