[TechAssist] Re: RCA PTK 169 PCB Model NA , Still Dead
- From: "ktaylor" <kntaylor@xxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 29 Jul 2002 12:27:03 -0400
This applies generically to the 169 chassis Larry. But maybe it will be of
help.
Check for start-up voltage at pin 16 of U4101. If missing check R4003 &
R4150 - C4118 & 4153. If voltage is more than 0 but less than2.5 volts
suspect the IC or a component connected to it. Check resistance between
pin 16 and cold ground. Normal is in excess of 40,000 ohms. Check CR4101,
it has a high failure rate. Check IC in circuit by removing power and
applying 13 volts DC to pin 16 while you monitor pin 14 for an 8 volt PP
wave form. If the waveform is present check for base drive at the chipper
transistor. If the waveform is missing at pin 14 check for a 20Hz clock
signal at pins 10 & 11. If this signal is missing check C4107 & R4105. If
good change U4101.
If the voltage at pin 16 fluctuates between 7 & 11 volts think in terms of
over-current shut-down. Here are some quick resistance checks to help you
locate the source of current drain.
140 volt supply cathode of CR4116 reading should be 50k or better
15 volt supply cathode of CR4118 reading should be 500 ohms or greater
+7 volt supply cathode CR4117 4k or better
+17 volt supply cathode of CR4119 4k or better
-17 volts cathode of CR4120 4k or better
I took the trouble to look this up in the book by Bob Rose on RCA & GE
televisions which is published by Howard Sams and I include this plug just
in case they recognise that it was taken from their publication
Ken Taylor
Zap electronics
kntaylor@xxxxxxxxxxxxxx
----- Original Message -----
From: "Larry E." <videotech@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Monday, July 29, 2002 11:03 AM
Subject: [TechAssist] RCA PTK 169 PCB Model NA , Still Dead
>
> Hi guys, still need help on this PTK169 PCB, Thanks for all the ideas
> given so far. I have replaced C4145, pulled the anode from the splitter,
> shorting the collector of Q4304 does not force the set on, still
> nothing, no ticking, no clicks, no attempt from High Voltage to come
> up.In standby,
> Switch mode is operating, regulated B+ is 146.6, CR4118`s cathode is
> 13.3, CR4117`s cathode
> is 7.2, CR4119`s cathode is 24.9 volts. standby 5 volts is good and is
> at pin 19 of the micro. It
> is definitely baffling the heck out of me as to why the set won`t run,
> I`ve never had to replace a
> U3101 or U1001 in a 169 chassis but maby the problem lies with one of
> them? Any help is
> definitely appreciated !!
>
> Larry Eastman
> American TV & Electronics
> Crystal River, Fl.
>
> ------------------------------------------
> To REMOVE your email address, click here:
> http://www.tech-assist.org/unsubb.html
> To CHANGE your email address, click here:
> http://www.tech-assist.org/change.html
> ------------------------------------------
> ***NEW*** Tips Added Instantly!!!***
> Submit Repair Tips here:
> http://www.tech-assist.org/secure/tip/
>
------------------------------------------
To REMOVE your email address, click here:
http://www.tech-assist.org/unsubb.html
To CHANGE your email address, click here:
http://www.tech-assist.org/change.html
------------------------------------------
***NEW*** Tips Added Instantly!!!***
Submit Repair Tips here:
http://www.tech-assist.org/secure/tip/
Other related posts:
