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06-20-2013, 05:39 AM   #1
Ningyou
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Old flash on DSLR

Hi,
although I have searched the forums a bit and have read mostly negative news about
old flashes on modern DSLRs.
I still want to test this (maybe stupid)... but actually i tested it already.

How do I know that the flash has damaged my camera while it still works now?

I have a Pentax K-x and the flash is an old Philips Flash P36 Computer TL.
Does someone have a manual or any information about this one? Because I've tried finding
info about this unit but there isn't a lot out there in the web.

06-20-2013, 05:51 AM   #2
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Have you measured the trigger voltage of the flash with an electronic multimeter? There are various opinions but as far as I know the consensus is that as long as the trigger voltage is less than 25V or there about, it should not damage the camera. There are old flash units triggering at 240V and even more. Some say they've used them without problems, but I would rather stay on the safe side. I'm no electronics expert, but who knows for sure if the damage at such high trigger voltage do immediate damage or perhaps only over a period of time? Perhaps some of our more knowledgable electronic minded members might give some more details, so join as a member and ask the question in the Pentax Flashes and Lighting Technique - PentaxForums.com section...
06-20-2013, 06:55 AM   #3
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QuoteOriginally posted by First Poster Quote
I have a Pentax K-x and the flash is an old Philips Flash P36 Computer TL. Does someone have a manual or any information about this one? Because I've tried finding info about this unit but there isn't a lot out there in the web.
Manual is here:
Old manual - a set on Flickr

Trigger voltage is reputed to be 5.2
06-20-2013, 06:58 AM   #4
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what altopiet says is correct, if it is a high voltage trigger then its probably a matter of when rather than if it breaks down, older cameras used a mechanical switch to short the trigger voltage to ground, this voltage was typically in the order of 200V to 300V, modern cameras, DSLRs use a solid state switch which will have a max voltage rating maybe 20 to 40V, connecting a high voltage to this solid state switch will break down the semi conductor material leaving it permanently shorted and possibly further damage. Having said that, some old style flash units do use a low voltage trigger. I would advise not to connect it again until you able to confirm trigger voltage.

06-21-2013, 02:56 AM   #5
Ningyou
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I have measured with a multimeter, however I don't think I have done it correctly. first, I used rechargeable batteries which were charged but perhaps some energy already leaked because of long time of no usage, 2) when measured with the multimeter it gave a voltage of 3,8V~4V nowhere near the 25V or something like that.

When I used the multimeter I had set the knob on DC current, 200V... i'm no expert in this kind of stuff

Yeah... I'd rather not join because I'm not a frequent forum goer (lame excuse, perhaps)
06-21-2013, 04:53 AM   #6
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QuoteOriginally posted by Ningyou Quote
I have measured with a multimeter, however I don't think I have done it correctly. first, I used rechargeable batteries which were charged but perhaps some energy already leaked because of long time of no usage, 2) when measured with the multimeter it gave a voltage of 3,8V~4V nowhere near the 25V or something like that.

When I used the multimeter I had set the knob on DC current, 200V... i'm no expert in this kind of stuff

Yeah... I'd rather not join because I'm not a frequent forum goer (lame excuse, perhaps)
Try the multimeter on 20V. I presume the flash has a single centre pin in the middle at the bottom of the shoe? Switch the flash on until the light indicating it is charged goes on, hold the red connection of the multimeter to the bottom pin of the flash and the black to the metal protruding through the two gaps where you slide it into the camera mounting, that should give you an indication. If it is more than 20V, go back to 200V on the multimeter as you've done, and just check again, to make sure. I've got an old Topman flash I use that gives about the same readings you get , just double check...
06-21-2013, 08:37 AM   #7
Ningyou
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how do you quote?
Well I have bought some new fresh batteries and measured the voltage again.

Multimeter set on 20V and I got a reading of 4.30~4.36V
Multimeter set on 200V, reading is 4.2~4.3

so is it safe?
06-21-2013, 09:33 AM   #8
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QuoteOriginally posted by Ningyou Quote
how do you quote?
Well I have bought some new fresh batteries and measured the voltage again.

Multimeter set on 20V and I got a reading of 4.30~4.36V
Multimeter set on 200V, reading is 4.2~4.3

so is it safe?
Yip, I think you are safe, I've used mine at same voltages on my K-x and K-30 without problems for a long time now

06-21-2013, 09:51 AM   #9
Ningyou
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Thanks for your help altopiet and others

kind regards
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