Re: Something wrong with AT PSU - hissing noise and not powering on

Posted on 2020-08-06, 08:04

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The PWM ic looks to me like there are several strands of spider web on it rather than cracked. If the PWM ic is bad or blown, I don't think there will be any hissing as there is nothing driving the MOSFETs which drive the transformer. @Mattyice1994 you can try wiping the ic (with power cord …

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Re: Mode Q timings

Posted on 2020-08-06, 07:37

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes. 256x256 is a plane based video mode (a.k.a unchained mode). The only non-plane based 256 color mode on standard VGA is mode 13h. [...] It is actually mode 13h (320x200 linear) that is the odd one out, it's actually an abstraction on top of 320x200 plane based to make it easier to work with but …

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Re: Something wrong with AT PSU - hissing noise and not powering on

Posted on 2020-08-05, 07:54

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

PSU pictures: https://imgur.com/a/7Qv7NxA Wait a second: In the last picture, you have a good image of that 16-pin control chip (most likely a TL494 or a clone like the KA7500), and it seems to have a crack straight through the whole chip. If that's the case, some catastrophic failure severely …

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Re: Cirrus Logic GD5424 (maybe)timing problems on some games

Posted on 2020-08-04, 07:49

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Basically I have a 486 build I use to play old dos games and I noticed that while games using CGA (like golden axe or Commander Keen 4 in CGA mode) or VGA (doom, duke nukem 3d, Dungeon Keeper, quake, Monkey Island 2, etc) work great (well quake is a slideshow, but it still runs stable), games that …

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Re: horrible ide performance on sis496 mainboard

Posted on 2020-08-04, 07:22

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

i tried it on a umc8881 board and its equally slow, and so is the cf card. it displays pio4 mode but i feel its actually pio1 performance. would it get better in windows98? Does your BIOS offer "IDE block mode" and/or "IDE 32-bit access"? If yes, make sure that both options are enabled. The SiS496/ …

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Re: AWE32 - issue with installed DRAM / distorted MIDI

Posted on 2020-08-04, 07:15

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

In that case, the issue sounds like broken traces or solder connections between the EMU8k chip and the DRAM sockets. You could try to buzz out that all relevant pins at the memory sockets (parity-related pins are not relevant) are indeed connected to the synthesizer chip. Yes I know RAM modules …

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Re: AWE32 - issue with installed DRAM / distorted MIDI

Posted on 2020-08-03, 07:30

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

I recently acquired AWE32 CT3980 good in all aspects besides working with ext RAM modules "DIAGNOSE.EXE" in pure DOS is not detecting installed DRAM at all "AWE Control Panel" in Win98 is reporting installed memory size corectly Sound bank loading also works, properly changing "Available" kbytes …

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Re: Something wrong with AT PSU - hissing noise and not powering on

Posted on 2020-08-03, 07:14

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hissing noise of an AT power supply is a very typical sign for a short circuit at the output. While other causes are possible, the first thing I would do in this case is checking the PSU and mainboard for shorts on all power rails. You can easily do it with your digital multimeter. Put it into …

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Re: Intel DX4-100 write-back (&EW) won't post Edit: Probably a fake chip

Posted on 2020-07-31, 15:41

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

5) don't increase your 486dx4-100 CPU voltage past 3v. ( you will damage the chip ). The usual spec of a 486dx4-100 CPU is 3.3V to 3.6V, with 3.45V being nominal. I guess that's what you mean, but it could be read as "do not exceed 3.0V", which would be wrong. 3.0V is out-of-spec (too low) for any …

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Re: trying to explain edo vs fpm

Posted on 2020-07-29, 14:16

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't see where your "RAM must wait for cache" claim comes from. There is no reason for the L2 cache to not accept a cacheline fill (this is what happens on a read miss) as fast as it can do a read burst. So if the cache can do 3-2-2-2 at 50MHz when the processor reads from it, it should be …

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Re: Bought these (retro) hardware today

Posted on 2020-07-28, 19:40

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So, it's Compaq-specific. I have the square-shaped piggyback module - there are quite a few numbers on it that are mostly hidden. Have taken more photos of the layout of the board, as well as the oxidation of sorts - haven't done cleaning yet. Wasn't keen to remove the upgrade module yet - looks as …

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Re: Pinball Illusions Deluxe (CD Version). Error message on PC - But works under DOSBox

Posted on 2020-07-28, 08:33

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by mkarcher

in DOS

in DOS

You start the game with ILLUSION.BAT and on the PC I get this error screen: https://i.imgur.com/0yO6Kenl.jpg https://i.imgur.com/Xn04nYvl.jpg However... When I mount the CD in DOSBox, the game runs perfectly. All the Music is through CD-Audio and tracks change correctly. Also when I disable HIMEM. …

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Re: Bought these (retro) hardware today

Posted on 2020-07-28, 08:28

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

RAM CARD: I don't know if that's proprietary but it's probably valuable. 4MB ram is quite handily enough for a 386 too. Those RAM CARDs are proprietary Compaq stuff. The Deskpro 386 series used memory cards that could be upgraded with square-shaped piggyback modules. This applies both to the 386s ( …

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Re: Another 386-motherboard to identify

Posted on 2020-07-26, 14:59

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It's a pretty sweet board...TTL logic. No chipset. 128kb cache. That seems to be the penalty to being to market early with so much cache. The design costs of that board must have been enormous, look at the nearly 30(!) GAL/PAL custom logic chips (recognizable by the paper label indicating the …

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Re: Opti 82c930 impressions and some Windows Sound System observations

Posted on 2020-07-26, 14:06

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

I just had a closer look, and found that the card in the original post is just 930, while mine is 930A, so there may be some differences. I don't have a 930, but I've found another 930A - and the problem is the same: distorsions in Pinball Fantasies, no matter if it's set up for SB1, SB2, or SB Pro …

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Re: Bought these (retro) hardware today

Posted on 2020-07-25, 21:03

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

and the one big adapter on the top that I can't quite figure out yet... fits a 386DX CPU on... what exactly? 486 boards? x3 It's not as absurd as it might sound. There actually are some chipsets that can work with either a 386DX or a 486 CPU, and there even are 386/486 combo boards like this one: …

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Re: Need a DIY MIDI FM synth module

Posted on 2020-07-25, 08:41

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

No, it definitely exist. Some time ago (prior to making this thread) i found this . The video description says: MIDIbox FM V2.0 is a homebrew 36-voice FM synthesizer based on two Yamaha OPL3 (YMF262) sound chips The video description even have a link , but i unable to find firmware and PCB files …

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Re: Sound issues with Sound Blaster 16 WavEffects

Posted on 2020-07-21, 13:26

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by mkarcher

in Marvin \ Sound

in Marvin \ Sound

Is Waveffects the designation for soundblaster 16's with a waveblaster port? No. The WavEffects designation means that the card is shipped with a license to use the WaveGuide software synthesis for 32 MIDI voices. It's the same software that expands the AWE64 to "64" voices, that consist of "32" …

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Re: How hard is it to program a 7x9 pin AWARD bios chip?

Posted on 2020-07-20, 22:32

by

by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

[...] Thanks. Can I run that linux program ona chip in a usb programmer or does it need to be stuck into the motherboard? If you have a programmer, you don't need the software (which works with EEPROM connected to the system, so yes, stuck in the motherboard). Use whatever software comes with the …

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Re: How hard is it to program a 7x9 pin AWARD bios chip?

Posted on 2020-07-20, 19:36

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by mkarcher

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Your question would be easier to answer if you could provide an actual part number off the BIOS chip . Programming an EEPROM is usually quite easy with a compatible programmer . So what I actually want to do is swap this AMI bios with a socket-compatible AWARD bios, so I can go from a Compaq bios …

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