[TechAssist] Re: Sony KV27TW75 Blowing Q601 and Q602

  • From: "AURTRON" <Aurtron@xxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Sun, 24 Apr 2005 07:53:22 -0400

Small timing caps in base ckt of switching transistors frequently short/leak
after transistors fail. should be 4 of them.
Don
Aurora Electronics
Florida
Aurtron@xxxxxxxxxx
----- Original Message ----- 
From: "Peter oliver" <oliver_peter1@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Sunday, April 24, 2005 12:27 AM
Subject: [TechAssist] Sony KV27TW75 Blowing Q601 and Q602


> Sony
> KV27TW75
> Chassis LN-1  (very simmilar to the AA-1 in the KV27TS27....)
> MFD 1992
>
>
>              Set came in with blown HOT, SW mode transistors and fuse.
> Connections on HDT were ok but wax had melted out of it.  Replaced then
HDT
> with one from a AA-2 chassis (same #) Pulled flyback (1-439-498-12) it
rang
> 31 times one I had on the shelf (a leftover that didn't fix another set
rang
> 46 times) so I swaped it out with the one on the shel. used 2SD1880 (from
> B&D). Used 2SC4834 M instead of 2SC4664 B for Q601 and Q602. Set ran long
> enough to show a picture for a minitue then blew Q601 & Q602 and the fuse.
> Found a service bultien in the filing cabinet to change R647 to 1&#937;.
But
> is still blowing Q601 &Q602 about a miniute after the picture appears (the
> 2nd time used so left over pulls from a power supply C4106 to test)
Ideas..
> Caps etc...
>
> Peter Oliver
> Tucson Radio TV
>
>
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