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MB-8433UUD-A Ver.3 Floppy not wokring

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First post, by Turboman

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I recently acquired a MB-8433UUD-A Ver.3, physically the board looks great no visible damage. When I first got the MB it would say cmos defaults loaded, I knew the battery was dead. I replaced the battery it is working and holding the bios settings and the date and time. I keep getting Floppy Drive Fail C0, I've tried different bios settings, different cables, different drives, same thing. I then replaced the bios chip with a Winbound W29EE011-15, I have the latest bios installed that I got from here. I do not know what else to do, what I could check to see if something is bad with a meter. I even re-flowed the solder on all the pins for the floppy connector.

Reply 1 of 20, by feipoa

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Some basics for testing:
Try only one floppy drive - drive A.
Ensure the red stripe on the cable is next to pin #1 on the MB's floppy header.
Some cables have options for two drives on one cable. I recall this MB being particular about where the A drive cable goes, so try both locations and both cable orientations.
Ensure BIOS has FDD enabled
Ensure BIOS has A: 3.5" or 5.25" selected on the first screen.

These are all very basic ideas which you have probably checked, but I too have gotten into thinking something was wrong with this particular board when the drive wasn't plugged into the correct spot on the floppy cable. And then there was the MB-8433UUD which had a bad Super I/O chips, which is where the floppy controller is. If you are beginning to think the issue is with the Super I/O, you may need to replace it. See this thread where I have replaced mine and got the floppy working again.
How to fix your dead on-board floppy controller

Plan your life wisely, you'll be dead before you know it.

Reply 2 of 20, by Turboman

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I have done all that no luck, reading your thread I have begone trying to trace all the pins on the UM8663BF, looking for anything that doesn't show continuity. Do you have a diagram showing where all the pins go? so far as I can tell all of the pins on the bottom go to ISA slots. I am also tracing the floppy connector pins, I do not know where pins 3 and 5 go, I got connection from the rest of the pins to the top and left side of the UM8663BF. The resistor pack next to the chip when reading pin 1 to the rest I get 4.7 except for the last pin I am getting 9.3 if I read from that pin to the rest I get 9.3. Should I replace the resistor pack?

Reply 3 of 20, by feipoa

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I created a really hard to read diagram at some point as to where all the UM8663 pins go, however, I think it is unlikely that a trace or solder point has gone bad. What is more likely is that some aspect of the UM8663 has stopped working. It is becoming more common with increasing age of these electronics.

I think there were a few NC pins on the UM8663. You should be able to trace out a similar trace-point diagram, but I think it is not really necessary unless you are going to replace the UM8663. Many of the pins lead to the southbridge chipset.

Plan your life wisely, you'll be dead before you know it.

Reply 4 of 20, by Turboman

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I just noticed something, when the board is booting it shows serial port and parallel port "none" they are enabled in the bios.

Reply 5 of 20, by feipoa

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strong probability that the SuperI/O needs replacement.

Plan your life wisely, you'll be dead before you know it.

Reply 7 of 20, by feipoa

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I think the letters following the datecode are just to identify which batch or die lot they came from. The IC you've linked in eBay should be the one you want, though it is a bit expensive. You can also try aliexpress to see if a merchant is selling this item. It might be smart to grab more than one replacement chip in case you mess up.

Plan your life wisely, you'll be dead before you know it.

Reply 8 of 20, by Turboman

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Alright, I'll check there. I know how to solder but I'm not that good, what is your recommend procedure on how to remove the chip without destroying the board? is it possible to solder the new chip onto the existing one? I was thinking of soldering to the existing leads of the old one. I have a Weller adjustable station with many different tips.

Reply 9 of 20, by feipoa

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Cut the leads of the old UM8663 IC with a sharp, preferably new, razer blade. Then the remaining leads are easy to desolder one by one. Install the new IC your smallest weller tip and 0.3 mm thick solder.

Plan your life wisely, you'll be dead before you know it.

Reply 10 of 20, by Turboman

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I tried my best but ruined the board, must have ripped about 20+ traces. I was so happy when I finally got a hold of this board, I've been wanting one for so long, now I'm sad. Do you know if it Is safe to run the board without the chip installed? will an ISA serial port card work without the chip? and will the ps2 port work without the chip?

Reply 11 of 20, by feipoa

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I am rather surprised by your outcome. I remember the first time I cut off an IC - it had more than 100 pins and I only partially ripped up one trace. Not sure what technique you used, but I use an razer blade attached to an Olfa stye blade holder.

The PS/2 mouse port is unrelated to the UM8663 and should be unaffected.

You should be able to install an ISA card with the same UM8663BF super I/O chip as on the motherboard. Leave everything in the BIOS to enabled and plug the serial and diskette cable into the ISA card. At least this worked for me when I had a defective 8663 chip.

On the other hand, with a lot of patience, you may even be able to wire up those 20 broken traces if you decide to put the UM8663 back onto the motherboard.

Plan your life wisely, you'll be dead before you know it.

Reply 12 of 20, by Turboman

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Is was thinking about fixing it but at this point I'll just wait for another board to buy, I'll try out the card, thanks for the tips.

Reply 13 of 20, by Turboman

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I'll have to locate one of those controller cards.

Reply 14 of 20, by feipoa

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Can you upload a photo of the trace devastation?

Plan your life wisely, you'll be dead before you know it.

Reply 15 of 20, by Turboman

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Here they are, not a pretty site, I'm sure if anyone else but me did this it would have been fine. The thing I noticed as I was cutting some of them were pushing and ripped really easy, maybe the problem all along was cold solder or the solder came loose off the pads, I probably should have tried to re flow the solder first.

https://flic.kr/p/XivYRR

https://flic.kr/p/W2PNBu

https://flic.kr/p/Xiw1fn

https://flic.kr/p/W2PP7s

https://flic.kr/p/Xiw1re

https://flic.kr/p/W2PPoE

Last edited by Turboman on 2017-07-31, 23:39. Edited 5 times in total.

Reply 16 of 20, by gdjacobs

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Photobucket is restricting third party linking now. You either have to upgrade your account or host the images some other way for them to display in Vogons.

All hail the Great Capacitor Brand Finder

Reply 17 of 20, by Turboman

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I posted new links.

Reply 18 of 20, by feipoa

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Ouch! I can't imagine how that happened. Did you use an fresh blade?

Plan your life wisely, you'll be dead before you know it.

Reply 19 of 20, by Turboman

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I did everything you suggested, it's just my luck and technique that's not very good. I know I'll never attempt this again. I did try and trace most of where they go, I was thinking of trying to fix it but I just don't want to spend countless hours wiring it up now. I guess my best option is to wait and buy another board or find a card for this one.