All: Now that I have got my 576 working reliably, I was going to start calibration and I found a pair of what appear to be silicone washers laying in the bottom of the unit. I have no idea where

Bruce, There are 2 fundamental differences that need to be taken in to account when replacing “vintage” caps. And I use the term vintage loosely. One is tolerance. In the worst case I can

I had a 7904A recently for a short time. The fan was one reason I sold it - the noise is obnoxious to me. I don't think there was anything wrong with the fan, but I'm sensitive to that white noise -

It might help if I posted the values of the capacitors that were originally in the scope. I'll do this below in the quoted text. To replace the tantalum I broke (C1091), and the other one I removed

I just finished creating the binary files for each of the Option ROMs v2.1 and also a 16bit binary that could be used for disassembly and posted them in the ROMs folder on my github repository for the

I can speak of this from the 7904 perspective, since I have two that work, and some backup parts sources, I had 7904's available, and no 7904As. the 7A19 are the "appropriate" plugin for a 500 mhz

As a precaution, some switching supplies don't work well with a voltage below the operating voltage. For a linear supply, as the voltage to the supply rises, the regulator generally (if it has a

I stand corrected. Sometimes you can teach an old dog new tricks! ;) Thanks, Raymond! Jim

Issues and features that I recall: 7904 has lots of tantalum caps, and a couple are bound to blow. They are easy to find and fix. 7904 has a weak power supply that can't handle many of the

‎Hi folks, Here's my proposed parts order on Digi-Key, except that I haven't decided between the first or second set of tantalums. The caps below those are to replace the large C1412, 14, 42, 52,

My email should have read “no well-known problems”. I had both a 7904 and a 7904A; I gave the 7904 away to a good home when I moved across the country, reducing my collection to five 7xxx

Hi Reginald, Advantages of the 7904A over the 7904: - Newer, so possibly less failure-prone - Easier to service because of split construction - Front panel layout very much like the 7104 (or is that

We can get the 4041 service manual scanned from the vintagetek.org microfiche library of all Tektronix documentation - after COVID-19 is over. Right now Oregon is still in lockdown. They only charge

Reg, As you may know from our prior conversations, I have both a 7104 and a 7904A. The 7904A is definitely my workhorse because, as you mention, I want to preserve and protect the mcp tube in the

The 7904A is easier to wotk pne because it has the “kickstand” feature where one can split the display section up off of the lower section to make repairs. I’ve never compared the specs of a

I have a 485 and a 7104. The fragile CRT of the latter discourages regular use unless needed. Reed refurbished my 485 and obviously it's a really fine instrument. I'm mulling over getting a 7904 for

IIRC, only the 432, 434, and 485 had switchers. The 485 was much like a 7K with the Tek-made controller chip. The 43X's were discrete. -ls-

Hey guys! Look at me with my newly acquired acronyms! ;-)

Still great advice for later when I'm working on a DUT with a SMPS. :-)

Hi Eric, Must they be removed from the circuit to get decent readings? If so, I'll do it. This thing seems to have been designed to make it easy to remove them once the large caps are