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Re: Dimensions of Turbo/MHZ Display

Posted on 2021-01-17, 18:48

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

In general I think many of the displays were around 0.5” if I remember correctly. Also, many of them had a bunch of jumpers on them for programming the two displayed speeds. So what, three leads? I think a modern version should be 888 not 188 If you have any input on the design, I'd be happy to …

Re: Dimensions of Turbo/MHZ Display

Posted on 2021-01-17, 18:46

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Here is what I have worked up so far. Filename Front.JPG File size 112.48 KiB Views 509 views Filename Back.JPG File size 74.93 KiB Views 509 views Filename pcb_front.png File size 131.94 KiB Views 509 views Filename pcb_back.png File size 136.44 KiB Views 509 views

Re: Dimensions of Turbo/MHZ Display

Posted on 2021-01-17, 18:34

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The bay insert is exactly what I had in mind. An easy way for people to convert ATX cases to fully support AT motherboards. As for the design, I’ve pretty much have the board design done. Just need to tweak a few things. The design I’ve gone with is based on a Microcontroller. And would allow simple …

Re: Duke Nukem Joystick Problem

Posted on 2021-01-16, 18:38

in Marvin \ Software

in Marvin \ Software

Duke is always moving to the right unless I actively try to change directions to the left. Yup, that's definitely a speed problem. Joystick input is always CPU-speed-sensitive by design. To read the analog values of the x/y axis, the code basically has to count how many times the CPU can read the …

Duke Nukem Joystick Problem

Posted on 2021-01-13, 00:48

in Marvin \ Software

in Marvin \ Software

I've been trying to figure this issue out for quite some time. But I've been unable to find a fix, all of the potential culprits I've found have to do with DOSbox, and not original hardware. System Specs ALI Chipset ATX Motherboard K6-2 400mhz 384MB Memory Soundblaster PCI 128 Joysticks: …

Re: DOA 486 Motherboard (that I have an urge to fix if possible)

Posted on 2021-01-11, 17:11

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Been fixing several 486/386 boards lately. One did have an issue with the -5v, which was required by the video card to get a picture. That said, there do look to be several vias that are corroded, and may have lost conductivity. You’ll need to trace all of them back to their respective ICs (in all …

Re: Dimensions of Turbo/MHZ Display

Posted on 2021-01-11, 03:30

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

wiretap wrote on 2021-01-11, 02:05: They vary from case to case. There is no universal size or hole placement. I have maybe 15 or so MHz displays, and all are different. Ok, for some reason I thought they were somewhat universal. Thanks for the info.

Dimensions of Turbo/MHZ Display

Posted on 2021-01-11, 00:36

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I do not have one on hand. So I cannot measure for myself. Does anyone have the dimensions of the MHZ displays, along with proper hole placements? I understand these are somewhat universal in their hole placement, and LED locations in later machines. I'm in the process of designing a replacement …

Re: ATX I/O shield models for 3D printing

Posted on 2021-01-07, 04:05

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well, I was just sitting down getting ready to take measurements to begin designing a I/O Shield for an AT motherboard when I ran on this post while doing research to see if anyone else had thought of this. Low and behold, Kaputnik beat me to it. Thanks a ton, buddy!

Re: Solved: Repairing 386 MB, Need ideas...

Posted on 2021-01-03, 21:17

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What's the PLD ? Do you mean the GALV16 chip ? If so, sure ! I have no way of storing it right now, but as it can be incredibly useful, I'll add that feature ! Yes, GAL16V8, 20V10, 22V10, etc are what are called PLDs. Or "programmable logic devices". And in reality, prior to this they would have …

Re: Solved: Repairing 386 MB, Need ideas...

Posted on 2021-01-03, 02:04

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Deksor wrote on 2021-01-02, 15:00: Nice job ! Meanwhile I have completed the UH19 page with the bios and photo you've posted here 😀 http://www.win3x.org/uh19/motherboard/show/3539 Nice. You want me to post the PLD code as well? Those things do occasionally go bad. I can break out my programmer and …

Re: Am386DX/DXL not posting

Posted on 2021-01-01, 22:42

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

As mentioned above that trace near the batter going from the KB Controller to near the ISA slots does look to have been eaten through by the leakage. This can be fixed by soldering a jump wire. But you need to check it to see if it is connected. If it were me, I'd probably desolder the KB Connector, …

Re: Repairing 386 MB, Need ideas...

Posted on 2021-01-01, 22:33

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well, I figured the issue out with this board this morning. Knowing that the issue was a problem with being able to read or write from the CMOS memory, I knew the problem was with the HM6818P circuitry. After some further thought, I couldn't see how the 6818 would have any issues with it at all. …

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 16:12

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Good investigating ! I cannot see the TC4069 in the picture. There are a few Tant caps around U37/U38 also c40, c62 and around the CPU that could be near shorting though doubt that would effect your scope reading much. Still think something could be up with bad traces around 82C311...is late am not …

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 05:00

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well, interesting results from the oscilloscope.... Pin 1 - MOT: 32khz square wave at 50mv (way out of spec for TTL logic) Pin 2 & 3 - Oscillator: 32khz square wave at 5.5v Pin 23 - SQW: No activity, logic low. Pin 22 - PS: No activity, logic high. Pin 21 - CKOUT: 32khz square wave at 5.5v Pin 20 - …

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 04:27

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well, I did consider the CMOS memory. The only thing I can think of that is battery backed is the 6818 RTC/SRAM. I’m pretty sure these are compatible with the 146818, so I ordered a few to see if I could get it working that way. I suppose it could be the 82C311 is just dead. Which would be a shame …

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 02:43

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It's a tiny bit of solder that bonded to the leg while reworking it. I was doing it by hand, so it wasn't the prettiest job. But it worked.

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 01:39

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

That picture is about the best I can do with my camera. But I've tested it, and it is soldered securely, and shows continuity between it and the 386.

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 00:51

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm thinking it could be the HM6818 RTC/SRAM that may have gone bad. As I'm fairly certain that BIOS settings would be set there. I've ordered a few from China, but they'll take a few months to get here I'm sure.

Re: Repairing 386 MB, Need ideas...

Posted on 2020-12-21, 00:50

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

One step ahead of you. Here is the BIOS. I can read the PLD if needed...

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