7200 120mhz info needed.

[imactheknife]

Acquired a board from a friend who had some caps and pads come off. He sent board up to me and i fixed everything except one 47uf cap. It attaches to one via but there is another one on the other side of pad which may or may not have been attached to pad as well. Dont have a board to compare unfortunately. Thanks for any help.

 

[imactheknife]

Well, she turns on, but no chime or display of any kind, so either something isnt connected, or he butchered it elsewhere unfortunately. Does it need to be in a case to work? Grounding properly?

 

[stynx]

I have seen a lot of dead 7200 boards that will no longer be repairable. Even a complete recap did not work most of the times. I thankfully own a working and recapped 8200/120, which is in storage. If i get the time, i will make a photo of the board at the position that you have shown.

I have at least 5 dead 7200 boards myself and I have no idea what the reason for the high failure rate of them is. I suspect that the soldered CPU might be the culprit since some of the boards have a visually broken 601 CPU due to the heatsink pressing on the thin ceramic chip when stored without protection. But even when the 601 looks good, the board is often dead with sometimes no reaction at all, just the PSU-fan spinnig or a chime with black screen and no boot.

-Jonas

 

[imactheknife]

I have seen a lot of dead 7200 boards that will no longer be repairable. Even a complete recap did not work most of the times. I thankfully own a working and recapped 8200/120, which is in storage. If i get the time, i will make a photo of the board at the position that you have shown.

I have at least 5 dead 7200 boards myself and I have no idea what the reason for the high failure rate of them is. I suspect that the soldered CPU might be the culprit since some of the boards have a visually broken 601 CPU due to the heatsink pressing on the thin ceramic chip when stored without protection. But even when the 601 looks good, the board is often dead with sometimes no reaction at all, just the PSU-fan spinnig or a chime with black screen and no boot.

-Jonas

Yeah i have had a few bad 61/71/8100 boards that stayed dead or did the exact as what you said above. I do believe the 601 is the main issue.

The board i have was known working and then he tried to recap it. He also pulled heat sink off and possibly he affected the 601?? Too bad i guess.

I do have a 7200/90 that i was able to check and figure my original questions out. I originally assumed the 7200/120 board was different than the 90mhz because the processor was at an angle. The rest looks the same. So either by a Christmas miracle or stroke of luck, this board is probably dead.

 

[stynx]

He also pulled heat sink off and possibly he affected the 601?? Too bad i guess.

I can't really say. There are so many possible reasons why a board no longer works. It is possible that simply removing a heatsink may damage the CPU. The solder of the connections to the PCB might have become brittle or come loose. Releasing the pressure of the heatsink might have introduced some weakened connections. The heatsink may have stuck due to dried up thermal grease or popped off at an angle ... the possibilities are manyfold.

Maybe checking the pins of the CPU for loose connections might be a start. I often use a needle which i heated up at the tip (to get it soft) and folded that tip over to get a very tiny hook (or 90° angle), barely visible with the naked eye. Then inserting the back of the needle into a whine-cork for better grip. You can carve the whine-cork a bit for it to be more ergonomic. Such a tool is perfect to carefully pulling and pushing QFP-pins.

-Jonas