Scope Telequipment D61A;horizontal position fault

Thread Starter

patpin

Joined Sep 15, 2012
388
Hallo,
My X axis stops at the third vertical division (from the left) . I can only move the axis to the left I would like to have an X-axis image on the full screen. I have tried to adjust R113 which is supposed to be dooing that, but it does nothing.
Horizontal is OK.
I still can view (a small portion of) the calibarting signal (0,5V).
Any ideas?
 

Hypatia's Protege

Joined Mar 1, 2015
3,197
You speak (well... write) as if the readers have intimate knowledge of the instrument in question (am I missing something?) --- A schematic of the 'deflection' circuitry would seem 'prerequisitory' of assistance...

Best regards -- and with apologies for 'lexical liberties' :eek:
HP
 

ian field

Joined Oct 27, 2012
6,539
Hallo,
My X axis stops at the third vertical division (from the left) . I can only move the axis to the left I would like to have an X-axis image on the full screen. I have tried to adjust R113 which is supposed to be dooing that, but it does nothing.
Horizontal is OK.
I still can view (a small portion of) the calibarting signal (0,5V).
Any ideas?
Outside of college - my only experience with Telequipment scopes is, that one of the plug-ins has a row of blade contacts on the side as well as the bulk connector at the back - these blade contacts can catch as the plug-in is being refitted and causes some odd faults.

If all else fails - check for that.
 

Thread Starter

patpin

Joined Sep 15, 2012
388
contains only 2 jpg files which I could not include separately using "update a file"; this function simply doesn't find them ... dont worry. I m using Norton.
 

Thread Starter

patpin

Joined Sep 15, 2012
388
contains only 2 jpg files which I could not include separately using "update a file"; this function simply doesn't find them ... dont worry. I m using Norton.
Thanks for yr answer. Can you tell me how to measure without a scope
 

Hypatia's Protege

Joined Mar 1, 2015
3,197
Hallo,
My X axis stops at the third vertical division (from the left) . I can only move the axis to the left I would like to have an X-axis image on the full screen. I have tried to adjust R113 which is supposed to be dooing that, but it does nothing.
Horizontal is OK.
I still can view (a small portion of) the calibarting signal (0,5V).
Any ideas?
Responses to to these questions would be helpful...

Does the sweep appear linear on the visible portion of the trace?
Does R113 produce some effect on the trace over its (R113's) entire range? If not please explain...

Thanks for yr answer. Can you tell me how to measure without a scope
A cursory test of BJTs may be accomplished via use of a digital multimeter set to 'junction test' mode (such that the test EMF is sufficient to bias semiconductor junctions) --- Silicon devices should enter forward bias (B-E and B-C) in the range of 0.5v through 0.75v there should be no measurable conduction under reverse bias. Germanium devices will exhibit similar behavior but at significantly lower forward EMFs --- For best results this test should be preformed out-of-circuit

Note: the procedure outlined above does not assay 'gain' (i.e. the characteristic quantified as one of '[hybrid] forward transadmittance [aka hFE]' or 'beta' -- dependent upon the system used by the 'characterizing agency') That said, it is generally sufficient when applied to investigation of conspicuous malfunction.

Good luck :)

Best Regards
HP
 
Last edited:

Thread Starter

patpin

Joined Sep 15, 2012
388
Responses to to these questions would be helpful...

Does the sweep appear linear on the visible portion of the trace?
Does R113 produce some effect on the trace over its (R113's) entire range? If not please explain...



A cursory test of BJTs may be accomplished via use of a VOM set to 'junction test' mode (such that the test EMF is sufficient to bias semiconductor junctions) --- Silicon devices should enter forward bias (B-E and B-C) in the range of 0.5v through 0.75v there should be no measurable conduction under reverse bias. Germanium devices will exhibit similar behavior but at significantly lower forward EMFs --- For best results this test should be preformed out-of-circuit

Note: the procedure outlined above does not assay 'gain' (i.e. the characteristic quantified as one of '[hybrid] forward transadmittance [aka hFE]' or 'beta' -- dependent upon the system used by the 'characterizing agency') That said, it is generally sufficient when applied to investigation of conspicuous malfunction.

Good luck :)

Best Regards
HP
Yes the X axe appears lineair. I can judge better if I pull the time/div knob ; then the X axe is X5 and fills more than half of the screen. The R113 does nothing.
TR33: BE 0,69; BC 0,67; TR35:BE 0,69; BC 0,68; all reverses give -;
 

alfacliff

Joined Dec 13, 2013
2,458
how about the y axis, is it working normal? if not, a common problem is the power supplies, one or more get dried out electrolytics and drop voltage. these days, I check all supply voltages on scopes (there are usually severeal different voltages out) by the way for those out there not familiar with telequipment, it is tektronix- uk.
 

Thread Starter

patpin

Joined Sep 15, 2012
388
how about the y axis, is it working normal? if not, a common problem is the power supplies, one or more get dried out electrolytics and drop voltage. these days, I check all supply voltages on scopes (there are usually severeal different voltages out) by the way for those out there not familiar with telequipment, it is tektronix- uk.
X axis is functioning normaly. Could it be the sweep generator instead? (lenght of sweep?)
 

Hypatia's Protege

Joined Mar 1, 2015
3,197
Yes the X axe appears lineair. I can judge better if I pull the time/div knob ; then the X axe is X5 and fills more than half of the screen. The R113 does nothing.
TR33: BE 0,69; BC 0,67; TR35:BE 0,69; BC 0,68; all reverses give -;
Very well -- the junction analysis results, along with verified maintenance of linear response, effectively 'exonerate' TR33 & TR35 --- Moreover we now understand the difficulty to be that of balance -- as opposed to gain/distortion...

Let's start with the 'too obvious' beginning with R113 itself and including all components affecting balance but exerting little or no effect upon gain...
As a matter of course please verify the +110v and -13v supply EMFs

Keep us posted :)
HP

EDIT: On a safety note, please be advised that the deflection plates will be near accelerator potential while, in some designs, the chassis will be near that of the cathode... (while this particular hazard does not appear manifest in this instrument one cannot be over cautious...)
 
Last edited:

Hypatia's Protege

Joined Mar 1, 2015
3,197
So... a few thoughts...

Please check R69 over its entire range with special attention to its ground and -13v connections, verify R66 and, again, the -13v supply EMF. --- It's 'telling' that S23 produces the proper effect...

Best regards
HP
 
Last edited:
Top