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12-30-2009, 12:36 PM   #1
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Sunpak Autozoom thyristor 933

I'm the new owner of a Sunpak Autozoom thyristor 933 flash dedicated for Pentax. It was made in 1983.

I'm having trouble finding any anecdotal information regarding this unit and want to know whether it's safe to use on my K-x.

12-30-2009, 01:59 PM   #2
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First of all, download a copy of the manual: linky.

(A plug for Mike Butkus: a $3 donation as requested is a very inexpensive way to show appreciation for his effort).

Knowing Sunpak, I think the trigger voltage is OK for the K-x. But to be safe, I recommend you measure the particular flash unit. If you don't have a digital multi-meter, get one and learn how to use it. An inexpensive multi meter such as this one costs only a few $ (this particular one is $3.99 sale price every other week), and can also be used for other things around the house.

I don't have the particular Sunpak model, but I guess that if you set the K-x at A-v mode, the flash, when fully charged, will set the shutter speed to 1/50 or 1/60 sec. I can also set the shutter speed in other mode, you'll need to experiment to find out.

I think it can also set the aperture in some modes, but if it is like my Sunpak 36DX, the aperture is not correct.

Please post back what you find out.
12-30-2009, 05:21 PM   #3
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QuoteQuote:
I don't have the particular Sunpak model, but I guess that if you set the K-x at A-v mode, the flash, when fully charged, will set the shutter speed to 1/50 or 1/60 sec. I can also set the shutter speed in other mode, you'll need to experiment to find out.

I think it can also set the aperture in some modes, but if it is like my Sunpak 36DX, the aperture is not correct.
The flash is not going to be able to set anything on the camera. The flash is TTL, but the camera is P-TTL only.
12-30-2009, 06:29 PM   #4
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QuoteOriginally posted by alohadave Quote
The flash is not going to be able to set anything on the camera. The flash is TTL, but the camera is P-TTL only.
Dave,

Do you have direct experience with this flash, or are you guessing?

I don't have this particular flash. I'm guessing based on my experience with other models of Sunpak (in particular 3600, 36DX, 422D, and 444D), and by reading the manual.

From what I know, this flash does not have TTL. It has full-power manual, and 2 levels of auto using its own light sensor.

It can set sync speed on some Pentax film bodies, and illuminate flash confirmation LED in the viewfinder. This is very similar to my 36DX with module PT-1D. The 36DX can set sync speed on my K10D. Thus my answer.

In some modes, the 36DX with module PT-2D can set sync speed and aperture on the K10D (similar to the Pentax AF280T and AF200T can), but unfortunately, the aperture is incorrect. I guess Pentax changed communication protocols somewhere between the AF200T and the AF200S, because the Pentax AF200S sets aperture on the K10D incorrectly too.

I don't know if the foot of this Sunpak model is similar to that of module PT-1D or to that of module PT-2D.

12-30-2009, 07:11 PM   #5
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Thanks for the replies. The flash came with its manual in pristine condition. The manual has some good tips for flash bounce lighting, but it didn't list anything like voltage.

I was going to put a diffuser cone on it and use it to supplement available lighting.

I was surprised that there was no information about this flash online other than lots of user manuals for sale.

Since I don't have a voltmeter, I'll probably hold off on trying it out. It came with a 50mm A 1.7 lens, so I've reduced my need for a flash for the time being.
09-05-2010, 05:19 AM   #6
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I just got the Sunpak 933 and it is super awesome. A powerful flash that tilts and swivels

The trigger voltage is safe, I use it on my Nikon D40.
11-11-2011, 10:37 PM   #7
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so i have both the volt meter and the sunpak 933 flash but dont know how to figure out how to test it but i have used it on my k10d a bunch of times and it did not kill my camera but if you want to know the voltage please tell me how to test it and i will.
11-11-2011, 11:55 PM   #8
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- Let the flash charged up until ready (pilot lamp on).

- Measure the DC voltage between the center pin of the foot (sync. signal, positive, red arrow in the photo below) and a terminal on either side (ground, green arrow).

- The reading on the volt meter is the trigger voltage.



11-11-2011, 11:58 PM   #9
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well i have two conectors on the hot shoe and i read on a web site that you thest the center pin with the red and the one off to the right and back with the black and that came up as 4.84 and then i tried the way you said and it came up as 7.51 so now i am very confused

Last edited by lguckert79; 11-12-2011 at 12:04 AM.
11-12-2011, 10:50 PM   #10
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QuoteOriginally posted by lguckert79 Quote
... i have two conectors on the hot shoe and i read on a web site that you thest the center pin with the red and the one off to the right and back with the black and that came up as 4.84...
Can you please post the URL of where you read it from.

QuoteOriginally posted by lguckert79 Quote
i tried the way you said and it came up as 7.51 so now i am very confused
IMHO, 7.51V trigger voltage is OK.

Why are you confused?
11-13-2011, 12:47 AM   #11
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cause you would think that both ways would have the same outcome

here is the site that showed me the other method
how to measure flash trigger voltage
11-13-2011, 08:26 AM   #12
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That site shows how to measure voltage for Minolta flash (I used to be a Minolta film shooter, still have some equipment). Minolta has a different hot shoe/foot.

My way is correct for a flash for Pentax (and Canon, Minolta, Ricoh, ....).
11-13-2011, 08:06 PM   #13
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ok so it is safe and i am very happy to hear that now i got a flash to use and i spent one dollar on it at the goodwill this is great thank you for all your help. now i got to rig up a softbox for it i got some plans in mind for it awsome thanks again
04-12-2012, 12:41 PM   #14
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Still have this flash but haven't used it, yet.
04-12-2012, 01:31 PM   #15
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I still use my Sunpak 933 all the time, on my Pentax K200d

It's voltage is safe for dSLR

And wireless with "poverty wizards" (PT-04 ) and "peanut slaves" (SYK-3)

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