SMPS low Vout

[madan1]

Re: SMPS low Vout

Ok, so 14V@0.6A through the daylights module connected straight to the transformer ( still on the board ). See the attached image for the input waveform.

So, first of all - lot's of hi-pitch noise coming from the board ( I guess the transformer? ).
Second - the following voltages on the secondary sides:
c709 - 0.85v
c708 - 1.76v
c707 - 4.27v
c620 - 6.3v
c663 - 6.9v

[R_J]

Re: SMPS low Vout

Was the top247 out of circuit? or the transformer primary isolated from the top247? You should have had D661 removed also. Its hard to isolate the switcher with the pfc circuit connected. but it does look like something was getting through the transformer, What about the voltage on C663? if this winding has 0 volts it might be the problem

[madan1]

Re: SMPS low Vout

Everything was on the board ( just soldered wires on the primary winding and connected them to the power supply ).
I added above and the readings for c663 ( ~7V ).
On the secondary side there are about 4v on the optocoupler.

[R_J]

Re: SMPS low Vout

So when the primary is being switched there are voltages on the secondaries, which seems to point to a bad top247?
All the secondary voltages are roughly 1/3

[madan1]

Re: SMPS low Vout

Bought another top247 and this time it worked.
The odd thing is that the faulty IC reacts normally to all resistance tests...
Thank you for the assistance, I really appreciate it!