Flexmod graveyard :(

[ZeroPoint]

I'm taking a shot in the dark here or maybe DrLava will be willing to chime in but I've got quite a few dead P3's lying around and I'm hoping to try and resurrect at least one of them. Most are probably completely toast but I have one in particular that seems like it might have some life left. Nothing is visibly burnt and the red LED lights up as soon as power is connected to it (so i know power is getting through some of the circuit and back to ground). Normally that would indicate either an open interlock circuit or open output circuit. Surely one of these circuits is open but it's somewhere on the chip itself and not in my wiring. Has anyone tinkered with these at all and can give some advice? It's a bummer that there's no schematic available, although that's completely understandable. It's just too bad attempting a repair is so difficult without knowing the circuit or expected values at given components. I'll keep poking around with my probes hoping something catches my eye but if anyone else has any knowledge they could toss my way I would be grateful.


Thanks,
Luke

[Galvonaut]

Hey Luke

I've no experience with Flexmods but am a relatively successful amateur repairer. I usually go with changing the components that take the highest current - only because high current seems to accelerate ESD damage. Do the flexmods use an LM317?

Not sure if this'll be any help but my theory has saved me lot of time (and knowledge) in the past

Keith

[kecked]

change the fet.

[ZeroPoint]

Hi Keith, Thanks for the quick reply. The Flexmod does not use an LM317. I'll probably start with the MosFET and precision resistor since they are the largest components and likely handle the largest currents. I'll only call it quits when I get down to the little SMD resistors lol. Maybe I'll get lucky, who knows. Thanks again for your advice.

Cheers,
Luke

[Galvonaut]

If you want tips on SMD soldering/de-soldering, let me know - used to be my job many moons ago and it's pretty simple, as long as your eyes haven't been lasered!

[kecked]

The large sense is not a problem. If it isn't the fet then change the opamps. If that all fails then toss it. DON'T mess with the microprocessor as you will not be able to reprogram a new one. The other passive parts don't tend to blow.

[ZeroPoint]

Thanks Kecked. I guess I forgot to refresh the page before posting my other comment, I hadn't seen your first post. I'm going to check it out now and keep my fingers crossed. The other gamble is that I haven't bought any new components. I'm just trying to make a frankenstein P3 out of all the dead ones I have so it's quite possible none will have the working component I need. We'll see.

Keith, I am definitely interested in working with SMD components in the future but until I get a decent rework station I'm going to leave anything smaller than a laser diode alone. To be honest I dont even have a proper soldering tip on the iron right now but it will do.

[kecked]

just buy the fets. That is the usual suspect and cheap.

[Galvonaut]

To be honest I dont even have a proper soldering tip on the iron right now but it will do.

Don't throw away your old soldering iron tips. The oldest ones are the best for doing SMD chips as a concave tip holds plenty of solder for quick application to multiple pins (with flux).

Don't spend masses on an infrared reflow oven either. A great way of doing it is with those utterly useless and very cheap infrared (quartz) heaters with a few modification to ensure correct heat application.

Keith

[dnar]

Double check your soldernpadcwire connections. I had a lot of intermittant issues when I first used these drivers, the pads solder yet they dont due to a conformal coating used....