Re: Inverter Welder Strangeness
I'm thinking that the problem is with the PWM controller or circuitry, as having another look, but with a fresh head, reveals that the two outputs of the SG3525 are unequal when measured across to pcb main ground.
VCC to ground pins, reads only +0.02 volts, when according to the datasheet it should be between +8 and +40 vdc.
Granted the tester is not a Fluke but it generally gives a good idea
Anyway, taking an AC voltage measurement on the SG3525, it fluctuates around 2.5 v on both outputs, and the frequencies are around 40KHz on output A, and 35KHz on output B.
In 'Frequency/Duty Cycle' test mode however, the readings are fluctuating at just over 170KHz on 'A' and just over 160KHz on output B.
Both outputs float around 61% duty cycle in relation to ground and adjusting the control knob makes no difference at all.
When measuring between both pwm controller outputs, the duty cycle reads a stable 50% with the frequency also stable at 45KHz regardless of knob position.
My lack of experience aside, surely in order for this to work, the switching must be in unison?
So if anyone has any other ideas as to where and what to test, I am all ears.
I'm thinking that the problem is with the PWM controller or circuitry, as having another look, but with a fresh head, reveals that the two outputs of the SG3525 are unequal when measured across to pcb main ground.
VCC to ground pins, reads only +0.02 volts, when according to the datasheet it should be between +8 and +40 vdc.
Granted the tester is not a Fluke but it generally gives a good idea
Anyway, taking an AC voltage measurement on the SG3525, it fluctuates around 2.5 v on both outputs, and the frequencies are around 40KHz on output A, and 35KHz on output B.
In 'Frequency/Duty Cycle' test mode however, the readings are fluctuating at just over 170KHz on 'A' and just over 160KHz on output B.
Both outputs float around 61% duty cycle in relation to ground and adjusting the control knob makes no difference at all.
When measuring between both pwm controller outputs, the duty cycle reads a stable 50% with the frequency also stable at 45KHz regardless of knob position.
My lack of experience aside, surely in order for this to work, the switching must be in unison?
So if anyone has any other ideas as to where and what to test, I am all ears.
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