- Thread starter Justin K
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Jan-DIY
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- Lower Saxony Germany
As you can see in diagrams fans and also solenoid is driving by mains voltage.
Hi Justin,
what did you mean when you said from "one side of the fuse to the other", was this the voltage measured across the fuse or at both ends of the fuse with respect to the 0V (or other) power rail ?
D
there is a simple way to add pre and pos flow on the external gas valve box.
Jan-DIY
Member
- Messages
- 822
- Location
- Lower Saxony Germany
Please share your information here.
I fried my 30 year old DMM because I stupidly forgot to disconnect the HF start
. No second chances.I have what looks to be the same welder . My ptc has the same NTC47D-15 Only they have only installed two and jumpered where the middle one is . Is it better to install three as I need to replace one that's damaged anyway.
G'day and welcome to the Forum !
If the track location for one of these 47-Ohm thermistors has been jumpered, it means they must be in series. Seems the designers have decided that the soft-start circuit only needs an initial resistance of 94 Ohms now, instead of 141 Ohms.
However, damage to the soft-start circuit usually means that excessive current is flowing downstream of the capacitor bank, most likely due to short-circuit semiconductors in the inverter power switches.
If the track location for one of these 47-Ohm thermistors has been jumpered, it means they must be in series. Seems the designers have decided that the soft-start circuit only needs an initial resistance of 94 Ohms now, instead of 141 Ohms.
However, damage to the soft-start circuit usually means that excessive current is flowing downstream of the capacitor bank, most likely due to short-circuit semiconductors in the inverter power switches.
Thanks I don't know if it is related but It was taking some time to turn on . I am hoping this is the issue .One of them was cracked and upon removal and fell apart. I have ordered three . I guess my main question is it better to have three of them Or does the change in resistance effect the circuit .
The turn-on time should be fixed, depending only on the timing circuit for the operating coil of the relay whose contacts short-circuit the soft-start thermistors.
The higher resistance of three thermistors in the series chain, i.e. 141 Ohms vs. 94 Ohms, means a lower initial current surge into the empty capacitors, which should be a good idea. Hopefully by the time the relay closes, the capacitors will be pretty full, and they will be by the time you are ready to strike an arc.
The designers must now think that having only two thermistors, drawing a higher current spike from the supply, does not cause a problem.
If the one that cracked was not damaged by a short-circuit in the power transistors but just by normal initial turn-on surges, then fitting three thermistors would hopefully avoid another early failure.
The higher resistance of three thermistors in the series chain, i.e. 141 Ohms vs. 94 Ohms, means a lower initial current surge into the empty capacitors, which should be a good idea. Hopefully by the time the relay closes, the capacitors will be pretty full, and they will be by the time you are ready to strike an arc.
The designers must now think that having only two thermistors, drawing a higher current spike from the supply, does not cause a problem.
If the one that cracked was not damaged by a short-circuit in the power transistors but just by normal initial turn-on surges, then fitting three thermistors would hopefully avoid another early failure.
