10ee moduler wont run smoothly

We found terminal 42 . The lathe was running, it has suddenly started to fire and drop each tube, Drumming rapidly while trying to work. It has two good tubes and a new t/8 transformer .Tube E-T1 Glows nicely. Whats up?

david tt said:

We found terminal 42 . The lathe was running, it has suddenly started to fire and drop each tube, Drumming rapidly while trying to work. It has two good tubes and a new t/8 transformer .Tube E-T1 Glows nicely. Whats up?

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I'm not sure about the reference to "terminal 42", perhaps it's a reference to the message you edited to say "delete"?

Usually, if the thyratrons are flashing it's either in the compensation or field acceleration relay. In the modular drive that's effectively the same thing. If you played with the compensation adjustment you'll want to go back through he setup, if you didn't change anything before the problem appeared you'll have to diagnose the problem.

You should be able to disable the FA relay and see if the problem continues. If so I'd replace the diodes in the REC 4 group. Previous postings in the group have documented making inexpensive replacements for the stock diodes. If bypassing the relay "fixes" the problem (for low speed starts) then it's possible that the relay itself is sticking, mine had some oxidized oil that made the relay hang a bit and cause some interesting problems.

Have you.
Checked all diodes in module.
Adjusted speed compensation pot on module.
Try running machine with module removed.
Checked the condition of all switch contacts in right hand compartment.

We tryed swapping the moduel with a good one,also tryed to run it with no moduel, she still drums.Maybe this will mean something, as it trys to run the dynamic brake is chattering.

The next item I would try, is changing is the C3J tube, those can cause that sort of problem even if they appear to be good.

"Maybe this will mean something, as it trys to run the dynamic brake is chattering."

Check again, it could be the field loss relay which is chattering.

Donie ,I have a new c3j I'll try it.The one thats in it now glows nicely.
Peter,I'll check the field relay too.
Thanks, Dave

The C3J conducts in the forward direction, only.

The REC 3 diode captures the "back EMF" of the motor and, effectively, makes up for the one-half cycle in which the C3J is not conducting.

This produces the net effective field, which is the sum of the two.

When the Module is removed, the REC 3 is also removed, and this automatically causes the effective field voltage to be reduced, and is but one reason why removing the Module causes the rpm to increase.

Another reason is the armature is turned on fully.

Once the flaky components have been identified and corrected, this drive settles down pretty well.