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PCChips/Hsin Tech M755LMR V7.1 missing components

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First post, by pixecs

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Hi,

I acquired a PCChips/Hsin Tech M755LMR V7.1 motherboard from flea market and it has a lot of components missing.

MLCCs: BC10, BC61, BC62, BC63
Cell battery holder: BHT1
Electrolytic capacitors: EC1, EC8, EC11, EC12, EC13, EC14, EC15, EC16, EC17, EC18, EC19, EC21, EC22, EC23, EC28, EC30, EC33, EC48, EC49, EC55, EC61, EC69
Keyboard port: PS1
Transistor: Q23
SMD resistor: R233
IC: U9, U10

I suppose most of the electrolytic capacitors are around 1500uF/6.3V, some 1000uF or even smaller.
MLCCs are around 1uF/10uF for local decoupling
U10 is the BIOS chip, U9 I suppose is a AMS34063/MC34063 inverting regulator.
Q23 no idea what is, but there are a lot of PN2222A transistor on board, so maybe is one of them.
PS1 is a DIN5 connector
R233 should be around 1K?

Maybe someone can confirm this suppositions.

Reply 1 of 10, by rasz_pl

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Sorry to say this, buuut This and PCPartner MVP3BS7-954 are both boards that are only good as part source to begin with. They didnt even work 100% correctly when brand new.

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

Reply 2 of 10, by pixecs

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Well, it seems they've already been used as donor boards. 😀
However, I will try to revive them.

Reply 3 of 10, by nuno14272

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Not whorth it.. several holes are destroyed..

1| 386DX40
2| P200mmx, Voodoo 1
3| PIII-450, Voodoo 3 3000

Reply 4 of 10, by Ydee

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pixecs wrote on 2026-02-27, 16:02:

Well, it seems they've already been used as donor boards. 😀
However, I will try to revive them.

I have soft spot for "bastards" like this, but if I can give advice - spend your time for more reliable things. PC Chips aka Hsing Tech aka bambillion others "brand names" has even some relative solid mobos, but that's not one of them.

Reply 5 of 10, by pixecs

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Its alive....
For BC10, BC61, BC62, BC63 i used some MLCCs from a socket 370 board, capacitors for decoupling...
For EC14, EC19, EC17, EC28, EC11, EC13, EC18, EC16, EC15 i used electrolytic capacitors at 1200uF/6.3V
For EC21, EC22, EC12, EC23, EC30, EC33, EC8, EC61, EC55, EC49 i used electrolytic capacitors at 1000uF/6.3V
For EC48 i used an electrolytic capacitor at 1500uF/6.3V
For EC1, EC69 i used electrolytic capacitors at 100uF/6.3V
For Q23 i used an PN2222 transistor
For R233 i used an 147 ohm resistor
For U9 i used an 34063API IC
For U10/BIOs i programmed an TMS27C020-15 EPROM
For keyboard port i used half of PS/2 connector from an AMD board

Reply 6 of 10, by pixecs

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The board after fix

Reply 7 of 10, by verysaving

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Good Job.
Put a heatsink on the GX chipset.

Reply 8 of 10, by nuno14272

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thats a LOT of fixes !!!! for a pcchips..

1| 386DX40
2| P200mmx, Voodoo 1
3| PIII-450, Voodoo 3 3000

Reply 9 of 10, by pixecs

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I put a heatsink on chipset but the chipset seems to be cool without one...

Reply 10 of 10, by rasz_pl

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Heatsink might have been provisioned for those hardcore 3d gaming sessions 😜 it does accelerate 3d somewhere below Intel Real3D i740 speed.

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

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