Fluke 79III water damage

[budhafoo]

As stated in the subject. Any schematics? Where do I start to get this back to life.. Tried cleaning it with brush and alcohol. Havent poke around with my meter yet. Hope just the LCD went bad?

[retiredcaps]

As stated in the subject. Any schematics? Where do I start to get this back to life..

No schematics for the 79 III that I know of.

To start, tell us what works and what does not.

1) Does DCV work when reading a 9V battery?
2) Does ohms work when reading a 1k ohm resistor?
3) Does continuity mode beep when shorting out the probes?
4) Can you post a clear focused picture of the pcb?
5) Does it turn on?

[budhafoo]

It doesn't turn on. Here are some pics..









Where should I start ?

TIA

Sent from my Nexus 5 using Tapatalk

[ModemHead]

A very thorough inspection with magnification is always a good practice, especially if any sort of corrosion damage is a possibility.

Check the unit's current draw with a fresh 9V battery, with the switch off and the switch on.  Should be zero when the switch is off. I can't remember exactly what normal draw is for a 79-III, but it is probably in the 1 to 2mA ballpark.

If the current draw is too low, it could be battery connections, switch contacts, or some of the power supply circuitry has failed open.  If the current draw is about normal, the processor and all could be running normally and just the display has failed.  If the current draw is excessive, then some of the power supply circuitry has failed short or one of the chips is bad.

[Grapsus]

If you think only the LCD is bad, you can put the meter in continuity mode and it should still work.

This 79III looks a little like the 79II but with both digital and analog chips regrouped into one and it still uses the same rotary switch design from the 70s. The possibility of a repair here will probably boil down to the question whether the main chip is dead or alive.

[edisitaru]

Hello
If you still have the motherboard, I'm interested. I need the rotary switch.