OLD Minolta flash wont pop from optical slave.

Minolta 20.

fires just fine from the srT200 that was also in vogue at the time.

any ideas?

Not sure what you mean by optical slave...like a Wein 2 prong?

http://www.adorama.com …Jb1hcaYkbYCFYid​4AodSkkA3A

If so, there is a polarity, try reversing the unit.

it's an optical slave with a hotshoe.

the slave fires my three other flashes just fine.

My only guess is a possible issue with electrical connectivity. Minolta has used a different configuration of contacts. See the link:
http://en.wikipedia.or​g/wiki/IISO_flash_shoe

Nope. It's the standard type of mount. Both the camera and flash date from the mid to late 70's.

It's not that I really need this thing to work, just the curiosity of why it doesn't work.

For what it's worth, I fired it via PC to off camera hotshoe that is of a similar make as the optical.


cheers!

Check your spacing? Could be that your slave's hot shoe has too much of a gap and won't let it complete a connection with the flash.

Also does your srT200 fire the other flashes? Not familiar with the gear in question, but don't be too quick to rule out the problem of pin-out variances. Could simply be that the slave's hot shoe isn't actually closing the circuit properly if there are multiple pins involved.

Only other things I could think of is a difference in resistance causing a problem, but I doubt it. Could be you have a short somewhere along the line when connected to the slave hot shoe that is keeping things from firing properly?

There is a possibility of a polarity compatability issue between the Wein optical trigger and the Minolta 20 flash.

I have seen issues with the PC cord polarity causing a dSLR camera to NOT trigger a studio flash, simply because the H-plug at the power pack was inserted 180 degrees out; switching the H-plug at the power pack then allowed the camera to trigger the studio flash properly!

hes gone wrote in post #15747125
=he's gone;15747125]I fired it via PC to off camera hotshoe that is of a similar make as the optical.

Not the most elegant solution, but a slave sensor with a PC socket could be connected to said hotshoe with a PC cord.

Things to consider.

1) The optical slave polarity may be reversed. Check the polarity of the flash. The center hotshoe contact on the flash should be positive.

2) MOST (but not all) cameras will fire a flash with a cord even if the polarity is reversed on the flash. This in NOT true for an optical slave. The polarity must be correct for the optical slave to work.

3) Some models of flash units just will not work with an optical slave. These models are rare, but not totally unknown.

Enjoy! Lon

FlashZebra wrote in post #15748249
1) The optical slave polarity may be reversed. Check the polarity of the flash. The center hotshoe contact on the flash should be positive.

this was/is the problem!

I couldn't find my multimeter until one of my 4.5 year olds decided to start poking around in my tools and found it in part of my tool box that is usually reserved for small screwdrivers.

I am by no means educated in the ins and outs of electrical current, but here's what I've found.

My multi-meter isn't digital, it has a needle, so readings are approximate. Using the Ohm - Ω - setting with the red probe on the center contact and black on the side of the minolta, the needle moved backwards a bit, so I reversed the placement of the probes to determine its reversed polarity.


old Minolta 20, rechargeable batteries installed:

red probe placed on the side of flash, and black on center contact, flash on and ready to go:
Ω =17

red probe on side of flash, and black on center contact, flash off and discharged:
Ω=200


Nikon SB-28 rechargeable batteries installed:

red probe on center contact and black on side of flash, flash on and ready to go:
Ω=4.66

red probe on center contact and black on side of flash, flash off and discharged
Ω=4.66


placing the probes on the minolta didn't fire the flash, but it did on the Nikon.

FZ, I wouldn't mind an explanation of the differences if you have a moment.

cheers!

You don't want to measure Ohms. You want to measure voltage. DC volts to be specific. Use that setting on your multimeter.

Then, with the flash turned on, check the voltage across the contacts on the flash foot. Like Lon said earlier, you should get a reading when you put the positive test lead on the center contact and the negative test lead on the side contact.