🔴 Heathkit IT-1121 Curve Tracer Refurbishment - No.994

[@t1d100]

Great piece of kit to find! Here, in the USA, we have a product called "Liquid Electrical Tape." It comes in a can similar to PVC pipe dope. It might do, to coat the first half of the mains plug ground pin, to prevent the shock you described. It would not be thick, like heat shrink, so it should allow you to push the plug completely in. It does dry hard, but it would be subject to wear, so you would want to inspect it, periodically. Hope that helps.

[@Johadart]

Hi Scott, nice to actually see someone finally use a spanner to get stuff undone instead of pliers, great job mate, keep up the great work 🤙🏼🇦🇺

[@TheEmbeddedHobbyist]

The down side of the UK 13A plug is that they can lay on the floor pins upwards :-( and people say that lego bricks hurt. Not as much as 3 cold copper spikes. :-)

[@peterferguson2344]

This is so true, I'm reliving the pain as I write 😧

[@TheDefpom]

@@peterferguson2344 me too.

[@andymouse]

Nice preventative stuff and I'm looking forward to some tests !...cheers.

[@MsFireboy2]

Thanks for posting. Nice job.

[@tomgeorge3726]

Nice video, I'd be in there replacing those old resistors, it looks like a lot of noise on the traces. Great old machine, I used one at Uni way back for electronics prac. You need to team it with a proper analog scope.

[@craxd1]

The tan era started in the sixties. That tracer is almost as old as I am, as I was born in 1965. That was when they manufactured the best looking equipment in my opinion. They switched to blue in the seventies, as I have a scope I built from that era. Their last was hurrah was the little blue plastic cabinets and dark brown amateur gear, when Zenith ruined the company. These are not that complicated, as a stairstep generator is the secret behind them, along with a multi-voltage and current supply.

[@garynichols1502]

I've got this curve tracer also. I changed the banana plugs on the back to BNC connectors. Makes connections to the scope faster.

[@TheDefpom]

Yes that is exactly what I was planning on doing too.

[@danishnative9555]

Does seem a little noisy. Maybe that is to be expected from an inexpensive vintage tracer. What does it look like with the HF filter on the scope turned on?

[@TheDefpom]

It uses banana cables, I intend to change it to BNC connectors so that each signal is shielded to the scope.

[@wa4aos]

FYI; There is a proper tool for installing and removing Heyco strain relief connectors. New they are about $80 but on ePay, you can find a decent pair for MUCH less. I paid ~$20 for mine and they are worth every penny. The one you want to get has the BLUE handles. The red ones are cheap knock-offs made in asia and are crap.

[@robertendl9205]

So...what brand caps was marked with a plus (+) ?

[@marka1986]

Most electrolytics in the 60s and in into the 70s had the positive marked, at least in US equipment.

[@TheEmbeddedHobbyist]

Passive in circuit testing with two probes is always a problem. You can use 4 probes or more and set up guard probe positions. But the easiest is to test all components and compare the values to those taken from a known good board. Not something the average repair guy has to hand. At least with HeathKit you have the build manual so you have a great starting place.

[@Chris_Grossman]

Many electrolytic capacitors are -20% +80%. The capacitors you replaced may have been in spec.

[@TheDefpom]

Maybe, but they were old, and I want this to work for many more years to come.

[@NiHaoMike64]

The US plug has the same touch safety issue. The Australian plug solved the issue by sleeving the live and neutral pins.

[@alpcns]

Very nice, Scott. A little noisy traces, perhaps?

[@TheDefpom]

I think it was to do with the cabling to the scope, it uses banana jacks, I think I will modify it and add a pair of BNC connectors instead, that way both cables will be shielded which will help with the noise.

[@wittbit4768]

nice piece of kit :)

[@SeanBZA]

Capacitance increasing is a sign of degrading oxide film. They will probably reform with applied voltage, but yes replacing is good, unless you want the look, and can take the risk of them going out with an earth shattering Marvin the Martian kaboom. Carbon composition almost always drift high, depends on the value, over 10k they drift high a lot, below 1k only a little, unless they have been well toasted over time.

[@stevenbliss989]

What is that wierd "pairing/splitting" of the lines, ....I think you have an issue.