42PD5000 (or 32/37/42) PD5200 (e) MPF7409 PSU

[thevolatile1]

,,Well I'm struggling here. I've got 42PD5200 with a blown out smd transistor on IC201 - daughterboard of the MPF7409 Power board. I've removed the IC board & tried scanning it at 19200 dpi in order to read the tag on the transistor - no joy other than its a CQ  with some other digits that are so small you'd need a microscope to read it..
It's really annoying when everyone says 'check ic201 if changing fused resistors & mosfets' & nobody knows what to do if a fault is present.. so yes,, ic201 is at fault,, yes the smd transistor is blown,, so the question is.. 'WHAT VALUE is the SMD TRANSISTOR ?????'
'CQ' smd is listed as 2sc2411k n npn darlington by Rohn   OR  MSD710Q Motorola pnp  OR  2sc4097 - another npn transistor 32/40v @ 0.5a.. amongst others.. it seems the more you search on 'CQ smd' the more you get..
I've also had suggested that its 2sk3018 which is a 30v 0.1a n channel mosfet based switch.. so now i'm confused..
any experts out there that have a definitive answer,, please let me know.. or if you've got an IC201 or indeed a MPF7409 psu spare,, let me know 'cos im stuck !!
cross ref to my other comments about this tv set - http://www.tv.quuq.org/forum/index.php?topic=2425

[daz]

If all else fails try to find a transistor with the same markings some where else on the power supply, remove it, then check the resistance between the pins, this will tell you if its a npn pnp darl or a fet, but its more than likely a small signal transistor either npn or pnp so a bc817 or a bc860 will usually do the trick. I would check all transistors on this pcb in case more than one is short/leaky. If there are no other transistors with that markings I would replace the module, try Charles Hyde they are normally good for parts.
Im really annoyed as I know I’ve had this fault some time ago but didn’t write down fault details (not for the first time)
Hope this is of some help
Daz

[thevolatile1]

,,,fair comment !! think i may trace the whole circuit from the blown parts & start removing all the components,, must be a short somewhere to cause the blowing.. seems pointless to just replace the obvious parts for it to just blow them again..

[thevolatile1]

,,,and the transistor required is....... a bc848 !!!! job done !!

[thevolatile1]

ps... if youre struggling to find service details - heres a hint  http://www.scribd.com/thevolatile1

[aoi3610]

I have 4 Faulty MPF7409 PSU's if anyone wants them for a minimal fee, might help you fix this one.??

[chrisward2010]

Hi,

Looking for a bit of advice here. Had the R005/R003 go short and Q201 blew. As advised checked the IC201 daughterboard and everything seemed fine.

After replacing the faulty parts and Q220 with a KT54 kit from CHS it worked fine for about a week, but it's just gone again!

The repair kit was nearly £30 so I don't want to keep throwing money at it, but does anybody have any ideas?

Ideally I'd just replace the whole PSU but these seem to cost around the same price as new TV so it's got to be worth another try.

Any suggestions greatly appreciated.

[tigermit]

I have a faulty MPF7409 PSU and bought the repair kit. Now it keeps blowing the fuse. First it blew R003 then R005 went. Time for a replacement PSU I reckon. Does anyone know where to get hold of a second hand or refurbished one?