RCA PTK195 Random Operation

T

TV Fixer1

Guest
Got a RCA PTK195 (projection). Set has random behavior, turns itself on/off,
changes channels, etc. as long as front keyboard is plugged in. With keyboard
unplugged, set functions OK (remote operation). I've read about some problems
with conductive glue under SMD parts on this chassis, is this one of the
circuits affected? TIA

TVFixer1
 
Check those Tac switches one by one pull them out if you have to.
Maybe dirt or liquid got behind them causing trouble.

kip


--
"Watch the return E-Mail addy its false"
"TV Fixer1" <tvfixer1@aol.com> wrote in message
news:20030826170050.21660.00002191@mb-m07.aol.com...
Got a RCA PTK195 (projection). Set has random behavior, turns itself
on/off,
changes channels, etc. as long as front keyboard is plugged in. With
keyboard
unplugged, set functions OK (remote operation). I've read about some
problems
with conductive glue under SMD parts on this chassis, is this one of the
circuits affected? TIA

TVFixer1
Click to expand...
 
On Tue, 26 Aug 2003 18:36:02 -0400, "john" <va3mmSPAM@niagara.com>
wrote:

Check those Tac switches one by one pull them out if you have to.
Maybe dirt or liquid got behind them causing trouble.

kip


--
"Watch the return E-Mail addy its false"
Click to expand...
Alteratively, pull the button circuit board assembly out and clean
both sides off (especially if that area is heavy smokers), and replace
all six switches, they're inexpensive to buy new switches. These
switch panels in RCA is still through hole technology.

If other problems, unplug all wires to the Gemstar module and run this
way. Otherwise do the mods on the tuner and replace both 22pf SMD on
that SCA/SDA I2C lines just inside the tuner and one resistor (marked
R6) changed from whatever to 100ohms.

Cheers,

Wizard
 
Wizard !
Is the new resistor 100 ohms or is that the bad value of R6
if so what is the correct value of R6.

kip

--
"Watch the return E-Mail addy its false"
"Jason D." <jpero@sympatico.ca> wrote in message
news:3f4be81c.961155@news1.on.sympatico.ca...
On Tue, 26 Aug 2003 18:36:02 -0400, "john" <va3mmSPAM@niagara.com
wrote:

Check those Tac switches one by one pull them out if you have to.
Maybe dirt or liquid got behind them causing trouble.

kip


--
"Watch the return E-Mail addy its false"

Alteratively, pull the button circuit board assembly out and clean
both sides off (especially if that area is heavy smokers), and replace
all six switches, they're inexpensive to buy new switches. These
switch panels in RCA is still through hole technology.

If other problems, unplug all wires to the Gemstar module and run this
way. Otherwise do the mods on the tuner and replace both 22pf SMD on
that SCA/SDA I2C lines just inside the tuner and one resistor (marked
R6) changed from whatever to 100ohms.

Cheers,

Wizard
Click to expand...
 
On Tue, 26 Aug 2003 19:44:02 -0400, "john" <va3mmSPAM@niagara.com>
wrote:

Wizard !
Is the new resistor 100 ohms or is that the bad value of R6
if so what is the correct value of R6.

kip
Click to expand...
100 is correct, simply do both 22pF SMD capacitors to keep things
easier, both are side to side right by tuner shield, both resistors is
connected to this capacitors, then via 2 jumpers then on to the PLL
IC. Everything are hidden under the tuner bottom covers. This is for
the I2C bus to the tuner PLL. This mostly affects the tuner
intermittent snowy w/ loud static noise from speakers because PLL IC
get confused by intermittent corrupt I2C and get switched around for a
instant. Also there is another resistor, near a ground post, this
posts is in a row nearest rear edge, one of them has one end of on
that ground island.) that should be 39 ohms not 10.

If tuner has one solder point on bottom tin, they has to go. Discard
both bottom tin and zinc liner, install both new I-bar and 2 point
solder bottom tin. Old style covers was a big pain in butt to work
with and liner get damaged every time. Warps & cracks easily from
that soldering heat and mechanical stress during removal &
installation. The new design is easier to work with.

Bulletin says to realign 5 specified channels with tuner covers
installed and soldered after that 39 ohm & cover (if required)
modification, I simply do whole realignment thing (29 of them).

That completes tuner's 3 bulletins. This what I just did just that
today spread over two days, I did not want to spend too much time on
it there was several things to do that day, alignment was done
following day without incident. :) Oh yes, that was paid for
everything by owner and that set was out of warrenty.

This stuff applies only to xxx195 and CTC197

I'll post more details with notes next day. Very tired tonight and
been eyeing to take a shower then bed.

Cheers,

Wizard

PS: Today fixed an older 1990 vintage Mitsubishi, big two piece
chassis with high end stuff (relabeled as Electrochrome). Pix looked
like ringing (vertical edges had bands (nasty case of ringing) and
comets (like sparklers) and found nine lousy caps, except one was
totally dried up (that was in cool location, go figure. With
electrolyte leaking. Coworker thought tube had it. I saw that tube
had good life left so I didn't beat it up with CRT rejuvenator.

Cheers,

Wizard
 
This is a very common problem,usually caused by leaky tact switches on
the keyboard assembly itself.I usually replace the keyboard assy.The
most common one used is part# 239125.Yours could be a different
number.I would need the exact model # to be sure.
6 Aug 2003 21:00:50 GMT, tvfixer1@aol.com (TV Fixer1) wrote:

Got a RCA PTK195 (projection). Set has random behavior, turns itself on/off,
changes channels, etc. as long as front keyboard is plugged in. With keyboard
unplugged, set functions OK (remote operation). I've read about some problems
with conductive glue under SMD parts on this chassis, is this one of the
circuits affected? TIA

TVFixer1
Click to expand...
 
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