# Faulty Curtis



## CPLTECH (Sep 14, 2007)

*Re: Faulty Curtis 1231C*

Been on vacation or would have responded sooner,
My guess it is used as a voltage regulator for that circuit board.
A circuit of the 1221 [similar] is found at: http://cafeelectric.com/curtis/

When my 1995 Curtis 1231/120V decided to let the smoke out last year, it went into what I call a limp mode… low power since many of the mosfets blew. Many say that most just die the death. Curtis factory service http://www.fsip.biz/ wanted a little over $900 when I could buy a new one at EV-America for $1495. The good folks EV-America said they could point me in the direction of another less expensive shop if I desired, but due to the age of mine, said “NO”, but thanks. Send me a new 144V one. Phone # 603-569-2100 http://www.evamerica.com/

Hope this helps,
94 S10 

In my previous life, I repaired industrial electronics & even made jigs to test units on the bench. But it seems that others have gone before me when it comes to repairs of controllers & I hesitate to go there since some ventured off into their own controller designs & how many warranty jobs did they have to eat in the beginning? Did not repair my own controller. Trust me, it’s no fun to wait for a tow truck to take you home.


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## johnstan (Jun 16, 2009)

I have also been away from home for a week, here in Aus. we have school holidays, being grandparents we seem to br away a lot at this time.
I have removed the suspect transistor and found it to be faulty (dead short all pins both ways) Have picked up a replacement transistor today will replace it and do some more testing before trying it in the car.
Following is a short history of my controller problems, can you think of any component that would cause this fault.
During the first year we noticed a slight flat spot or momentary loss of power, which appeared to be connected to the potbox. Bylong in Sydney (Curtis representative) replaced it for us free of charge, but the problem nevertheless persisted, and by 2007 had developed into a noticeable hesitation. Once again Bylong obligingly replaced the potbox for me.
By 2009 we were driving our E.V. for all our local driving without needing to charge in town. But our flat spot problem remained, and had developed to the point of feeling like a slipped gear In early March I decided to try an extended trip from Swan Reach to Swan Hill, towing a small aluminum trailer fitted with a 5.5 kva generator with 13hp motor. I didn’t try to convert the 240volt AC to DC, but simply ran the AC to the onboard 20 amp chargers…..not very efficient, but simple.
I drove from Swan Reach to Yallourn Nth, about 190km, using the back roads and keeping the speed down to 60kmh. At Yallourn Nth plugged into 240v and recharged for 6 hrs, then started off on the freeway. With the multi-lanes I was able to keep to no more than 60kmh.
At Warragul, my dash voltmeter showed very good battery charge, and I felt confident of reaching Melbourne. Then my flat spot problem returned and this time I lost all power, and had to hire a small truck and trailer to get my EV home. On testing the problem proved to be the Curtis controller. Curtis denied warranty as the controller was three and a half years old; I had always claimed that the problem started in the first months of purchase.


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## johnstan (Jun 16, 2009)

Update on Curtis problem, I removed the transistor from the board and found it to be faulty, dead short all pins both ways, apart from this the only other visible damage was a burn out of the printed circuit in the vicinity of the connecting pins that connect the control board to the power board.
I replaced the transistor, assembled the controller and installed it in the car, "no go." I then dismantled the controller and removed the transistor. The test this time showed the transistor was good, open circuit one way B to C, and B to E, closed the other way , C to E not connecting either way. From this I assume that the present problem is something that the transistor has blown. On close inspection I can see that there may still be blown circuits connecting to the pins that connect to the power board.
I am back to grandparent duties tomorrow but should be home by Monday, I will then repair anything that looks suspect and try it back in the car.
I am a complete novice so would appreciate any advice you Techs can offer, my only redeeming feature is that I am persistant or some might say dogmatic..... I will try to not let Curtis beat me.


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## Tesseract (Sep 27, 2008)

johnstan - I don't think the Curtis 1231C schematic is publicly available so it's a bit much to expect any of us to be able to figure out what's wrong with yours from a tiny section of the pc board. If you take the time to reverse engineer the schematic in that area then I'll try to help you figure out what might have gone wrong, but I won't expend the effort to do both


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## rillip3 (Jun 19, 2009)

While I've worked on PC boards before, what I've seen as a fualt is not present here. I defer to your more advanced electronic skills. 

But you mention a couple of times that you were loosing power and that the pins appear to be heat damage. Controll heat buildup is a fequently cited cause of power loss, and it would explain the heat damage. I'd look into putting additional cooling (heatsink/fan/some sort of water cooling) once you get the board sorted out.


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