Three sick Tektronix 465B's (was: two sick Tektronix 465B's)

[MrSlack]

Thanks to another forum member, I've obtained a third unit! This one is slightly more unhealthy than the other two by the looks. The front panel is absolutely immaculate as it has been stored with the front protective case on. However the inside is not so good. Rather gunked up with various hairy things living in i.

After a quick earth check to make sure it wasn't going to kill me and a cursory inspection of its guts looking for burns and burst caps, a quick power up and drop into X-Y mode shows an absolutely huge shift horizontally. Step one as always is to check the power rails. First with a meter, then check any suspicious ones with a scope.

The meter check showed all the rails being within tolerance apart from the 110v rail which was down at 103v. So a quick poke with another unit:



Hmm that's not right. Quick poke of the unregulated line and it looks just as bad.



C4439, C4429 look to be the suspects here as there is precisely no smoothing on the unregulated line.

C4429 is specified as 1200uF 100v electrolytic. Replacing with 1200uF Nichicon 160v RS part 846-6694. £2.89 ex.

C4439 is specified as 550uF 100v electrolytic. Replacing with 560uF Rubycon 100v RS part 749-7235. £2.31 ex.

Ordered.

[MrSlack]

Had an hour spare today so I did a front panel clean and massive knob swapping and refurb session on the best operating unit, the objective being one mint scope, one second best and one parts mule. Some of the knobs had broken entirely on the original unit and some of the grub screws were completely corroded away. Despite this, I didn't have to drill any out or resort to violence. A slightly larger Wera spiky Torx jammed in the hole on the grub worked nicely. The vernier dial on the delay timebase was a dick to get on and off. The top has a grub screw and the base has a collet ring with two holes - pliers worked in the end in the holes.

If anyone is interested, IPA (RS 567-890) and Plenty tissues for cleaning. No issues with legends being dissolved.







Scrubs up well for a 35 year old piece of kit!

Edit: I just noticed I missed the scale illumination knob....

[kayvee]

Nice MrSlack.  I have two 465B's awaiting similar treatment.  If I could just find the spare time....

Any idea how to get those coupling and source toggle plastics better looking, they seem to have developed a whitish chalky surface finish with age?

[MrSlack]

All mine have that problem. I tried giving them a wipe with water only and nothing happened. Then I cautiously applied some IPA on a tissue. This worked fine for a bit and they look a lot better but the finish seems to go chalky again pretty quick.

I'm not too bothered as the plastics aren't compromised by this by the looks. Will just have to live with it.

Since last post I've replaced the mains lead and position controls on another unit. Mains lead isn't trivial and requires some soldering.