A while ago, i accidentally left my sb800 flash for a dslr camera up in the attic “it was during the summer i believe”
I recently found it, and it everything seem to be fine. The 4 AA battery in it was dead, and luckily no sign of any acid leaking from it. So i replaced it with new battery, but still it does not turn on.
I have dissemble the flash:
-traced for power making sure there is power going to the board (there is power)
-all hardware components seem to be okay, capacitors does not have any sign of leakage.
-no broken trace.
Luckily the schematic for both the power and control board can be found on pdf page #49 of the service manual. The unit has two PCBs:
A-PCB (microprocessor-based controller)
B-PCB (logic power supply, Xenon tube power supply, other stuff)
Things that might degrade while being in a non-climate controlled environment such as an attic, although this seems unlikely. Obviously something has gone awry.
Corroded switch contacts due to humidity
Capacitors??? (due to high temp, but seems unlikely)
Connector surfaces oxidized
The first thing to check (as you’ve done) is the power. I’ve attached the schematic and wiring diagram from the service manual. On the schematic I’ve annotated some of the expected voltages. If those voltages are present then amacha’s suggestion that the power switch may be the problem merits a closer look.
According to the service manual (page E2), the ready light won’t come on until the flash tube voltage is ready, around 330V. I’ve added some notes to the schematic showing where to check for flash HV.
Here’s a quick view of the voltages described above.
I don’t know anything about that particular piece of equipment but I spent years doing general electronics troubleshooting. I don’t know how hot your attic gets but I don’t think it is likely that it burned out any components or melted any hot melt glue that might have run down into switches or contacts. It’s possible that one of the circuit boards cracked from temperature change from summer to winter, and soldered connections might have cracked for the same reason.
I’d do as suggested above and check the power switch for tarnished silver contacts. That’s pretty likely. Then visual the PCB closely for cracks or bad solder joints.
If any of the components are surface mount if try there looking for cracked solder joints. Look over it really well. I had a surface mount solder joint crack on me, I missed it the first couple times. Found it the third time.
