Mobility Scooter Power Supply Repair (2)

Thread Starter

KV4ATV

Joined Apr 18, 2024
2
Any experience fixing an Pihsiang MB-24/3 mobility power supply would be gratefully received as new ones are exorbitantly priced.

These units are for charging the 24V batteries in mobility scooters.
The faulty one appears to have an intact transformer with a CT 60-0-60 main secondary and a much lighter 10-0-10 for the control electronics. The main 20A output fuse is also intact.

The control appears to be using two BT151 thyristors in a biphase rectifier (not smoothed) arrangement with the main secondary.

The control circuitry comprises two HA17324 ICs, which I think are equivalent to LM324 quad op amps.There is 18 pin DIL IC which I do not recognise, labelled CF74S an ??47P. I think this is a PIC processor.
The one in the charger I'm working on has U4 printed on the board and the print on the IC is CF 745 if this is of help.
The U2 IC is an HA17324A. I'll be testing the 2 SCRs that are in it also with my O-scope and component tester on my Scope.

Moderator edit: new thread created from this.
 

Thread Starter

KV4ATV

Joined Apr 18, 2024
2
Here are some pics. Note the red fault light on the front panel in the first one it is flashing.
Exactly the same board in mine.. Same problem. Red light blinking and not charging. I may replace all 3 IC chips and the e-cap. I'll also be testing all parts with my O-Scope and component tester.
 

MisterBill2

Joined Jan 23, 2018
18,934
Before replacing any parts I suggest a close inspection of all the connections in the system. That may not be the source of the problem,but it could be the source.
 

MisterBill2

Joined Jan 23, 2018
18,934
Certainly good advice about checking all the connections. And if there is a circuit board, examine all of the solder connections because they are known to break. And the connections of the cords, especially at the battery connector end.
 
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