Indeed No effect in the stated position 'EXT X". I measured with the probe! I guess I safely can repeat with the DMM directly in order to have more exact values?

Yes, please do!

 

Indeed No effect in the stated position 'EXT X". I measured with the probe! I guess I safely can repeat with the DMM directly in order to have more exact values?

With DMM directly: 103V; no effect at all of R69

 

With DMM directly: 103V; no effect at all of R69

Are you certain you are measuring between pins #10 and #12 -- as opposed to #3 and #1???

 

all ref to frame:
At 156/C5 (after TR31)
C55: 4.23->4.12V (varies with R69);
F: 108: (no effect of R69)
G: 4,8V: (no effect of R69)

 

all ref to frame:
At 156/C5 (after TR31)
C55: 4.23->4.12V (varies with R69);
F: 108: (no effect of R69)
G: 4,8V: (no effect of R69)

I ment: 156/C5 = 156/C55=C55= 4.23->4.12V (varies with R69);

 

@patpin --- Did you see post #103?

If you are certain of the pins please measure:
Pin #10 to chassis (for R69 at CCW and CW)
Pin #12 to chassis (for R69 at CCW and CW)

Caution -- Use HV probe!!!

 

pin 10 to chassis
CCW:0V
CW:0V

pin 12 to chassis:100;
no change with R69

 

pin 10 to chassis
CCW:0V
CW:0V

pin 12 to chassis:100;
no change with R69

Very interesting!!! -- Now we're getting somewhere!

So here's the deal -- I must be going for today - In the meantime I'll study the schematic in view of the test results and get back to you tomorrow!

Very best regards
HP

 

Very interesting!!! -- Now we're getting somewhere!

So here's the deal -- I must be going for today - In the meantime I'll study the schematic in view of the test results and get back to you tomorrow!

Very best regards
HP

Fantastic !!CU tomorrow

 

Previously after 3 months I thought I was lazarus. Now the scope is. I have a flikkering image of both channels. In the warming up period they occupied full screen!!! After a few minutes 2/5ths of the screen again. About 20 to 50 times a minute the screen flickers and the lines dissapear for a fraction of a second.
No button has an influence on it. If I turn intensity to less than 6 on a scale of 8 then the baselines are not visible anymore. (This is like it was the last years). If I augment the intensity from 6/8 to 7/8 and to max (8/8) then the baslines of both channels go furher from each other. After 10 minutes the flickering disappeared...I have now a stable screen but only 2/5th's of the screen. Aft 10 minutes flickering again etc. I measured voltage on R69 slider. When lines are at utomst right pos (2/5th's of screen) then O volt; when turning CCW voltages goes slowly to -12V; no interruption besides the flickering mentioned above). When I gently knock on position button or channel I volt/div the flickering alters!! It appears to be the last one i'll have to clean.
But finally still I have only 3/5 th's of the base lines and at the warming up period the lines ware 100% OK.
The original problem remains the same. Only the warming up period might be a clue? Any idea?

 

I checked TR 33 and TR37 again BE and BC 0.7; infinite in reverse.

 

Was the scope connected to the mains when you unsoldered/resoldered R68 and R69? If so, it is possible that the electrically 'leaky' soldering iron 'altered' a semiconductor component --- Again, I'll have a close at the schematic and get back to you latter on --- Those deflection plate readings are very suggestive/interesting!

Best regards
HP

 

In the meantime here's something to consider:

Re: post #110 --- Please note that the described symptoms pervade at least three 'systems' (tabulated below):

System: 'Bias' aka 'Z-Axis' aka 'Video' ⇒ Symptom: Flickering
System: Horizontal deflection ⇒ Symptom: Insufficient deflection or fulty balance following warm-up
System: Vertical deflection ⇒Symptom: Change in baseline position with intensity adjustment during warm-up

The above 'smacks' of readily serviceable power supply issues (Spec: regulation or filter capacitors)...

'See' you later on!

 

For convenience here's a schematic of the horizontal circuitry applicable to your scope:

 

pin 10 to chassis
CCW:0V
CW:0V

pin 12 to chassis:100;
no change with R69

Are you absolutely certain that you're measuring pins #10 and #12???

 

Do you have ready access to test points 156/G and 156/F ??? (see uper right of schematic in post #114)

If so please verify that 156/G is connected to CRT Socket Pin #10 and 156/F to CRT Socket Pin #12

 

I checked TR 33 and TR37 again BE and BC 0.7; infinite in reverse.

--Please check for collector to emitter conduction also (CE should test ∞ in both directions) While, in theory, this should be unnecessary -- practice, however, doesn't always agree

--Also please double-check TR31

Please see posts #115 & #116

 

Was the scope connected to the mains when you unsoldered/resoldered R68 and R69? If so, it is possible that the electrically 'leaky' soldering iron 'altered' a semiconductor component --- Again, I'll have a close at the schematic and get back to you latter on --- Those deflection plate readings are very suggestive/interesting!

Best regards
HP

indeed it is possible that I d'nt disconnected from the mains... but on the other hand the scope is now in the state in which it was before the soldering. So there must be another cause.

 

Do you have ready access to test points 156/G and 156/F ??? (see uper right of schematic in post #114)

If so please verify that 156/G is connected to CRT Socket Pin #10 and 156/F to CRT Socket Pin #12

Yes they are;
BTW did U read #110?

 

indeed it is possible that I d'nt disconnected from the mains... but on the other hand the scope is now in the state in which it was before the soldering. So there must be another cause.

I concur with your assesment that the Scope's return to 'partial life' pretty much rules out such damage!

Yes they are;

This is truly bizarre! -- Ok... Now that the scope is "working" again -- please check check X1 and X2 (pins #10 and #12) to each other and to chassis ground again --- Please remember to set the 'Time/Div' control to 'Ext X' prior to the test