The notch is pin 1, lower left corner in your photo. the part number is near pin 7. This is a quad 2 input NAND gate device from the fist vintage of 7400 series TTL. Made in 1972. Tom Bowers

The notch identifies pin 1 which is at the lower left. That's also a quad nand gate, not an op amp. The circle is a mold mark. -- Paul Amaranth, GCIH | Manchester MI, USA

I meant to say Quad Dual Input NAND device. Carl

It is not an op amp.  It is a quad nand gate.  On round devices, the tab is the last pin. Carl Hallberg (W9CJH)

https://groups.io/g/TekScopes/album?id=245683 Here is a rather unusual design at least for me. This chip contains both the notch and the circle, I want to say the notch is pin 1 but I am not 100%

Yes, Steve, that is what I understand to be the item in question. However, I wouldn't particularly call them "pins", more "connectors" as they are thin and flat; I think of "pins" as being more

Colin and David, If you look at eBay item: 133386313435 it is the plug-in backplane for a 7854. In the fourth photo, I believe it shows one of the connectors that is missing the cover on one side of

Thank You, David, I am now un-flummoxed. It is exactly the part that I was thinking of, but the 3 inch measurement is way too short. As you suggest 4 inch is about right. These parts are also used on

For avoidance of doubt this is p/n 200-0950-00 shown on the mechanical parts breakdowns in all the 7000 series Service manuals. There are two of these used on each plugin socket on the main interface

I thought that I knew what you were talking about until you gave the size as 1 inch by 3 inches. I am now flummoxed, because that isn't the size of the plastic parts that keep the (gold-plated)

I was not aware of this YouTuber (TomTekTests) until I stumbled across this video on a 570 restoration. https://youtu.be/AphQLWbN8nI Here is part 2: https://youtu.be/U2GVbmi4Wso Makes me want a

Well said, Yachad, especially setting off professionalism against rigid traditionalism. Doing things in an unorthodox way can work! You gave very clear instructions. And you even express my stated

Regarding the issue of causing damage to the SMD pads, using this method. Just goes to prove that there is no shortage of amateurs who call themselves "techs". I have repaired / overhauled HUNDREDS

Received the OK to use the eBay listing photos, created the Interad 7121R wiki page ( http://w140.com/tekwiki/wiki/Interad_7121R ) and updated the Third Party Tek 5000 Series Scopes wiki page

We got some hand me down Hitachi analog cameras for the NEWS department of the TV station that I was CE for. NEWS just had to have the working cameras in the field NOW. About 50% of the bad cameras

So, what does conformal coating do to prevent leakage? Possibly hide the damage?  Glenn -- ----------------------------------------------------------------------- Glenn Little ARRL

Hello. I have a 2252 scope with a fault thats driving me mad. Both channels 1 and 2 exhibit DC drift. ie. input is grounded, so centre the trace with the vertical position knob. Switch to DC coupled

200-0950-XX, IIRC -ls-

Grabbing and twisting the entire condenser off the board seems very risly. Crushing and removing the can then going after the base seems to be a more reasonable idea. I have a few Sony Betacam

Hi Victor, My 2467B and 2467BHD are both in the B050XXX range, so it seems I've been very lucky! I have no serial numbers of my other 2465B/67B's at hand. My 2465 is Heerenveen-made, so no easy