Thank You Brad

Typically you need a faster repetition rate on your test signal for it to be bright at 500pS/div. I'm guessing that you were using a fast rise pulse from a CG551AP or CG5001 or PG506 for

Stephen wrote on 8/17/2020 12:37 PM: If anyone truly needs genuine  NOS 2N3565s, I have FS  a factory-sealed bag of 40 pieces. These were manufactured by Sprague and predate RoHS and the

I will put in the 3904 then. It’s in the power section, not the amplifiers. And thank you for the offer Ed. I may need some parts. Will let you know as I move along with repair.

Update: - Locating a new switch was going to be a fools errand - Repairing the switch also seemed impractical - I got lucky because the missing signals were simply grounding control

I was working on some 7000 series plugins and I noticed some strange behavior out of my 7904A. during the high frequency calibration I found that the scope was a little dim readable for the

The 2N3904 should do in a pinch, the 2N3565 is only rated at 25V Vce. Only concern might be frequency response if in the vertical or horizontal amplifier circuits. I am parting out a number of SC503,

I think many people consider the covers as shipping material and don't take care of them later unless the scope is used as a portable. A scope sitting on a bench would be sold off later, the cover

There's some on ebay.

" In TDS3000 Series NVRAM contain ONLY User Settings, RealTime Clock and Operation Hours." ...and the baseline offset calibration. Dave

I wonder if Tek had made the covers for the 400-series scopes more like the one for the 465M, where there's a somewhat useful storage compartment built-in, whether the covers would have stayed with

The cover for the 485 is similar to those that fit the 465 and 485 (I know because I owned a 485 with a cover). That is, plastic, no catches other than a molded clip on either side that snaps over the

Isn't the 485 a bit like the 453, in that the cover is made of metal and is held in place by catches on either side? The other 400-series scopes have a plastic cover that just clicks into place. There

Later Tek catalogs had a section showing all spare parts for probes still in support. Like this http://www.hakanh.com/dl/docs/probe_parts.pdf I think was scanned from the 1995 catalog. Unscrew

Thanks for the link. It applies to the P6139 not P6139A. Hopefully, but no guarantee, that the "whisker" problem was fixed in the "A" version. I will, however, fully disconnect the cable from the

Is it safe to replace it with a 2N3904? That’s all I have available at the moment. The 3565 seems to be unobtainium.

It was very hard to see the, not charred, but very dark solder joint to the diode. These transistors are hard to probe. All the leads are extremely short, almost flush on my unit.

After another round of checking and replacing Q940 and Q960 , and making sure I was putting Q940 the right way (E to B of Q935), I noticed that Q935 has a BC short. Could that induce what I’m

I don't have a 465 so this is hearsay, but I do have a 475 which has some broad similarities. You channel 1 problems sound like an issue with dirty contacts on the attenuator (V/div) and or the input

My bad, I confused R940 with R943. It means that I have 0V at this TP, whether the SC502 is in the ON or OFF state. I have nothing at the test point. Not that I can see. No burn marks, no charred