What Diode to test???

[Irrig8or]

New here, and I have looked at everything I can about test a new to us cart. The cart is an e z go 36v. We have installed new batteries and tested the motor (A1-to +Battery and S1 to -Battery and connected the A2 and S2) yes it works... The controller is a Curtis PMC controller and I do not get a reading from the B+ post. I have opened it up and removed it from the aluminum case. I have looked on youtube but no one has posted where to put the test leads to check the diodes, and which ones to replace. I do not know electronics but the basics...any help would be great.
Thanks in advance

[kellybell]

Welcome to BGW! What year, and what drive system? Is it PDS? If you don't know, can you post the serial number?

[Irrig8or]

Thanks, I don't know...here is the S/N 793175.

[whizzo]

If its a curtis controler, its not the diodes that are too much the worry its the FETs.

First start with a visual inspection..any burnt resistors, any FETs with cracks splits or the faces blown off.
The FETs are the 3 leged square packages screwed to the heat sink

Progress with the nose inspection...any thing smell burnt

Past that you need to learn a bit about electronics and use of a multimeter.
If you have ideas of fixing this, you will need some electronic experience and some printed circuit rework skills.

For someone with an electronics background it should not be too much of a problem....but if you have no experience with these things...leave the repair to someone else

If you google arround, you should be able to find the installation manual for your controller..maybe from curtis, this should give you a diagrame for a test rig and test procedures.

you need to give us some idea of what controller it is.

remember over in the US, there are several companies that will repair or exchange controllers.....I don't lnow how they view units that have been opened.

cheers

[Irrig8or]

Thanks, yes it is a Curtis 1204-027. Nothing smells burnt or looks like it is blown out. I do have some experience with a multimeter. I trouble shoot irrigation controllers. I have looked for Curtis info., but there is no schematics for the 1204 that I can find. Is it top secret?? I also have that clearance from the Air Force. I am just looking to change out a diode or FET and get this running for cheap...Thanks for your help.

[kellybell]

It is very top secret! LOL.... JK.......

[JohnnieB]

Originally Posted by Irrig8or

I do not get a reading from the B+ post.

The serial number says it left the factors as a 1994 Marathon.
Here is a schematic for that cart.

Not having voltage on the Controller's B+ post indicates the problem is out side the controller.
Get all the proper voltages to the controller before digging into the controller any further.

----
FWIW: I had a TS-SS when in the AF. That and $3 will get you a small Soy Latte at a Starbucks.

The only thing I can find on a 1204 is the attached block diagram.

[sportcoupe]

You can send it for repair here. Fast turnaround and cheap.
http://capsservice.com/index.html

[whizzo]

As has been mentioned..first prove or disprove the controller in a test circuit.

All covered in the 1204/5 manual.

If its snotted, they don't seem hard to repair.....the hard work is getting them appart in a civilised manner.

there is a circuit running arround...it is not for a 1204, but it will give you a pretty fair idea of what gives.

I've just rebuilt a comprehensivly snotted 1205..and it runs.

the FETS in the lower voltage controllers are IRF540N....common enough.
The freewheeling diodes are no longer available the MUR2020R appears to be a reasonably available replacement ....I have not tested this....my diodes where fine.
the fet driver transistors often fail with the output stage...mine where fine inspite of every FET and half the drivers resistiors bing toast.

The three fet drivers are 2N4401, pretty common, MPS650....look for MPS651 and MPS750..look for MPS751.

The desoldering is hard work due to the small pads and the thru hole board.
Don't cut the links between the controller boad and the power board as is sugested in one on line article......persist with desoldering braid..resoldering and desolding and gentle force.
I cut the legs off the FETS and pulled em out with tweezers, then cleaned up with desolding braid.
The resistors come out easy with tweezers.

Throwing a few extra fets in is an easy done upgrade....

cheers

[DOOmsman]

Not a sparky by far, but are the resistor and solenoid good?