nt-2701 chirping

[ZMB]

I have two chasis boards that have come out of goldentees. both are nt-2701s and make a chirping sound and thats about it. One of them blew the 10uf np c550? any help will be awesome.

[Kevin Mullins]

Not NT2701 specific..... but I would start with checking the voltage regulation. (B+)

[qrz]

any time a smps is chirping , always check for shorts or heavy loads on the secondary.
have a look at the h out xistor . likely shorted.
 that cap is in pin correction, so check the pin out xistor as well.
i will need to pull a print to provide specifics...

qrz

[ZMB]

The B+ is pulsing with the sound of the chirp. My meter is not fast enough to give a decent reading but from what my fluke gave I was seeing anything fro 0.007 to 2 vdc. I wil pull the H xsistor and see if things settle down.

[ZMB]

ok...just got one of them up....the H out tranny was shorted Q402...one more board to go.

[ZMB]

on the other 2701 I pulled the h xsistor out and powered it up and I now have a B+ at 105 vdc....flyback perhaps?

[ZMB]

ok...I replaced the H out (bu2532al) with a 2sc5589...I now get a solid vertical line...no horz deflection....any clues as to where to look next?

[qrz]

just to verify your terminology :

loss of vertical deflection results in a HORIZONTAL ( r/l) line across the center of screen.                 -------------

                                                                                                                                                                    i
loss of horizontal deflection results in a VERTCAL (top/bottom) line in the center of screen.                      i
                                                                                                                                                                    i
                                                                       

if it is the 1st item, check the vert output circuitry.
2nd item, look for a cold solder joint/burn mark on foil side of pcb near yoke connector

qrz