advertisement


Help with OM-1 Repair

M

MartinC

pfm Member
I am trying to get my aged OM-1n up to speed, and everything is ok except the metering. I purchased a MR-9 adapter to allow it to use 1.5v cells. Measuring the voltage with the adapter in the camera it is still too high and hence the meter is off. The instructions with the adapter say it needs a 10k resistance to give enough current draw to regulate. Measuring the resistance of the camera it's around 15k, testing the adapter with a 15k load sure enough shows that the voltage isn't being dropped sufficiently.

My question is whether the internal resistance of my OM-1 is higher than normal? Does anyone have a OM-1 that they can remove the battery and measure the internal resistance? This would be very good to know before I delve deeper into what might be the issue.

I did check that both CdS cells are functioning and the meter works but is around 2 stops off which corresponds to the metering just seeing too high a voltage.
 
Hi Pete - the MR-9 battery adapter includes either a diode or a voltage regulator to take the voltage down, problem is that I believe it needs a 10k or lower resistance to work. Others found that the adapter works fine in their OM-1's, mine is a OM-1n and I wonder if Olympus changed the design over the years and the internal resistance changed?

I will have to see if the diode trick will work, or else like you, use the hearing aid battery option.
 
Mmmmmm turns out my battery wire is knackered , it’s corroded and needs replacing which looks like a fun job, not.

So sorry no readings.

Pete
 
Sorry to hear that. The difficult part is stripping the wire to resolder as it is so fine. I held the wire with a needle nosed plier and scraped the insulation off with a scalpel on one side, then bent the wire so the fine conductors stick up then trimmed the rest of the insulation off. If you use a non-clean flux resoldering is pretty easy just be careful putting the battery holder back in so you don't snag the wire. You also may need to move the winder a bit to locate the battery holder as it also acts as the lower mount for the take up spool.

I ended up putting in a hearing aid battery any my OM-1n meter now works perfectly and matched my other cameras, seems like the current Kanto MR-9 adapter wont work with OM-1's now, perhaps they changed the regulator?

Good luck with your repair.
 
A…

Wein MRB625 1.35V Zinc-Air Battery, fits and works as a replacement. Can be bought from​

Amazon
eBay
The Small Battery Company
Weinproducts.com
and a number of camera shops…😎
 
I ended up using a zinc-air type 675, they are about 1/5th the cost if the Wein cells and although they are smaller you can use a cheap adapter to fit them into the OM-1. Took the camera out for its first use in many years after replacing the light seals, worked perfectly.
 
You must log in or register to reply here.


advertisement


Back
Top