Quote:
Originally Posted by SiriusHardware
There is also an outside chance that the solder joints at the tapered ends of CR1 / CR2 are cracked, and are only making contact with the PCB pads when you press your meter lead against them, bending them sideways slightly.
AJ suggested earlier that you should reflow the solder joints on all the diodes but I don't think you got that far - better do that next, and while you have the board out thoroughly inspect not only the JP4 connector pin 4, the solder joint, the connection between the pad and the track running up to it - is there a crack across the track where they join?
Look into the pin 4 socket in the JP8 plug connector, do the contacts look as though they are spread apart, do they look bright, or dark or burnt? Look at pin 4 on the JP8 PCB pin connector, does it look bright or dull, dark or burnt? If it looks dull, try scraping it clean.
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Hi. Okay, to give an update. I took the board outand had a good look around JP8 pin 4. On the back of the board I didn't see a trace coming from it. On the top of the board, it was a bit difficult to see due to the capacitor next to the pins, but it did have continuity to the tapered end of CR1/2. I reflowed pin 4 as well as all teh diodes in that area. I also cleaned down all the pins and gave them a good clean with IPA and contact cleaner. With the board being out I also took the opportunity to unscrew the terminal where the two red wires go to the off board capacitor and gave them a clean.
The JP8 socket looked okay, but I cleaned with contact cleaner again.
On putting everything back together, we then had life. Good news. I decided to power off/on again, but then no screen. On checking the voltages, I found that when pressing on the top metal part of the pin (pin 4 on JP8), the PET sprang into life. I've attached a picture of this pointed to by the probe. To test this again, I unplugged the connector, then turn the PET on - nothing. So then just touched the top of the pin and the screen came on. I then took JP8 off and pressed down on the metal connectors at the top with a screwdriver; since doing this the PET has turned on successfully on each attempt. So it looks like when the connector was being pushed on, it maybe moved slightly, thus not making a connection.
As it stands, I've now a PET which displays a screen every time it is turned on. I'm not sure if there's much else I can do about the connector, or if anyone has any other advice, but at least it's some headway and seems to explain what's happening.
Thanks again,
Tim.