UMCE22/13B - suspect PS problem.

[Turnip]

Hi Folks,

Have one in where set is dead and PS (PC40005) has outputs of 5v and 12v but when plugged into main board, supplies drop to near zero. Checked main for shorts on the 5 and 12 but found none.

Notice there seems to be a control chip on PS secondary with some sort of S/by function, but without a shematic - as ever, a bit stuck.

Wonder if anyone has had problems with this PS ?   Thanks - Chris.

Admit - The Main board is a bit like those B'crap - whatsit cheapy ones with the Eeprom troubles, but it's MKT5330C1 - DVD 1.07 so natch again suspect Eeprom trouble as UMC tellies are usually total rubbish.

[Davy]

Just curious, isn't there a couple of voltages missing, 3.3V, 5V and should there be a 24V as well?

Have you checked the voltage on the main smoothing cap. on the primary side in case it's 'sagging' under load and downing the secondary voltage? Might be worth checking the reccy diodes on secondary side too.

Dave

[downunder]

Hi Chris,

Have you tried to run the PSU on it's own on the bench. Use the "danger leads" to connect it to mains, and link PS-ON pin to ST-BY 5V pin via a 100 ohm resistor to hoodwink it into thinking "hey, I'm being told to pull the finger out and switch on". Any secondary voltages should then tell a story.

But you're probably right, even the brand name has connotations of cheap s#!t................Bruce

[Turnip]

Hi Folks and thanks,

Think a few piccies. Was puzzled as both 5v and 12v are present when out of the set, but haven't yet used a  load to see If I can get a couple of Amps out of the 12v which might prove something or other.

Thanks again - Chris.

[downunder]

Hi Chris,

They say a picture paints a thousand words but atm I can't think of one. Said power supply looks remarkably like one out of a brand marketed over here as Bauhn, which are Aldi specials.

Spell check on as per normal.           Bruce.

[Turnip]

Ho Bruce,

Had a check with an 12v 18w car lamp, and found the 12v dropped to 10v. Tried it on the 'Always 5v' and the board went into sulk mode, and on switching on again, the 12v was there but the 5v wasn't, even though the single 5v diode was OK, and using just one transformer - Curious.

Thought 'dries' so soldered most everything, and still no 5v.

Tried later and the 12 and 5 were up again.

As Dave suggested, checked the main cap - OK, but think found an answer on Fleabay with a replacement board.

Downside is that the chap I mostly mend for, bought set a couple of months ago on the Flea, and repair will cut his sales margin somewhat - Thanks - Chris.

Later - Had a better look at the old power board where the chopper driver chip FAN7602 had been re-soldered on just one side for some reason.

Other side had no obvious dries on it's 4 pins, so think another chip for the next set that comes by, as guess chip was a bit duff from the start.