May 2013: SP 500

I 've been offered a superb Honeywell Pentax SP 500, unfortunately the lightmeter does not work: the needle remains obstinately stuck to the top, regardless of the light. I removed the hood, draw my multimeter and found the problem: one of the CdS sensors is short-circuited. This makes sense: the more light it sees, the more current a sensor lets pass. So if a maximum passes, the needle behaves as if there was too much light...

I bought on eBay another SP 500 for parts. I chose a very ugly one, not to be tempted to restore it!

The first challenge will be... succeeding in setting a battery to test the meter!
Removing the baseplate, passing hot water... the cover finally comes. And given the thickness of dirt, the test will be done with the battery cover of the other camera!
Phew, the lightmeter works!

Disassembly ...

Locating the wires.

Recovering the sensors.

I prefer replacing the two sensors together: they are probably paired, to avoid an imbalance in right-left metering. And as the wires are twisted and welded together, it is much easier!

The sensors are now in place, the welding is much easier when the wires naturally fall to the right place.
I have set the shutter speed selector back, in order to make an initial adjustment, by comparison with my Spotmatic which is opportunely nearby.

The lightmeter works well. Reassembly (yes, needs to remove that f... speed knob before replacing the cover...)

Finished!