Running TV chassis
 

KV27TS27. Refuses to quit, but now it has gone through another CRT and
SBX1437. I do not want to put the fourth CRT into a set this old. Damn
thing won't quit though.

After some capping and soldering, what might be the life of this
chassis ? Without the load of the CRT, might be awhile huh ? OK, my
intent is to turn a working TV chassis into a sophisticated diagnostic
tool.

Understand what you have in a regular TV chassis, Houtput collector
drive can be capacitively coupled to almost any HOT or HVOT circuit,
thing is it must be regulatable by a control.

Modifications for HDTV might include sending the fly less B+, just
build a regulator. Might want a higher frequency but we'll burn that
bridge when we cross it. I am sure without geometry concerns or
anything else we can probably tackle it.

In a regular TV chassis we have waveform generators for most functions
of a similar (NTSC) set. We can replace the yoke drive, the sound
carrier, sandcastrle is almost standardized for NTSC now too. With the
old style video outputs we can replace cathode drive to the CRT(s).

Nothing says you can't hook a Sony chassis up to a completely different
yoke and tube. Something that requires little if any dynamic geometry
correction by the chassis. With the input synched to the output, you
can now test any signal path. You can inject HF drive to flybacks
(LOPTs), yokes, all of it. Test them at actual working voltage,,,,,,,,
and dare I say it,,,,,,,,, beyond. Accelerate troubleshooting of
troublesome intermittents. got a HV arc, crank it up, what arcs first
has arced it's last. Think I'm kidding ?

Why not ?

To be able to apply high voltage to those things that deal with high
voltage should be a very useful diagnostic tool. Even more valuable
might be an old Zenith 25GC45 chassis, the ones that would run the Hout
into a shorted tripler until the circuit breaker tripped ?

Now something like that could also supply about 6 Kv AC, which could be
rectified and used to test focus circuits etc. It might also be better
if there is a really catastrophic short in the HV to hit it with 5 or
6Kv at first. If the problem isa obvious then, you have saved not only
the cost of another Hout transistor, but also the time to procure and
replace it.

Even on the Sony chasis, I could drive the flyback with like 4 2SC5150s
and use an active crowbar "Zener" type circuit for voltage protection.
Of course I would get rid of the Sony SMPS immediately. I might let it
run the signal section though, I don't have all year. I want knobs
connected to potentiometers to control the current limit and the
voltage. I can design said circuit. It is not that difficult at all.

We would literally have all kinds of pulses etc. to choose from, and
demodulation, although it may be less useful, have it and not need it
then. Byproduct.

Now you can really test a CRT, see the condition of the screen. Know
for sure if the yoke is good, and find those pesky intemittent arcs.

I know many techs have analysers and all that, but this is something
that will probably get discarded. I can apply the vertical waveform to
the yoke, leaving the original yoke in the circuit and simply not
connect the feedback.

If I hook up speakers I can detect a sound carrier on NTSC.

It also has a remote detector which could be connected somehow to give
a visual indication. You DO remember getting pay channels on cable by
resistoring the H pulse to the IF circuit I hope. Those in the know
know you need to slow the time constant of the IF AGC as well.

Anyway, I mean as a service tool. I think it would be great.

Whaddya think ?

JURB

Running TV chassis
 

You are going to a lot of trouble to make a jig for troubleshooting TV sets.
Using a good scope and DVM should be adequate for most of the problems.

If you use another chassis Horiz HV drive output to drive another one in
another set, there is the issue of impedance matching.

Also, CRT type TV's in a few more years, are going to be scarce for finding
new ones, and especially parts for them. Most people are no longer having
their older sets serviced. They are simply replacing them.

--

JANA
_____


wrote in message
oups.com...
KV27TS27. Refuses to quit, but now it has gone through another CRT and
SBX1437. I do not want to put the fourth CRT into a set this old. Damn
thing won't quit though.

After some capping and soldering, what might be the life of this
chassis ? Without the load of the CRT, might be awhile huh ? OK, my
intent is to turn a working TV chassis into a sophisticated diagnostic
tool.

Understand what you have in a regular TV chassis, Houtput collector
drive can be capacitively coupled to almost any HOT or HVOT circuit,
thing is it must be regulatable by a control.

Modifications for HDTV might include sending the fly less B+, just
build a regulator. Might want a higher frequency but we'll burn that
bridge when we cross it. I am sure without geometry concerns or
anything else we can probably tackle it.

In a regular TV chassis we have waveform generators for most functions
of a similar (NTSC) set. We can replace the yoke drive, the sound
carrier, sandcastrle is almost standardized for NTSC now too. With the
old style video outputs we can replace cathode drive to the CRT(s).

Nothing says you can't hook a Sony chassis up to a completely different
yoke and tube. Something that requires little if any dynamic geometry
correction by the chassis. With the input synched to the output, you
can now test any signal path. You can inject HF drive to flybacks
(LOPTs), yokes, all of it. Test them at actual working voltage,,,,,,,,
and dare I say it,,,,,,,,, beyond. Accelerate troubleshooting of
troublesome intermittents. got a HV arc, crank it up, what arcs first
has arced it's last. Think I'm kidding ?

Why not ?

To be able to apply high voltage to those things that deal with high
voltage should be a very useful diagnostic tool. Even more valuable
might be an old Zenith 25GC45 chassis, the ones that would run the Hout
into a shorted tripler until the circuit breaker tripped ?

Now something like that could also supply about 6 Kv AC, which could be
rectified and used to test focus circuits etc. It might also be better
if there is a really catastrophic short in the HV to hit it with 5 or
6Kv at first. If the problem isa obvious then, you have saved not only
the cost of another Hout transistor, but also the time to procure and
replace it.

Even on the Sony chasis, I could drive the flyback with like 4 2SC5150s
and use an active crowbar "Zener" type circuit for voltage protection.
Of course I would get rid of the Sony SMPS immediately. I might let it
run the signal section though, I don't have all year. I want knobs
connected to potentiometers to control the current limit and the
voltage. I can design said circuit. It is not that difficult at all.

We would literally have all kinds of pulses etc. to choose from, and
demodulation, although it may be less useful, have it and not need it
then. Byproduct.

Now you can really test a CRT, see the condition of the screen. Know
for sure if the yoke is good, and find those pesky intemittent arcs.

I know many techs have analysers and all that, but this is something
that will probably get discarded. I can apply the vertical waveform to
the yoke, leaving the original yoke in the circuit and simply not
connect the feedback.

If I hook up speakers I can detect a sound carrier on NTSC.

It also has a remote detector which could be connected somehow to give
a visual indication. You DO remember getting pay channels on cable by
resistoring the H pulse to the IF circuit I hope. Those in the know
know you need to slow the time constant of the IF AGC as well.

Anyway, I mean as a service tool. I think it would be great.

Whaddya think ?

JURB

Running TV chassis
 

wrote:

Whaddya think ?




I thought you were giving up the Wild Turkey Jeff!!

I thought about doing that several times, but the chassis are too big.
It's much easier to build test fixtures and tools using parts of
chassis (maybe your Sony) than the whole deal. I started building a
real flyback tester, using a jungle chip, driver XFR, paralled horiz
outs, and switchable inducters to simulate yoke loading. It's still
unfinished as most of these projects end up.

John