Re: Tantalum recapping project

Posted on Yesterday, 10:43

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Polymer electrolytics do explode. In fact the lack of any deliberate structural weak spots (the grooves on top of typical electrolytics) causes them to build up gas and then launch the outer shell with potentialy eye-taking velocity, while the guts are rapidly spread all over the PCB. I know from my …

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Re: A reminder on lithium batteries.

Posted on 2025-04-04, 10:20

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Must be some stern materials to hold back a lithium fire. Only the finest asbestos. I'm joking of course but I don't think you can contain such a fire if it's big enough. So these bags are most likely good for just one, maybe a couple of cells. New cells are usually made, shipped and stored at …

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Re: Help request - PC motherboard/CPU damage after power supply failure

Posted on 2025-04-01, 16:10

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

These mobos did suffer from capacitor plague, did you replace the ones near CPU slot? If not take the mobo out, the CPU out of socket, and test the caps for shorts. Chances are one of the CPU power rail caps has shorted, took out a MOSFET, which in turn killed the PSU. It's a theory but it's not …

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Re: TSR-Programming/Assembler: my TSR program executes (seem to install) and then every other program run crashes dosbox

Posted on 2025-03-30, 19:33

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by Deunan

in Marvin \ Software

in Marvin \ Software

i don't jump twice/or getting called twice - the call after string-replace only calls the original handler can you explain differently? What I mean is AH=9 is just one of many functions of int 21h. Consider this approach: cmp ah,9 ; is it print je run_print jmp far ptr cs:[tsr_info.old_interrupt_ …

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Re: TSR-Programming/Assembler: my TSR program executes (seem to install) and then every other program run crashes dosbox

Posted on 2025-03-30, 10:57

by

by Deunan

in Marvin \ Software

in Marvin \ Software

push cx push dx ... pop cx pop dx First, correct the push/pop sequence. Second you should consider jumping on AH=9 to your code, rather than jumping twice on AH!=9 to old address. It's not a huge issue, the 21h handler is not that fast, but I like doing things properly for performance reasons - …

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Re: TSR-Programming/Assembler: my TSR program executes (seem to install) and then every other program run crashes dosbox

Posted on 2025-03-29, 20:23

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by Deunan

in Marvin \ Software

in Marvin \ Software

run_original: jmp cs:[tsr_info.old_interrupt_21h] ; jump to original int 21h I have not used WASM a lot, back in the day I would use MASM, then TASM, and now NASM - so I'm not 100% sure about this, but shouldn't that jump be explicitly far? As in, "jmp far cs:[...]". The way you have it now it …

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Re: Resurrecting a 40 year old electron microscope

Posted on 2025-03-27, 22:22

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The burnt jumper was the one connecting the HDD power ground to the chassis ground. However, the errant ground wire didn't connect to the chassis anywhere near the HDD chassis ground... That would mean this is the lowest resistance connection between GND and chassis. Perhaps even the only one. …

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Re: Resurrecting a 40 year old electron microscope

Posted on 2025-03-23, 19:23

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I made a very foolish error already by connecting a ground wire to the 5v rail. More details please? What wire, where did you connect it, was the system powered at the time, etc. I mean how did it even affect the HDD and not the PSU if you basically created a short on the 5V power rail. Did you …

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Re: Gigabyte GA-5AX 4.1 blue resistor in the middle of ZIF Socket

Posted on 2025-03-23, 18:55

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You can bend it slightly towards the PCB with your finger. The leads are pretty thick so it will give some resistance to force but should not break. Don't bend it too much because it will cause an air gap between it and the CPU, and the temperature reported will be lower.

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Re: Schneider Euro XT, start problem

Posted on 2025-03-18, 11:22

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The antique light bulb method is okay, in modern times I would at least install an RCD switch that disconnects the circuit very quickly if there's a short. I think you mean RCBO not RCD, but if the PSU input shorts then the breaker will still need to go into overcurrent protection which is usually …

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Re: Schneider Euro XT, start problem

Posted on 2025-03-18, 11:08

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Just connect Schneider to atx PSU 5, 12, -12. As I beleive to multimeter - voltage is right. There is no any life signals... Found that I don't know why, but onboard video ram is overheated... (41464 modules) any ideas? And that is another reason why I use lab PSU with current limiting. So that if …

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Re: Schneider Euro XT, start problem

Posted on 2025-03-17, 17:21

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

PSU repair is not that difficult but you need to have a proper testing setup. Preferably with isolation transformer but that is not stricly required if you don't try to stick your hands everywhere, and you keep track of your tools. But you should have a ligthbulb in socket, several preferably to …

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Re: Chinon FR-506 1.2 MB unit not reading floppies

Posted on 2025-03-13, 14:35

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm getting a weird exception in Windows XP when running the command from the command line. That is odd. What kind of exception? What does it say? Is the drive doing anything at all? Most (but not all) 5.25" drives will start the motor for a few seconds when floppy is inserted. This is to help …

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Re: Possible to low level format old ESDI drive with 256-bytes sector size?

Posted on 2025-03-12, 22:12

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

That's a nice, big HDD. I like those. Sadly yes, everything mechanical will die at some point and these drives are no exception. I don't understand why there are switches that change the head count, possibly to accomodate machines that could not work with more heads for some reason? Or to better …

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Re: Chinon FR-506 1.2 MB unit not reading floppies

Posted on 2025-03-12, 21:47

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Do you have any floppies you don't mind being erased? If so, try formatting it in this drive. If it works and the floppy is now readable then your drive has poor head alignment. Or the previous drive that was used to write that floppy had it. If it doesn't work then chances are there is something …

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Re: "Fixed disk 1 failure" on ESCOM Paradigma 486 Despite Working HDD

Posted on 2025-03-12, 21:45

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Was this HDD working properly in this machine before, or did you add it yourself? In the latter case did you set the master/slave jumpers properly? Some older IDE drives have a separate master and master with slave settings, and wrong setting can lead to bad PDIAG behaviour, which in turn can …

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Re: Possible to low level format old ESDI drive with 256-bytes sector size?

Posted on 2025-03-12, 16:42

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I own an IBM 5363 (mini mainframe). The hard disk in there was formatted using 256 bytes sector because that's what the OS needs (called SSP). However it seems that these drives were pre-formatted by IBM internally as there is no option in all software I found to do the fomat. When I try to re- …

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Re: Possible to low level format old ESDI drive with 256-bytes sector size?

Posted on 2025-03-11, 23:30

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hm, I've read your fist post again and now I think I misunderstood your question. So you already have a DOS-compatible format on this HDD? With 512-byte sectors, which was done with WDFMT util? But you want to have 256 byte sectors instead? In that case WD1007-WAH is not going to help you much …

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Re: Possible to low level format old ESDI drive with 256-bytes sector size?

Posted on 2025-03-11, 18:08

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

WD1007-WAH works only in hard sector mode, so it depends on the disk in question. Your HDD must have unformatted bytes per sector > 512, and sectors per track >= 35 as well. I guess it must also respond to bytes per sector command, which is optional, to change current 256-byte setting. However if …

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Re: Schneider Euro XT, start problem

Posted on 2025-03-10, 14:16

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Before you start testing everything with the scope make sure that: 1) There isn't any corrosion from battery. Even if battery was already changed perhaps some traces were already corroded and not cleaned properly. 2) Is the PSU working properly? Are all voltages present and in spec? Re 1: Some …

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