1970s Zenith Console - Troubleshooting - Page 3 - Videokarma.org TV - Video

BeamT · #31 02-07-2023, 10:41 PM

From Zeno the Zenith 212-139 crosses to a 800-791 in the Zenith Replacement line of triplers. I can see the same information. Also crosses to a NTE/ECG 521 if you are willing to stray to a non-Zenith part. In both the 800-791 and the NTE/ECG 521 there is a focus tap that is unused in this application, so you clip the lead and cover it over with silicone.

From everything I can find the original 212-139 was a 6 step tripler, rated at 30KV max, no focus tap. Sams indicates the Focus Divider is 200meg tapped at 40 meg. It appears to me the NTE/ECG 530, Zenith 977-9530, is close. They are also 6 step triplers, rated at 30KV max, with an internal divider, 240meg tapped at 40meg. Sams indicates we should see 25KV at the CRT, and there is no adjustment.

I haven't found any documentation/information this was a recommended replacement for both the tripler and the divider, but I know this was done back in the day.

It would be nice to hear from anyone that has gone down this path. I asked the same question in my thread about a single replacement for both.

Hope this helps, good luck with your set.

BeamT · #32 02-07-2023, 10:55 PM

Good catch with the HOT. I always had good luck with ECG 165. Be mindful of the insulator and the heatsink compound. The tripler may still be bad, and took out the HOT. You know the the divider has been arcing at some time in the past.....

ThePlague · #33 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 · #34 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 · #35 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 · #36 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 · #37 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 · #38 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 · #39 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 · #40 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 · #41 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 · #42 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.

zeno · #43 02-13-2023, 09:12 AM

Good work ! Comments:.
63-9895 subs to 63-9896 also Only $6 back then !
Use the 4.7meg to center F & check the HV.
Check CRT socket. Look & smell. Most get damaged.
I dont see jail bars

Arcing. Sit behind it with lights out to spot the flash. Around the anode
they would sizzle from to much HV & leave carbon tracks. Clean up
real good with 91% isopropyl. The 2 hole anode cap also. IIRC
P## is 15-276-01 for the two holer.
Chromatic ON switches to a 2nd set of controls for bright, contrast,
color & tint. They are accessed through the hollow control shafts.
I always ran it in off pos.

Electronic M · #44 02-13-2023, 10:41 AM

On my 1971 Zenith hybrid I think I added 10-20M in series with the ground as it drifted over a couple of years in the early part of using it as a daily driver over a decade ago. Interestingly it stopped drifting and has been stable for years now.
If the focus divider is off the HV and has a path to ground then it will automatically discharge the HV after a few seconds...A splendid feature of that circuit.

ThePlague · #45 02-13-2023, 09:58 PM

Thank you all for your generous help! Certainly would not have gotten to this point without it.

I will make a list of items to work on a knock them off the list when I can. I think cleaning the contacts on the duramodules will also go a long way.

There is definitely some carbon tracks on the socket (I believe visible in one of my early photos of the set) so that will get the cleaning treatment and possibly a replacement if its too bad.

I found the source of the snap. Its my fault. There voltage divider kit I used had too short of cable for the focus and ground wires. I spliced it with the wires from the old divider (solder) then filled around the solder with silicon and heatshrinked it. Apparently it wasn't thick enough and its arcing from the solder joint to ground (about a millimeter arc). Is there a more suitable way to lengthen high voltage cables besides finding the right kit?