[TechAssist] Re: Panasonic TV CT-3269SCW Chas. AMEDP311 repeatedly blows regulator [FIXED]
- From: Gary McCartney <gary@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 31 Dec 2003 13:37:08 -0500
THanks to Dominic and others, I have this set fixed and out the door.
Appreciated, everyone.
R808 and R809 , 1 Ohm fusibles, were the cause of the B+ not getting
through to the flyback. To verify that the power supply was regulating
at 130V, I removed the HOT and inserted a 40W 120V light bulb from
collector to ground and set the variac at 75V ac. Pressed the power
button and the light lit up nicely and my voltage reading was bang-on at
130.7 Vdc. I raised the variac up to 125V ac and B+ stayed at 130V, so
this was a relief. I installed the HOT and fired set up and checked B+
and collector waveform. Everything checked ok so I test ran and closed
set up and shipped it.
Everyone, have a Happy New Year!!!!!!
Gary McCartney
McCartney Electronics
Guelph Ontario Canada
Est. 1984
email: gary (at) number63.ca
Gary,
Info from a similar chassis ABP331.
The 2SD2539 is a non damper transistor, the 2SD1880 has a built in
damper.
Your regulated B+ should be 130VDC. This B+ passes thru a fusistor pair
R808
and 809, 1 Ohm 1/2 watt. These pass B+ to/thru L803 and to pin 9 of the
FBT
out pin 10 to the horiz out transistor. Horizontal driver Q501 is fed by
a
resistor pair R510, 511 3.6k 3wt.
Let me know if this helps with your chassis layout.
Dominic DiLeo
Atlantic TV
Freeport, Maine
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In a message dated 12/30/03 11:13:08 AM Eastern Standard Time,
gary@xxxxxxxxxxx writes:
> I have received the new regulator IC and HOT from Panasonic. I replaced
> a number of capacitors, D825 and it's filter cap, and I checked the
> flyback out of circuit with my HR Diemen flyback tester and it shows a
> good collector waveform and 30kv readout. I installed the new reg. but
> decided to use a 2SD1880 to test the set with until I know it is ok to
> install the (expensive) OEM HOT 2SD2539. I fired it up on 95V ac on the
> variac. The set does not start up. I get 148V dc on cathode of D825 and
> I get 31V dc on the B+ pin on the flyback.
>
> I don't have a schematic to trace the reason for the B+ voltage drop
> between the source and the flyback. I am only assuming that the cathode
> of D825 is the (130V?) B+ source for the flyback. Tried tracing it on
> the circuit board but got lost.
>
>
> Any help appreciated, especially a partial schematic for this this
> chassis or similar chassis which includes
> an STR58041A regulator.
>
>
>
>
> Gary McCartney
>
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
>
>
>
>
>
>
> My original message:
>
>
> I have worked on this Panasonic 32" TV model CT-3269SCW Chassis AMEDP311
> about 4 times in the last year or so. One time the HOT and regulator
> (STR58041A) were blown and I replaced with OEM Panasonic parts along
> with a few supporting parts in the regulator circuit which I don't
> remember at the moment. Another time the flyback was shorted. About a
> month ago, the regulator was shorted so again I replaced with OEM part
> and today the customer called and said he is bringing the set back in
> first thing Monday morning, hoping to have it repaired for Christmas. He
> heard a POP and the set went dead.
>
> It seems there must be something I am missing when I'm replacing HOT's
> and regulators on this set. Is there a service bulletin or a known list
> of components which need attention while serving? I have soldered the
> hor. driver transformer. I don't work on many Panasonics but the ones I
> do usually are dogs.
>
> I am wanting to be able to order parts by noon on Monday so I can
> hopfully get this set shipped before I close down for the holidays.
>
> Merry Christmas to everyone and thanks for any help.
> --
>
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