[TechAssist] Re: RCA PTV Model#PS61670 Ch# CTC195C. No Power. 2nd request.
- From: Philip Bader <tjanphyl@xxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 19 Nov 2003 09:43:34 -0500
A mulitude of issues could do this, but from my files, this has had a
recurrent theme:
"Dead, no clicks, possible storm".
SMPS was up and running in standby.Chipper check showed error 3
indicating "12 volt run supply problem".
At the front of the main board, I went to regulator IC U14701 "dual
voltage regulator"(+5 & +12V). Pin 6 was the 12V run output. It was
zero, so no run volts. Why?. I unsoldered coil L14702 in that line to
isolate the 12V reg. pin from the chassis and the 12V returned to the
IC's output . Had a low ohms load "down stream" on that 12V line. Traced
the short to the tuner area to a flat pack tuner IC U17701
"UHF/VHF/Mixer/OSC" underneath. It's Vcc 12volt pin was pin 8. With a
pick and solder iron, I lifted the Vcc pin 8 from the trace. Now the TV
powered up (without tuner function of course). The IC's pin 8 was zero
ohms to ground. IC U17701 was loading down the 12 volt run buss.
Replacing IC U17701 restored operation. U17701 is# 227007.
Phil Bader
"D.Panday" wrote:
>
> Hi All.
> This unit have no power with the voltage on clk and data line from main eeprom
> varies from 2.3v to 4.9v whenever power on button is press.
> The 5 volts supply is steady.
> B+ when unit is plug into AC is 157VDC.
> I replaced the eeprom - still not powering up.
> TIA.
> Panday
>
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--
Philip Bader
Jan Phyl TV Inc. (estab. 1976)
3420 Recker Hwy. Winter Haven, Fl. 33880
Fax (863) 299-8821
email: tjanphyl@xxxxxxxxxxxxxxx
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