T20 System board replacement

[fisherm]

Hello all, I am a long time listener, first time caller. I am replacing the system board of my T20. I bought it used, and the sound doesn't work at all (speakers or jack). Found a gunked up spot on the system board @ FL8 (backside of HDD connection). I tried cleaning this and reassembling to no avail. I opted to buy another T20 system board off eBay as a replacement. After installation of the "new" board, I boot to error 175 "Bad CRC1" and no further (however I do get a couple beeps proving that the sound problem is fixed). In my research I have found that this is a BIOS checksum error, and from what I can gather it means that my new system board knows it's not installed in the original machine it came in. I need help trying to either: fix the old board so sound works, or getting the new board to work in my machine. Thanks in advance.

[RealBlackStuff]

The bad news first:
the second board with the error 175 will not work and can not be fixed.

The not so bad news: now that you have a dead board, but with working sound, you can cannibalize it for parts, or return it for a refund.

Check that all the speaker connections are clean (i.e. no oxidation). Use a piece of very fine sandpaper if necessary, but make sure you get no 'grid' in the laptop itself.
Check if a pair of external speakers works, using the headphone OUT.

Can you elaborate on FL8?

[fisherm]

Don't really need a refund, only paid $11 for it. I've checked all the connections I can find, everything appears clean. The FL8 "thing", that is the marking nearest the part that I thought to have been the culprit on the PCB. My thinking was that it was kind of like a map coordinate. I'm not electrically inclined enough to know the type of part I'm looking at, nor do I think I'd be comfortable soldering and re-soldering parts from board to board. I feel like I'm right back at square 1.

[rkawakami]

"FL8" is a part designation for a particular component on the motherboard and does not refer to any positional information like a map coordinate. "FL" is typically used to denote a filter. Looking at a scan of a T20 motherboard that was just handed off to me this morning by Timoti, I'd have to say that it is connected to the speaker output:

http://www.kawakami-ca.com/images/t20_s ... output.jpg

edit: Oh, and for what it's worth, the 0175 error may have been caused by an earlier owner and was probably not something that you did or didn't do. I think that some of the earlier T2x system BIOS revisions were susceptible to corruption if the system was powered off at a particular time during boot. You might also want to try other memory module(s) and see if that helps. I was looking at a T21 last year which threw a 0175 error (along with other problems) and changing the memory appeared to fix that.

[fisherm]

Thanks so much for that information. Do you happen to know if the filter is replaceable, and/or if that could be whats causing the problem. Sounds like it could be to me, but that's not necessarily saying a whole lot. On the system board note: Could I possibly find a donor board that wouldn't give me the same error. Like I said earlier, I read that the error could be caused by the non-matching serial numbers in hardware versus the BIOS. Simplified question, can I buy a different system board and possibly have working results?

[vanaya]

I think the MB that Ray was referring to was probably mine. (Possible, since he has a herd of them) I would double-check the memory. The stick came with the machine I got off of ebay. That was the only thing wrong with machine.

[rkawakami]

The filter would be replaceable, given you have the tools needed to un-solder the one from the 0175 board and put it on your old one. If that indeed were the only problem; it may not be (more on that in a sec). It might also be possible to find one from an electronics component supplier if there's suitable markings on it. As schematics are not available, we are left with decoding part numbers and looking around for people that still sell those components in single unit quantities.

As far as what else could be wrong... any one of those components in the picture I posted before could be bad. Of particular note would be the four tiny resistors located above the four copper pads that the speaker mounts to. If they are disconnected, I would assume that could cause a problem with sound not getting to the speakers. Would it also cause the headphone jack to not work either? Don't know. There could be a problem "upstream" towards the Crystal audio chip, located just to the left of the area in the photo. It's marked "U18".

As far as I know, the 0175 error should not be caused simply by swapping the motherboards around. The system information (serial numbers) are stored in a special memory on the motherboard. When you change out the motherboard, whatever is on the replacement is what's going to show up when the BIOS is accessed. And the BIOS is also on the motherboard. Most likely is that the eBay seller knew he/she had an issue with it since it's a fairly common problem. If you still have the eBay item number and it is a recent transaction, we can look at the auction description.

You could get another replacement motherboard and as long as the seller guarantees that it's not DOA or have any easily known problems (like a 0175 error, BIOS lock, video problem, beep codes, etc.), then you should be okay.

And vanaya is correct, that was his board I was referring to. It was a very perplexing problem until I narrowed it down to the memory. I believe I also received a 0175 error on a T23 that had a weak CMOS battery before so you should look into that as well.

[DPHMIN]

Ray,

<<I believe I also received a 0175 error on a T23 that had a weak CMOS battery before so you should look into that as well.>>

PMJI, but did changing the CMOS battery fix your 0175 error? I have a T23 with the 0175 error, and am interested in getting it fixed (for less than the $99.00 cost of a motherboard on Ebay).

[rkawakami]

I think I received a 0175 error at one point with a T23. Pulled out the CMOS battery and it read about 2.8V so I replaced it and did not get any more boot errors. This was awhile back and only occurred once. I'm sorry that I can't be more definitive about this. The only other time I've fooled around with a 0175 error was with vanaya's board, which had a definite error and was solved by changing the memory. That surprised me since I was under the impression that such an error was more or less permanent.

[fisherm]

Ok, I will look into replacing the CMOS batt. today. But I don't think thats really the problem, as the computer boots fine with the old system board just not with the replacement. I'll also try to order some new RAM sticks and see if that helps. Thanks again for all your time and input.