Re: A bit confused about two TEAC FD-55GFR 5,25 floppy drives

Posted on Today, 13:11

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

- the I jumper must be ON to get it working 300 rpm or 360 rpm (depending on the HD signal). Deunan, your drive works with HD floppies in DOS? It seems to be configured to get ALLWAYS 300 rpm, I'm a bit confused about it. It's not a drive in active use but I'm pretty sure I run some tests in DOS on …

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Re: Unknown card: Cambridge Research Systems AS-1.

Posted on 2023-06-02, 23:40

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Looks to be scientific or industrial data acquisition or control card. Analog inputs, at least some of them - I spy two DACs and one ADC with 4-channel sample/track/hold chip. And 186 MCU for local control - back then we didn't have Cortex ARMs so if you needed more program or data space than '51 …

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Re: Killed two Nforce2 south bridges with a faulty POST diag card...

Posted on 2023-05-31, 18:45

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

On more than one occasion I've put the POST card into ISA slot the wrong way around. PSU would trip right away, but there doesn't seem to be any mobo damage. Wasn't such a "modern" PCI mobo though. Also, different POST card. As for the lifted pads, could be weak glue on the PCB. I don't deal with …

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Re: A bit confused about two TEAC FD-55GFR 5,25 floppy drives

Posted on 2023-05-31, 18:11

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

DC signal is not properly detected. What did you set in the BIOS? Is the drive set to 1.2MB? Can you read entire HD floppy without any issues? Try removing the I jumper (green on your photo), it shouldn't be required for PC operation - DC signal should work independently of speed settings but best …

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Re: Palette inverted when using a VLB video card and Sound Blaster and compatible cards

Posted on 2023-05-31, 16:59

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm thinking it's the PCI implementation that could be buggy. Do you have VGA Palette Snoop option in BIOS? Make sure it is set to Disabled. It shouldn't really affect the (S)VGA but I've seen some DACs that are sensitive to write timings, so depending how the snoop is done it might just affect …

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Re: can I oil an IDE hard disk ? (not MFM)

Posted on 2023-05-27, 20:10

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

FYI high temperatures will tend to erase the magnetic media (even if not really that close to Curie point) - so you might need to do a reformat. But running Spinrite is usually doing the same thing since it rewrites the data. If that HDD gets worse try low-level format on a mobo with BIOS that has …

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Re: What is the purpose of that 7.2V built in battery in most notebooks?

Posted on 2023-05-27, 20:02

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What is that inner 7.2V battery supposed to do in most laptops? Isn't that for powering RAM in sleep mode? I think the PSU in these early laptops was not efficient enough at low power draw to use the main battery and not drain it too quickly. But that's my educated guess, I'm not really into old …

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-24, 08:45

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

tonata wrote on 2023-05-23, 18:33: What is the 4069 is doing indeed? See if the clock advances properly when the mobo is turned off.

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-22, 13:52

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Exactly. Keyboard is the only external device that plugs directly into mainboard and needs power, so it's a good idea to have a fuse for it.

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Re: 5" FLOPPY under modern linux

Posted on 2023-05-21, 17:43

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So, 5" goes to A position at the end of the cable. Drive select stays "1". Tried that. This was MOST I got out of this setup. It still did not moved head but it read at least track 0 and "main" directory entry out. Oh so it does read track 0? In that case drive is selected properly. Could be an …

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-21, 16:24

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Fuses are rated for nominal current. The voltage rating is only the breakdown voltage, in fact not even that, more of a safety indicator. Higher voltages need more gap/separation so the fuse will be bigger. So since this is a 5V circuit any fuse will do.

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Re: 5" FLOPPY under modern linux

Posted on 2023-05-21, 16:20

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Do not change the floppy device selection jumper - it's supposed to be set to 1 (if the count starts at zero, on some drives it starts at 1). Connect the drive at the end of the cable, after the twist, to get it to be A: drive.

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-19, 09:53

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes. I figured you'd want to test it right away to know if it's the missing fuse or not - I would. Since you haven't (?) then perhaps get a real fuse (something 500mA to 1A) if you are not comfortable with a wire.

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-18, 20:28

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'd say removed. If this is the same mobo then, without some mod to bypass the fuse, there won't be 5V power on the keyboard port. If in doubt it's easy to check that, just measure the voltage on pin 5 (do note that DIN pin numbering is a bit weird). No 5V on that pin means the keyboard won't work. …

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Re: Toshiba T4700CT Floppy Drive Belt

Posted on 2023-05-18, 12:55

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't remember the correct length / diameter for that belt but FYI the size you want is 1.5mm wide, not thick. 2mm should work too if installed with care. As for thickness it needs to be 0.5mm at most, better a thinner one if you can find it. Or else the belt will not have enough clearance around …

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-18, 10:52

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

1) I think what fixes the problem currently is that I added 5V and a 3.8V 18650 battery with wires. Seems stable for now. The 18650 is only fo testing now. So I think the most important is that the BIOS/CMOS line is powered. 2) Currently I got the 5V from one of the legs of keyboard bios chip. I …

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-17, 23:05

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

3) J7 is the external battery connector (P1 is the BIOS reset) . Are you talking about it when you say pin 4? Yes, that is the external battery connector, usually it takes the battery terminals on the two outside pins. You can easily check which is GND with an ohm meter - and in fact you should, …

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Re: Repair of m458 p80 motherboard 386 / 486

Posted on 2023-05-17, 11:52

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

- I do not now for sure pins 1,2,3 are for external/internal battery, but I assume so Is this the mobo you are repairing? https://theretroweb.com/motherboards/s/auva-computer-tam33-p8-tam40-p8-cpm25-p8-cp In general the external battery connector is 4 pin, not 3, but one pin is often unused. Your …

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Re: 5.25" floppy drive doesn't read most of my old floppies.

Posted on 2023-05-12, 11:31

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is it possible that one of the heads is broken, and as such the drive is "acting" like a 360 kb drive and not a 1.2 MB one? DD floppies have tracks twice as wide as HD ones. So if your drive somehow got misaligned it is possible that heads are not positioned correctly for HD, but it's good enough …

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Re: Help with repair 286 mainboard

Posted on 2023-05-11, 13:43

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is that corrosion from a battery leak or some rust deposition (barn find that was stored under something that rusted)? You might need to fully clean the mobo first - do not be afraid to wash it with water and soap, use soft brush only for any scrubbing. The important thing is to properly rinse it …

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