Re: Identify motherboard thread

Posted on 2023-01-30, 11:45

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I think the 20K line says that they're made by Kemet and are 20V rated. Replacement doesn't have to be Kemet, just 22uF and 20V rated. Actually, depending on which voltage supply it's connected to then other voltages might also be ok. Not sure about the size, maybe 2917 (7343 metric, so 7.3mm long …

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Re: Identify motherboard thread

Posted on 2023-01-26, 15:47

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Looks pretty close to this: https://theretroweb.com/motherboards/s/dec-pc-386sx-ce-p3348 https://theretroweb.com/motherboard/manual/33997.pdf Not sure about the DEC listing there. Looks like it was used in the Philip P3348: https://www.it-info.hu/2020/09/08/retro/

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Re: Asterisk (*) sign at CPU during POST?

Posted on 2023-01-15, 20:16

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Since it shows CPU1, I wonder if the BIOS supports SMP, even if the board doesn't, and the * indicates the default CPU? I found a picture of an SMP boot on the Award Medallion BIOS here:https://www.askwoody.com/forums/users/dave3283/replies/ which shows CPU2 with a *.

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Re: AwdFlash part number mismatch error

Posted on 2023-01-14, 10:02

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Had a quick look at the datasheets and the original w29c011a supports 5V erase and programming, but the mx28f1000ppc needs a 12V supply. So it's possible that the motherboard can't write to the mx chip. I haven't checked to see if there are other differences, but things like block sizes might cause …

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Re: DigiPOS adventures!

Posted on 2023-01-07, 17:29

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So, the keyboard has a good +5 supply, but no good Ground? And I think clock and data lines both have pull-ups on them. So the only time the keyboard would see a ground on any pin would be when the motherboard tried to send a status byte to the keyboard and pulled clock and data low. Doesn't sound …

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Re: DigiPOS adventures!

Posted on 2023-01-07, 15:23

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

megatron-uk wrote on 2023-01-07, 10:21: starts measuring at 10M Ohms and increasing until it goes off-scale at 30M Ohms. Capacitative charging? Is that fuse on the Ground side? Might explain why there was still 5V on the pin.

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Re: DigiPOS adventures!

Posted on 2023-01-06, 15:39

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What's the voltage on the PS/2 +5? Think there have been cases with similar symptoms of random disconnects where there was some resistance on the +5 line causing the keyboard to reset when drawing current.

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Re: Anyone know where to source IDE cables like these In various lengths?

Posted on 2023-01-02, 15:31

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This places claims to have some in 48cm and 90cm lengths: https://www.cabledepot.co.uk/ide-c-100_101.html You can get jacketed flat cable like this: https://www.farnell.com/datasheets/910926.pdf but the prices may cause a minor coughing fit.

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-21, 13:22

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Found some pictures of one: Abit_Postman_FrontBack.jpg (just for the record, on this one the pinout colour order is the same at both ends). Looks like one sold on German Ebay in October this year (which is where I found the pictures). I guess the motherboard sends the POST codes out over the SMBus, …

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-20, 12:55

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Wow! That's some Sherlock Holmes-level deduction you've done. I think i'll have to read your comment at least a couple of times to understand it, and get back to you. Sure, I can measure some resistances with the power off. That's safe stuff. More spinning a tale to try and fit what we know, then …

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Re: Compaq Armada 1550DMT fun.

Posted on 2022-12-19, 10:18

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Not sure. I think the table ought to be: BF1 BF0 (pins 185 and 186) 0 1 x3 0 0 x2.5 1 0 x2 1 1 x1.5 (default) but there's a note here: http://www.cpu-zone.com/Pentium/Pentium%20processor%20specification.pdf about a correction to the MMX datasheet regarding the x3 multiplier that This bus ratio is …

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Re: Compaq Armada 1550DMT fun.

Posted on 2022-12-18, 23:02

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I tried to raise FSB frequency above 66MHz by experimenting with the FSB option resistors, but to no avail. Most likely clock gen. does not support FSB frequency higher than 66MHz. Where you able to find the datasheet for the MK1491-01 to ID the FSB resistors? Out of curiousity I had a quick look …

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-18, 22:14

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Nice. I'm going to make some wild guesses and then ask if you can make a few measurements to check. Assume that in that photo of the official connector that Red is +5, Black is Ground, White is Clock and Green is Data, and that both Clock and Data have a pull-up resistor connected to +5. From the …

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Re: Panasonic Caddy CD ROM drive

Posted on 2022-12-16, 17:24

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

At least the disc spins up. I don't know if it's true of all drives, but the Panasonic 562b will only spin up after it's got a focus lock. Then once it's spinning it tries to get a track lock. As well as checking the capacitors (agree that they don't look great), might be worth making sure the read …

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-14, 19:08

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't think it has a manual of its own, but the way it should be connected can be found in the manuals of the mainboard with which it was delivered... I already looked it up and forgot :-) the guru link is some data from the mainboard and a connection (3pins?maybe 2) to the cmos reset jumper on …

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Re: Creative AWE 32 CT2760 ISA apparently dead ?

Posted on 2022-12-14, 17:48

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I think those are 1MB SIMMs, so 2MB in total. Based on datasheet here: download/file.php?id=152414&mode=view saying the chips are 1M address * 4bit, so 0.5MB on each chip.

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-14, 17:36

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

ok, I was wrong about the EL thing, was jumping to conclusions based on other photos. Might be a nothing to do with the problem, but I'm slightly curious about what's connected to what though, looks odd to have the GuruLink cable off to the side of the connector, and having a separate cable going to …

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-10, 21:39

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

is kind of blue-green glow. Blue-green a bit like this maybe (picture of a different guru panel)? IMG_5356.jpg (from https://hexus.net/tech/news/peripherals/9026-abit-incorporates-wifi-esata-guru-panel-pr-man-goes-crazy/ ) Think I've also seen different orange EL displays. And these people https:// …

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Re: Lucky Star 5i-VX1 or LS_P54CE? Fake Cache? Documentation?

Posted on 2022-12-10, 14:24

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by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I believe I'm on top of the Ps2 port pinout - I checked virtually every socket 7 lucky star motherboard doco i could find and they all have the same pinout. Gonna trust that its the same again for this. You should be able to ID which pins are +5 and GND with the board off by measuring resistance to …

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Re: Repairing a specific LCD: Abit Guru Panel GP-02

Posted on 2022-12-10, 14:19

by

by snufkin

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Looks similar to the types of backlight used in synths, which I'm pretty sure are electro luminescent (EL) displays, here's a short video of someone replacing one: https://www.youtube.com/watch?v=HGoZCSdIAvA If it is an EL panel then be careful if working on it when it's powered up, they run at …

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