D61A oscilloscope
 

Hi,
D61 oscilloscope turning the focus control i can not obtain a thin line its about 1/4 of inch.
The resisters for the focus control i can not see them on the circuit diagram, would i have to remove front cover of the scope.
could any one help
kind regards
cinema1.
Eric.

Re: D61 oscilloscope
 

None of the photographs I found show what is behind the focus and brightness controls so I cannot say if you need to remove the front panel or not, and the information is not in the manual.

Connected to one terminal of the focus control is a1M5 resistor and the other side is a 390K. The chances are that one of them has changed value.

Proceed with caution and make sure the 'scope is disconnected from the mains for a few minutes to allow the capacitors to discharge. A 1,000 volts hurts!

Re: D61 oscilloscope
 

If it is like the D61a then the focus and brightness pots are on the back chassis top left and right corners, just remove back cover.

Mike

Re: D61 oscilloscope
 

Hi!

You didn't get a D61A manual by mistake by any chance?

These two resistors are marked on the D61 Manual obtainable from "Jon's Valve Page", asterisked as *not mounted on the PCB" – the 390k is shown between chassis–earth and the clockwise end of the "focus" the control, whilst the 1M5 is marked between the anti–clockwise end of the control and the intensity control circuit!

Chris Williams

Re: D61 oscilloscope
 

The manual downloaded from thevalvepage.com for the D61 shows the focus and intensity on the front above the CRT. Page 32 shows the CRT components separate form the main PCB but does not show a CRT base PCB so I assume they are behind the controls.

Re: D61 oscilloscope
 

Thank you all for your help with the focus fault on the D61 OSCILLOSCOPE, i made a mistake with the model number----its a D61A Model.
thanks for all the info.
kind regards
cinema1.
Eric.

D61A oscilloscpe telequipment.
 

Hi ,
Can any one help with the following, I've been on the forum about focus fault two weeks ago with good info.But removing the panels on the sides and half the front panel i can not fined the , back of the focus control resisters----
R302 1M5------R304 390K . They could be reason why i am not seeing a fine
line after turning the focus down.
appreciate it.
kind regards.
cinema1.
Eric.