[TechAssist] Re: Toshibas, CF3566A,CF3572B,(TAC9190)shut down issues,fixes

  • From: "Jim Myers" <jr.myers@xxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Thu, 11 Sep 2003 16:38:38 -0500

I would suspect that the L78M05 was bad but not because of the 5v VCC output
being too high, rather that something was wrong with the reset output pin.
This is a 5 pin device and is used to reset the micro as well as supplying
the 5 volt VCC.
**************************************************
Jim Myers
Since 1972
Telrad Electronic Services Co.
Fort Wayne, IN 46815
*************************************************
----- Original Message ----- 
From: <hartstv@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, September 11, 2003 4:30 PM
Subject: [TechAssist] Re: Toshibas, CF3566A,CF3572B,(TAC9190)shut down
issues,fixes


Phil,Glad you got your 2 units repaired.I have a question on the Q840 reg
that you replaced.If it's 3/4 of a volt too hi this will cause shutdown or
intermittent startup?If it was low by this amount I would have replaced it
but hi by this amount I would have missed this as a fix.I know you also
replaced a filter;but I'm just curious as to how you knew to replace the 5
volt reg.I would assume with the plus & minus tolerance of my meter & the 5
volt reg,a 3/4 volt difference high would be over looked.Not trying to be
pickey,very good t/sing on your part.The B+ for the micro's on these units
must be very critical........
Don of HARTS-TVCR-ASC
9 Robert St,Oromocto,NB,Canada,E2V3N2
Tel-506-357-9785,Fax-506-357-6010
hartstv@xxxxxxxxxxx



----- Original Message -----
From: "Philip Bader" <tjanphyl@xxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, September 11, 2003 1:58 PM
Subject: [TechAssist] Toshibas, CF3566A,CF3572B,(TAC9190)shut down
issues,fixes


> Both 35" Toahibas in for shutting down intermittantly, getting
> progressively worse until one stayed dead.
> Both Chassis# TAC9190.
> One came to life replacing an open cap C871 (22mfd/50V) on the smps
> board.
> The other came up with the same C871 (22mf/50V) cap plus a regulator
> Q840 (LM78MR05) that was outputting about 5.75VDC on a pin that should
> have been a steady 5VDC Standby. Measure that output across the
> 100mfd@xxxx Cap C844. Near the LM78MR05 IC.
> Always ESR all caps,and solder good.
> The group helped a lot with these.Good group.
> Phil Bader
> --
> Philip Bader
> Jan Phyl TV Inc. (estab. 1976)
> 3420 Recker Hwy. Winter Haven, Fl. 33880
> Fax (863) 299-8821
> email: tjanphyl@xxxxxxxxxxxxxxx
> For Professional Technicians Only
>
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