You are here

NAD 7020 rev2, FM mute dead, D905 shorted

My NAD 7020 SN:A7224061 with updated PCB = NOT schematic as in most Internet .pdf files, only:
rev2 NAD 7020 service manual, starting at serial number 7218469: NAD 7020 SM
http://lydian.ca/wp-content/uploads/2016/03/NAD-7020-SM-1.pdf

has no FM Mute output, no stereo light, no centre green tuning light.  The FM, AM, AUX, Phono still work OK but the unit now gets warm near the power transistors & smells to the right of them.  When opened up found -33V on the top of C537, still -27V after turned unit off for 5 hours!  Definite burning/chemical smell & heat forward of the 4 power capacitors 2200µf each.
Looking under the main PCB found burn marks around D905, measured R = shorted!!  D905 does not show up in parts list, & was hard to find on schematic = grounds a centre tap directly on the transformer. 
My question is: what other parts are likely destroyed as well?  Or the whole FM MPX circuitry?

Any help would save me a lot of time & grief.
Kurt
 

Comments
zsugori
zsugori's picture

1

0

Vote up!

You voted ‘up’

Kurt

to: zsugori
Your pic is of the 1st NAD 7020 circuit.  Mine is the revision, 
starting at SN7218469. 
I uploaded the service manual SM:

Filename:NAD_7020_SM_1.pdf
Size:4574232 byte (4.36 MB)
File information:NAD 7020 revision 1, stereo receiver, starting at SN7218469
Status:OK

0

Vote up!

You voted ‘up’

zsugori
zsugori's picture

0

Vote up!

You voted ‘up’