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Thread: Z110 PSU +12V not working

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    Default Z110 PSU +12V not working

    I picked up a Zenith Z110 recently with bad PSU. From what I've tested, it looks like the +12V is only putting out +3V.

    There is no schematic or guide to this thing - Zenith's technical manual simply says it's not serviceable. I'm wondering with +12v what I should be looking for? Bad voltage regulator? Caps? I'm not sure what to hunt when it's +12V.. with +5V I know to look at the regulator.

    I might be wrong but it looks to me like a couple of caps are bursting (kind of have a blue color to the tops).

    Pic here: https://drive.google.com/drive/folde...30?usp=sharing

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    Good! I'm glad it doesn't work! IT'S A JOKE.

    I've talked myself out of numerous Z100s and such over the years. It's just not fair.

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    Quote Originally Posted by tipc View Post
    Good! I'm glad it doesn't work! IT'S A JOKE.

    I've talked myself out of numerous Z100s and such over the years. It's just not fair.
    Lol! I feel like there's a story here.

    I generally haven't been that enthused by Zenith gear, but this one caught my attention because of the PC/S100 dual personality. I refused to pay more than $100 for it. I found as I read about it though that it's a pretty cool machine over all, weird as it is. I even managed to score a Zenith ZVM135 for it.. although I have to find the oddball db25 to db9 cable it uses for rgb.

    It's definitely a bit of a weird one.

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    It's weird and rather lovely.

    One BYTE author suggested it's use as a baseline MS-DOS compatible (not IBM compatible).

    They came in 2 varieties, the low profile version, w/o a monitor. And I reckon the version you have, w/the built in monitor. I prefer the latter version.

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    Quote Originally Posted by tipc View Post
    It's weird and rather lovely.

    One BYTE author suggested it's use as a baseline MS-DOS compatible (not IBM compatible).

    They came in 2 varieties, the low profile version, w/o a monitor. And I reckon the version you have, w/the built in monitor. I prefer the latter version.
    Mine is the one without the built in monitor. The first thing that caught my eye about the Z110 was a reference to being able to do 8 colours, which was a bit unusual for a "DOS" machine. So when I started actively looking for one of these I insisted it be colour, and I understood the Z100 is monochrome for some reason. I got really lucky and a ZVM-135 color RGB monitor came up on ebay right after I bought my Z110, so in theory I have colour, if I can get this thing working again.

    And also if I can find the cable. I don't understand why Zenith put a 25 pin connector on the monitor, if the computer was only 9pin. I have to find a pinout somewhere and will have to make a cable as there's no way I'm probably going to find the original.

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    Zenith made CGA compatible monitors. I'm not aware of any models that will work with the 100 series, but that doesn't mean they don't exist. If I had to guess the built in monitor takes 400 lines. Perhaps the color output is lower res.

    Zenith made a good deal of IBM compatibles. And monitors to go with them. Perhaps the low profile 100s had matching mono or color monitors (certainly 1 type at least).

    Some integreated Z's were green screened. Others were white (as to phosphors that is).

    Edit: I confuzzled myself. I thought you said you had the one with the monitor. In any event they're both groovy. I really should try to get one after all these years. Someone wanted to donate me one, but I confessed I wasn't fit to own it. Hmm wonder if he's still got it. He's the dude that donated me my Lisa. Yeah that worked out real well...
    Last edited by tipc; January 16th, 2021 at 08:02 PM.

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    so this basically what you acquired:

    https://www.ebay.com/itm/Vintage-Zen...IAAOSwm-del3Q-

    I don't know the difference between the 100, 110, 120 (were there more?).

    You know the damned thing looks an awful lot like a Franklin Ace 1200 LOL! I had to weasel into my garage, fixing my boiler, and caught a gander of my FA1200. The one I left out in the rain for too long. Still looks nice though. Still haven't cleaned the mouse schnitzel off the motherboard though. Maybe I'll just hack a peecee motherboard into it and consider myself more fortunate then those w/Zeniths. I'll certainly be able to run more s/w LOL.

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    Yup.. that's it! Didn't pay nearly that much though.

    Question to others reading.. You're not supposed to be able to see the 'triangles' at the top of the caps at all, right? The tops of the ones with the visible breaks are smooth and seem to be sealed with some kind of blue stuff.. but I notice on the other caps there are no visible lines on top.

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    Quote Originally Posted by falter View Post
    Question to others reading.. You're not supposed to be able to see the 'triangles' at the top of the caps at all, right? The tops of the ones with the visible breaks are smooth and seem to be sealed with some kind of blue stuff.. but I notice on the other caps there are no visible lines on top.
    See the photos of electrolytic capacitors at [here]. By "triangles", I presume that you are referring to the triangular segments shown in the second and third photos. If you are, then the 'triangles' are due to indentations being pressed into the metal by some manufacturers as one way of creating 'weak' points, just in case excessive pressure builds up in the capacitor. All four photos show the results of excessive pressure. Maybe the first photo is of a capacitor that had no manufacturer created 'weak' points.

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    Ok. Yeah I think these caps may be different brands and thus may not be the same. I don't see the usual capacitor 'cheese coming out the tops where the segments are most visible.

    I wish there were a schematic available that would explain how the 12v is derived. I feel like this is something simple.. like a bad regulator or such, only allowing me +3v where there should be +12v.

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