Hello all, I got a free Chromacolor II today that I need a bit of help with. The tv powers on but there is no picture at all. The tube lights up in the neck but displays nothing but darkness. I was told the tv worked fine in 2010 before being stored in a closet, so I was guessing a cap issue.

My thing is I just do not know where to start with tvs since I mostly do vintage audio. Any help is really appreciated.

Got the right voltage of HV? Got a schematic to check electron gun voltages against?

Actually I got this thing going. The screen was pitch black so I looked on the boards for something with a light or brightness label. I found a "low level luminescence" board and found a bad cap along with a few bad joints along some sort of long white component with many legs. All of this was done in my mobile shop (A Volvo 240) in maybe 30 minuites. So if anyone else has this issue don't worry too much.

Replaced the cap and re soldered the joints, and the tv is back alive (for now anyways). I guess I should have waited to make a thread, but sometimes it's nice to know where to look first.

Thanks!

Very nice work. The long white pkg is a resistor pack. They were made in Littleton, Ma. just 2 miles from my shop ! Anyhows whenever one
came in that was a "must check" problem even if there was no brite
complaint. Whenever you see them on any Zenith board check the
connections. They get hot & get cold joints.

73 Zeno
LFOD !

This set is actually mine now, I thought about starting a new thread to avoid confusion but there's no sense in having multiple threads on the same set. Sealtest is welcome to take over my thread on the TV I traded him.

Now,on to why I'm here. This set has one minor issue that I'd like to fix. It's constantly got snow like it's an over the air signal even when I feed it a signal. I have heard that CCII sets have a fantastic picture but so far my 16" system 3 impresses me more than this 23" CCII.

And the horizontal just died after watching a few hours of tv.

Here's what it does

Depending on the exact chassis check the 330 ohm resistor
on the bottom left of the 9-90 horz board. Replace with a
1 watt flameproof.

For snow try the RF AGC on 9-87 board. With a STRONG signal
adjust til the snow JUST clears up & you have no jitter.

As far as the S3 looking better it has an EFL CRT & will be brighter
& sharper. It may also have a comb filter which makes a huge
difference in resolution.

73 Zeno:smoke:
LFOD !

This set is actually mine now, I thought about starting a new thread to avoid confusion but there's no sense in having multiple threads on the same set. Sealtest is welcome to take over my thread on the TV I traded him.

Now,on to why I'm here. This set has one minor issue that I'd like to fix. It's constantly got snow like it's an over the air signal even when I feed it a signal. I have heard that CCII sets have a fantastic picture but so far my 16" system 3 impresses me more than this 23" CCII.

I know exactly what you mean about the snow. I just got a 17" remote Chromacolor II set with an extremely bad snow problem that I'd like to clean up and get going. Snow in the picture is one thing that I will NOT tolerate on an old set. I want it Krystal clear.

Board is a 9-90-02c "horizontal apc and osc" I'm not seeing any toasty resistors and I don't see a 330ohm one.

Board is a 9-90-02c "horizontal apc and osc" I'm not seeing any toasty resistors and I don't see a 330ohm one.

The -02 is a redesign. IIRC had an IC & a horz hold pot. There still may
be a horz osc coil mounted along the bottom of the chassis. It may
be against its stop. If so pull out on the outer sleeve & turn it beyond
the stop.
The other slim chance is the 9-87 board. It has the sync sep & AGC
coming from it & may cause the snow also. BUT no horz sync causes a slow
sideways roll not diagonal lines as a rule.

73 Zeno:smoke:
LFOD !

That's the thing. It played fine for around 2 hours watching TV and then the horizontal hold went off instantly with a small pop. This thing makes some interesting noises on power up I might record for you.

https://youtu.be/6APtYKvBQrs

I know it's simple but I'll ask anyway: all the connections coming in to the tuner are in good shape? Once, maybe twice now, I've had a bad 75-300 converter cause this, too.

Noise at turn on just the degausser. I would look in the 9-87 area.
It just dont look like the horz is off. Looks more AGC or video prob.
One long shot. These usually have the selector, two tuners & a
tuning control board. Tilt the chassis down & resolder the control
board under the connectors. If it has one big tuner resolder the tuner
under the connectors also.
BTW whats the chassis number? 23?C45 ?

73 Zeno:smoke:
LFOD !

...

I'm not sure if Zenith did it, but some of those early solid state sets would throw the horizontal frequency way off if the HV went too high. It's worth checking the HV if you can.

Zenith never used that HVSD scheme. Off hand I remember RCA,
Hitachi, Panasonic using it. The Zenith CC2 & flat chassii had NO HVSD
circuits. The dept of HEW approved both the S caps in parallel & the
4 lead caps for X-ray protection. Most mfg's both US & Jap in the mid 70's on their top of line sets copied the Zenith fero-resonance supply & cap
arrangement some without HVSD. Looking back Zenith & Maggy regret not
having HVSD:tears:

73 Zeno:smoke:
LFOD !

Zenith never used that HVSD scheme. Off hand I remember RCA,
Hitachi, Panasonic using it. The Zenith CC2 & flat chassii had NO HVSD
circuits. The dept of HEW approved both the S caps in parallel & the
4 lead caps for X-ray protection. Most mfg's both US & Jap in the mid 70's on their top of line sets copied the Zenith fero-resonance supply & cap
arrangement some without HVSD. Looking back Zenith & Maggy regret not
having HVSD:tears:

73 Zeno:smoke:
LFOD !
That being said, am I correct in assuming that my Heathkit GR-2000, with its RCA-design SCR sweep also uses this HVSD scheme? I can't keep horizontal locked on that thing and when it goes askew a transformer on the horizontal out board makes an arcing noise.

Look for a bad 20-30 volt zener in the "x-ray protect" circut.

That being said, am I correct in assuming that my Heathkit GR-2000, with its RCA-design SCR sweep also uses this HVSD scheme? I can't keep horizontal locked on that thing and when it goes askew a transformer on the horizontal out board makes an arcing noise.

Easy test is put it on your variac & turn down the voltage. If it clears
up its either too much HV or a fail in the HVSD. The ones I remember
were the 19" delta tube sets. A shorted pass transistor was almost always
the culprit. This chassis IIRC was only in 19" & didnt use SCR's. Twas
my favorite 1970's RCA.

BTW Maggy can be added to the list. IIRC it was the ones with the
703744-## PS boards. Didnt stop them from cutting the neck off CRT's.
Since Zenith sold 20%-25% of sets then they took all the blame.Maggy
had the horz shift & a 4 lead cap to prevent catastrophic failure. Didnt
always work.:tears:

73 Zeno:smoke:
LFOD !

Look for a bad 20-30 volt zener in the "x-ray protect" circut.
Not sure if this one was meant for me as I don't know of a circuit by that name but I got out the manuals and found a 1N4741 on the horizontal oscillator board and an interesting tidbit in the circuit description:

Transistor Q564 and associated circuitry make up a failure indicator device for detecting when there is a failure in the high voltage section, which allows the high voltage to increase beyond a predetemined level.

Zener diode ZD567 prevents Q564 from conducting until the base reaches 10.6 volts or more. The voltage divider; consisting of resistors R583, R584 and R585; ensure the Q564 is off unless the voltage sampled from the flyback increases sufficiently to bias Q564 on. When Q564 is conducting, it pulls the horizontal out of sync and cannot be reset until the high voltage section is repaired.

It makes sense to me now why that zener diode could be the culprit. I'll certainly try the variac trick when I can. Sometimes I can turn the horizontal hold control lock-to-lock and get the picture to snap back in but it never stays. I saw degaussing instructions in one of the manuals, I'll have to go over the whole darn thing once I do get a proper coil instead of trying to rig up a potential fire hazard. Considering a discussion I saw here fairly recently I'd say the power relay is magnetized and has gotten worse since I got it. I usually have to push the power button quite a few times before it will turn on or off, and often times the set will turn on the instant it's plugged in.

Oh, and on the subject of snowy pictures: this set had that problem as well and the AGC control had little effect. Then I found the RF bias control on the AGC/sync board and adjusted that slightly; presto, no more snow. Get off my screen and onto the ground, thank you.

Back to our regularly scheduled programming.

RF bias is RF AGC. Changes the voltage to the RF amp
at the base or gate if its a FET. Usually turn til the snow
just goes away. Too much causes jitters. IF AGC controls
are rare in SS sets. IIRC the first Zenith flat chassis ( C-line)
had both.
You can home brew a great DGS coil but I dont remember how
many turns of wire so check the internet & old books. Just
be SURE to use a spring loaded on/off switch. It will brew
up if you forget to turn it off.

73 Zeno:smoke:
LFOD !

It's an odd setup for sure, an RF bias control on the AGC/sync board and another control simply marked "AGC" on the preset tuning board.

I looked into the home brew coils but chances are the magnet wire would cost as much or more than a ready-made coil. I've already called one for my B-day in a few weeks so problem solved.