VOGONS


First post, by khg0084

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Hello to all!

Last week I’ve grabbed my old Radeon 9800 Pro from storage, but unfortunately I recognized that a chip was cracked. A small heatsink is glued on the chip / IC and I assume that in long storage period something has cracked or broken the IC package. So i would have to change it to a new one, but unfortunately I haven‘t found a 1:1 replacement.

The marking of the chip is: 4226M and the second line is: 442013.
ChatGPT answered that it could be the MIC4426BM (MOS-FET IC). The package looks identical, but it’s not sure that’s the same of course.

My question would be very simple, does anybody of you know if there is a replacement chip available?
(See also to attached picture).

Every hint or idea for repairing would be welcome.
(The original chip is divided in two parts and not usable anymore, as it is may not seen on the pictures…)

Many thanks in advance,
Carl

IBM PC 750 (Model 6887)
--> Pentium MMX 233 MHz CPU, 128 MB EDO RAM
--> Matrox Millenium 4MB PCI, 3DFX Diamond Monster 3d II 8MB
--> Multiboot (Boot Magic) - Dos 6.22 / WfW 3.11 / Win 98 / Win XP
Wishlist: Powerleap PL-K6-III, Slot 1 Dual CPU MB

Reply 1 of 3, by momaka

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I think this might be it: 4226M-VB - dual N-channel 30V MOSFET. Datasheet below.
https://dfsimg1.hqewimg.com/group6/M00/00/58/ … hJPodsY4368.pdf

Just to double-check, see if pin 2 connects to pins 5 & 6 on the Radeon 9800 board. Also, I think pin 4 will be connected to ground (again, on the board), but not 100% sure. Let me know what you find with your multimeter.

If the above confirms and this is a dual N-ch MOSFET, just know that you don't need an exact part replacement. The new FET just needs to be rated for 30V V_ds, 20 V_gs, around 8 Amps continuous Drain current, and similar Gate charge ratings. Most likely, modern equivalents should be easy to find on reputable part distributor stores (i.e. Digikey, Mouser, RScomponents, Farnell, etc.)

Reply 2 of 3, by khg0084

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Thanks for your fast reply!

Pin 8&7 and Pin 5&6 are connected together. Pin 3 is connected to ground. Pin 1 is connected to 5&6.

Is that something with you can work with?

Thank you in advance,
Carl

IBM PC 750 (Model 6887)
--> Pentium MMX 233 MHz CPU, 128 MB EDO RAM
--> Matrox Millenium 4MB PCI, 3DFX Diamond Monster 3d II 8MB
--> Multiboot (Boot Magic) - Dos 6.22 / WfW 3.11 / Win 98 / Win XP
Wishlist: Powerleap PL-K6-III, Slot 1 Dual CPU MB

Reply 3 of 3, by momaka

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khg0084 wrote on 2025-03-06, 10:18:

Pin 8&7 and Pin 5&6 are connected together. Pin 3 is connected to ground. Pin 1 is connected to 5&6.

Hey Carl,

Yes, that's correct, and sorry for my mistake - indeed pin 1 should be connected to 5 & 6, and 3 is GND. I was just offset by one for some reason (funny, since I had the datasheet right in front of me.)

So your findings confirm this is a dual N-ch MOSFET is SOIC-8 package.