hi..I just want to ask questions on this 3000 watts inverter of mine.
Its a Chinese made inverter..with 8 SMPT transformers, 16 FETS , with 4 TO-247 package FETS for
Final AC conversion.
This Inverter is controlled by 2 "TL494" PWM chips with LM 324 circuits.

The problem is its cycling over and over, but there is a PWM waveform on oscilloscope turn off and on .
The capacitor is charging up to 250 volts, but it keeps on cycling everytime you turn it on.
The beeper is also oscillating.
Can you please give some advice on what are the possible causes of this..on what particular section in which
I will need to focus my troubleshooting.

Thanks!

REM

 

What is the input power source and what is its voltage and current doing while the inverter is cycling?

 

Its probably sensing over voltage or over current on the output transformer, pin 4 on the TL494 is the shutdown pin, the Lm324 will probably be used as a current sense or shorted output, just like an atx psu, the 4 fets will be in an h-bridge pushpull mode for the pulse transformer.

Best option is to take pictures of the pcb both sides or get the datasheet for that model of psu.

Have a look here for circuit designs.

http://danyk.cz/s_atx_en.html

 

hi..I just want to ask questions on this 3000 watts inverter of mine.
Its a Chinese made inverter..with 8 SMPT transformers, 16 FETS , with 4 TO-247 package FETS for
Final AC conversion.
This Inverter is controlled by 2 "TL494" PWM chips with LM 324 circuits.

The problem is its cycling over and over, but there is a PWM waveform on oscilloscope turn off and on .
The capacitor is charging up to 250 volts, but it keeps on cycling everytime you turn it on.
The beeper is also oscillating.
Can you please give some advice on what are the possible causes of this..on what particular section in which
I will need to focus my troubleshooting.

Thanks!

REM

hi..I just want to ask questions on this 3000 watts inverter of mine.
Its a Chinese made inverter..with 8 SMPT transformers, 16 FETS , with 4 TO-247 package FETS for
Final AC conversion.
This Inverter is controlled by 2 "TL494" PWM chips with LM 324 circuits.

The problem is its cycling over and over, but there is a PWM waveform on oscilloscope turn off and on .
The capacitor is charging up to 250 volts, but it keeps on cycling everytime you turn it on.
The beeper is also oscillating.
Can you please give some advice on what are the possible causes of this..on what particular section in which
I will need to focus my troubleshooting.

Thanks!

REM

 

The input voltage I used a variable DC regulated supply with current limited to 4Amps, and the voltage I turn it to 13volts DC.
while cycling the DC voltage 13 volts goes down to 11 volts then back to original setting.

I tried to swap the boost TL494 with the H bridge TL494 swticher on the final stage,but still same problem occurs.

I almost check the corresponding parts arround each IC's, i even desolder the 3 IC's and replaced the IC sockets to further
inspect whats underneath, maybe some cut pcb trace, but there is no cut off pcb trace.

 

The

What is the input power source and what is its voltage and current doing while the inverter is cycling?

The voltage goes down from 13 volts original to around 11 volts DC, and also the current. The current started with 2.4 Amps, then goes down to around 0.6 Amp, then the cycle repeats, like an oscillator., When I measured the output AC, its millivolts, and when I put the dmm probe to any of the terminal it measured only 1.5Volt AC.

 

The input voltage I used a variable DC regulated supply with current limited to 4Amps, and the voltage I turn it to 13volts DC.
while cycling the DC voltage 13 volts goes down to 11 volts then back to original setting.

That's likely your problem right there. You have way too small of power supply for the unit to properly power itself up with so it keeps cycling into low voltage shutdown mode then recovering once the power supply voltage goes back up again.
Hook it up to a decent vehicle battery and see if it keeps having the issue. I suspect it won't.

 

That's likely your problem right there. You have way too small of power supply for the unit to properly power itself up with so it keeps cycling into low voltage shutdown mode then recovering once the power supply voltage goes back up again.
Hook it up to a decent vehicle battery and see if it keeps having the issue. I suspect it won't.

Thanks for your advice, I'll find a decent Car battery or Deep cycle.