Good day.
I'm currently on a vacation and a friend from the camp site asked me to check why his camper power supply does not charge the batteries when hooked to the mains.
The PSU is cramer and from what I've found the same mainboard is used in both cbc-b7 and bcc-b7. The control module/interface panel is Cramer D-5750.
So what I've found so far - the transformer seems to be working fine and the board has no visually damaged components. I tested most of the diodes and transistors with a multimeter (the only tool I got here) and they read fine.
The two thyristors have been disconnected from chassis/ground/anode and gate and at some point someone has soldered a resistor between the cathode and the gate to keep them non stop open(?).
I connected the thyristors as shown in the schematics (gates to gate connectors on the mainboard and anode to chassis), but now I'm getting some strange voltage readings (Vac).
When using chassis for reference with disconnected gates:
T1
Cath. - 17.1 Vac
Anode - 0
Gate - 16.6
T2
Cath. - 1
Anode - 0
Gate - 1
When using transformer winding midpoing for reference (this is the V+ used for charging the batteries) with disconnected gates:
T1
Cath. - 12.34
Anode - 9
Gate - 12.34
T2
Cath. - 12.3
Anode - 9
Gate - 12.3
I suspect the thyristors went bad and that is why they were disconnected.
Is there a way to test them with only a multimeter?
On the board, both gates show 3.3Vac 50Hz and 1.3-1.4Vdc so probably there is some switching going on there..
I'm currently on a vacation and a friend from the camp site asked me to check why his camper power supply does not charge the batteries when hooked to the mains.
The PSU is cramer and from what I've found the same mainboard is used in both cbc-b7 and bcc-b7. The control module/interface panel is Cramer D-5750.
So what I've found so far - the transformer seems to be working fine and the board has no visually damaged components. I tested most of the diodes and transistors with a multimeter (the only tool I got here) and they read fine.
The two thyristors have been disconnected from chassis/ground/anode and gate and at some point someone has soldered a resistor between the cathode and the gate to keep them non stop open(?).
I connected the thyristors as shown in the schematics (gates to gate connectors on the mainboard and anode to chassis), but now I'm getting some strange voltage readings (Vac).
When using chassis for reference with disconnected gates:
T1
Cath. - 17.1 Vac
Anode - 0
Gate - 16.6
T2
Cath. - 1
Anode - 0
Gate - 1
When using transformer winding midpoing for reference (this is the V+ used for charging the batteries) with disconnected gates:
T1
Cath. - 12.34
Anode - 9
Gate - 12.34
T2
Cath. - 12.3
Anode - 9
Gate - 12.3
I suspect the thyristors went bad and that is why they were disconnected.
Is there a way to test them with only a multimeter?
On the board, both gates show 3.3Vac 50Hz and 1.3-1.4Vdc so probably there is some switching going on there..
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