Zenith Z-19 ?

[G. Beat]

This Zenith terminal, Z-19 appeared on Facebook Marketplace.

Seller in Antioch, IL area , states it does not Power On.

https://www.facebook.com/marketplace/item/28370459975872209/?

IF any potential buyer attending VCFMW in September,

could pass by (if still available).

greg

[Lee Hart]

Looks like it sold for $75. Somebody got a great deal. :-)

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[George Monroe]

I have a old h19 that crapped out and I am unable to find any schematics for it. I have some pictures that show it is different than the schematics I can find

[Lee Hart]

I think all the schematics and manuals are online. Try Les Bird's and Norberto Collado's website. If not, I have them as well. One way or another we can get them to you!

What seems to be wrong with it? Are the power supplies working? Do you get a "beep" when you turn it on? Does the CRT light up?

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[george...@gmail.com]

No signs of life at all it use to work find can’t check power without real schematics though

Sent from my iPhone

On Aug 4, 2026, at 2:25 PM, Geo Monroe <george...@gmail.com> wrote:



On Mon, Jul 27, 2026 at 6:58 PM G. Beat <gregor...@gmail.com> wrote:

This Zenith terminal, Z-19 appeared on Facebook Marketplace.

Seller in Antioch, IL area , states it does not Power On.

https://www.facebook.com/marketplace/item/28370459975872209/?

IF any potential buyer attending VCFMW in September,

could pass by (if still available).

greg

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[george...@gmail.com]

The schematics I obtained don’t seem to match the boards in the unit I posted pictures I was able to take from inside 

[Geo Monroe]

[Geo Monroe]

[Lee Hart]

That doesn't look anything like heath's H19 video board. Perhaps someone has replaced it with some other monitor?

If it's totally dead, there's a fuse in the outside rear near the power switch. Have you checked to see if it's blown?

The power supply is fairly easy to check. It's the small board in the rear right corner. It supplies +8v, +16v, and -16v to the logic board, and +56v to the monitor.

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[Glenn Roberts]

The factory-made z19s have PCBs like that. Not sure I trust the power supplies on those. Terry Smedley had one and he had to upgrade or replace the supply.

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On Aug 4, 2026, at 5:57 PM, Lee Hart <electr...@gmail.com> wrote:



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[norberto.collado koyado.com]

This is what I have:

 

Z19 manual: https://koyado.com/Heathkit/H19C_Terminal_files/Heath%20Z19%20Terminal%20Operating%20Manual.pdf

 

Schematics:

 

https://koyado.com/Heathkit/H19C_Terminal_files/H19A_Schematics.pdf.zip

https://koyado.com/Heathkit/H19C_Terminal_files/H19A_Video_Schematics.pdf.zip

 

Hope it helps,

Norberto

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[Joseph Travis]

Norberto -

He has a late model Z-19 which has a different power supply and video board than the H-19.

Joe

To view this discussion visit https://groups.google.com/d/msgid/sebhc/SA3PR01MB791854DE3F057EA3E7AE81A4F7D32%40SA3PR01MB7918.prod.exchangelabs.com.

[norberto.collado koyado.com]

WOW! So, it is a new Zenith upgrade.

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[Joseph Travis]

Zenith was always looking to reduce costs. If I recall correctly, the newer video board and power supply were manufactured in Mexico (instead of Heathkit in Michigan).  I believe the terminal model number is Z-19-CN.  It's been a lotta years so my memory may not be completely accurate.

Joe 

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[norberto.collado koyado.com]

So, the manual I have is correct.

 

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[Geo Monroe]

It is totally dead . I wanted to check the power supply but I could not find the schematics for the unit.

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[Terry Smedley]

I have a working Z19-CN.  On this factory-made model, the power supply is a generic board mounted on the floor of the cabinet rather than on the corner pedestal above the power inlet/fuse/switch.  I don't have a schematic for that power supply.  I did replace the tiny factory-supplied transformer, which was much smaller than the ones used in the Heath models and ran too hot to touch.  

The video board in my CN model is labeled "Zenith Radio Corp DS12-LK-1" which appears to be a generic display board sold by Zenith for use in OEM monitors.   I found this manual that seems to mirror that video board and has a (very) limited description of the video circuit and adjustment points.   There is a schematic and detailed component list for the video board, but I have not verified that it matches the installed board exactly.  The document contains an exceptionally brief mention of a power supply with components numbered in the 500 series as found on the power supply PCB in my CN,  but the component callouts in the description do not square precisely with the installed board.  The document has no schematic for the power supply.

tas

[George Monroe]

Thank you for the info

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[Mark Garlanger]

I'm also having a problem with my Z-19-CN. I recently pulled it out to see if the character ROM was actually different than on the H19. The manual shows that the graphic symbol for "j" was different. I wanted to verify on the screen before taking the chip out to dump it. When I turned it on, I see the cursor, but it is not processing any characters from the keyboard. I have the "off-line" key down (also tried with it up, and repeatedly messed with that key in case there was some dirt). The other keys have the keyclick when pressed. It will allow me to press up to 8 keys, and then any additional key presses cause the ^G.(bell) tone. If I press shift-reset, it allows 8 more key presses before doing the bell again. I'm guessing the keys are filling up some buffer, but the CPU is not processing them from the buffer, so it fills up. Any suggestions on where to look? I'm thinking maybe CPU/interrupt handling.

Thanks,

  Mark

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[glenn.f...@gmail.com]

The MM5740 (?) keyboard encoder chip fails on these sometimes. Terry and I developed a replacement that adds some new features (auto-repeat, keyboard macros, etc.).

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mark Garlanger
Sent: Wednesday, August 5, 2026 9:32 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] Zenith Z-19 ?

 

I'm also having a problem with my Z-19-CN. I recently pulled it out to see if the character ROM was actually different than on the H19. The manual shows that the graphic symbol for "j" was different. I wanted to verify on the screen before taking the chip out to dump it. When I turned it on, I see the cursor, but it is not processing any characters from the keyboard. I have the "off-line" key down (also tried with it up, and repeatedly messed with that key in case there was some dirt). The other keys have the keyclick when pressed. It will allow me to press up to 8 keys, and then any additional key presses cause the ^G.(bell) tone. If I press shift-reset, it allows 8 more key presses before doing the bell again. I'm guessing the keys are filling up some buffer, but the CPU is not processing them from the buffer, so it fills up. Any suggestions on where to look? I'm thinking maybe CPU/interrupt handling.

To view this discussion visit https://groups.google.com/d/msgid/sebhc/CAAjkm7-44KdZ18%2Ba89Hh0OyN16QVdEoLT-G5e6KN752%3Dixn9Sw%40mail.gmail.com.