[TechAssist] Re: Sony RA-2A KP-46C65 instantly blows IC601 & R608
- From: "Leonard Caillouet" <lcaillo@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 20 Jul 2005 16:55:36 -0400
Larry,
Start it up very slowly and as soon as it starts switching measure the
frequency. If it is below 50kHz you may have a bad switching transformer.
I have had several of these after lightning. They are a PITA because there
is no way to test it other than to start it up.
You may be able to see some heat stress on the windings which are very tiny.
Leonard Caillouet
Electronics World
1261 NW 76 Blvd
Gainesville, FL 32606
352-332-5608
352-332-5668 fax
----- Original Message -----
From: "Larry E" <videotech@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, July 20, 2005 4:16 PM
Subject: [TechAssist] Re: Sony RA-2A KP-46C65 instantly blows IC601 & R608
Damon, thanks for the reply, got in the IC and resistor today, whatever is
shorting IC601 and opening R608 is worse off than before, installed new IC
& resistor and set did not start by itself, front led was on (not blinking)
12v standby was
there, started set with 117 on variac and R608 made a loud snap and fried it
& IC608.
Before I plugged in the set I pulled and checked on the cap tester
C602,603,604,605,606,607, 608,612,615,616,617,618,& 621, checked for shorts
on Q654, 656, & 659.
Checked for shorts on T604 & 605, HOT is not shorted, main fuse does not
blow so it
doesn`t appear to be outside the power supply, checked from hot to cold
ground for short
none found, I can`t troubleshoot the dam thing because only the 12v supply
runs in standby and it blows up
with more than 97 volts applied through the variac, I would think as quickly
as it blows
that it would have an obvious short, but I sure can`t find it, any ideas
appreciated., Larry E
Larry Eastman
American TV & Electronics
Crystal River, Fl. 34428
----- Original Message -----
From: "Damon" <DamonEB@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, July 15, 2005 11:22 PM
Subject: [TechAssist] Re: Sony RA-2A KP-46C65 instantly blows IC601 & R608
> 124 V Ac ain't gonna whack the MX0841, most power systems will have 105 to
> 140 out in the country, and these tv's are built to handle that variation.
> Since it fired up ok with the isolation transformer, and SINCE you brought
> it up slowly, then I'd take a closer look at what parts are affected with
a
> large surge of INSTANT 124V rather than 0 20 40 60 80 100 120 124V.
> My first guess is the MAIN CAP, next is the inductive kickback circuit
> (diodes or caps-since you don't have VDRs) --there are several on the C-E
> junctions.....are those the BLUE caps??
> How about a blown soft-start circuit......got one of those on the RA-2???
> That chassis number seems a little low for that, but the MX0841 were
around
> the same time the soft start was introduced.
>
> How about the MX0841 itself, is it from Sony or another supplier? (I kinda
> doubt that, compared to the open main cap or bad kickback circuit.
>
> Gonna look at schematics, IF I find anything, I'll let you know.
> Found a lot of things......
> Q659, Q656, and Q654 are your soft start transistors, uses 18V and 11V
> supplies from SMPS, uses a winding in regulator transformer T604 to gently
> bring up your SMPSvoltages.
> C 608/C607 are your half-wave voltage doubler caps, should have about 340V
> dc across both caps.
> C612 is a damper cap, many more in there-suggest checking all HV caps.
> C616/617 are duty-cycle caps
> BTW did you check the duty cycle? Don't want one of those transistors in
the
> MX0841 doing more work than the other.
>
> Damon B
> Telrad Electronics
> Fort Wayne IN
> ----- Original Message -----
> From: "Larry E" <videotech@xxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Friday, July 15, 2005 4:24 PM
> Subject: [TechAssist] Re: Sony RA-2A KP-46C65 instantly blows IC601 & R608
>
>
> > Phil, no vdr`s in this chassis, I`m looking at the isolation issue only
> > because I find no
> > parts in the primary circuit that are bad, (or the secondary for that
> > matter) yet it runs
> > if I power it from the variac? I`ve ordered new IC`s and resistors, I`ll
> try
> > operating
> > it from the variac when I get the parts in and if it runs off the variac
> > I`ll try
> > running it directly from the shop wall outlet, if it runs from my AC
> outlet
> > then
> > Bob Waterman may be right there may be an issue with the customers AC as
> he
> > said he had a violent strike of lightning 2 days before the set went
out,
> > you know
> > the drill down here, sprinkler system, garage door openers, etc. etc.
His
> > outlet
> > read 124 volts though when I was there, we`ll see when the parts come
in,
> > Thanks for the reply, Larry E
> >
> >
> > Larry Eastman
> > American TV & Electronics
> > Crystal River, Fl. 34428
> > ----- Original Message -----
> > From: "Phil Bader" <tjanphyl@xxxxxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Friday, July 15, 2005 5:01 PM
> > Subject: [TechAssist] Re: Sony RA-2A KP-46C65 instantly blows IC601 &
R608
> >
> >
> > > You are assuming this is an isolation breakdown issue. Maybe not. Does
> > > this chassis use VDRs around the MXO841? These VDRs do go bad.
> > > Just a thought. I'll polk around when I'm not fixing table radios.
> > > Phil
> > > Phil
> > >
> > > Philip Bader
> > > Jan Phyl TV Inc. (estab. 1976)
> > > 3420 Recker Hwy. Winter Haven, Fl. 33880
> > > Fax (863) 299-8821
> > > email: tjanphyl@xxxxxxxxxxxxxxx
> > > personal/ alt. email: pbader@xxxxxxxxxxxxxxx
> > > see our ad at:
> > >
> >
>
http://jan-phyl-television-pc-monitor-service.9601288257006.worldpages-ads.c
> > om/
> > >
> > >
> > >
> > > Larry E wrote:
> > >
> > > >Hi Guys, My week for headache sets, this Sony RA-2A covers the
> following
> > models
> > > >KP41T65, 46C65, 48S65, 53S65, & 61S65, went to customers house and
all
> > pins
> > > >of IC601 (MX0841AB-F) were shorted to each other, also R608 the .1
> 1/2w
> > > >fusible resistor was open, pulled all of the little blue caps around
> > IC601 and checked
> > > >them on the sencore, all ok. I ordered a new IC & resistor, installed
> > them and when
> > > >I powered up the set they instantly blew, pulled set to shop,
> > re-installed new chip
> > > >& resistor, plugged into variac & brought up slowly, set started and
> > worked fine, heres
> > > >the fun part, I brought the set back to the customer hooked it up and
> all
> > I get is a
> > > >constant blink of the led, of course IC601 & R608 were blown again,
> > Obviously my
> > > >Sencore variac being an isolation transformer let the set run but
> > connectiong to the
> > > >customers AC outlet lets the parts short, I have pulled every cap in
> the
> > "hot" side
> > > >of this power supply and found no shorted caps, checked the 2.2 meg
> > resistor
> > > >R601, there is no continuity between hot & cold ground, customer told
> me
> > second
> > > >time out that they had lightning problems 2 days before set went down
> but
> > I see
> > > >no arcs etc on board, main fuse was not blown, HOT circuit good,
seems
> to
> > me it
> > > >has to be hot & cold ground connected somewhere???
> > > >please help if you can, I`m pulling hair out at this point, Larry E
> > > >Larry Eastman
> > > >American TV & Electronics
> > > >Crystal River, Fl. 34428
> > >
> >
>
>---------------------------------------------------------------------------
> > --
> > > >This Email List is Public. Remove:
> http://www.tech-assist.org/remove.htm
> > > >Set Vacation
> > mailto:ecartis@xxxxxxxxxxxxx?subject=set%20techassist%20vacation
> > > >Lost Password: http://www.tech-assist.org and select "Login
> Problems?".
> > > >Email Archives: //www.freelists.org/archives/techassist/
> > > >
> > > >
> > > >
> > > >
> >
>
> --------------------------------------------------------------------------
> > ---
> > > This Email List is Public. Remove:
http://www.tech-assist.org/remove.htm
> > > Set Vacation
> > mailto:ecartis@xxxxxxxxxxxxx?subject=set%20techassist%20vacation
> > > Lost Password: http://www.tech-assist.org and select "Login
Problems?".
> > > Email Archives: //www.freelists.org/archives/techassist/
> > >
> > >
> >
> >
>
> --------------------------------------------------------------------------
> ---
> > This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
> > Set Vacation
> mailto:ecartis@xxxxxxxxxxxxx?subject=set%20techassist%20vacation
> > Lost Password: http://www.tech-assist.org and select "Login Problems?".
> > Email Archives: //www.freelists.org/archives/techassist/
> >
>
>
> --------------------------------------------------------------------------
---
> This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
> Set Vacation
mailto:ecartis@xxxxxxxxxxxxx?subject=set%20techassist%20vacation
> Lost Password: http://www.tech-assist.org and select "Login Problems?".
> Email Archives: //www.freelists.org/archives/techassist/
>
>
-----------------------------------------------------------------------------
This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
Set Vacation
mailto:ecartis@xxxxxxxxxxxxx?subject=set%20techassist%20vacation
Lost Password: http://www.tech-assist.org and select "Login Problems?".
Email Archives: //www.freelists.org/archives/techassist/
--
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.323 / Virus Database: 267.9.0/50 - Release Date: 7/16/2005
-----------------------------------------------------------------------------
This Email List is Public. Remove: http://www.tech-assist.org/remove.htm
Set Vacation mailto:ecartis@xxxxxxxxxxxxx?subject=set%20techassist%20vacation
Lost Password: http://www.tech-assist.org and select "Login Problems?".
Email Archives: //www.freelists.org/archives/techassist/
Other related posts:
