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Need help on a chicony 486 CH471B motherboard

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Robin4

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I hope someone could help me on this.

I have a chicony CH-471B motherboard here with bios version VBS1.04 with the date: 10/11/94-SIS-85C471B/E/G-2C4I9C21-00

Its having problems with recognize my AMD 5x85 P75-133mhz processor.. Its sees as a 80486DX2 cpu at 132 mhz..

I hope someone have a bios version from the year 1995 for me..
 
Have you seen this link?

http://stason.org/TULARC/pc/motherboards/C/CHICONY-INC-486-CH-471B.html#.UniJN1p3vSo

Whether or not your board can fully support an AMD 5x86-133 if kind of iffy. Your board only configures to 3.3 VDC for the CPU, and the AMD 5x86-133 requires 3.45 VDC. You may need to find a voltage adapter for the CPU and then get creative on the settings. I'm not sure a BIOS upgrade is going to be of much help on this one. Good luck on your project.
 
@ Agent orange..

I know of that sheet on stason.org.. I was only looking for a replacement bios en hoping i could solve the detecting problems..

@ Diodenmann...

Very thanks for that bios.. Can you tell me where you get that one?? Is that one on a german retro forum or so??

Do you maybe have a full picture on this board on the place where the VRM is place on the underside of the board... My board is missing this part.. I like to know the resistors values to solder in so i can solder the VRM part by my self..
 
The version is "Version VBS1.06 CH-471B" so that is also released by Vobis at one time. I couldn't find this one in the archive.org copy of their support files, so I wonder now if not everything was archived.
 
Some years ago I had such a board with this Bios version, which I dumped back then. To my knowledge it is nowhwere available on the net. On my board the voltage regulator components were also missing.
 
That no problem if it is a vobis bios.. Its better something then nothing..

Thanks both for the information..

I guess all OEM motherboard lacks the VR`s because that it wouldnt be possible to upgrade to a newer processor. So in mind to buy a new motherboard..

I hope someone have this motherboard with VR part installed.. Like to know the value for those resistors..
 
Recently found a board with populated voltage regulator section.
Regulator IC: Micrel MIC 29152BT
Resistor values:
R62 - 94,5k
R63 - 88,1k
R64 - 82,5k
R65 - 70,6k
R69 - 158k

Bios Version is 1.08. Will post an image later.
 

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Unbelievable you gave me just a heart attack diodenmann.. You are the best!!.. Never got this most usable information, tried to find everywhere.. And then i just give me the total solution..

Can i get a copy of that bios version 1.08 too?? I know that those blue resistors are for setting up different voltages setting.. It seems it having a lot of voltage settings (i dont know exactly which they where).
But i guess it was 3.3 volt. 3.45 volt, 3,6 volt and 4.0volts. And i know that this board having a seperate voltage part.. So you need to set the three jumpers on the right to the left side for 5volt only.. But it will disable to whole other part..
When setting those three red jumpers to the right, it disables the 5 volt part and enables the custom voltage setting part.. then the left jumper you only may set one for each voltage setting..

Can you tell my why theres that single resistor (i guess it that 158k one) in this setup? I guess it is to step down the 5 volts to 3.3 on de VRM??
 
@ diodenmann

How did you calculate those resistor values.. When i use an online resistor calculator for a 5 band resistor i get different values then the ones you giving to me..
Like:

R69 i get 13.9 Meg ohms (+- 2%) out of the calculator.. Colors: Brown, orange, white, green, red..

If i red the colors to the opposite way i get 259 K ohms (+- 1%) out of it..
 
Thank you for pointing this out, I read it that way: brown, green, grey, orange, brown.
Have you tried the 1.06 bios? I suspect that the file is corrupted.
 
Yes i had tried it with a different brand of eprom chip, because i dont want a dead motherboard after all.. So i want to spare the orginal cmos chip..
I wrote bios 1.06 on that new cmos chip, but the board doesnt want to start up and the screen keeps blank.. So i dont know if the bios file is bad or maybe a different kind of new eprom that doesnt want to work on that motherboard..
I was thinking to order new same eproms as the orginal, but (translate piece ->)am not further along come. I have spend this month already an amount of money on those vintage computer parts (i buy them once for al my systems) But iam almost done with the bigger buyings.. Then focusus more on smallere electronic parts..
So when i have money left i should order shame brand of eproms and tried again and see if it would work..
Do you all ready knows when you could upload that version 1.08 you recently had. Then ill try that one too.

By the way the first color stripe on that film resistor isnt brown.. But its red.. If you look good, you can see its a little different. Is it true that does resistors are 1%?
 
I hope someone could help me with a newer VBS 1.06 version or higher..
 
All my computer stuff is attic-stored at the moment because of some "little" renovation activities.
As I remember, there was no advantage in recognizing the Am5x86 with the newer versions. I remember the issue you described in your initial post, but with the newer ones the system does not start at all. I used the P24D setting shown in the manual, which should suit all needs of the Am5x86 :-(
 
Ok, but isnt no problem for me if i need to wait a little longer, because i cant do anything on that board right now.. But when you are finished with the renovation.. Ill hope you could help me with that newer bios you have / had..

You also helped me out with that voltage spot on the motherboard.. Ill trying to find those resistors.. But is it true, that those resistors are very rare at this moment.. I looked on ebay.. But couldnt find the right values i need to have.. Ill only could find those from 82.5K ohms ones.. The others looking rare to me..
 
I need 258K for the latest.. because its red, green, gray, orange, brown.
They also need to be 1% tolerance.. Not 5%..
 
Dont know if 1% or 0.1% would be the same.. Iam not that high educated on electronics.. But i think it wouldnt be a problem i guess.
Only they not in stock.. And i need to buy them as Bulk packages i guess. Iam making more concern about those 94.5K ohms = for 3.3 volt cpu voltage..
And 88.1 K ohms = for 3.45 cpu voltage.

Why theres a 258K resistor in that circuit, i really dont know.. Maybe there goes 12volt in the VRM and that 258K maybe convert it to 5 volts or so..
 
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