another z-4000 problem

So the light doesn't blink but fluctuates, eh?

That is usually an issue with the feedback design of the circuit. Kind of a built in issue with all feedback circuits.

It may change to somewhat stable if you change the voltage setting somewhat.

I think it is very noticeable with lamps, but not so with motors, etc.

Did you try the fixed accessory output (if there is one) for a more stable output.

This was discussed before as I recall.  Several people observed at certain loadings the output would fluctuate.

Are you saying that only the left hand side of 4 different Z-4000 will do this, but if you use the right hand side NO fluctuation/blinking?

Is the blinking the accessory lights or the indicators on the Z-4000?

Also, what does the left hand side Voltage and current read during this fluctuation?

While I could see a fluctuation or voltage droop occur, the lights blinking which you can see means a voltage loss, more than a voltage change.  If it only does the left and not right side that might be a design issue, worthy of asking MTH about.

If it is doing it to both sides and it is actual blinking, I would try removing a few lights loads to see if it stops the problem, you might be at an overload condition, though that should not happen at 7.5amps.

Or there is some unique issue with these accessories.  What are they?  G

GGG,

  I do have several operating items on each circuit, but have disconnected them to see if they were causing the problem. It would then be only lights. As stated it is 4 different z-4000's, left side only, and either circuit connected to the left side.

That is a new one on me, can't explain it.  G

So help me out here, is it blinking of fluctuating? Fluctuating is a characteristic of a feedback control system. Not desired, but somewhat common and has to do with the design of the system. The need for the fast response of the output voltage requires a fast time constant designed in, and may be border line for this kind of oscillation.

In the case of the CW-80, the throttle side fluctuates, but the accessory side does not. I attribute that difference to the accessory side design for an output that does not have to change with external adjustment very fast.

MTH may have an answer to this for those transformers that fluctuate based on their experience with production variations of component values used on their circuit boards. I would go to them directly and ask the question.