Metz 45-CL4 low output

[BeBu Lamar]

I just got 2 very used Metz 45. One is the 45-CT4 and the other is the 45-CL4. The 45-CT4 is fine. Full power manual as I measured is GN125 in feet (short of the 145 specs but that is to be expected). But the 45-CL4 is only about GN 57 or so. Auto exposure is correct and if the distance or f/stop chosen is small it would not light the confirm light. So the autoexposure part is OK but the flash just can't have the power it's supposed to have. I check and compare the current draw on the 2 units. Initial draw about 7A on both unit but when the unit charged up the good CT4 still draw 0.5A while the CL4 only draws 0.25A. The ready light on the CL4 comes on very fast but leaving it on for a few minutes before firing does not result in more power (OK about 1/10 of a stop). I wonder what is the problem. I removed the cover, disconnect the capacitor and made capacitance measurement on both units with a DMM and they both show about 1500 microfarads. 

I wonder anyone has any idea?

[rodeo_joe1]

The flash energy is proportional to the square of the charged capacitor voltage. So a drop of about 30% in the inverter voltage will cause a loss of a stop in flash output. 

The capacitor should charge to about 350 volts with these old Metzs. So if you're feeling brave, and lucky, you could measure the fully charged voltage on the capacitor. 

Bear in mind that these things are 30 years old or more. Some loss of performance is to be expected in a proportion of them. And shorted transformers, open-circuit/altered value resistors, loss of gain in transistors, etc. are all common faults in old circuitry. They're also not obvious without diagnostic knowledge, and not necessarily fixable due to component obsolescence.