1999 48V GEM2 Need DC/ DC Circuit Board

GEM Forum
21

Dave,

So the circuit board and dc/ dc are both good? Car has no response when key is turned and we have no idea what else the issue could be as 48v is going to this.

Thanks.

22

It needs two things for board to output 12v.
Thanks to Gem_E2 schematic.

#1-48v in on molex connector.
#2-voltage in on pin 7

Pin 7 charges C4 on pcb for time delay. When voltage reaches threshold of an Fet-T1, relay L3 pulls in, turning on it’s NO contact-K3 to enable dc to dc. (gate pin)

Pin 7 is fed from interlock circuit of charger.
Same wire pulls in main cont.
Charger interlock comes from terminal “curtis pwr” on controller.

I have not found a “key” or power switch yet. As it is not needed for what I’ve deciphered so far.
If there voltage at interlock, the rest should be easy.

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1 Like
24

Someone look at the diagram for an on-off switch.
I don’t see it.
What is the RADSDC between ist and 2nd battery?
System needs good pre-charge resistor to start. IMO.

25

My error, “key” I am referring to is ignition…

26

Few more photos:

image1.jpeg1224×1632 746 KB

image2.jpeg1224×1632 734 KB

27

Could the key have been added? Can’t find it.
Should be between interlock and M.C.

48vschematic.png1034×652 527 KB

28

Again, can I call you or you me?

Mike Harvath
443-822-5113

CROWN CASTLE
513 Progress Drive, Suite M
Linthicum Heights, MD 21090
CrownCastle.com

29

Again, referring to ignition key. Not a key on schematic.

30

You say there is a key. How is it connected?
It should go to M.C. coil and pin 7 of pcb.

48vschematic.png1034×652 528 KB

31

“Key” I am referring to is the ignition key (when turned to forward or reverse the solenoid would “click” – it does not anymore)….the only other electrical switch is the battery on / off switch.

32

Got it, so the F-R switch is the key.
Can’t help anymore trouble shooting the car. There are mistakes on the drawing in the F-R switch area…
See if you have 48v at pin 7 of the DC-DC plug.
As you can see on the diagram. +48 at the key common goes directly to M.C. coil and pin 7.

33

Thanks Inwo for pictures

34

Let me know if you need anything repaired.
These are rare I suppose, but look easy to repair. The actual DC to Dc section could be swapped with any generic converter.
I wonder if the 72v recalled boards are like that?

35

Dave,

Have you received the funds and is the part back on its way to me?

Thanks for all.

Mike

36

Yes, sent priority mail.

Michael Harvath 9405509699938240467591 Shipped

37

Great and thanks again.

38

Seems u may be the only one that could tell me about this board my cart will work for a second and quit but only if I fool around with the board I took it off and soldered the big red wire on the bottom left the prong was loose but it looks like part of the board around the middle is burnt might not be making good contact what would be the best way to test the board with a meter to see make sure that’s my problem and also could u recommend a replacement for me to buy and how to go about changing the wires over, sorry but there’s literally nothing on the web about this thing it’s like Sasquatch this is the most info I’ve ever seen about this board any help at all would be greatly appreciated thanks.

39

As I recall it is a pretty simple board. I don’t have one in front of me to look at.
I will check it for you at no charge if you ship it, but I think you already know it’s bad.
Can try to repair it for $100 if you want to do that.
If it needs a new dc-dc (part that plugs into pcb) it might be more.
Most likely it’s something on the board. Look for a corroded trace or connections. They can be jumpered if you can solder.

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