Defective PCB/scroll saw

[KTW]

I'm not sure if the saw was being pushed to the limits but that connecting rod or aluminum link arm is attached to a very heavy weight, you can see it at the bottom of the picture.
The arm broke so I'm thinking without all that extra weight the motor is running wild.
He said it was running wide open and couldn't be controlled.
I can't do much more until he decides to repair or replace the arm.
Did the electronics cause the breakage or is it the broken arm that is the cause for the failure?Not sure yet.
http://www.ebay.ca/itm/Craftsman-Co...f9643e&pid=100011&rk=1&rkt=10&sd=151967249890

 

[73's de Edd]

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Sir KTW . . . . . . .

WIth every little bit of information . . .it is becoming clearer on its mechanics.

http://www.manualslib.com/manual/486723/Craftsman-113-236400.html?page=24#manual

Looks like this was Sears best contractor grade 20 inch scroll saw unit made in 1999 in Taiwan and was rebadged as Sears.

I see that the encoder disk is on the back of the motor as is the attached photo-interruptor assembly, so the damaged "link" will not be directly involved, other than its loading aspect.

On your given e-bay listing . . . . I wonder if your owner was the one that snapped up that one of a kind unit at the very last moment ?

If the green light is still on for the repair of the unit . . . . .pending that links replacement . . .I can go back and cue you in on the correct testing of the control boards Q6015L5 triac . . . .back when you tested it originally, you were doing a mere static testing which could result in error due to a "sneak path" / leakage of voltage passing thru the triac.
A dynamic test would be the method to use instead . . . . it merely needing a 100W incandescent lamp to simulate the motor load.

Finally . . .you say . . . .
Did the electronics cause the breakage or is it the broken arm that is the cause for the failure?Not sure yet.

I can possibly see a failure problem IF there was no blade in the saw or if it snapped while running at that break neck speed.



73's de Edd


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[KTW]

Thanks for hanging in there Edd.
This is a nice saw, all heavy cast iron and I'd hate to see it scrapped.
The saw belonged to his father in law and has been in the son in law's garage out of the weather, it's in great cosmetic shape.
The curious thing is both the new and old board operate similar to each other output wise so this broken arm may be the only thing wrong with it.
I'm awaiting delivery of the new used part and will keep you informed.
Thanks again.

Kevin.

 

[KTW]

Well Edd;
The saw is up and running, variable speed and all.
The problem all along was this broken arm.

I put the old board back in and the guy has a new spare which is long out of production.
We saved this saw from the landfill.
Thanks for your patience and support.

Kevin.