NTP 277-500

[timtom]

I got this very nice NTP Meter and hooked it up like this:

1 = +22 to 32V
2 = 0 V
3 = Chassis
4 = AGC OFF
5 = Screen
6,7 = balanced input left
8 = Screen
9,10 = balanced input right

when I play a mono signal the line is off center. Correlation is on +1.

Does someone has the schematic, manuals, docs for this NTP meter?
Or is there maybe a trimmer somewhere inside to adjust the L and R input?

To Turn off the AGC I need to connect pin 4 with ground, right?

Thanks

 

[timtom]

I opened the meter and found 6 trim pots to adjust the following parameters:

P1 Balance adjust -24dBu
P2 Balance adjust 6dBu
P3 Vertical Position
P4 Horizontal Position
P5 Vertical Gain
P6 Horizontal Gain

I calibrated it by eye but is there a way to do it more technical?

 

[thomasdf]

Hello

Does anybody have some sort of manual for this unit ? or at least know its power consumption ?
Thanks !

Thomas

 

[zamproject]

@thomasdf
NTP documentation are hard to catch...
Can't you measure with an A meter ? There is probably a high voltage convert inside for the CRT, but this is low current I suppose.
Beside that I'll like to get one of this NTP goniometer one day look cool and my desk have monitor/selector out for that, but the scope were missing.

Correlation is on +1.

To me this look normal with a mono signal

I calibrated it by eye but is there a way to do it more technical?

For the scop/visual display part it's the way I suppose, like for a VU you visually align a needle to a dot scale.

By speculation the 6 trim you mention should offer a logical way to align
2 -knee- setting for low and high level (for accuracy in large dynamic range)
2 position for 0° and 180° line depending of in phase and out of phase signal, paralleling the scope trace to the XY scale
2 gain for the trace to be adjusted within the +/-1 scale

Probably you should start with -24 adjustment then pos/gain, then +6 and pos/gain again, maybe repeat 2 or 3 time ?

Cheers
Zam

 

[thomasdf]

@thomasdf
NTP documentation are hard to catch...
Can't you measure with an A meter ? There is probably a high voltage convert inside for the CRT, but this is low current I suppose.
Zam

I'm waiting to receive mine, and I'll have to build a proper PSU for it... So I'd rather shoot in the correct ballpark rather than overbuilding and measuring etc etc. I don't have a lab power supply. Which I should buy one day, obviously...

 

[mindlessstudio]

My 277-500 sort of died a few months ago, screen got increasingly hard to read and now it's all black. I guess the CRT has gone to see it's maker. According to the connector pinouts (mentioned here as well) there are two 'screen' pins. Is it as simple as taking those two to a phone plug and hook up an old CRT screen? Don't wanna ruin anything and can't work out the 'format', so any thoughts are welcome

 

[gyraf]

..most often it's high voltage failing, not the CRT..

 

[timtom]

I recently had a problem that the mono signal was not center and the pots couldn't adjust it more.
After a recapping it could be adjusted again.
Just those pcb's are shit to desolder. the eyelets go off so easily.