Humax LU26-TDR1 PSU Standby chip blown

[nogger]

Hi all, i have a power supply from a Humax LU26-TDR1 TV in for repair at the moment. It uses a Dongyang PW607D power supply (pics attached). The standby chip (Viper 22a) has blown sky high & took with it a couple of small components, a zener diode and a cap both of which are surface mounted.

The marking on the smd diode (3 legged device) is Z27, can anyone confirm that the just means it's a 27 volt zener (which seems logical to me but you never know with these tricky smd devices;-) ). I can probably work out what the cap value is but if anyone has one of these boards in stock or has the drawing (long shot) then i'd be grateful for a copy.

Pics attached, apologies for the quality but light was drawing in, i have highlighted the diode in a red square.

Thanks
Graham

[budm]

Re: Humax LU26-TDR1 PSU Standby chip blown

That is the Zener clamping Diode connected between VDD pin 4 and circuit ground, so 27V Zener is OK, the Vdd OV threshold is 42V (TYP.). The AUX winding of the STBY transformer is rectified by diode DS2 and filter cap DS7 to supply the running Voltage.
VDD start up is 14.5V (TYP.)

[nogger]

Re: Humax LU26-TDR1 PSU Standby chip blown

Cheers BUDM, have you got the drawing for this PSU ?

Graham

[budm]

Re: Humax LU26-TDR1 PSU Standby chip blown

NO, I just trace out your board from the pictures, the spec sheet of the IC also give the info on how it is used and it is pretty close to what you have.