Acer
I am unable to fix this Socket 7 motherboard!
I am unable to fix this Socket 7 motherboard!
#unable #fix #Socket #motherboard
“Tony359”
From a previous Mail episode, I’m re-visiting this Acer V58 Socket 7 motherboard but I need your help to find out what’s wrong with it!
Thanks PCBWay for sponsoring this video:
#repair #pentium #electronic
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Great video!
For not being an "expert" you do make an honest effort in your troubleshooting!
Have you checked that cpu clock is present ? i couldn't see it on post card btw Great video !
A week ago I had the same issue with S7 MB, zero activity. The problem was in the NB, maybe more than 10 legs were unsoldered, after full reflow the board works just fine.
Hi Tony, thanks for all your great videos. Have you tried this with another type of cpu, like a Cyrix M2, or Amd K6 ? or even perhaps one of the slower and older intel cpu's?
Amazing, in-depth video, as always. Thanks for bringing great content, Tony. As I read the comments, there's a lot of knowledgeable people, hoping they can give you the right hints. What I think may need to be checked, although I might be wrong, apart from re-balling the North and South bridges, is the CPU socket itself – inspect it for corrosion or dirt.
BGA chipsets. I have a couple of boards that are doing similar things. Re-ball those & it should start working again.
I need to save up so I can get the equipment to do the same for my boards.
i was wondering if this board is one of those that will not power up if the CR2020 battery is flat, I've watched The Electronics Repair on YouTube and he found a few boards like that.
You mentioned moving jumper JP1 at the beginning of the video but not being sure what it is for, this is used so the system can be configured for either an AT or ATX power supply, ATX supports wake from standby, AT does not, there is a special connector marked JP6 near that jumper where the board expects the 5v standby power (since it lacks a ATX connector) I guess this used some special Acer power supply, never seen this before, anyway there is also a second jumper, if you look at The Retro Web there is a manual with only jumpers, this shows when you move JP1 you also need to move JP15, did you do that? Other than that some boards actually measure the power consumption of the fan and will not start if a load from the fan is not sensed… Finally there is a green LED on the board, is it called HW Monitor? I can't see in the video but this might be related to why it will not start, refer to the same jumper diagram on the retro web: JP7, JP9 & JP10
Check the south bridge because the south bridge loads the BIOS into the RAM. Processor without a code can not doing anything. That is the case according to my knowledge.
Have you checked the signals on the CPU from the top? Could simply be a broken connector in the socket. CPU is behaving like there is no clock at all. But the CPU looks like the pins are available for contacting from the top.
Check the ADS# pin as well. The CPU should drive this low once it is in a bus cycle, so if it never starts one to even try and read from the BIOS ROM then it should remain negated (high).
The CPU also isn't necessarily going to execute byte by byte like older CPUs, there's a lot of parallelism going on (64 bits at a time). The BRDY# pin will be asserted by the chipset towards the CPU once it has presented some data in response to a read, or taken some data in response to a write, so that might be a good one to look at too.
Also rather than trying random address bus pins I would be a bit more targeted. The Pentium doesn't have address 0-2 pins, instead it has 8 "byte enable" pins. So I'd also take a look at these to see if there is any activity. For each byte out of an 8 byte chunk that the CPU wants to read/write it will assert the corresponding BEx# pin (maybe multiple at a time too).
And of course, know your enemy! Look at the behaviour of the pins on a known working board so that you know what they should be doing out of reset.๐
I dont remember hearing you checked retro web for the Acer V58? I might've missed it. JP5 is curious though. Bios is Atmel chip which is 5v (2-3) but JP5 is set to 12v (1-2). Not sure if that is only for programming it from a utility, will adjust VCC, or something. Manual mentions 3-4 for the default "normal" operation but i can only assume they mean to dangle the jumper off the 3rd leg, and if so then maybe it isnt VCC. VCC on the Atmel is pin 32, or on the right of the "top" notch. Would verify it is 5v to be safe. Then would start verifying clocks from the CY2273AVPC as it has several clock outputs. Pin 5 of the PS2 ports is another clock and could help with elimination. Good luck with this. Will be interesting to see what you find when you fix it ;D
i recently worked on a slot1 board, also dead with no activity on the bios pins, turned out to be a dirty processor socket, give deoxit a try i guess
Bios OK? Test Jumper Frequencys
I'd suspect the north bridge also. Check if it is getting too hot to the touch, or try pressing it, in case it's a bad solder ball underneath the chip.
Maybe you could measure and compare the resistance values of the address and data lines. And/or check capacitors for shorts.
You could check all the traces of the cpu, pci and xD bus for continuity. Maybe a short has burnt one of the traces? Also it might be worth checking the chipset pins for activity, they should do something as well. Also the pci bus. I guess the chipset is broken. But if there is activity on the pci and xD bus you could narrow it down maybe.
If the chipset is broken, last option would be to replace it with a known working chipset. It might not be worth it for the hardware, but it would be nice to know if that is the case here.
Very interesting information in this video! Broken chipsets are a problem it seems. I once killed a mainboard by placing it on some metal. I guess I shorted some pins of the chipset and itโs dead. Not much one can do I guess.
I'm wondering if the CLR CMOS circuit is stuck on, the board would not start if that's the case. Or you simply have the CLR CMOS jumper set on..
This is just a hunch. ๐
I suspect the problem is with one of the chipset BGAs. There might be a bad connection due to physical stress or oxidization. Try to push the BGA towards PCB moderately and hold during reset. Sometimes, it helps enough for the board to POST.
There are already some good comments that point to the same what I already thought about, which is the reset vector. As this points to the beginning of the last 16 bytes of addressable space, it is normal that mostly all address pins go high. The reset vector is the first code the CPU looks for, and as there are only 15 bytes available (the 16th is the checksum), it is a Jump command that enters the main BIOS POST routine. There must be some logic to translate the CPU address to the limited amount of address pins on the BIOS, which I'm afraid is likely the northbridge.
Next thing can be checking the caches – it's connected on the cpu bus and any fault block cpu completely.
Any scratched traces under the board?
some (but not all) pure pci based main chipset boards (the isa is handled by the southbridge on this one, if i recall) don't output post codes to the isa bus, so if you haven't stuffed the post card in a pci slot, thats worth a shot.
i'd be tracing down the clock signals at all points to ensure its getting what it needs where it needs, confirming jumpers for all elements since some of these older ones have them for almost everything it seems.
beyond that, if you have a plain jane p100/133 or whatever in the lower end laying around, set the board to run that and try it that way. could be the 3.3v side of the equation.
Hey Tony359 maybe you could try to gentlty push, hold down the SMD chips on the board and then power on? I had two old boards this procedure helped. There were bad solder joints due to e.g. mechanical stress. I could not see that from visual inspection. However resoldering the identified chips then solved the problems permanently.
Is there a "reset BIOS" jumper and is it in the correct state?
Is there a scorch mark on the underside of the board near the CPU?
I'm sorry for suggesting the obvious, but what about CMOS battery? Some boards won't start with flat battery and I once almost discarded one of good boards for that reason.
Tony my humble contribution…
I'm pretty sure you already tried this but just in case you haven't…
1. Many boards I have dont like the post analyzer… specially on the ISA slot… some show the same behavior as yours
Try starting the board without the post analyzer and just plug the pc speaker to see if you hear an error code.. or plug the post analyzer on the PCI slots instead
2. Many times I need to press the rest button several times to make the cpu start
3. With the post analyzer pluged tap on the power components with your fingers .. capacitors, inductors, transistors to see if you see some fluctuations on the voltage leds on the post analyser
Faced a similar issues a while back. It ended up being the Super I/O that was dead. On the platform I was troubleshooting, I was missing basic clocks generated by that IC, and that's how I figured it out. So, finding the your Super I/O datasheet and making certain everything is being generated could be a good next step (Would also prevent the CPU from initializing, which seems to be your case). Good Luck!
I see the 2 videos and no see if you check the clock in the bios (bios send data have cpu or not if they have power and clock) so the clock is missing, the bios is broken or the chipset is killing it.
Have a small cristal near the bios.
I would check for short on chipset and compare resistances with working board