Re: Asus P5A not working

Posted on 2023-02-04, 20:25

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It has the cpu and a memory module and the cr coin battery, I disconnected the ATX cable. I remeasured just to be sure, it starts low as 200 and goes to 450. If you get low value even without CPU and RAM installed there could be something wrong with the diode or capacitor. EDIT: I guess that value …

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Re: Asus P5A not working

Posted on 2023-02-04, 20:04

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thank you very much, I remeasured the values, the most sure difference is on pin 4 of the HIP6013, I get 0.L which I suppose means infinite, while you get 7m. Same goes for pin4 on the other chip, I get a completely different value from yours, I tried with continuity and it seems in short. I'm …

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Re: Asus P5A not working

Posted on 2023-02-04, 19:20

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I made reference measurement from controllers. No CPU & power attached. HIP6008: Copy code to clipboard 1 >3k 2 8M 3 23k 4 13k 5 8k 6 5k 7 INF 8 >12k 9 zero 10 8M 11 >2k 12 6M 13 38k 14 38k 15 7M 16 1.4M and HIP6013: Copy code to clipboard 1 7M 2 >3k 3 7M 4 7M 5 3,5k 6 >12k 7 zero 8 >1k (480) 9 6M …

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Re: Asus P5A not working

Posted on 2023-02-04, 18:29

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Nemo1985 wrote on 2023-02-04, 18:24: I see thank you... Should I try to measure again until I get the highest value? If it rises to some "highish" value it's OK. I would be more interested about those low ohmic values 200-300 ohm.

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Re: Asus P5A not working

Posted on 2023-02-04, 18:22

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Crazy means that the multimeter start with a low value and then it goes up up up up That happens when you have large capacitor connected in parallel with the multimeter charging up.

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Re: Asus P5A not working

Posted on 2023-02-04, 17:56

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Shorted transistor can do nasty things like lead 5V on the Vcore rail. You are lucky it's not that in this case. Good luck hunting.

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Re: Asus P5A not working

Posted on 2023-02-04, 16:10

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I would check these next, just to be sure they have supply voltage etc. HIP6008 -pin 14 (VCC) 5 or 12V -pin 10 (PGOOD), may not be connected HIP6013 -pin 14 (VCC) 5 or 12V -pin 6 (enable), should be above 1V regulator to be enabled

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Re: Asus P5A not working

Posted on 2023-02-04, 14:35

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Those two PWM controllers HIP6013 near both transistor pairs switches transistor to generate selected output voltage. Clearly something is wrong with the control. Look for missing or weird looking components around them. I haven't heard of poor capacitors in P5A? Of course doesn't mean it's …

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Re: Asus P5A not working

Posted on 2023-02-04, 14:23

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Regulator inputs should be 5V, measured from transistor tabs. Green arrows in edited picture.

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Re: Asus P5A not working

Posted on 2023-02-04, 14:01

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes, I got that. USB/PS2 port cover is fine. That pentium is common rail and interconnects Vcore and VIO. For what it sounds, Vcore supply is possibly missing and draws VIO down with it. It would tell more if you have dual rail CPU f.ex. MMX or K6(-2).

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Re: Asus P5A not working

Posted on 2023-02-04, 13:39

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Orange is Vcore and 2.1V is OK. But I was wrong with the CPU, for VIO (yellow arrow) measurement CPU must be inserted. Otherwise they are about the same value. Also try to change GND point if value looks strange. What CPU are you using?

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Re: Asus P5A not working

Posted on 2023-02-04, 12:54

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I would measure these two regulator output voltages. You can do it without CPU. Just check that Vcore jumper is set to something, like 2.1V. Orange = Vcore Yellow = VIO Green = 5V reg input

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Re: What retro activity did you get up to today?

Posted on 2023-02-02, 19:06

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Two days of depressing search for this Aztech I38-MMSN850 AZT2316 DOS config & drivers. Every time I get "Card not found" slap on my face. In other system running Win98 it works fine. I could try to set it on different IRQ once more...

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Re: Toshiba T5200 mods and upgrades

Posted on 2023-02-02, 08:27

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Someone interested in 2MB and 8MB 40pin SIMM memory kits? Nothing is ready yet. Just scouting before I make any PWB & chip orders because these are not cheap. Also have to repair my test bench first, no RAMs without it. I'd be interesting, depending on cost. I'm thinking of trying to install …

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Re: Toshiba T8500

Posted on 2023-01-31, 18:45

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

System up and running. Installed DOS 6.22 on very quiet 120GB Samsung Spinpoint. 2GB partition sounds like a waste. There's no way configure or even disable HDD 0&1 configuration. System "autodetects" somehing there, max 100MB. Installed XTIDE on ethernet ROM + overlay and works fine. System …

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Re: 80386 BIOS image collection

Posted on 2023-01-30, 18:53

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

#: 101 Manufacturer/Identifier: TOSHIBA T8500, 34T702456G 02 F0, FWS203 Chipset : Toshiba/Fairchild BIOS : 1.02A ID string : 2 * 27C256 (ODD/EVEN)

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Re: Toshiba T8500

Posted on 2023-01-29, 14:49

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Maybe is better that way due to module pin order. *** I replaced PS circuit board with generic hec 250W ATX. Unoccupied Adruino Nano breakout board was volunteer to work as an adapter. Not the best one, but it will do. I arranged wires better after these pictures. It's a complete package again. I …

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Re: Toshiba T8500

Posted on 2023-01-28, 18:41

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes, these chips are 16bit + 2bit parity (2CAS) each. In SIMM module there is 2 RAS lines to select chip. So there are two double 8+1-bit column chips in 2 rows. In the 8+4 chip module there is... ok here is hopefully illustrative picture. So that one 42-pin chip is the same thing as all green RAS1 …

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Re: What retro activity did you get up to today?

Posted on 2023-01-23, 19:47

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

BitWrangler wrote on 2023-01-23, 18:10: Sanity check your fuses, I've found one open circuit while not appearing blown before. Think it was mechanical shock detached it one end or something. Fused were ok, but I found 5W wirewound 15R resistor with infinite resistance. It has functioned as a fuse.

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Re: What retro activity did you get up to today?

Posted on 2023-01-23, 17:17

by

by fool

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have tried to repair this stupid Toshiba power supply. Main switching transistor was shorted, but replacing that didn't solve the actual problem. It's totally dead. Power supply PWM controller is MB3759, same as TL494. It's build around 89-90, but has ATX style power-ON button. I think fault is in …

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