[TechAssist] Re: Sony TV KV27V15, power supply problem
- From: "Gemini Computer & TV" <geminitv@xxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 20 Oct 2003 19:01:39 -0400
I think you are good to go. What happens if you try to fire it up at normal
line voltage?
Bob Waterman, CET® #RI-28
Master Technician License #9109
Service Manager / Parts Manager
Gemini Computer, TV, & Security Alarms
(508)695-7302
(508)695-7769 FAX
geminitv@xxxxxxxxxxxxxxxx
geminitv@xxxxxxx
www.geminicomputertvsecurityalarms.com
----- Original Message -----
From: "Gary McCartney" <gary@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Monday, October 20, 2003 4:36 PM
Subject: [TechAssist] Sony TV KV27V15, power supply problem
> I have this Sony KV27V15 which came in with the HOT and power supply
> transistors shorted. I replaced the HOT, resoldered the driver Xformer,
> changed the 0.47uF, changed the 2 2SC4834's in the PS, plus the 3 VDR's,
> the 4 -0.22 caps, R607 (0.1 ohm) and changed R644 from 6.8 ohm to 4.7
> Ohm as per instructions. Checked all other parts in PS primary and sec.
> for shorts, nothing else found.
>
> Fired set up at 30 AC and did measurements with ground lead of meter and
> scope on the junction of the 2 main filter caps. C607 (-) and C608 (+)
>
>
> DC measurements:
>
> Q601:
>
> E= -1.5V
> B= -1.7V
> C= +49.6V
>
> Q602:
>
> E= -49.7V
> B= -49.7V
> C= -1.5V
>
> I get a square wave of 100V p-p on base of Q601 but no waveform is on
> base of Q602. I am expecting I should have 100V p-p only of out phase
> compared to the Q601 base waveform. I checked Q602 with ohmmeter and it
> checks ok. I checked winding of T603 pins 1 to 2 and pins 5 to 6 both
> measure 0.6 ohms in circuit. I made a few other resistance comparisons
> between the Q601 circuit and Q602 circuit and didn't find anything out
> of line.
>
>
> Just want to verify that I am doing this testing correctly before I
> continue later tonight on this set. I will do more indepth invaluation
> of the components in the base circuit of Q602. I'm supposed to have this
> set ready for the customer tomorrow.
> --
>
> Thanks for any help.
>
>
> Gary McCartney
>
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
>
>
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