Oscilloscope problem

[Tinkerer]

My BK PRECISION 2120B oscilloscope ceased to function.

Does anyone have experience in fixing oscilloscopes?

Any help is appreciated.

Tinkerer

[WM6]

My BK PRECISION 2120B oscilloscope ceased to function.

Does anyone have experience in fixing oscilloscopes?

Any help is appreciated.

Tinkerer

If there is no signal, probably CRT is dead, or power supply only. You need to open it and look if there are visible working cathode heater (filament) inside near to socket of CRT. If there is no visible heating present, measure heating and other voltage at CRT socket. Read type of CRT and search for its technical data on web. In case of no scope signal in most cases error can be found in CRT or power supply.

[Tinkerer]

If there is no signal, probably CRT is dead, or power supply only. You need to open it and look if there are visible working cathode heater (filament) inside near to socket of CRT. If there is no visible heating present, measure heating and other voltage at CRT socket. Read type of CRT and search for its technical data on web. In case of no scope signal in most cases error can be found in CRT or power supply.

Thanks for the help.
I opened the scope and found that screwing with the pots I could adjust it to work again. Having the manual and schematic helped.

Tinkerer

[WM6]

Thanks for the help.
I opened the scope and found that screwing with the pots I could adjust it to work again. Having the manual and schematic helped.

Tinkerer

Relative frequent error due oxidising trim-pot contacts. Problem with trim-pots managing is that calibration is gone and scope need to be recalibrated.

[Nezocas]

Thanks for the help.
I opened the scope and found that screwing with the pots I could adjust it to work again. Having the manual and schematic helped.

Tinkerer

Hi,

I repair Tv´s and LCD´s
It sounds like you have bad cap´s or out of spec resistors and your fine tunning on those pots you got your power supply working again, probably due to high voltage on power supply.

Regards

[Tinkerer]

Hi,

I repair Tv´s and LCD´s
It sounds like you have bad cap´s or out of spec resistors and your fine tunning on those pots you got your power supply working again, probably due to high voltage on power supply.

Regards

Thanks for the help.

I had nothing except a flash across the screen at switch off. Opening the box, there are adjustment presets for the knobs on the control panel. fiddling with these presets, I got some wave form from the calibration square wave. Adjusting one by one, everything works again except the trigger setting works only on the negative going slope.

So I suspect the problem is at the trigger.

I will leave it at that for now.

Tinkerer

[WM6]

So I suspect the problem is at the trigger.

Tinkerer

If you are talking about Time-base Trigger it is in connection to Y-deflection amplifier too. Maybe you need to put some trim-pot in those amplifier on previous position.

[Tinkerer]

If you are talking about Time-base Trigger it is in connection to Y-deflection amplifier too. Maybe you need to put some trim-pot in those amplifier on previous position.

OK, I will reopen the box tomorrow and try to adjust both, the trigger DC level adjust (at present does not react) and the X-DC level adjust for X-Y mode.

As you are talking about the Y deflection, I look at the X-Y mode and notice that there is a problem there.

Thanks for the help.

Tinkerer