From my 453 repair journal:
++++++++++++++++++++
Then I noticed that B trigger wasn't working. The culprit was tunnel
diode D675 (TD3, 4.7mA). Luckily I had a spare.
Later I lost B trigger again. Q684, replaced with Soviet KT3126A.
PNP 20V 20mA 500MHz 2.5pF .
++++++++++++++++++++
HTH,
Dave Wise
From:
[email protected] [mailto:
[email protected]] On Behalf Of quadzillatech via groups.io
Sent: Tuesday, November 16, 2021 8:11 PM
To:
[email protected]Subject: [TekScopes] 453 trigger issues
hi ive got issues with the triggering on my 453,firstly it wouldnt trigger on ch A or B,i washed the whole scope down in the shower and dried it,it now works fine on ch a but has a hard time triggering on ch b,its odd if i remove q454 and q 464 it makes no difference,the displayed waveform is very jittery but sort of triggers,the level control seems very sharp on chB but normal on ch A,any idea where i start looking? q454 was dead so replaced it but made no difference i suspect a cap ,Its a later scope with the fet front end.
