Hello,

Hope this reaches older TV techs from Uk or Europe ;-)

Set in question: ITT model 1922u, with 20 axu chassis.

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.

HOT is ok, 300v at the mains rectifier OK, 26v line Ok. I suspect I
need to replace the LOPTX, but have no reference number to go by. If
anyone still has a schematic for this beast and could scan in the
relevant section, or just look up the transformer ref. for me, I'd be
grateful .

TIA;
B.

b wrote:

Hello,

Hope this reaches older TV techs from Uk or Europe ;-)

Set in question: ITT model 1922u, with 20 axu chassis.

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.


cant help with a cct diag, and dont recognise the model, but those
machines are some of the easier ones to fix with no schematic, because
you've typically got a simple dropper supply and little or no fire
protection circuitry. IOW the psu takes no notice of what the
horizontal section or anything else does, so you've got no interaction
complications.


HOT is ok, 300v at the mains rectifier OK, 26v line Ok. I suspect I
need to replace the LOPTX, but have no reference number to go by. If
anyone still has a schematic for this beast and could scan in the
relevant section, or just look up the transformer ref. for me, I'd be
grateful .

By whine do you mean horizontal frequency whine? Doesnt fit with no
filaments. 'HOT ok' is a bit vague too... with more info maybe the many
of us without schematics could help too.


NT

b wrote:
ha escrito:
b wrote:

Hello,

Hope this reaches older TV techs from Uk or Europe ;-)

Set in question: ITT model 1922u, with 20 axu chassis.

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.

HOT is ok, 300v at the mains rectifier OK, 26v line Ok. I suspect I
need to replace the LOPTX, but have no reference number to go by. If
anyone still has a schematic for this beast and could scan in the
relevant section, or just look up the transformer ref. for me, I'd be
grateful .

By whine do you mean horizontal frequency whine? Doesnt fit with no
filaments. 'HOT ok' is a bit vague too... with more info maybe the many
of us without schematics could help too.

thanks for the reply.
a few pics:

http://img164.imageshack.us/img164/3364/itt1yf9.jpg

http://img164.imageshack.us/img164/1254/itt2nm0.jpg

http://img144.imageshack.us/img144/2376/ittchasmi5.jpg

Right, more recent than the sets I had in mind. Probably not a dropper
psu. Once you get it going the ultrasonic remotes, at least of the
another brand sets I played with, work much better than the later IR
ones.


By HOT ok, I meant there is no short on the horizontal output
transistor which i measured out of circuit. The whine is a faint line
whistle. There is no EHT being produced. Typical LOPTX failure symptoms
in these early sets?

What V / waveform have you found on the supply to the horiz outputs,
and what output from the trs to the transformer? Also does it have
separate tripler or one built in to the loptf? What ac v is on the tube
filament pins? I wonder if the horizontal section is running at well
reduced output for some reason, dont know though.

Least your lucky its not one of those horrid sets where the horiz
section and main psu are heavily interdependant, and the psu wont start
without passing stuff all round the set.


NT

ha escrito:

b wrote:
ha escrito:
b wrote:

Hello,

Hope this reaches older TV techs from Uk or Europe ;-)

Set in question: ITT model 1922u, with 20 axu chassis.

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.

HOT is ok, 300v at the mains rectifier OK, 26v line Ok. I suspect I
need to replace the LOPTX, but have no reference number to go by. If
anyone still has a schematic for this beast and could scan in the
relevant section, or just look up the transformer ref. for me, I'd be
grateful .

By whine do you mean horizontal frequency whine? Doesnt fit with no
filaments. 'HOT ok' is a bit vague too... with more info maybe the many
of us without schematics could help too.

thanks for the reply.
a few pics:

http://img164.imageshack.us/img164/3364/itt1yf9.jpg

http://img164.imageshack.us/img164/1254/itt2nm0.jpg

http://img144.imageshack.us/img144/2376/ittchasmi5.jpg

Right, more recent than the sets I had in mind. Probably not a dropper
psu. Once you get it going the ultrasonic remotes, at least of the
another brand sets I played with, work much better than the later IR
ones.


By HOT ok, I meant there is no short on the horizontal output
transistor which i measured out of circuit. The whine is a faint line
whistle. There is no EHT being produced. Typical LOPTX failure symptoms
in these early sets?

What V / waveform have you found on the supply to the horiz outputs,
and what output from the trs to the transformer? Also does it have
separate tripler or one built in to the loptf? What ac v is on the tube
filament pins? I wonder if the horizontal section is running at well
reduced output for some reason, dont know though.

Least your lucky its not one of those horrid sets where the horiz
section and main psu are heavily interdependant, and the psu wont start
without passing stuff all round the set.


NT

Hi,
This set has a tripler separate from the LOPTX, I will take some better
pictures of the board this evening . Also, the PS is switch mode - no
beefy transformers.I haven't got a scope (yet!) so can't check the
waveform for the horizontal. I will have another go at it later on,
and check the voltages you mentioned though.

At present my money is still on the LOPTX due to the lack of EHT and
heater , which i think may be derived from one of its turns, plus the
familiar quiet whine - maybe open winding?

thanks again for your contribution,
Ben.

b wrote:
ha escrito:
b wrote:
ha escrito:
b wrote:

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.

HOT is ok, 300v at the mains rectifier OK, 26v line Ok. I suspect I
need to replace the LOPTX, but have no reference number to go by. If
anyone still has a schematic for this beast and could scan in the
relevant section, or just look up the transformer ref. for me, I'd be
grateful .

What V / waveform have you found on the supply to the horiz outputs,
and what output from the trs to the transformer? Also does it have
separate tripler or one built in to the loptf? What ac v is on the tube
filament pins? I wonder if the horizontal section is running at well
reduced output for some reason, dont know though.

This set has a tripler separate from the LOPTX, I will take some better

thats good news

pictures of the board this evening . Also, the PS is switch mode - no
beefy transformers.I haven't got a scope (yet!) so can't check the
waveform for the horizontal. I will have another go at it later on,
and check the voltages you mentioned though.

At present my money is still on the LOPTX due to the lack of EHT and
heater , which i think may be derived from one of its turns, plus the
familiar quiet whine - maybe open winding?

heater voltage should tell us quite a lot. I dont see how this could be
caused by an open winding, but who knows. With the loptf usually
producing various supply lines theres no knowing what it may be failing
to power up. And of course one may boost a supply line as well... messy
things.


NT

ha escrito:

b wrote:
ha escrito:
b wrote:
ha escrito:
b wrote:

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.

HOT is ok, 300v at the mains rectifier OK, 26v line Ok. I suspect I
need to replace the LOPTX, but have no reference number to go by. If
anyone still has a schematic for this beast and could scan in the
relevant section, or just look up the transformer ref. for me, I'd be
grateful .

What V / waveform have you found on the supply to the horiz outputs,
and what output from the trs to the transformer? Also does it have
separate tripler or one built in to the loptf? What ac v is on the tube
filament pins? I wonder if the horizontal section is running at well
reduced output for some reason, dont know though.

This set has a tripler separate from the LOPTX, I will take some better

thats good news

pictures of the board this evening . Also, the PS is switch mode - no
beefy transformers.I haven't got a scope (yet!) so can't check the
waveform for the horizontal. I will have another go at it later on,
and check the voltages you mentioned though.

At present my money is still on the LOPTX due to the lack of EHT and
heater , which i think may be derived from one of its turns, plus the
familiar quiet whine - maybe open winding?

heater voltage should tell us quite a lot. I dont see how this could be
caused by an open winding, but who knows. With the loptf usually
producing various supply lines theres no knowing what it may be failing
to power up. And of course one may boost a supply line as well... messy
things.


NT

have traced the board and in this set the LOPTX provides heater, rgb
stage and various other low voltages. I removed it and after clearing
away the dust and crud, under an outer plastic laminate layer the
reference TFAT 1109/201.57 was visible (EQUIVALENT hr 1127). so will
look into it.

pics:
http://img171.imageshack.us/img171/8...triplerjy1.jpg
http://img97.imageshack.us/img97/765/loptxlw9.jpg

-B.

b wrote:
ha escrito:
b wrote:
ha escrito:
b wrote:
ha escrito:
b wrote:

Am trying to restore this early transistorised colour, ultrasonic
remote set. Estimated vintage 1976 or thereabouts.
At present there is no sound or raster, no tube filaments lit. Just an
audible whine when set powered up.

have traced the board and in this set the LOPTX provides heater, rgb
stage and various other low voltages. I removed it and after clearing
away the dust and crud, under an outer plastic laminate layer the
reference TFAT 1109/201.57 was visible (EQUIVALENT hr 1127). so will
look into it.

you found out its faulty? If it is thats bad news, terminal I'd say.
Unless you have another similar set and time on your hands.


NT