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Old 13th Jan 2021, 5:15 pm   #2
MotorBikeLes
Octode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 1,747
Default Re: Telequipment D67 Fault

OK, you have a spot at switch off, which says the HV side is OK. Probably an unblanking circuit problem, but check deflection first. I assume you have set ALL the controls as per the info in the instructions. Connect a test meter (250v range) from ground to one of the Y-plates and operate the vertical shift, you should see the voltage increase or decrease as the invisible beam goes up and down. The other plate should do the same (but in opposite directions) to the first.
Centralise the shift, and now check for horizontal deflection. Set the speed very low (say 1 sec per division) and with test meter connected to each X plate in turn (wrt chassis), you should see the voltage rise slowly then shoot down again. If OK, time to investigate the unblanking.
CAUTION. That part of the circuit is at HIGH VOLTAGE.
If you look at the PSU circuit, the bottom section shows the two voltages used in the unblank circuit, 13v and 45v windings, with the centre tap linked to the CRT heaters. I forget off hand, but expect well in excess of 1KV there.
It might pay to check TR261/261, but do this WITH POWER OFF.
If you remove the link to the HV part (670v winding), you can do some testing with a scope, but at this stage, try simple tests on parts with no power.
One other very common problem with the D67 series. The PCB is double side print, and the thro links (rivets in TQ speak) are regular dry joint sites. Carefully reflowing the thro links solves VERY MANY D67 faults.
Les.

Last edited by MotorBikeLes; 13th Jan 2021 at 5:17 pm. Reason: sp. winds to windings
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