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Dolch Motherboard Question

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RadRacer203

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Just got a new Dolch project in the mail, apparently dead. I turned it on and it did actually work, but I figured there would be some issue with it and I found the problem. It has the American Megatrends Super Voyager VLB-III motherboard and the battery leaked badly enough that chup U52 fell off and was rattling around inside. Is that chip necessary? Like can I run without it after I remove the bartel battery? Or should I be searching for a new motherboard?
 
Well I got the barrel battery taken off and the little bit of corrosion cleaned up. The only problems I have are a couple lines in the screen (only in some colors), and the hard drive controller throws an error every time.
 
Out of curiosity, what *is* the chip? (IE, markings, labels, etc.) The typical Statson references have jumper locations, not chip locations.
 
Yeah, I was checking the jumpers on there but there wasn't really any relevant info on there. I would post the chip labels but its completely worn off. Only marking is on the bottom and it says "portugal CG20"
 
Maybe a photo would help someone else guess? I mean, if it was the chip sitting right next to the barrel battery I would hazard a guess it's the CMOS/RTC chip, in which case it's definitely something you want.
 
Hrm. The standard Motorola 146818-compatible NVRAM/RTC clock IC that was used in the original ATs has 24 pins, that little chip has 20. There certainly are 20 pin RTCs in surface mount packages, like the I2C DS3232, I don't know if that's likely to be something you'd find on a 486 board?

Is soldering it back on definitely not an option?
 
It's pretty bad and the pads on the motherboard are pretty much gone. Weird thing is this is the only part that was visibly corroded. Guess I'm looking for a new motherboard?
 
RadRacer203 said:
The only problems I have are a couple lines in the screen (only in some colors)
Click to expand...

FWIW, it's likely the lines on the screen are an issue with either the LCD or its cabling. I had a somewhat newer Dolch for a while (Pentium 200) and it had intermittent screen line/garbage issues that you could fix/trigger by messing with the cabling or pushing gently on the LCD board. Did not seem to be aging particularly gracefully, that machine.
 
RadRacer203 said:
It's pretty bad and the pads on the motherboard are pretty much gone. Weird thing is this is the only part that was visibly corroded. Guess I'm looking for a new motherboard?
Click to expand...

Given it's a multi-layer motherboard then, yeah, if it's really rotted out then you're probably in a pretty bad way to trace out where to solder bodge wires without a schematic.

The Pentium Dolch I had was just a plain Baby AT motherboard so, sure, if the 486 one is the same if you have any boards lying around I'd say see what fits. Dolch machines were "premium" (in terms of price) but there really isn't anything special about them so I wouldn't worry too much about trying to keep it original. The main issue will be if the replacement motherboard has the CPU socket in a different place or whatever it might cause fitment issues. Was pretty snug in there, as I recall.
 
Yeah, I have a few boards on the shelf but none of them will work... I'll put a wanted ad on here, I'm looking for something pretty specific
 
The really weird thing is the hard drive is recognized immediately by the bios. I tried a few different known good drives to see if it was something to do with the controller not liking the drive but nothing works. According to stason there aren't any jumpers that have anything to do with the ide settings aside from disabling it
 
It worries me that it was a 20 pin apparently unlabeled IC package that fell off, because there's definitely a chance it's a GAL16v8 or other piece of programmable glue logic, in which case it could be for *anything*.
 
Yeah, that IC that fell off is kind of worrying... I got the Dolch knowing it has issues and I had a hunch it was probably going to need a motherboard but I didn't realize any of the ones on my shelf would fit! I posted a wanted ad and I hope someone on here has what I need.
 
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