tek 453 trigg issue?

[m3vuv]

Hi all,ive an old tek 453,i have just got a new probe so thought i would use the cal sig to compensate it,no mater what i do i cant seem to get the cal signal steady on the screen,its moving from left to right,it takes about one second for the left side of the trace to get to the left side,the trigger level adjust just makes it not trigger at all at the far ends of the travel either way,it slows the walking down but wont halt it,any ideas?

[CaptDon]

It sounds like it is free running. Possible dirty sync selection switches Line, AC, DC, etc. or I think there is a trigger stability adjustment which may have the triggered sweep free running. If you get a sweep with no trigger then either your trigger selection is set wrong or there is a stability problem. There are many ways to mess up triggering on a 453 since it also has the delayed timebase feature. You probably have something set wrong.

[med6753]

The following set up is off a Type 454 but your Type 453 should be nearly identical.

Assuming your probe is on channel 1.

Vertical mode - channel 1.
Trigger - channel 1 only.
Horizontal display - A
Mag - Off
A Sweep Length - Full
A Sweep Mode - Auto Trig
Coupling - AC
Source - INT

Adjust the Level control to middle. It should lock. If it doesn't you do have a trigger issue. 

[m3vuv]

thats exactly how its setup,deffo looks like a triggering issue!,luckily i have more working scopes!,cheers m3vuv.

[m3vuv]

well,i took the covers off of the scope and took the scope into the shower,used a small brush and some detergent and scrubbed the lot(keeping the water away from the hv section as best i could) gave all the wafer switches and front panel controls a good scrub and dousing with hot soapy water,then put it in my airing cupboard for 2 days,the upshot is that the whole lot looks like new and the trigger is working fine now on both channels,just one last thing,the fan is noisy,ive had it apart a few times in the past but the bearings are past there best!,i have a fan from a 453a,has anyone any idea if it will fit the 453 not the A version? tia.

[m3vuv]

well i thought this worked but it didnt last long,now have no trigger on either channels,any ideas anyone,when i turn the trigg level the trig light flashes for a split second  but imposible to adjust it to stay on,feels like it would be ok with a 100 turn pot!