[TechAssist] Re: Sharp 27" TV - CN27S18 - Turn ON then OFF - Followup
- From: "David Lessard" <mr_fixit@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Tue, 22 Jun 2004 15:49:32 +0100
SECOND FOLLOWUP:
OK, upon reviewing the STRF6626 specs closer I found that initially the
startup supply voltage is derived via R715 (off the AC) and C709, after
a successful oscillator start, the supply voltage is derived via R710,
D706 and R709. What would cause this regulator not to start; again I am
not familiar with this type of switching regulator circuit at all and
would appreciate any help.
Thanks again,
David Lessard
mr_fixit@xxxxxxxxxxxx
Alexandria, Ontario
-----Original Message-----
From: David Lessard [mailto:mr_fixit@xxxxxxxxxxxx]
Sent: Tuesday, June 22, 2004 2:17 PM
To: 'Gemini Computer & TV'
Subject: RE: [TechAssist] Re: Sharp 27" TV - CN27S18 - Turn ON then OFF
- Followup
FOLLOW-UP:
Replaced shorted zener D713 with 33 volt zener, should be a 32 volt
device however STRF6626 specs specify a maximum supply voltage of 35
volts, should be OK here. Also, replaced STRF6626 as it checked bad too.
NOW I still don't have a 18.5V supply at pin4 of STRF6626, therefore
STRF6626 is not working. Question: Where does this supply voltage
originate? I have a schematic and can't seem to find out where this
voltage originates from. I'd appreciate any help as I am not familiar
with chassis at all.
Thank-you in advance,
David Lessard
mr_fixit@xxxxxxxxxxxx
Alexandria, Ontario
-----Original Message-----
From: Gemini Computer & TV [mailto:geminitv@xxxxxxxxxxx]
Sent: Monday, June 21, 2004 1:35 PM
To: mr_fixit@xxxxxxxxxxxx
Subject: Re: [TechAssist] Re: Sharp 27" TV - CN27S18 - Turn ON then OFF
David,
I do not have this exact manual (Canadian model I believe) but I do have
the
27NS100 which has that same power supply configuration. D713 is indeed a
high failure item and is a 32 volt zener diode, Sharp part#
RH-EX0673GEZZ.
D713 should be loacted between pins 4 and 5 of IC701 (pin 5 is ground
and
you should have 1bout 18.5 volts on pin 4 of IC701). I will privately
email
you a PDF portion of that power supply area. I would also replace IC701
when
you replace this diode. Here is the PDF:
Bob Waterman, CETR #RI-28
Master Technician License #9109
Service Manager / Parts Manager
Gemini Computer, TV, & Security Alarms
(508)695-7302
(508)695-7769 FAX
geminitv@xxxxxxxxxxx
geminitv@xxxxxxx
www.geminicomputertvsecurityalarms.com
----- Original Message -----
From: "David Lessard" <mr_fixit@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Sunday, June 20, 2004 9:19 AM
Subject: [TechAssist] Re: Sharp 27" TV - CN27S18 - Turn ON then OFF
> I need the value of D713 near STRF6626 regulator. I believe it's 30V
but
> I'm not sure. This zener is shorted. Could it be the cause of the
> problem described below? Does anyone have a print for this model?
>
> Thanks,
>
> David Lessard
> mr_fixit@xxxxxxxxxxxx
>
> -----Original Message-----
> From: techassist-bounce@xxxxxxxxxxxxx
> [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of David Lessard
> Sent: Friday, June 18, 2004 2:09 PM
> To: techassist@xxxxxxxxxxxxx
> Subject: [TechAssist] Re: Sharp 27" TV - CN27S18 - Turn ON then OFF
>
> I should elaborate on this problem. There seems to be no +B from the
> switching regulator. I do hear the relay activate and I can trace AC
to
> the regulator circuitry but that's it. Standby voltages are obviously
> working because the micro is responding to panel buttons and the
remote
> causing the relay to activate. I imagine the micro is also monitoring
> the +B or some secondary FBT voltage, if it's not present the micro
> turns off the relay. Question is, does the SMPS in this chassis fire
up
> when the relay activates or is it always on like in the RCA chassis's?
> Are those STR=F6626 regulators a common failure?
>
> Thanks again,
>
> David Lessard
> mr_fixit@xxxxxxxxxxxx
>
> -----Original Message-----
> From: techassist-bounce@xxxxxxxxxxxxx
> [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of David Lessard
> Sent: Friday, June 18, 2004 1:25 PM
> To: techassist@xxxxxxxxxxxxx
> Subject: [TechAssist] Sharp 27" TV - CN27S18 - Turn ON then OFF
>
> When I press the "ON" button I hear the relay "click" ON then two
> seconds later it "clicks" OFF. Protection? What are the common (if
any)
> causes for this problem? HOT is good, standby voltage is good, what
else
> should I look at? No schematic here.
>
>
> Thanks in advance.
>
>
>
> David Lessard
>
> Alexandria Electronics
>
> 50 Harrison Street
>
> P.O. Box 1366
>
> Alexandria, Ontario.
>
> Canada
>
> K0C-1A0
>
> mr_fixit@xxxxxxxxxxxx
>
>
>
>
>
>
>
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