Fixing the fixing machine

OK, I will admit that I’ve got a hangup on old analog Oscilloscopes these days.

Tektronix is especially one of my favorites, and I gather these are considered the best there is among analog scopes.

So I currently have aquired five Oscilloscopes. Three of these are Tektronix, one 454A and two 2445.

But all of these need some love and care. The thing is that the electrolytic capacitors in any old electronic equipment will start to leak and go bad over time. Excessive capacitor ESR is one of the most common causes of bad circuit behaviors

Of course the state you will find these secondhand will also heavily depend on how they have been stored. IE. in a garage or in an attic, with potential humid condensation and fungi.

My two Tek 2445 were both manufactured 1983 and the serialnumbers show that they are only 149 units apart in the produciton line in Portland, Oregon.

Bad behaviour

So first thing first, if you at all dare to power them on, you might experience some “magic smoke” and you might experience other irregularitues like missing readouts etc.

Some say you should never power them on until all capacitors are changed, because of the fact that any defect in these components could cause even bigger damage to other components like IC chips that are hard to get a hold of.

So my approach was to fire it up, and fire it did!

Magic smoke escaped from the Rifa capacitors on first power on..it zapped and smoked good

Blown Rifa, a very common error on old units

Old leaking capacitor. These can leak in terms of physical leakage, they can also leak electronically in terms of not keeping their capacitance.

Next step

Get a hold of a capacitor kit for your unit. Allthough you could try sourcing these by regular means, these units are presicion intstruments that needs specific types of capacitors like the Panasonic FR series and high quality Nichicon caps.

I contacted Yachad Menahem from Israel, through https://condoraudio.com and received a perfect kit for both of my Tek scopes after a couple of weeks.

First out the powersupply on these units needs to be dead on stable so this is allways a good start.