Got a new M919 - (Power regulator question) \ VOGONS

Got a new M919 - (Power regulator question)

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First post, by Rav

Posted on 2023-07-04, 20:18

Rav Offline

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Hi there, I got a "new" M919.

I did look at many pictures and they all seam to have two mosfet while the one I got have only one for some reason.

Does someone could tell me if I need the second one for an overclocked Cyrix 5x86 and if so, which one go there? Same one as the other one or?

There is also two "pins" visible in the vlb slots, I guess I can push them in place or something.

Here the board :

Here a zoom of the missing mosfet region / Vlb pins :

Reply 1 of 4, by Nexxen

Posted on 2023-07-04, 21:02

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https://theretroweb.com/motherboards/s/pcchips-m919-ver-3.4b

PC#1 Pentium 233 MMX - 98SE
PC#2 PIII-1Ghz - 98SE/W2K

Reply 2 of 4, by paradigital

Posted on 2023-07-04, 21:46

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Mine only had one. It was dead though, would only provide 5v, not 3.3v or 4v.

I replaced with two (and two new heatsinks so they matched), and it’s been great since running an overclocked Am5x86-P75.

Reply 3 of 4, by Rav

Posted on 2023-07-05, 04:08

Rav Offline

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paradigital wrote on 2023-07-04, 21:46:

Mine only had one. It was dead though, would only provide 5v, not 3.3v or 4v.

I replaced with two (and two new heatsinks so they matched), and it’s been great since running an overclocked Am5x86-P75.

Thanks, it answered my two question.
Will look for two of the same kind and replace them just to be sure.

Reply 4 of 4, by majestyk

Posted on 2023-07-05, 04:41

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BTW the 2SC3420 is not a MOSFET but a regular bipolar junction transistor (BJT).

https://pdf1.alldatasheetde.com/datasheet-pdf … BA/2SC3420.html

PC-Chips loved to use these to save a few pennies. They also operate in parallel without any additional circuitry, which is not "state of the art" because due to tolerance the transistors tend to not share the current, but one of them takes more or all of the load and dies quickly. It´s a very poor design.
(It´s a different matter with MOSFETS that can operate parallel.)

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