It is becoming a touchy subject for me. All my life I have been a very fast touch typist. I spent a lot of time writing programs, and later writing documentation, and could always type quickly and

Your description is pretty accurate. The more modern scopes have compensation circuitry that changes the focus voltage with the instantaneous intensity setting.... and changes the

I make typos all the time. Especially with multi spellcheck in different languages. It writes whatever it wants... If I don’t double check... Don’t worry, it’s okay. I understood you were

No, the typo doesn't matter in so far as that is what it was. I was just curious because I am trying to get a FG504 working correctly and not doing too well at the moment. I didn't mean to insult you

Honestly, does it really matter that I mistyped FG504? I am talking about ceramic trimmers that exist in hundreds of Tektronix instrument models. -Chuck Harris Colin Herbert via groups.io wrote:

Luis, Since both channels are equally affected the fault must be either in the beam switching circuitry (not very likely) or in the Y amplifier stages following the beam switching. There is a fairly

Do you mean an FG504? I can't find any FG540 on TekWiki.

I am not an expert on this, trained in physics not electronics. When you look at a low rep rate signal at 500ps/div the beam is on a very small fraction of the time, about 5ns every msec so one part

Just to clear up some confusion: This note is about subminiature ceramic disk type trimmer capacitors. Tektronix equipment from the 1980's onward is littered with these little timebombs. It is a

Hi John, This is normal stuff when you calibrate an instrument for the first time in decades. These little subminiature trimmer caps break all the time. Every time I try to turn one for the first

Trimmer caps is short for trimmer capacitors. -Chuck Harris keantoken via groups.io wrote:

I believe he’s talking about precision adjustable capacitors, not trim pots... 🤷‍♂️

Wow, Chuck, it was worse than I thought, but it sounds like you have prevailed. john

You mean these trimmers? https://www.mouser.com/ProductDetail/?qs=HHuYZtQ5iDWVDisM2QQAHw%3D%3D I had them fail in 2 ways. The caps became loose so the wipers had no contact, or they get dead spots

Hi All, Just a note. As happens to all of us, one of those little ceramic trimmers in an FG540 was broken. The screw turned and turned, but the ceramic disk on top didn't. It was frozen

Thanks Chuck for the detailed explanation! Much appreciated. Regards Luis

Hello Roger, I am glad to inform you that I have made good progress after following your advice with CH1. Thanks so much! I am still, however, facing some challenges. Armed with ISO and strips of

There are a bunch on eBay. Search for Tektronix 7854 Calculator. -Bob N3XKB wrote:

I’m not educated enough in electronics to understand why that would matter, but I’m sure you’re right.

I looked at the schematic and the parts list, and the Common Design Parts Catalog. Q930 switches off the power. Q935 and Q965 handle current limiting. All three only need to handle about 10mA.