Tektronix 213 Scope repair

[km6xz]

Good that you got it, but there is a lot of corrosion. It is probably from the battery being left in uncharged for years. There was definite liquid stains on the bottom cover and on the bottom side of the main board. The board with a shield over it should be inspected carefully with that shield removed since it appears to have some corrosion under the shield. Is the fuse blown like in blackened or is it barely melted and open. I would not bother with caps unless you see one that is definitely failing because they fail very seldom in such a "new" unit. I have had probably 100 Tektronix pieces over the years and the newest one I bought in i 1985 and only two, older units ever need filter caps. My current two scope, the 2236 and 465M did require getting into recently, cleaning Cha 1 attenuator in the 2236 and a low voltage cap in the power supply of the 465M which is probably older than most of the people on this forum. Replacing filters is more important in consumer grade equipment that gets hot like guitar amps which use the cheapest possible parts for the price point. That little scope cost $2100 when new which was when 2100 was real money.
The other reason everyone replaces caps as the first resort is they want to feel like they are doing something when they never diagnosed the problem in the first place.Good techs never start with replacing parts unless known to be a contributor to the symptom. They do restoration later after the problems had been reproduced, diagnosed and corrected.

[nsubulysses]

Thanks Stan. the fuse is not blackened. I would called it barely burned open as you describe. Maybe it happened when it was plugged in to see if it worked before selling?

Anyway, all components look good visually. There are no burnt parts or anything that looks stressed. Just corrosion all over the place. I have a wire brush and plastic brush I will probably use to clean the corrosion. Would you recommend using a cleaning solution as well?

[Tom Phillips]

...The other reason everyone replaces caps as the first resort is they want to feel like they are doing something when they never diagnosed the problem in the first place.Good techs never start with replacing parts unless known to be a contributor to the symptom. They do restoration later after the problems had been reproduced, diagnosed and corrected.

Right On Stan!

[loudthud]

Anyway, all components look good visually. There are no burnt parts or anything that looks stressed. Just corrosion all over the place. I have a wire brush and plastic brush I will probably use to clean the corrosion. Would you recommend using a cleaning solution as well?

Use isopropyl alcohol and a soft brush like a tooth brush. Don't use a wire brush! A little bit of baking soda might be used on the battery acid but remove it all with the iso. Use a tissue, rag or compressed air (safety goggles or face shield required) to mop up after cleaning before the iso evaporates so the board is clean and dry. Look around on ebay for a pdf of the service manual. If the serial number starts with B, it was made in Beaverton. I don't think these scopes had anyting to do with Sony.

IIRC the meter in these scopes was true RMS, a big deal at the time.

I got a 465 for $5. Found a broken trim pot in the horizontal and replaced is in under 30 minutes. It worked for several years before a filter cap gave out. Replaced that and it still works today.