[Junah]

I have just acquired a AF400T to use with my 67ii.
When I switched it on to test it, it hums but test light never comes on, is it faulty?
I also have a TR3 battery pack to connect to my AF540 but the cord does not fit the AF400.
Would it be worth trying to find the correct cable, or is there a fault on the AF400?
I have put new ever ready batteries in, should I try Duracell?
What are the best settings to test it on? (off the camera)
So many questions, thanks, in advance, for your help.

[SOldBear]

When I switched it on to test it, it hums but test light never comes on, is it faulty?

By "the test light," do you mean the "power indicator" on the TR-3? If yes, it should come on.

If you mean the "ready pilot lamp" on the AF400T, If it hums but the pilot does not come on, the capacitor is probably toasted. I don't think it's worth repairing.

I also have a TR3 battery pack to connect to my AF540 but the cord does not fit the AF400.
Would it be worth trying to find the correct cable, or is there a fault on the AF400?

I don't think Pentax made a generic cable to use with the TR-3. From what I know, the cable for the TR-3 works only with AF540FGZ and AF500FTZ. You may be able to make a cable for the AF400T, however.

This post may help: link.

I have put new ever ready batteries in, should I try Duracell?

You don't have to use any particular battery brand.

What are the best settings to test it on? (off the camera).

Let's try to make the flash to fire first.

[grhazelton]

If an electronic flash hasn't been used for a long time the capacitor may need to be reformed. I think all you need to do is to turn it on and hope. This can take a long time, and since the AF 400 T is power hungry you might consume 6 AAs or more in the process. I hope that is the problem! As far as brand for the AAs, any good alkaline would do. I don't remember whether the flash will handle NiCad cells or not.

Pentax made an external battery pack for the AF 400 T; my understanding is that the pack for the AF 540 is identical except for the connector. These packs produce high voltage! Don't consider just kludging up an adaptor with 6 D cells or whatever to plug into the AF 400 external port. The pack gives rapid recycle and for long shooting sessions no need to fumble changing the AAs. Somewhere I saw a method to adapt the external pack to the other flash, as I recall just a matter of the proper connector. Anyone out there remember?

That said the AF 400T is a fine unit. I use mine with my LX with which I have a ready light in the viewfinder, automatic switch to X synch speed, proper exposure indication, etc. TTL is a wonderful way to flash, electronically that is! Pentax used TTL in their first DSLR then switched to PTTL. I've never seen a good explanation of why.

Mike Butkus has a downloadable manual for the AF 400T here: Pentax Flashes, AF280t, af200s, af200t, Pentax AF220T, af160, AF330FTZ, pentax AF 360 FGZ, Pentax AF 400T, Pentax AF 500 FTZ instruction manual, Pentax flash instruction manual, user manual, free PFD camera manuals The external battery pack turns up occasionally at KEH, etc.

Good luck!

[SOldBear]

Can you please post a close-up photo of the AF400T's high voltage port. Dimensions would also be helpful. Thanks.

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Last edited by SOldBear; 02-05-2013 at 11:47 AM.

[Junah]

I have spoken to my 85 year old camera guru, he has given me the same advise as grhazelton "Switch it on, and leave it for a few hours" and lo, the test lamp has come on and the gun flashes!
It takes a little while to come back on, but I presume the batteries are now low.
Thanks for your advise.
Gary.

[grhazelton]

Always happy to have my advice echoed by a guru! Maybe I can be a guru when and if I hit 85!

Glad it worked out, and yes, you've probably exhausted the cells. A 102 watt-second flash needs a lot of juice. I hope you can turn up a TR power pack, although the combination of a Pentax 67, the flash and the powerpack may put a strain on your back. I found that shooting a wedding or such with the AA cells I went through them pretty rapidly. The 6 C cells in the powerpack will last much, much longer.

[Smolk]

My AF400T does not power up from the 6 AA batteries any longer, but oddly, it does power up from the TR power pack. What might be wrong with it?

[SOldBear]

My AF400T does not power up from the 6 AA batteries any longer, but oddly, it does power up from the TR power pack. What might be wrong with it?

1. Problems in step-up circuit.

2. Dirty battery contacts. Use an eraser (pencil eraser is OK, pen eraser is better) to clean all contact surfaces. If that does not fix the problem, use very fine sandpaper.

Let's hope it's (2).

[Smolk]

Thanks—alas, I think it's not 2, tried that.

I also notice something else: I have a second AF400T which after a drop cannot be fitted with the internal battery holder but still works with the external TR power pack. Oddly, this broken flash powers up much faster than the first flash with the power pack. I guess that may tell me something is wrong with my non-broken flash. Such a shame, I rather liked it.

[grhazelton]

Does Eric work on flashes? Sounds like you have problems with the HV supply in the handle, as SOldBear suggested. At least you can run it off the TR pack.

[SOldBear]

Does Eric work on flashes?

Only Eric know for sure But I don't think so.

Smolk is on the other side of the pond. Shipping back and forth may not make economic sense.

Sometimes I want to buy a used copy of the AF400T just for the fun of it. But if I buy one, I may not be able to save my marriage (I already have quite a few copies of Sunpak and Metz handle mount flashes).

[grhazelton]

Only Eric know for sure But I don't think so.

Smolk is on the other side of the pond. Shipping back and forth may not make economic sense.

Oops! I hadn't noticed that. I'm sure he's aware of these good folks Pentax User who doubtless have some local suggestions for repair shops.