Hello, I have a SYMSI70 gas heater board, which has issues with its primary side power supply, controlled by TOP247Y chip.
When I replace a TOP247Y it explode in 1 second. I have desoldered transformer and measured a winding ratio, so transformer looks like OK.
Transformer:
|Info| Primary | Aux | AB | CD|
|-|----------|----------|-|-|
|Ratio|1|25|40|12|
|Voltage AC|230V|9.2V|5.8V|19V|
|Voltage DC (*1.41)|230V|13V|8.1V|27V|
I have disabled a undervoltage protection of TOP247Y, disconnected secondaries and tried to power it up with voltage from 50 to 150V DC (I have connected in series multiple 32V DC printer power supplies).
When I connected all secondaries, all voltages were correct, display was showing an error "F10" as nothing was connected and "some relays" on board were switching. So board works correctly on 150V DC.
A Drain-Source current(on primary side) was about 50mA, power consumption about 8W. On the board, nothing is hot, so there are no hot components.
But when I connected it to 230V AC, which is about 325V DC, TOP247Y exploaded. This happen everytime. I have another older board which has some "logic issues" and chip TOP247Y works correctly in this old board, so the chip TOP247Y is not broken.
I have transformer out of the board on about 30cm wires.
It means that error must be in a snubber network, there are two, one around a transformer and the second around a Drain-Source of TOP247Y chip. I do not have ESR meter or oscilloscope, I have only simple "Non-True RMS multimeter".
I have even tried to put a P6KE300A tvs diode to primary snubber network,
Diode BA159 was OK, but I have replaced that with UF4007.
Snubber capacitor C803 (10n) I have replaced with two 6.3nF 400v capacitors
Second snubber capacitor C1, about 70pF was "white SMD ceramic MLCC" I have replaced with "simple ceramic" which is probably for low voltage only.
When I'm measuring voltages even with 50V DC power supply, snubber voltages are high, about 200-500 V on multiple places.
I have some P6KE130A (tvs diode), should I use it?
How can I check it safety? I wanted to use a tyristor dimmer to slowly rise a voltage (I do not have a variac), but it is just cutting some pieces of waves and does not limit max voltage, so TOP247Y exploded too. So I'm thinking of using some "capacitive divider" to make a lower voltage.
So there is no overcurrent, just an overvoltage caused by a snubber network malfunction. Please what can I do with that? Everything looks like correct
When I replace a TOP247Y it explode in 1 second. I have desoldered transformer and measured a winding ratio, so transformer looks like OK.
Transformer:
|Info| Primary | Aux | AB | CD|
|-|----------|----------|-|-|
|Ratio|1|25|40|12|
|Voltage AC|230V|9.2V|5.8V|19V|
|Voltage DC (*1.41)|230V|13V|8.1V|27V|
I have disabled a undervoltage protection of TOP247Y, disconnected secondaries and tried to power it up with voltage from 50 to 150V DC (I have connected in series multiple 32V DC printer power supplies).
When I connected all secondaries, all voltages were correct, display was showing an error "F10" as nothing was connected and "some relays" on board were switching. So board works correctly on 150V DC.
A Drain-Source current(on primary side) was about 50mA, power consumption about 8W. On the board, nothing is hot, so there are no hot components.
But when I connected it to 230V AC, which is about 325V DC, TOP247Y exploaded. This happen everytime. I have another older board which has some "logic issues" and chip TOP247Y works correctly in this old board, so the chip TOP247Y is not broken.
I have transformer out of the board on about 30cm wires.
It means that error must be in a snubber network, there are two, one around a transformer and the second around a Drain-Source of TOP247Y chip. I do not have ESR meter or oscilloscope, I have only simple "Non-True RMS multimeter".
I have even tried to put a P6KE300A tvs diode to primary snubber network,
Diode BA159 was OK, but I have replaced that with UF4007.
Snubber capacitor C803 (10n) I have replaced with two 6.3nF 400v capacitors
Second snubber capacitor C1, about 70pF was "white SMD ceramic MLCC" I have replaced with "simple ceramic" which is probably for low voltage only.
When I'm measuring voltages even with 50V DC power supply, snubber voltages are high, about 200-500 V on multiple places.
I have some P6KE130A (tvs diode), should I use it?
How can I check it safety? I wanted to use a tyristor dimmer to slowly rise a voltage (I do not have a variac), but it is just cutting some pieces of waves and does not limit max voltage, so TOP247Y exploded too. So I'm thinking of using some "capacitive divider" to make a lower voltage.
So there is no overcurrent, just an overvoltage caused by a snubber network malfunction. Please what can I do with that? Everything looks like correct
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