Re: CMOS error after changing battery on IBM PS/2 Model 76i

Posted on 2021-09-01, 08:17

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well, after a lot of reading and digging from old posts in this forum I determined that the most likely cause of this behavior was a bad DS1585S. So I checked online and found pretty cheapo spares in AliExpress. I pulled the trigger, the risk/benefit tradeoff was just too good to pass. I replaced …

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Re: CMOS error after changing battery on IBM PS/2 Model 76i

Posted on 2021-08-11, 16:50

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So, I have been looking at this issue. The new battery is perfectly valid, providing 3.28v that I have checked make their way all they way to the RTC Dallas DS1585S IC (pin 23, Vbat). Still, every time I switch off the computer (still plugged to the wall, but switched off) and reboot I will always …

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CMOS error after changing battery on IBM PS/2 Model 76i

Posted on 2021-08-05, 20:25

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, I am trying to bring back to life an IBM PS/2 I got from ebay some years ago. It wasn't booting or displaying any output, and that turned out to be a bad power supply. After replacing it I am now facing a new challenge. The computer complains about the system configuration and time/date not set, …

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Re: Gotek firmware update issue

Posted on 2020-07-03, 19:10

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the post, I am planning to flash my gotek in the next few days so this may come handy. Cheers! I'm not looking for help, I'm just wanting to post this in a Google-indexed place so retro enthusiasts of the future can save some time. I recently struggled to install FlashFloppy on a Gotek …

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Re: Clonezilla - restored Windows XP image won't boot

Posted on 2020-06-01, 11:15

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the tip about Bootpart, looks pretty handy indeed. For MBR fixing this may have been a better choice, at least faster and easier. boot-repair is a beast, it can repair pretty complex setups with dual-boot, secure boot, etc. Perhaps an overkill solution in this setting, I agree :D One …

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Re: Clonezilla - restored Windows XP image won't boot

Posted on 2020-05-31, 18:46

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi there, sorry to hear about this, my experience with clonezilla has been not so great in terms of user friendliness, but in the end I have always had success restoring my backups. Something that may work to fix your boot is: https://sourceforge.net/p/boot-repair-cd/home/Home/ I've used it in the …

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Re: PC Chips M912 BIOS update for Am5x86 and Cyrix 5x86

Posted on 2020-05-31, 18:36

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, sorry for the late response to this question, it's been a while since I logged in the forum. Unfortunately, I haven't had time to replace the fake cache chips on the board. It is pretty substantial amount of work, and I just don't have the time at the present time. If anybody has success with …

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Re: 80486 BIOS image collection

Posted on 2018-09-01, 21:35

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

#27 Manufacturer/Identifier: HOT-409 v2.2 / 40-0202-001343-00101111-111192-OPT495SX-F Chipset: OPTi 82C495 SX 4L05F2813 for INTEL 80487SX,80486SX/DX/DX2, Pentium Overdrive

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Re: PC Chips M912 BIOS update for Am5x86 and Cyrix 5x86

Posted on 2018-09-01, 18:10

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, sorry for resurrecting this old thread, just wanted to report that I could get my m912 to work with an AMD 5x86 (at both 133 and 160 Mhz) thanks to the information of this post. I am using the bios contributed by feipoa, but probably the one uploaded by BlasterMike works just fine as well. About …

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Re: 486 Motherboard working with 5v CPUs but not with 3v

Posted on 2018-08-26, 12:32

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes, that's probably a good idea. Both components are easy to find nowadays, however in my local electronics store they had run out of D882s, so I had to chose an alternative option. I went for a 2SD1666 (I think it's from Sanyo, but not 100% sure), you just need to make sure you mount it in the …

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Re: 486 Motherboard working with 5v CPUs but not with 3v

Posted on 2018-08-25, 12:15

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, I finally was able to replace both the regulator and the transistor for new parts. Soldering wasn't trivial, but not too tough either. Some experience with electronics definitely helps here. After changing the parts, the good news is that I have a reliable 3.3v feed out of the regulator+ …

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Re: 486 Motherboard working with 5v CPUs but not with 3v

Posted on 2018-08-22, 19:09

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Quick update, it was a pity that I didn't read @stamasd message before. I indeed changed the regulator (TL431) and was able to get 3.45 volts as the output! However it didn't last for long, probably because the transistor (D882) is burnt and without it the regulator just cannot handle the load for …

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Re: 486 Motherboard working with 5v CPUs but not with 3v

Posted on 2018-08-22, 07:09

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I agree the tl431 provides the 4v output, but it should provide the 3.3V output as well, shouldn't it? In any case, I'm not getting any reading close to any of these values, only 5V 🙁

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Re: 486 Motherboard working with 5v CPUs but not with 3v

Posted on 2018-08-21, 21:45

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi again, thanks everyone for your feedback. I've been investigating a bit more the situation with the mobo. There seems to be two parts working together to regulate voltage: a TL431 which does the voltage regulation, and a D882 transistor which is in charge of generating enough current. When set to …

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486 Motherboard working with 5v CPUs but not with 3v

Posted on 2018-08-21, 17:17

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, I've come across this annoying issue with my PC Chips M912 ver:1.7 motherboard. When I configure the board for 3.3V for using DX4s and 5x86 the CPUs will not work. In 5V configurations my DX/DX2 cpus work just fine. In fact, I had been using a DX4-100 processor at 5V for a while without even …

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Re: Cooling Intel dx2 66

Posted on 2018-08-13, 12:34

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

SW-SSG wrote: ^You could also just drive a common 40 or 50mm fan with 5V. It would likely be quiet enough + still provide enough cooling. Do you mean 5v as opposed to 12v to reduce RPM? Neat idea, I'll try that and report back!

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Re: Issues connecting a Roland SC-55 to an old 486

Posted on 2018-08-13, 10:53

by

by jsp

in Marvin \ Sound

in Marvin \ Sound

Alright, got my cable today ordered from https://www.serdashop.com/JoystickMIDICable and I can confirm it works perfectly fine when connected directly to my sc-55. So mistery solved, it was the cable! I am still amazed of the ability of the mt-32 unit to deal with such an imperfect cable and even …

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Re: Cooling Intel dx2 66

Posted on 2018-08-12, 20:57

by

by jsp

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Based on what you say, I guess my dx2 is faulty probably bc it was operated without any heatsinks by its previous owner. Damn :( I'm back to 33Mhz. I'll try the heatsink when it arrives as it's already on its way. Thanks! I forgot to report back from my experiment. My Dx2-66 is operating without …

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Re: Issues connecting a Roland SC-55 to an old 486

Posted on 2018-08-10, 15:02

by

by jsp

in Marvin \ Sound

in Marvin \ Sound

Ok, I got my setup working using the following hack: I connected the db15-midi cable directly to my mt-32, and used the midi-through of the mt-32 to feed the sc-55. Worked like a charm! The cable is obviously missing some electronics but the mt-32 copes with that pretty diligently. On a related note …

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Re: Issues connecting a Roland SC-55 to an old 486

Posted on 2018-08-08, 08:22

by

by jsp

in Marvin \ Sound

in Marvin \ Sound

Yup, I did init it by switching it on having both instrument left and right keys pressed. The demo songs play well. Hell, I can play midi files from my laptop using the usb<->midi cable. It's the 486 that won't be able to play music through it via the db15<->midi cable, but it would play the mt-32 …

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