Metz 60 CT-4 Always fires full power problem.
I registered here as this forum has been knowledgeable and helpful to similar questions in the past.
I just purchased a Metz 60 CT-4 and it always delivers a full power flash, regardless of settings. ie. All manual settings or automatic, it is always full power.
It has worked a few times properly so this gives me hope it may just be a dry joint or similar.
I have other 60 CT-4's and I have swapped out every component individually to isolate the fault to the power pack. I can swap the flash head, lead (and lithium battery) to a good pack and it works perfectly, and I can swap the other known working flash and lead onto this pack and it behaves in the same faulty manner. I have tested both outputs from the pack and both behave the same. Both outputs also have the right voltages on them (OV, 7.8V & 356V).
I am hoping someone may be familiar with servicing these units and might be able to point me in the right direction? I am handy with electronics but need a little guidance to get started. I am aware of the need to drain the dangerous high voltages and that all work performed is at my own risk.
Further does anyone have, or are aware of, a service manual online? (I have the owner's manual).
Thank you kindly and all the best!
Last edited by boosta; 08-17-2011 at 11:46 PM. Click to view previous post history.
It sounds like the thyristor, that is suppose to interupt the HV dc when sufficient light has been sensed from the on flash head sensor is not doing that.
In my metz CT-1 the lead from the pack to the head has three leads. One is negative DC. I thought that one is low voltage DC to run the sensor and dial calcuator electrronic in the head. The third is the HV dc plus.
I may be wrong in my past assumptions. Maybe the thyristor is in the pack, and the thirs line is the shut off signal line. That would suggest that the head gets power by bleeding HV off and stepping it down to run the head electronics.
I would inspect the sockets very carefully. On mine on the head socket there was arcing, and the socket had to be replaced. My CT1 pack came with the capability to drive two heads, so I scavenged the second socket from the pack and moved it to replace the socket in the head.
my real name, imagine that.
Mike would know more about the "innards" of these units than I do.
That being said, it seems to me that the fact that you can attach more than one head to each power pack is some indication that the heads themselves contain the thyristor.
In addition, I note that one of originally available accessories for the flashes was the "Power Pack N-20" which allowed you to run the heads directly from mains power, without an intervening portable battery pack. I'd be surprised to find a thyristor in an N-20.
One further thought built on Mike's comments - has the OP tried the other socket on the other side of the power pack?
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
I don't think it's a thyristor problem as, if I get the problem description right, the flash outputs full power also when used in the manual "partialised" modes: 1/2, 1/4 etc. When using those "partialised" manual modes, the thyristor is not involved.
If I had the courage to open such a device I would clean all contacts and check that they contact properly. Maybe there is some "spring shaped" metal stripe on a slider somewhere that must be reshaped.
this makes me thinking. I think (and can be very wrong) that the powerpack only supply high voltage to charge the capacitor and low voltage DC to run the control electronic in the head. I think the capacitor is actually in the head and not in the powerpack. So it seems once the flash is charged, and the actual firing doesn't involve the powerpack but your experience with swaping indicate it's the power pack problem. So I really don't know and it bothers me.
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For what it is worth, the capacator is in the 'power pack". (At least with the 60 CT1). Place your ahd on the power pack and fire the flash at full power and you can feel the capacator working, as if you were to thump the case from the inside.
My suggestion the power pack is low cost enough from KEH just get te new power pack. Once you get bit by the chared capacator the power pack will be a bargain.
I don't know how related is all the problematic of using the flash with Ni-Cd batteries but this web page might give some indication:
You might be using a modified power pack, or a power pack which doesn't use the proper accumulators, maybe this has this kind of effect on the flash. Just an hypothesis.
I believe the challenge that some vendors have in using NiMH batteries in AA style flash holders is the energy density that they pack.
I think it related to the current could get high enough, and the duty cycle high enough to heat the spring wire, though which the current flows such that it may loose some of it's spring characteristic.
In engineering terms, the metal would have yielded by the thermal exposure.
The other issue is the voltage output, as the flicker article discusses.
Since the original poster says that the thing works correctly sometimes, that would lead me to think that the problem is in the shut off circuitry, that feeds the power control tyristor. Thyristors like this don't usually go flaky, they just short closed.
The manual control, if it works, like for winder/motor drive modes, would show the thyristor is working. These modes switch in a fixed set of restistance to limit the shut off time to the thyristor.
The manual modes would also be a set of different ratio voltage divider pairs of resistors. I am basing this on a past opening of my Mecamat remote sensor to clean it after a mostly empty soft drink can dripped onto it. I will pack garbage separately next time!!!
I would not recommend taking it apart a Mecamat unless you have to. It is replete with a nest of resistors and contact pins and wiper arms that are a challenge to get safely back into their proper alignment to allow the case to close up.
my real name, imagine that.
Hi All and thanks for your responses!
Mike, I thought the same that maybe the flash controls the output by sending a cutoff signal to the thyristor in the pack that cuts the HV. Would this make sense that the thyristor is placed close to the capacitor? Perhaps, since the secondary heads made for these have their own capacitor so they probably have their own thyristor as well. I thought perhaps the low voltage line both supplies (control) power to the head and carries a shut off control signal back to the pack??? Maybe the fault is in that line between the pack connector and the thyristor??? Or the thyristor itself. I know very little about these circuits so I'm just guessing.
I have checked the contacts and they look good. The whole flash is in excellent condition. I pulled the pack apart and could see nothing obvious inside. I didn't pull the main board off the alloy frame so I haven't seen under there for dry joints yet.
Matt, Interesting point about the N-20 that would shoot the above theory down, I actually thought the N-20 plugged into, and powered, the pack. I didn't know it powered the head directly from AC? I'll look into that point. And yep, I've tried both sockets, both behave the same.
I can't get the head or lead to fail on another good pack, and I can't get the pack to work (except about 3 random occurrences) with a second known good head and lead.
Diapositivo, I thought the thyristor was only responsible for cutting power to the head and it gets told to act by other circuitry, auto or manual? Again, not fully sure? Also the flikr page is about the 45 series i think? As an aside regarding them I have measured different (lower) voltages on the cap when connecting Nihm to the Alkaline contacts, they work but Nimh should go through the Nimh contacts. That is the 45's though, I'm running the 60's on li-ion batts.
Chan Tran, It bothers me too!!! The cap is definitely in the pack. BIG sucker too. Scary thing it is
Thanks again everyone for your helpful responses and I hope I've understood them correctly so far!
Any knowledge of how to get a schematic or service manual on the 60 CT-4?
Where are you located? If you are in the US, you can get a (used) replacement power pack for about $20. Unless you have some sentimental attachment to the bad power pack, fixing it does not make sense.
Buy it here: POWER PACK 5316 from KEH.