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Newbie - Tek 465 Help Please

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Vintage-er
Posts: 1
Joined: February 12th, 2021, 7:26 pm
Country: Australia

Newbie - Tek 465 Help Please

Post by Vintage-er » February 12th, 2021, 8:02 pm

Hello,

I’m in Australia & hoping someone may be able to help with an old analogue Tek 465.

Love this CRO but, - mains fuse (240 v .75A), blew while working with it. (Thought we had a blackout)

Careful checking all filter caps. (OK), & replacing with a 1 amp fuse, (no .75A readily available), & slowly turning on via a variac, shows that raw 15v dc o/p supply from rectifier CR1541 seems to clamp at about 1.6 volts when applied mains voltage goes from 30 to 60 volts. C1542 seems Ok as it reads high on Ohm scale to earth.

I was not game enough to turn the variac any higher, so I am assuming it is the bridge rectifier CR1541. Only problem, - how do you replace it without virtually dismantling the whole CRO to get to the underside of this huge PCB. (Why didn't they put just the P/S on a sep. PCB ?)

Checking all other voltage rails & HV caps. with a multimeter shows no shorts or suspect low resistances. 1.5 A F1419 (feeding HT supply ??), is OK. Also, I have been putting up with a DC shift & slight jittery problem on Ch 1 for some time but can live with it. - I use this scope to look at very low residual levels from a THD null & also X-Y nulling. ( My Chinese “you beaut” digital scope is useless for this work !)

Any of you cluey TEK guys our there have any suggestions or experience with this sort of problem. I would really appreciate some expert advice as I'm not really into dismantling TEK CRO's !

Thanks,

Ron.

jrseattle
Posts: 2
Joined: January 23rd, 2021, 1:45 pm
Country: United States

Re: Newbie - Tek 465 Help Please

Post by jrseattle » February 14th, 2021, 4:06 pm

Remove the Trigger board and you'll have access to the bottom of the main interface PCB, at least the portion where the filter caps and bridges are.

JdR

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