1970s Zenith Console - Troubleshooting - Page 2 - Videokarma.org TV - Video

ThePlague · #1 04-07-2022, 05:43 PM

Hello all,

Thank you for all of the advice and tips! I have 3 of the 5 22-5001s in. Once I have all 5 and install them I will begin troubleshooting based on your recommendations!

This is going to be a big project, but will be more than worth it in the end.

zeno · #2 04-08-2022, 06:59 PM

The main thing is getting the HV up now & a raster. That way
you can be sure the CRT is strong before spending too much $$
on it.
Sounds like the tripler may be bad. Unhook the wire from the flyback
donut to tripler. At the flyback end you should get a nice 3/8 arc
into the air if you put a screwdriver near it. Will also stop tripping
the breaker.

Zeno

ThePlague · #3 02-04-2023, 03:59 PM

Hello all! I apologize for the delay. Got a new job, moved across the country, and now finally have some spare time to put into troubleshooting.

I got the base off and found these items upon inspection. It looks like one the safety capacitors (white) got quite hot at one point.

Also there this blue ferrite disc (choke or inductor?) that is broken in half. I need to get ahold of the schematic to figure out what it is and for.

I am currently working on previously mentioned troubleshooting steps.

ThePlague · #4 02-04-2023, 04:37 PM

Upon lifting the leg of the motor capacitor, I still have the same symptom of audio buzz and then the breaker blowing after a few seconds. There is no filament glow in the tube neck.

Update 1: Upon inspection of the chassis circuit diagram, the blue disc is R324 22 ohm thermistor for the degauss coil.

Update 2: After seeing the 22-5001 scorched on the chassis, I replaced all 3 on the unit with Zenith replacements. Looking at the HV tripler, is this the original unit or is this a replacement unit that combined the focus divider? It is a SCI 7234 "212-139".

Update 3 (closer to the issue): I checked out Q801, 802, 803, and 804 on the Horizontal Output module and they checked out good and within specifications. I replaced the HO module and removed the screws to the Horizontal Output Transistor and the breaker did not blow. The Filament in the neck is glowing. Seems like its either this transistor or the tripler. Will pull the transistor and check it out.

ThePlague · #5 02-04-2023, 09:06 PM

Update 4: I pulled the Horizontal Output transistor Q216 and measured collector to base and collector to emitter for a short. I did not find any.

I reinstalled Q216 and unsoldered the input from the flyback to the tripler. It is still tripping the breaker and there is no high voltage crackle.

According the schematic after Q216 there are multiple capacitor that could have failed and are shorting to ground. I will begin checking these.

ThePlague · #6 02-08-2023, 03:26 PM

Due to the state of the focus divider, I am not trusting anything past the HOT.

I didn't realize how hard it is to get a hold of parts for this era of Zenith.
I think I may have to go with a 800-791 tripler and get a hold of a new focus divider. I wasn't able to find the 63-9896, but there is the Zenith 800-616 kit that per the listing is compatible with the 63-9896? I really need to find one of those cross-reference books..

What Sams are you using? I am using the 25DC56 scan from the Sams site and it doesn't appear to mention anything about the focus divider other than it is R361. (not listed in the parts tables)

I picked up 2 HOTs just in case one goes during testing. Is there any specific heatsink compound that is required? I have some used for CPUs; figured that would work just as well.

Findm-Keepm · #7 02-08-2023, 04:16 PM

If you are looking for a Zenith voltage divider, look also at the Sylvania ECG replacement types - the Hi-Div series. An ECG Hi-DIV-3 replaces the 63-9896, 63-9897,63-9898, and the 63-9898-02. Various Mounting positions are possible with the ECG replacements too - unlike the Zenith OEMs.

The Internet archive has the ECG replacement guide from 1989, if you wish to look at the HI-DIV-3 data.

https://archive.org/details/EcgSemic.../n469/mode/1up

ThePlague · #8 02-08-2023, 05:55 PM

Quote:

Originally Posted by Findm-Keepm

If you are looking for a Zenith voltage divider, look also at the Sylvania ECG replacement types - the Hi-Div series. An ECG Hi-DIV-3 replaces the 63-9896, 63-9897,63-9898, and the 63-9898-02. Various Mounting positions are possible with the ECG replacements too - unlike the Zenith OEMs.

The Internet archive has the ECG replacement guide from 1989, if you wish to look at the HI-DIV-3 data.

https://archive.org/details/EcgSemic.../n469/mode/1up

I was unable to hunt down any of the ECG Hi-Div-3s. However, I was able to find a Zenith 800-616 kit which replaces the 63-9897 and 63-9898-02. Since the ECG Hi-DIV-3 also replaces those and also the 63-9896, its worth a shot thinking that a 63-9897 will work in place 63-9896.

Not sure if this logic works, but given part availability its worth a shot. I've been trying to find specification information on the 63-9897 to compare to the 63-9896.

Findm-Keepm · #9 02-08-2023, 07:53 PM

The 63-9897 is used in the 19EC13 chassis, and is featured in Tekfax 113, available over on World Radio History to the left on the ET/D (Electronic Technician/Dealer magazine page.

It's shown as R353, Focus Divider on page 152 of the Tekfax (or page 153, as indexed by Adobe Acrobat Reader). Two resistors shown, 200 Megohm and a 40 Megohm in series, tapped at the 40 Megohm.

Same page, in the parts list, R353 is listed as a 63-9897.

Just about all Zeniths back then had the 240Meg focus divider, tapped at 40Meg. Even when incorporated in a tripler (ECG523, ECG529, ECG530) - the focus resistor values stayed the same 200 + 40 Megs, tapped at the junction. The same ECG guide I mentioned earlier has the schematics of the triplers and a description of the HI-DIV focus dividers too. HI-DIV 1 and HI-DIV 3 are identical electrically, but mechanically different for the various chassis mounting consideration......in a pinch, either will do.

zeno · #10 02-09-2023, 09:11 AM

Quote:

Originally Posted by Findm-Keepm

If you are looking for a Zenith voltage divider, look also at the Sylvania ECG replacement types - the Hi-Div series. An ECG Hi-DIV-3 replaces the 63-9896, 63-9897,63-9898, and the 63-9898-02. Various Mounting positions are possible with the ECG replacements too - unlike the Zenith OEMs.

The Internet archive has the ECG replacement guide from 1989, if you wish to look at the HI-DIV-3 data.

https://archive.org/details/EcgSemic.../n469/mode/1up

Brian
The thing we were trying to do is stay OEM if posable. Reason for that is
in the 80's we had a few with jail bars & a few have shown up here also.
The common thread was new caps, tripler, divider were replaced.
The 800-616 kit did not sub some dividers IIRC the 14 & 16 inch
chassis. Also the kit had the barrier & a plug for the focus. It did
sub any hybrid chassis that had a divider. With some Zenith parts
like CRT sockets, A minor difference got a new part ## but no subs.
Almost all delta sockets were the same for abt 10 yrs. The difference
was plugs & lead length, one could sub them all.

73 Zeno

ThePlague · #11 02-12-2023, 04:23 PM

Update: My HOTs and Zenith focus dividers (63-9898-02) came in. I pulled out the old focus divider and it is.. FUBAR. It also looks like it was a 63-9895.

I have a universal Zenith HV Tripler Kit 800-791 coming in the post from Canada sometime next week hopefully.

Would it be unwise to put in the new focus divider and HOT and see if the tripler is okay?

ThePlague · #12 02-12-2023, 08:02 PM

Update 2: I replaced the focus divider with the 63-9898-02 and fitted an RCA SK3115 HOT.

There is life! Sort of. It clearly needs a purity adjustment or a degaussing.

The darker picture is with Chromatic engaged. Brightness and contrast controls are non-operable with Chromatic on. I'm not sure if this is the way it is supposed to work or not. Overall brightness seems a bit low and I am wondering if the HV tripler is slowly dying.

However, the best signal I can get through my RF modulator is.. non syncable. I can make it out a bit and the audio comes through but the picture is skewed and repeating.

There is also a light snap every 10 or so seconds coming from the HV area. Not sure what component is the cause.

The last picture was the closest I could get to a picture and this is only possible with the color turned to minimum.

BeamT · #13 02-12-2023, 08:57 PM

Good progress! I wouldn't be too concerned with the purity on the picture with the TV on its side. Wait until you are right side up. What signal source are you using? Its doesn't look like you are on channel? If this is an RF modulated source, usually you have a choice to output on Ch 3, or 4, make sure the tuner is the same, and fine tune for to the signal. Make sure you are connected to the VHF input, don't ask how I know. Leave the Chromatic button off for now, and adjust the individual controls for the levels you want. Sorry if this is too basic?

You can obviously see why someone mummified the old focus divider.

From my experience, Triplers seem to work or they don't, except the ones that arc in the mean time.

ThePlague · #14 02-12-2023, 10:42 PM

Quote:

Originally Posted by BeamT

Good progress! I wouldn't be too concerned with the purity on the picture with the TV on its side. Wait until you are right side up. What signal source are you using? Its doesn't look like you are on channel? If this is an RF modulated source, usually you have a choice to output on Ch 3, or 4, make sure the tuner is the same, and fine tune for to the signal. Make sure you are connected to the VHF input, don't ask how I know. Leave the Chromatic button off for now, and adjust the individual controls for the levels you want. Sorry if this is too basic?

You can obviously see why someone mummified the old focus divider.

From my experience, Triplers seem to work or they don't, except the ones that arc in the mean time.

Thank you! I had the fire extinguisher ready for the first power on.

I guess the RF modulator I was using wasn't strong enough. I pulled out my Agile Modulator and am able to get a usable signal at least. Color off and its not too bad, but color on even a little bit and its rough. All images are channel 4. With the agile modulator, I was able to broadcast on UHF; picture is a little bit cleaner, but more or less the same.

I was able to sort out the fine tuning of the channels and the last image is the best I was able to get. Still not great. This is also with the focus adjustment maxed out. My kit came with a 4.7 megaohm resistor if the focus can't be adjust enough, but that was for a different set. Not sure if it is applicable here.

BeamT · #15 02-12-2023, 11:51 PM

Very good! Now you have a good sense of where you are at! Turn the color off and work toward the best B/W picture you can achieve. Nothing is going to look right with the set on its side. I would concentrate on solving the snapping every 10 seconds. It wouldn't hurt to clean in the inside of the set. I usually use a vacuum with a small paint brush and work gently through the chassis. Others will use a gentle amount of compressed air. Looks like you are inside, so that might not be your first choice. Take the tripler screws up and clean underneath and look for signs of arcing. Make sure the area around the Anode on the CRT bell is clean. DISCHARGE first, you have HV now, it will hold a charge. There are several spark gaps that may have carbon tracked or on the way, make sure CRT socket is clean and look for discoloration. Sometimes you can see the arc/snap with the room totally dark and listen carefully.

Do you have access to a HV probe to measure the HV?

Hopefully Zeno or others will chime in. I believe the added resister in the Divider Kit was to center the range of the focus control.