[TechAssist] Re: SONY kv-27xbrr15 fast shutdown
- From: becyn <becyn@xxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 29 Dec 2004 12:32:43 -0500
Thanks to all who replied;
I disconnected power to the audio and defl b+. I connected a load bulb
to the B+ and monitored.
For the brief second that the supply says on, it peaked around 142v. The
schem says 135V.
Could be caps and/or regulator, so I'm going to spec a "rebuild" for the
supply.
By the way, this is a SMPS power supply, so the 'ol variac trick' will
not work as a diagnostic.
Under a full load condition, a SMPS will just keep the drive transistor
on longer and perhaps eventually
damage it unless shutdown invokes.
*Jim McVey
McVey Alltronix
327 Broadway
Newburgh N.Y. 12550
*NOT* a NESDA member
Factory authorized
service for over 20
major brands.
845 561 8383*
Shoreline Electronics wrote:
>Check this also.....There is one plug on the power supply board that feeds
>B+ to the audio area. You will read a dead short on this line if this zener
>is shorted.
>
>---------------------------------------------------------------
>Text pasted from WinSTIPS 2.0
>http://www.ServiceSoftware.com
>---------------------------------------------------------------
>
>SONY KV27XBR25
>
>Shutdown On Power Up. Must Unplug To Reset
>
>Bryn Mawr Tv
>
>Shorted D1409 (Rd39es-B4) In Audio Section "A" Cba
>Caused By Bad Solder Connections On Ic651 "G" Cba (Power Supply)
>
>
>---------------------------------------------------------------
>
>
>==========================
>Jeff Stielau
>Shoreline Electronics Repair
>344 East Main Street
>Clinton,CT 06413
>860-399-1861
>860-664-3535 (fax)
>jstielau@xxxxxxxx
>========================
>
>----- Original Message -----
>From: "Leonard Caillouet" <lcaillo@xxxxxxxxxxxx>
>To: <techassist@xxxxxxxxxxxxx>
>Sent: Wednesday, December 29, 2004 8:18 AM
>Subject: [TechAssist] Re: SONY kv-27xbrr15 fast shutdown
>
>
>
>
>>Bad regulator? Got one in the shop right now that loses regulation almost
>>immediately, B+ starts OK, then goes up and set shuts down. Had a bunch
>>of
>>bad caps in the PS and the regulator IC was bad. Try running it at a
>>lower
>>line voltage and see if it stays up with the B+ at 135v.
>>
>>Also, audio amp problems will shut it down. Disconnect the supply to the
>>audio to test.
>>
>>Pin amp and the related op amp will cause shutdown.
>>
>>Bad solder joints all over the place in the deflection circuits and PS
>>will
>>shut it down.
>>
>>Leonard Caillouet
>>Electronics World
>>1261 NW 76 Blvd
>>Gainesville, FL 32606
>>352-332-5608
>>FAX 352-332-5668
>>
>>----- Original Message -----
>>From: "becyn" <becyn@xxxxxxxxxx>
>>To: <techassist@xxxxxxxxxxxxx>
>>Sent: Tuesday, December 28, 2004 7:54 PM
>>Subject: [TechAssist] SONY kv-27xbrr15 fast shutdown
>>
>>
>>Hello all,
>>
>>I checked the tips database, but nothing fits.
>>This puppy has hv , but shuts down abnormally fast- about1 second.
>>It seems to be too fast for a deflection scenario shutdown (I scoped v
>>deflection-seemed to be there). I thought perhaps
>>a marginal fbt drawing too much current from the SMPS? SMPS overcurrent
>>shutdown???
>>There is no flashing light, or delay if I attempt to power-up again as
>>would be the case
>>with a micro or x-ray shutdown (hv=25kv).
>>
>>Whadduyathink?
>>
>>Jim McVey
>>McVey Alltronix
>>327 Broadway
>>Newburgh N.Y. 12550
>>
>>*NOT* a NESDA member
>>Factory authorized
>>service for over 20
>>major brands.
>>845 561 8383
>>
>>
>>
>>
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>>
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