Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.

"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can generate
24kV at?

Years ago I was messing around with the transformer from the PSU out of an
Amiga or somesuch - I'd turned the transformer around and driving one of the
original secondaries with a low VCEsat power transistor to get high voltage
from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc between
the pins of the high voltage winding. It was neccessary to complete the
circuitry including the regulation loop for safe operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.

Ian Field wrote:


"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving one
of the original secondaries with a low VCEsat power transistor to get
high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the
CRT; suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would
be nice to have nearly the same current capability as far down as 20KV
and then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do
run another oscillator - why re-invent the wheel when it is there and
nicely round?


So,how could one vary the output voltage?

"Robert Baer" wrote in message
...
Ian Field wrote:


"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving one
of the original secondaries with a low VCEsat power transistor to get
high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the CRT;
suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would be
nice to have nearly the same current capability as far down as 20KV and
then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do run
another oscillator - why re-invent the wheel when it is there and nicely
round?


So,how could one vary the output voltage?

Pretty much the same as the original self oscillating chopper, control
transistor (2N2222 etc) clamps the chopper base on overvoltage. The control
circuit can be simple as you like or complex as you need - simple voltage
divider is probably best if you sample from the end of the ladder.

Ian Field wrote:


"Robert Baer" wrote in message
...
Ian Field wrote:


"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving one
of the original secondaries with a low VCEsat power transistor to get
high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the
CRT; suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would be
nice to have nearly the same current capability as far down as 20KV
and then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do run
another oscillator - why re-invent the wheel when it is there and
nicely round?


So,how could one vary the output voltage?

Pretty much the same as the original self oscillating chopper, control
transistor (2N2222 etc) clamps the chopper base on overvoltage. The
control circuit can be simple as you like or complex as you need -
simple voltage divider is probably best if you sample from the end of
the ladder.
Thank you for not reading the question and avoiding what i asked for.

"Robert Baer" wrote in message
...
Ian Field wrote:


"Robert Baer" wrote in message
...
Ian Field wrote:


"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving
one
of the original secondaries with a low VCEsat power transistor to get
high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe
operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the
CRT; suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would be
nice to have nearly the same current capability as far down as 20KV
and then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do run
another oscillator - why re-invent the wheel when it is there and
nicely round?


So,how could one vary the output voltage?

Pretty much the same as the original self oscillating chopper, control
transistor (2N2222 etc) clamps the chopper base on overvoltage. The
control circuit can be simple as you like or complex as you need -
simple voltage divider is probably best if you sample from the end of
the ladder.
Thank you for not reading the question and avoiding what i asked for.



I chose to interpret the question as not being silly - the TV sweep section
is not designed for PWM (you might get away with burst mode thogh).

It seemed more sensible to assume you were asking how to regulate the
voltage on the PSU which was designed for PWM in the first place.

On Mon, 15 Oct 2012 13:17:23 -0800, Robert Baer wrote:

Ian Field wrote:


"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving
one of the original secondaries with a low VCEsat power transistor to
get high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe
operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the
CRT; suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would
be nice to have nearly the same current capability as far down as 20KV
and then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do
run another oscillator - why re-invent the wheel when it is there and
nicely round?


So,how could one vary the output voltage?

One thing to note is that the picture tube is part of the circuit. The
coatings on the inside and outside of the tube form the filter capacitor
for the high voltage. If you intend to remove this part of the PC board
from the TV and use it as a stand-alone power supply, you will have to
provide a replacement capacitor; probably around 500 pF @ 40 KV should do
it.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

"Jim Mueller" wrote in message
eb.com...
On Mon, 15 Oct 2012 13:17:23 -0800, Robert Baer wrote:

Ian Field wrote:


"Robert Baer" wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving
one of the original secondaries with a low VCEsat power transistor to
get high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe
operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the
CRT; suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would
be nice to have nearly the same current capability as far down as 20KV
and then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do
run another oscillator - why re-invent the wheel when it is there and
nicely round?


So,how could one vary the output voltage?

One thing to note is that the picture tube is part of the circuit. The
coatings on the inside and outside of the tube form the filter capacitor
for the high voltage. If you intend to remove this part of the PC board
from the TV and use it as a stand-alone power supply, you will have to
provide a replacement capacitor; probably around 500 pF @ 40 KV should do
it.

Good point. TV flyback HV supplies are designed for a certain operating
point, if adjustment of the voltage is needed, the current capability will
suffer. I'd like to see schemo's of Glassman HV supplies to see how they do
it. They are wonderful supplies, and even more wonderfully expensive!
Tom

hifi-tek wrote:
"Jim wrote in message
eb.com...
On Mon, 15 Oct 2012 13:17:23 -0800, Robert Baer wrote:

Ian Field wrote:


"Robert wrote in message
...
Attached is a truncated version of the manual as the 2Megs would not
transmit.
Also, are enlarged parts showing horizontal section; T703 output to
CRT is about 30KV.
Would be nice to have adjustment from around 10KV to full 30KV.

Thankx.


Do you actually need the full current that a CTV flyback stage can
generate 24kV at?

Years ago I was messing around with the transformer from the PSU out of
an Amiga or somesuch - I'd turned the transformer around and driving
one of the original secondaries with a low VCEsat power transistor to
get high voltage from what had been the primary.

Apart from turning the transformer around, it was the same blocking
oscillator style self oscillating chopper as the original circuit - the
problem encountered the first time I powered up was a continuous arc
between the pins of the high voltage winding. It was neccessary to
complete the circuitry including the regulation loop for safe
operation.

If you don't need a vast amount of current at EHT voltage, this basic
circuit driving a diode/capacitor ladder will do just fine.
I have no idea as to how much current these nominally supply to the
CRT; suppose it is maybe 1mA or so.
Current capability could decrease as voltage decreases but it would
be nice to have nearly the same current capability as far down as 20KV
and then decrease in current capability.

I see no sense in ripping out the xfmr, building another supply do
run another oscillator - why re-invent the wheel when it is there and
nicely round?


So,how could one vary the output voltage?

One thing to note is that the picture tube is part of the circuit. The
coatings on the inside and outside of the tube form the filter capacitor
for the high voltage. If you intend to remove this part of the PC board
from the TV and use it as a stand-alone power supply, you will have to
provide a replacement capacitor; probably around 500 pF @ 40 KV should do
it.

Good point. TV flyback HV supplies are designed for a certain operating
point, if adjustment of the voltage is needed, the current capability will
suffer. I'd like to see schemo's of Glassman HV supplies to see how they do
it. They are wonderful supplies, and even more wonderfully expensive!
Tom


Seems all adjustable HV supplies are in the $100 and up (mostly up)
range; cannot afford that.
The TV was wonderfully inexpensive (about $2.75 with sales tax).

Anybody know the current capability and/or what the CRT anode draws
at nominal brightness (30KV)?