Re: Anyone went nuclear and replaced all AT PSUs with ATXs?

Posted on 2020-10-28, 11:46

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have 3 "normal" size AT PSUs. 2 of them are from reputable brands. This is the 3rd, most questionable one. Heatsinks are tiny which explains how light it is. The label calls it a 250W but the PCB is marked "CWT 200PA" which seems to imply a 200W design. Maybe "Data Well" is a brand owned by " …

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Re: Yet Another PSU Went Pop Thread (NOS edition)

Posted on 2020-09-29, 07:40

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This looks pretty good, even though I can't read it without using a translator :P Pardon my ignorance, but what is so embarrassing about it? Thanks! It was right before I became an engineer and got my diploma. Back then some of my older collegues were picking on me for the wording saying it's too …

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Re: Yet Another PSU Went Pop Thread (NOS edition)

Posted on 2020-09-28, 07:25

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've had several of these old Enermax platforms with the exacts same faliure. Standby FET, controler, pimary FETs fail and some passsive components too :( I have this now emberassing article I wrote some years ago: https://logout.hu/bejegyzes/finalcaleb/enermax_sfca495_tapegyseg_noisetaker_ …

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Re: Help me identify a 286 board

Posted on 2020-09-25, 08:44

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The CHIPS plcc packages sit on through hole adapters and I noticed some of the vias barely had any solder and were very a bit wiggly. Vcc is present now but no change in behaviour! I've tested the passives in circuit and taken out too. Sometimes old resistors values start to drift and stretch. This …

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Re: Help me identify a 286 board

Posted on 2020-09-24, 15:10

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've done some measurements. Took the board appart a little. Several things seems to have failed. Nihm battery charging voltage is high 8V -9V. There is a shorted 4148 diode. Several open resistors and some out of their values. P82C206 has missing Vcc. One of the customs PALs is super hot at all …

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Re: Help me identify a 286 board

Posted on 2020-09-24, 08:56

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Deksor wrote on 2020-09-23, 21:30: Can I have a look ? If you figure out something I'll add every piece of info to uh19 😀 I've attached the orignal ROMs. Check it out 😀 Filename JAM-124-V5.rar File size 29.52 KiB Downloads 44 downloads

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Re: Help me identify a 286 board

Posted on 2020-09-23, 21:24

by

by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Alright, thanks everyone! I got the two ROM contents unified, but no hint to motherboard id or microcode . Looks like the 3.6v nimh battery was removed long ago. No damaged traces. I have to test those transistors and a lm339 and some passives. Frequencies 32.7Khz and 14.3Mhz are present. I might …

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Re: Help me identify a 286 board

Posted on 2020-09-23, 12:52

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Predator99 wrote on 2020-09-23, 10:47: What do you expect without CPU...? Install one and try again... I've put a 16MHz AMD in it. Changed the oscillator and used a 12Mhz Intel. Same thing. POST card registers constant RESET signal. Something must be dead on the board I guess.

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Help me identify a 286 board

Posted on 2020-09-23, 10:40

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hello! I recieved this big 286 mainboard. JAM-124-V5 https://www.vogons.org/download/file.php?mode=view&id=92771 I couldn't find any info about it. Looked through Stason.org, minuszerodegrees.net ...nothing similar. Has lots of unmarked jumpers that I couldn't identify/probe. Right now it has no cpu …

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Re: I recently found this hardware, AKA the Dumpster find thread.

Posted on 2020-09-01, 07:58

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

People hold onto stuff more. Hungary was behind the iron curtain for 45 years. Comecon countries were in outstanding debt and the economy was slow. Common food and household items were hard to get, they were often unavailable for months. I haven't eaten a banana until I was 4! In that environment …

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Re: Canon MD5511 restoration

Posted on 2020-07-27, 13:12

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The smd resistors and caps proved undamaged so I put them back. https://www.vogons.org/download/file.php?mode=view&id=88815 https://www.vogons.org/download/file.php?mode=view&id=88816 Not too pretty but it works. These new electrolytic caps should last long. And then... when I was reassembling it to …

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Canon MD5511 restoration

Posted on 2020-07-27, 12:39

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hello! Many of you might be familiar with this combo floppy model. The 3.5" unit might become unoperational. https://www.vogons.org/download/file.php?mode=view&id=88810 The culprit is usually the rottig/leaking electrolytic capacitors. In the past I had one drive that was beyond repair. The leaked …

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Re: Upgrading a DSTN display to a TFT in a laptop - is it possible?

Posted on 2020-07-15, 09:23

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I did something like this before. The TFT display required an additional signal connector on the vga board. Check the vga board. Maybe it only "suppoorts" DSTN panels by native.

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Re: PSU went pop but can't see anything popped?

Posted on 2020-05-11, 13:19

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The PSU doesn't make any noise and the fan doesn't spin at all :( I don't have a multimeter to test it out unfortunately Most likeIy something failed on the high voltage primary side. There might be something on the solder side of the circuit that shorted traces or leads of component. At this point …

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Re: PSU went pop but can't see anything popped?

Posted on 2020-05-11, 07:11

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Nobody could see the package ink to know that, nor does it make a difference when it comes to understanding the topology of the PSU. Detailed engineering and component testing is different, of course, but I usually consult the datasheet to confirm pinout anyway. Well yeah, it's the curse of the …

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Re: PSU went pop but can't see anything popped?

Posted on 2020-05-10, 21:29

by

by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Guys, this psu uses BJTs and not FETs . These are too very different transistor types. Almoststew1990, it is possible that the high voltage primary side is good and something has gone bad on the secondary output side. Does the fan twitch or does the psu give out some high frequency noise when you …

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Re: What is your opinion on these two old AT PSUs?

Posted on 2020-03-24, 12:17

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

That 'Emiter' at leas has a quad comparatior set up for power-good signal and voltage rail supervison function. Also components for a temperature controlled fan can be installed onboard. If someone is too bored and has the spares it might be worth beefing up a little. Otherwise both units are junk. …

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Re: A tale of two PSUs

Posted on 2020-02-24, 13:10

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Judging from the two primary 470uF fuhjyyu capacitors (bad brand), the EI33 type primary transformer and that 16 legged pwm ic on the secondary this is a 250W max capable half bridge topology unit. The 5V standby circuitry is not inspiring confidence. Very similir to those in the notorius Bestec …

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Re: Locating belt for Citizen W1D floppy drive belt.

Posted on 2020-01-31, 10:31

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Damn, you are right! I swapped two belts last June. One drive is from a 386 notebook. I'm pretty sure it was W1x something. Maybe A or B. Sorry.

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Re: Locating belt for Citizen W1D floppy drive belt.

Posted on 2020-01-30, 10:08

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by DAVE86

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Last year I got a few from here 100% match with the orignal one in a Citizen W1D! Had to change the rotting electrolitic capacitors too.

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