2PAC Mafia
Member
Hello,
I´m trying to repair the board you see at the scheme. This board belongs to one module used to monitor exhaust temperatures on a boat, where there are other boards interconnected. On the module I replaced this board by a new one and then it worked properly. After that I tried to repair the damaged board at workshop, I saw the DR01 burned and opened and also diod D02 damaged.
The problem is when I connect the 24 Vdc the T01 should switch at more or less 2Khz creating at secondary of TR01 a 5 Vdc but instead of doing that it´s always in saturation so I have a consumption of 3,8A from the power supply unit and the voltage drops down to 3 Vdc. In theory, I think the first operating amplifier is an square wave generator and the second one is a comparator.
If I remove the TR01 and I put a resistor instead of primary coil everything is working at the right side of the circuit, we have the wave generation at first stage, then the square wave at 2Khz / 2,5 Vpp at second stage and finally the same signal but 2KHz / 24 Vpp at collector of T01.
I supposed the TR01 had some problem on its coils so I changed but I still get the same failure. I also changed the T01 but without any difference. Then I thought that may be there was some short circuit at the 5 Vdc part of the circuit, left side of the scheme, so I disconnected the D04 leaving connected the TR01 to check the behavieur of the TR01 but still nearly 4 A consumption...
When I remove TR01 and put a resistor instead of the primary coil to close the circuit it´s working properly, at least the right side of the circuit and there is a consumption of about 200 mA.
Do you have any idea about where can I find out the wrong component on the board?
Thank you very much.
I´m trying to repair the board you see at the scheme. This board belongs to one module used to monitor exhaust temperatures on a boat, where there are other boards interconnected. On the module I replaced this board by a new one and then it worked properly. After that I tried to repair the damaged board at workshop, I saw the DR01 burned and opened and also diod D02 damaged.
The problem is when I connect the 24 Vdc the T01 should switch at more or less 2Khz creating at secondary of TR01 a 5 Vdc but instead of doing that it´s always in saturation so I have a consumption of 3,8A from the power supply unit and the voltage drops down to 3 Vdc. In theory, I think the first operating amplifier is an square wave generator and the second one is a comparator.
If I remove the TR01 and I put a resistor instead of primary coil everything is working at the right side of the circuit, we have the wave generation at first stage, then the square wave at 2Khz / 2,5 Vpp at second stage and finally the same signal but 2KHz / 24 Vpp at collector of T01.
I supposed the TR01 had some problem on its coils so I changed but I still get the same failure. I also changed the T01 but without any difference. Then I thought that may be there was some short circuit at the 5 Vdc part of the circuit, left side of the scheme, so I disconnected the D04 leaving connected the TR01 to check the behavieur of the TR01 but still nearly 4 A consumption...
When I remove TR01 and put a resistor instead of the primary coil to close the circuit it´s working properly, at least the right side of the circuit and there is a consumption of about 200 mA.
Do you have any idea about where can I find out the wrong component on the board?
Thank you very much.
