VOGONS


First post, by zecahue

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Got this motherboard that looks like it has a burned transistor.
I cleaned it up but need help from someone who has the same board to identify the component.

The board is a Intel AL440LX the version with the 2 Yamaha chips, I guess it is from a Micron Millennia SKU.

vx7JglZ.jpeg
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Thanks.

Reply 1 of 6, by Thermalwrong

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Checking my Dell AL440LX board, it is missing those components entirely so I can't suggest values sadly.

My current guess though is that they're connected to the FAN2 header on the mainboard since only that and the Line-In header are not populated on mine. That makes sense since those are power components that could be PNP transistors or perhaps P-channel MOSFETs - and probing around the FAN2 header middle pin does connect to the top pin of Q2F1 I think.

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Check out these pinouts in the manual, the main CPU fan is hooked straight to 12v but FAN1 & FAN2 say it's the FAN_CTRL line instead. I think this board could shut off these two fans when in a standby state or something.
The thing is, fans from the era did exceed what some of these headers were able to provide and it wasn't uncommon to hear of broken fan headers after installing a powerful fan in the computer.

You can test this by plugging a fan into each header to see which ones work.
If FAN2 doesn't power a fan anymore, you can check the FAN1 area for two similar transistors / MOSFETS. My board has "6Z" and "PC" marked transistors in that area, that matches with the "P" marking remaining on your burnt chip.

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Curiousity got the better of me and I pulled the "PC" mosfet around FAN1 off of mine to test it, it's reading as a p-channel MOSFET but I can't find any small package p-channel MOSFETs with "PC" as a marking code so far. Perhaps someone else could suggest a replacement.
However, it should just be that FAN2 header won't power a fan anymore and the board should otherwise be fully working. Be aware that if you do replace the MOSFET, you'll also need to repair that burned out trace adjacent to it.

Reply 2 of 6, by zecahue

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Thermalwrong wrote on 2024-05-08, 02:57:

That's absurdly correct ! I have tested and it's the fan2 circuit. Thanks.

I guess I will leave it like that.

Do you know if this board is Celeron compatible without a BIOS update? I know this board predates Celeron era but I haven't a P2 cartridge here, with a Celeron SL2WN (333/66) I am getting a 38-2F code with a generic POST diagnose card.

Reply 3 of 6, by Horun

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Depends on what bios version is on the board. According AL440LX Spec Update May 1999 on page 27:
"The motherboard supports the Celeron processor at 266 MHz with BIOS version 4A4LL0X0.86A.0023.P08, or later. Earlier BIOS versions will identify the processor as a Pentium II processor and will not work reliably with a Celeron processor.
The motherboard supports the Celeron processor at 300, 300A, 333, 366 and 400 MHz with BIOS version 4A4LL0X0.86A.0027.P10 or later."

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 4 of 6, by devius

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Just for completeness sake on my specimen it says "PCV" on that transistor:

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Reply 5 of 6, by zecahue

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Horun wrote on 2024-05-08, 13:15:

Depends on what bios version is on the board. According AL440LX Spec Update May 1999 on page 27:
"The motherboard supports the Celeron processor at 266 MHz with BIOS version 4A4LL0X0.86A.0023.P08, or later. Earlier BIOS versions will identify the processor as a Pentium II processor and will not work reliably with a Celeron processor.
The motherboard supports the Celeron processor at 300, 300A, 333, 366 and 400 MHz with BIOS version 4A4LL0X0.86A.0027.P10 or later."

I am unable to see the bios version because it cannot boot with the celeron 333 I have here. Now I am not sure if it is only a bios incompatibility or something else on the board.
Anyway I am trying to get an early P2 to be sure.

Reply 6 of 6, by zecahue

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devius wrote on 2024-05-08, 20:46:

Just for completeness sake on my specimen it says "PCV" on that transistor:

al440lx_closeup.jpg

That's awesome! Thanks : )
I may try to restore that for the "completeness sake" : )