VOGONS


First post, by Jonas-fr

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I'm currently restoring a KNS computer-in-a-keyboard which isn't working. The form factor is gorgous and reminiscent of the Amiga 1200 and I plan to make it my main retro battlestation.

Cosmetically it's in a so-so shape but the electonic inside it's ok, no sign of oxydation but it isn't booting at all. It doesn't have any 5V on the power connector (only -12v (-11.90V actually),+12V and -5V) but myabe it's the PWR_GOOD signal waiting for the motherboard to boot to activate? The wire colors aren't matching those of a standard AT power supply though.

I recapped the power supply to no avail, I also changed the dead BIOS battery, but it still wouldn't boot. I'm stuck for now I have to admit, would you know what I could test now?

Here's some pictures (WARNING: some pictures are big)

Album :http://imgur.com/a/XNAuG

Exterior: http://i.imgur.com/TMensVh.jpg
Closeup: cLlwQyM.jpg
Boxed (not mine): oQdm1u2.jpg
Motherboard: http://i.imgur.com/KAq8W9E.jpg
The setup (don't mind the spillage on the floppy, it's dry): http://i.imgur.com/gf4ZyCa.jpg

PS: the motherboard is a KAIMEI INS-486SLC-1, if someone has some documentation on it and/or the computer I'm all ears! Archive.org doesn't get me far on the now dead jamicon/kamei website. I also asked the new Jamicon company (which now makes only capacitors) about some info on it but I've got no answers so far...

Reply 2 of 10, by Jo22

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Jonas-fr wrote:

The wire colors aren't matching those of a standard AT power supply though.

I recapped the power supply to no avail, I also changed the dead BIOS battery, but it still wouldn't boot. I'm stuck for now I have to admit, would you know what I could test now?

Nice, it looks interesting for sure! 😀
I've seen another 486 system named "Shuttle", "SpaceStation" or similar.

I assume the power supply is something proprietary (don't trust the colouring!).
Perhaps you can measure the voltages from the floppy power connector ?

Some PSU testers do also have a molex port, which you could access by an floppy-molex adapter.
Another idea is to replace the power-mosfet transistor (if there is any in the psu) or the transistors/diodes in the power-good circuit.

Also make sure the voltages regulators are fine, too (are they discoloured ?)
If you can, ask your local electronics shop for assistance (the type of shop that sells electonics parts).

The people there should be familiar with 780X-type regulators and Mosfets.
They can also order the necessary replacements parts for you.

Sorry, that's all I can recommend.
It's always difficult to help someone from the far.. 😅

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 3 of 10, by Jonas-fr

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Jo22 wrote:
Nice, it looks interesting for sure! :) I've seen another 486 system named "Shuttle", "SpaceStation" or similar. […]
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Jonas-fr wrote:

The wire colors aren't matching those of a standard AT power supply though.

I recapped the power supply to no avail, I also changed the dead BIOS battery, but it still wouldn't boot. I'm stuck for now I have to admit, would you know what I could test now?

Nice, it looks interesting for sure! 😀
I've seen another 486 system named "Shuttle", "SpaceStation" or similar.

I assume the power supply is something proprietary (don't trust the colouring!).
Perhaps you can measure the voltages from the floppy power connector ?

Some PSU testers do also have a molex port, which you could access by an floppy-molex adapter.
Another idea is to replace the power-mosfet transistor (if there is any in the psu) or the transistors/diodes in the power-good circuit.

Also make sure the voltages regulators are fine, too (are they discoloured ?)
If you can, ask your local electronics shop for assistance (the type of shop that sells electonics parts).

The people there should be familiar with 780X-type regulators and Mosfets.
They can also order the necessary replacements parts for you.

Sorry, that's all I can recommend.
It's always difficult to help someone from the far.. 😅

You helped me well! I'll check again the power supply and its power-mosfet transistor transistor/diodes, I'm just no familiar with them for testing, I only know how to find a damaged capacitor ^^. Regarding the floppy drive it's a 26 pin version (the pinout seems non standard also but I can't find the service manual (TEAC FD-335H) for now) so no power connector to test!

MMaximus wrote:

looks like a cool machine! Best of luck for the restoration.
What is the keyboard/synth behind it on the second picture?

Cheers! The two synths are a small Casio PT-80 and a big ol' GEM Rodeo 37

Reply 4 of 10, by King_Corduroy

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Dude! Totally jealous! Did you get this from a guy on FB in some eastern country? One popped up on there not too long ago that I had made an offer on but he wanted too much for it for my taste. 🤣

Also nice keyboard, at first I thought the GEM was a MiniMoog with the top down. 🤣

Check me out at Transcendental Airwaves on Youtube! Also wtf, why are whoppers so good?!

Reply 5 of 10, by Jonas-fr

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King_Corduroy wrote:

Dude! Totally jealous! Did you get this from a guy on FB in some eastern country? One popped up on there not too long ago that I had made an offer on but he wanted too much for it for my taste. 🤣

Yes it was the one. Not the best transaction I had, since I paid a bit too much for a non working, corroded/marked externaly computer but, hey, now it is here and I have to rescue it!

Reply 6 of 10, by Jonas-fr

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Well there is so news, we're approching resolution 😀

I started looking again at the power supplies. Yes they are two of them. The first one is the primary one and it is external. It converts the 230V~ into three continuous voltages (-15V, +15V and +18V) and a ground. The second one in internal (under the keyboard next to the motherboard) and is the secondary: it takes the 3 voltages from the primary (again -15V, +15V and +18V) and outputs 4 voltages (4 wires: -5V, +5V (currently non working), +12V and -12V) plus a ground (on two wires) on a AT connector (non standard pinout).

Long story short, after I checked for the Nth time the primary, I took a short electrical shock (it's been 24hours I'm well I reassure you) and since then the voltages output by the primary are reversed (they are now +15V, -15V and -18V). Furthermore the transformer outputs 4 wires of two voltages normaly: 2 x 15V~ (thick blue wires on the pictures below) and 2 x 18V~ (thick yellow wires on the pictures below). I didn't mesured them before but now one of each set ouputs 0.5V~ instead of +15V~/+18V~ respectively (so I've got two +0,5V~, a +15V~ and a +18V~), I don't know if it could be the reason of the reversed voltages at the end.

Below are two pictures of the only PCB in the primary (provided that there isn't one under the wrappoins of the transformer). It consists of two big diodes and a PB152M bridge rectifier. The small resistor you see on the pictures is for the power led indicating when the primary power supply is ON.

iv6g

FtdE

Well that's as far as I am. If you got some info on how to test the big diodes and bridge rectifier I'm all ears! If you know why the transformer is outputing two +0.5V~ instead of +15V~/+18V~ I'm listening too 😀

Reply 7 of 10, by Jonas-fr

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Power supply fixed: for the reversed votlages it was only a matter of inversed leads on my DMM, I feel very dumb! Regarding the secondary I've changed a transistor (TIP42C) and now I've got a +5V! It was near the 5V wire so I said to me, why not change it, it doesn't cost much 😉

Now I'm in the process of trying it on the motherboard, I will keep you posted!

EDIT: It boots! The problem was the TIP42C transistor into the secondary power supply which was dead and thus no (vital) 5V was provided! I'm so happy it works

Reply 8 of 10, by FlashCade

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Some news?

IBM Ps-2 model 30 (8086 / Nec v30) - Tridend 8900d 1024 ram - floppy 720 kb - HDD 20 Mb (KO) - XT CF-Lite v4.1 with 1GB CF Microdrive IBM

Reply 9 of 10, by Horun

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His last post was in July and guess he found other interests

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor.

Reply 10 of 10, by Jonas-fr

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FlashCade wrote on 2019-10-13, 15:20:

Some news?

I've got a lot on my plate but I still got this little puppy on the backburner and I will get to it in the following weeks so I'll update this topic with more pics and info. In the meantime if you have question just ask away, I might have some answers : )