Hi All;
I just got another Scope to use on my TV's.. It was free from a neighbor.. Its a Tektronix 453, my other old scope that I was going to use for my TV's is a Tektronix R647A.. Can anyone suggest which would be better for use on older TV's ?? The R647A can go up to 20 volts per division, whereas the 453 only goes up to 10 volts per division.. They both go to .1 Msec on the time base.. And the 453 has Time delay..
THANK YOU Marty

Both are way more than sufficient for TV work so I would go with whichever one works best and fits best on your workbench. Also, most scope probes have a 10:1 divider which will extend your voltage range and bandwidth.

Hi All;
Bob, Thanks for the reply.. Ok, and I have dual probes, switchable to either 1:1 or 10:1, so Yes, I was counting on that for my semi higher voltages that Tubes take compared to modern lower voltage equipment..
On a slightly different question.. Is there still available high voltage probes for the scopes.. for the 10,000 voltage range stuff, and up.. I have from one of my Riders publications information on how to build a high voltage probe using a 1X2 Tube.. But, I have not tried it, as I am not sure if it can be used with scope.. When (years ago) I first got my 8T243, I borrowed one that was a meter on a stick (Probe).. from one of the Local TV repair places.. But neither He nor the other shop are now in business, and I have no idea of who the owner were or how to get ahold of them..
THANK YOU Marty

I would NOT use the scope for making high voltage measurements-use a meter-more accurate and a cheaper fix.
The voltage accuracy of scopes of that era are only about +/- 3 to 5%.
A modern meter on DC could be less than +/-1%.
Many can also go up to 1KV.
See what your probes can handle for AC voltage.
A 20 mhz scope with a 100 mhz probe will only display up to 20 mhz.
The bandwidth of a scope is built into the vertical amplifiers-not the probes.

...
A 20 mhz scope with a 100 mhz probe will only display up to 20 mhz.
The bandwidth of a scope is built into the vertical amplifiers-not the probes.

What I meant was that X1 probes have a larger capacitance and load down the circuit under test more than X10 effectively decreasing the bandwidth of the scope.

Hi All;
Thank You both for your great replys.. I had for the most part only planned to use the 10:1 probes.. And If I remember right Both scopes are 100 MHZ scopes anyway.. So bandwidth is no problem..
As far as the Hight Voltage probes, Yea, for making measurement, the VTVM or digital voltmeter would be fine with the correct Divider probe.. Which I am still asking are they arround at a reasonable price ??
But, my main reason for asking about using with a scope, was to look at waveforms on all those Very High Voltage Tubes, and asscoiated parts.. Damper Tube, Horizontal Output Tube, Width and Linerity pots or coils, etc... A meter will give me a voltage, but not a waveform.. Especially on my 8T243 Where Everything is Greatly out of "Wack".. Which is part of the reason "Why" I got the 630TS, In many areas, they have either the same part or are close, same with the circuits many of them are the same or similiar.. So, I can take some part out of the 8T243 and IF It would need to be checked or adjusted I would put it in the 630TS and adjust it and then put it back in the 8T243.. Working on a section at a time, Horizontal, Vertical, Sync, etc.. I realize that can only be done once I have the 630 working 100%..
THANK YOU Marty

I don't think there's much to be gained my poking around the HV circuits. They usually state on the schematic "do not measure".

Also, I'm not sure what you going to be swapping between chassis and adjusting. Coils ? Potentiometers ? You need to adjust those in the set they'll be used. There's way to many interactions between components within a set to isolate them.

Hi All;
Bandersen, I didn't see your reply till now.. The main reason for doing this is to get the part somewhat closer to what its correct setting should be.. Since as I have stated in other postings, everything and I mean everything in the 8T243, is not right.. And as you have stated, these parts all depent on each other and each part being somewhat correct.. The pots would not need to be taken out, but the measurement in one would be a starting place for the other.. Its mostly coils, like Horiz Lin, Width, etc.. that If put in the 630, after I get the 630 going correctly, then taking like the Width coil out of the 8T243 and temporially putting it in the 630, as everything else in the 630 would already be adjusted.. And the Width coil could then be made to work in the 630 or close to working.. it could then be put back in the 8T243 as a starting place for its final tweeking.. Also, when the circuit is the same or Similiar, I would have a scope on each one doing a comparison, section by section, tube by tube, etc.. Looking at what the RCA Service notes shows for each set, at a particular point.. Remember, these sets both use the same CRT, and much the same, circuitry.. Its not like comparing a Motorola to a GE.. I think it like comparing an apple to an apple, just a slightly different derivitive, like Jonathan to Macantosh..
THANK YOU Marty

I've never used a 647A, but the 453 is a great scope for general purpose troubleshooting. Far better than the scopes used by most TV shops back in the day. Even better if yours has the "Mod 127C" option, which adds a built-in TV sync separator to the triggering circuits.

Tektronix made a special X1000 high voltage probe (P6015), which enabled waveform measurements up to 40 kV. They are hard to keep in working order today, as they used a liquid freon dielectric fill, which slowly evaporated and is very difficult and expensive to obtain these days.

There isn't any real need for waveform measurements in the high voltage circuits of TV sets, anyway. A cheap high voltage meter or HV probe for your DMM is all you need.

Hi All;
N21XK, Thank you for the information. As, far as I know this scope does not have the Mod 127C.. Do you know If it is possible for me to put it in, or is it a module that plugs in somewhere ??
THANK YOU Marty

Taking those coils out is a bad IMHO . You risk damaging them and as I said they work in conjunction with other components in the set. For example the width and linearity coils typically are connected in parallel to windings on the flyback and have a subtle effect on it. In other words they are used to fine tune the flyback and associated components. Settings used in one set will not be correct for another.

Also, they have a very minimal effect and are used to make minor tweaks to the picture. Their setting is not at all critical to getting a watchable picture so don't worry about them being out of whack.

I don't mean to criticize, I'm just trying to save you a lot of unnecessary work :)

Hi All;
Bandersen, Not, at all.. That is why I post my train of thought, and ask others to point out the flaw in my logic.. That way You know where I am coming from, and so can better make a reasonable reply.. I treasure the responses from everyone.. That way we all learn.. So, OK, I won't go that route.. As, I have to get the 630 working first.. Maybe I will and can learn enough from it, to help when I do get to the 8T243.. So, for now I will concentrate on the 630..
THANK YOU to all for their Help and encouragement.. Marty
P. S. What is an IMHO ?? I'm sure its not a part..

IMHO = In My Humble Opinion