Sencore CR70

[tvcollector]

I just obtained another one of these off Ebay thinking there was a socket issue with the one I've had for a while..

Well testing the same tube with both of them, the new one I can't get cut off to move at all, as with the old one it will go into range.. The shorts range is different between the two.. When I switch over into Rejuv modes with the new one (without it hooked to any CRT, the breaker will trip powering off the unit).. I notice there is no buzzing noise indicating it's doing it's job.. Any clues?

[bandersen]

Try running through these calibration instructions to see if it's functioning correctly.


Set the CR70 controls to the following, F1 to 1, F2 to 2, K to 3, G1 to 4, G2 to 5 ,gun select to R/B&W ,CRT select to Video, function to Remove G1 short.

Hook a DC Voltmeter ground lead to G1 lead of universal adapter and the positive lead of the DVM to the K lead of universal adapter.
When the rejuv button is pressed the DVM should read greater then 350 volts DC.


Set the function switch to the rejuv position and re-press the rejuv button and check again for greater than 350 volts DC.


Set function to Auto Restore and set external DVM to DC current. Press the rejuv button and the CR70 should cycle three times. When on the current should read between 80 and 120 mA.

Set function switch to manual 1 restore.Press the rejuv button and the external DVM should read between 80 and 120 mA with no cycling.

Set function switch to manual 2 restore. Press the rejuv button and the external DVM should read greater than 150 mA

Set function switch to cutoff. Set external DVM to DC volts. You should be able to read the BIAS voltages.

Move the positive lead of the DVM to the G2 lead of the universal adapter. When the cutoff control is adjusted look for a voltage swing of 20 to 400 Volts DC.

Move the DVM ground lead to the F1 lead of the universal adapter and the positive lead of the DVM to the F2 lead . You should be able to read the filament voltage on the DVM. It will be dependent upon where the filament volts settings are set to.

Note: if your CR70 has two power transformers on the bottom panel the filament voltages will be AC volts.

[kvflyer]

Interesting info Bob. I have two of these testers and they are of different vintage with one being very different than the other "under the hood".

[bandersen]

I was surprised to learn that there is an AC filament version.

[tvcollector]

Thanks for the info Bob, I Don't get any kind of readings in DC mode, must be AC..

[kvflyer]

Bob,

My "good" CR70 is in Florida; the beater is here in MD. I will have to test and see what voltages they are, AC or DC by version. I think the one here has an extra transformer inside. I don't remember. Stuff starts to just run together after a while!

[tvcollector]

I get readings when in any other modes than the restore/rejuv modes, when in restore/rejuv modes i get real low readings.. also another thing is, when selecting moving the switch amongst the Rejuv/Restore modes (Without it hooked to a CRT of course) the power switch/breaker trips on the Sencore..

[bandersen]

You should get a boosted filament voltage in the restore/rejuv modes. Something like 20-30% higher. My breaker trips occasionally too - especially if I quickly switch between modes.