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Joined: May 2001
Posts: 376
F
frank Offline OP
Member
I have a benshaw redistart drive with control board 30005-01 being used on an AHU and after fire drill last night it refused to start.The model is an RSD6 REDISTART and the on board display was constantly cycling(segments were going around in circles)This is not listed in the manual as a pending fault and the dealer has no idea what it means either.Anywhay after leaving it powered up all night i came back and found the display showing a fault code(F95)Again this is not listed in the manual but i did find a reference to it being a shorted SCR on lines 2&3 from other benshaw manuals.Can an SCR go from a shorted condition to an unshorted condition?
After clearing the fault the unit started up and seems to be running fine for now.I'm also wondering if there has been a revition to the software and this is why the fault code and spinning display are not refered to in the manual?
I'm seriously thinking the board is the problem not the SCR but then again neither part is going to be cheap so any help you can give would be greatly appriciated.
thanks

Joined: Jun 2007
Posts: 301
J
Member
Sounds like the control board to me. Are you contacting Benshaw or their rep?
If you can get a Benshaw rep on the phone and explain, they may be able to help. They are good about helping and make some very good products.
Is Benshaw popular in Canada? I know they are not well known in the US. I used to rep them.

Joined: Nov 2005
Posts: 826
J
Member
Frank,
I know nothing about the equipment that you are working on but I do know SCRs. Perhaps the SCR had been triggered before the board was restarted. The SCR would not turn off until its cathode current was near zero. You will also find that higher current SCRs will not remain on after removal of gate drive, below a minimal cathode current.
If the circuit checks current through or voltage across the SCR on boot up, it might signal a shorted SCR.
Joe

Joined: May 2001
Posts: 376
F
frank Offline OP
Member
I am seeing more benshaw controllers around here.They seem to be very reliable and use plain English displays making them extremely easy to setup.
We have them on all our new applications and in 8 yrs this is the only real problem we've had other than the odd control board fuse.
We did ordered a new board from the rep but the cycling display and lack of reference to the fault code (f95) in the RDS6 manual kind of confuses everyone.
Like i said i found the fault reference in another manual for another Benshaw model but the SCR's show the proper resistance(more than 50k ohms)Now that its running i can check the gate firing voltage.Maybe the SCR is getting triggered as soon as the machine is powered up because the self test take forever and again it would be the card thats the problem.
thanks again

Last edited by frank; 12/22/08 06:42 AM.
Joined: Jun 2007
Posts: 301
J
Member
The control board is where the processor lies. Whenever you have display problems and unexplainable error codes I always look at this board first, then call Benshaw.
Don't work yourself to death trying to figure this out, make the call.


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