Log in

View Full Version : SNES won't turn on, checked the usual suspects already


mronge
09-16-2012, 10:13 PM
Hi!

I've got a SNES that recently decided to stop working. I've taken it apart and can't figure out what's wrong. I've followed the usual troubleshooting advice (tests below were done with my multimeter):

1) Verified the AC adapter is working
2) Replaced the fuse and tested it to make sure it is working
3) Verified the power switch works
4) Flipped the board over and checked the voltage coming in at the solder points where the power is connected
5) Removed the voltage regulator, hooked it up to a 9v battery and made sure it is working, (output is 5v)

All the above components look like they are working, yet it doesn't turn on. When I plug it in I see power is going to the board from the adapter, but when I read the voltage at the voltage regulator input it reads 0. To test this I plug in the board, turn it on and then touch the input and ground on the voltage regulator, and it reads 0

Any ideas on what to try next?

Thanks in advance,
omp!
09-17-2012, 06:12 AM
Where are you located? Have you checked (if it has one) the rectifier? You may have to trace it a fiar way in..
mronge
09-17-2012, 12:03 PM
Where are you located? Have you checked (if it has one) the rectifier? You may have to trace it a fiar way in..

I'm located in the US, so I don't believe my SNES has a rectifier?
ApolloBoy
09-18-2012, 03:53 PM
IIRC, there are some diodes that the input voltage goes through before getting to the 7805. Use your multimeter to check those diodes and replace them if necessary. Since everything else checks out that would be the only thing preventing the system from powering on.
jb143
09-18-2012, 05:10 PM
Did you check the caps near the regulator? They could short if dried out. Does the power supply get hot at all?
mronge
09-19-2012, 02:15 PM
IIRC, there are some diodes that the input voltage goes through before getting to the 7805. Use your multimeter to check those diodes and replace them if necessary. Since everything else checks out that would be the only thing preventing the system from powering on.

I'm new to working on electronics, so any tips on finding which diodes to test?
mronge
09-19-2012, 02:16 PM
Did you check the caps near the regulator? They could short if dried out. Does the power supply get hot at all?

How do I know which caps to test?

Also can I test the diodes and caps while they are still on the board?

Thanks, sorry new to working with electronics
ApolloBoy
09-20-2012, 03:10 PM
How do I know which caps to test?

Also can I test the diodes and caps while they are still on the board?

Thanks, sorry new to working with electronics
You can't test caps in circuit unless you use something like an ESR meter. Diodes are easy to test for; the first thing you do is set your multimeter to diode mode, place the red probe to the anode end and the black probe on the cathode (the end marked with a stripe). You should be getting some kind of voltage value when you do this. Then, flip the probes around and if the diode is good, you should not be getting any reading. Diodes are supposed to allow current to only flow in one way, so if there's a busted one then you have a problem.
mronge
09-20-2012, 03:51 PM
You can't test caps in circuit unless you use something like an ESR meter. Diodes are easy to test for; the first thing you do is set your multimeter to diode mode, place the red probe to the anode end and the black probe on the cathode (the end marked with a stripe). You should be getting some kind of voltage value when you do this. Then, flip the probes around and if the diode is good, you should not be getting any reading. Diodes are supposed to allow current to only flow in one way, so if there's a busted one then you have a problem.

Thanks!

Are you aware of any diagrams of the SNES that would show me which diodes and caps to test?