Help! With troubleshooting SMPS for a Denon reciver. (Low output voltage)

[23komma4]

Hi,

I'm trying to fix a power supply for a denon reciver, AVRX2100W, but now I'm stuck.

At first, the AC/DC converter (MAG258MG) had blown, so I replace that along with some diode's, see attached picture.

When measuring the output voltage I get 1V, and it should be 5.2V.

Any ideas on what could be the cause on the voltage drop? Thanks!

 

[Bluejets]

Denon are REALLY complex pieces of equipment.

 

[Martaine2005]

@Ferdi57 said to check the zener diodes.
He built a zener diode controller to speed up smps repairs.
(Google translate).

Martin

 

[KilgoreCemetery]

I'm no expert when it comes to this sort of stuff (read noob), but from what I understand, the optocoupler is supposed to regulate the amount of voltage that the SMPS puts out. If it's reading wrong it could throttle the output. Something like a bad zener mentioned above could certainly cause it