Hello
Fluctuating voltage come on Battery terminals 6v to 7 v dc. It should 12v dc.
I have replaced the transformer, lt1725 ic , all diodes, electrolyte capacitor and triac but problem is still. Transformer secondary voltage fluctuating 10 to 12 volt ac.
I have checked in working board, remove the secondary wires when I found transformer output voltage is 90 v ac.
Pls find the attachment.

 

I am not sure why you are getting 90 VAC on pins 5 & 6? It should be 0V. Transformers require AC input and I expect them to do nothing if DC is supplied instead.

 

DC transformer? Mono pole windings?

 

The chip bottom right corner, LT1725cs is a Switchmode psu chip, and is probably pulsing the Transformer.

Can we have the Full Picture of what this pcb is used for?

 

Without more details,I would hazard a guess that whatever is driving the transformer is "stuffed". It looks like some sort of switched mode charger, is that correct. Make sure that whatever drives the transformer is working correctly. Also check output circuit has no problems causing low output etc.

 

The chip bottom right corner, LT1725cs is a Switchmode psu chip, and is probably pulsing the Transformer.

Can we have the Full Picture of what this pcb is used for?

This is ECG machine (medical equipment) pcb

 

This is ECG machine (medical equipment) pcb

If that's the sort of reply you're going to provide, then you won't get much help on here.....

 

Yes

 

Ok i will upload the full picture of PCB.

If that's the sort of reply you're going to provide, then you won't get much help on here.....

 

If this is a SMPS supply so you cannot disconnect the secondary windings and read the voltages. These voltages are not going to be what a working circuit is going to have. The secondary AC output is going to converted to a DC voltage and a portion of it is fed to a voltage comparator circuit to monitor regulation. If the voltage is too high or too low then an offset/correction voltage is fed back to the primary side to modify the duty cycle to bring it back to proper regulation. This feed back are generally sent back from the secondary to the primary circuits via an opto-isolator chip. I cannot see enough of the circuit to determine if this is an SMPS (switched mode power supply).