576 Beaverton Prototype SN A01 - Page 1
Forum section: electronics / testgear

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 09, 2023, 07:09:21 pm
content: Hi, now in possession of TEK Prototype SN A01. The former owner Virgil Sipes was a VideoEngineer at the Beaverton plant. I think he was laid off some time in the 80s. Not sure if he was given equipment, or bought it from TEK.He met the renowned Audio Engineer Wally Heider, became good friends with him, worked on projects together, then went on to start his own video production company Teletek Video.You may notice several big differences between an early prototype 576, and production models. There are some in the photos.1.) Front panel lettering differs around switches and controls2.) Focus does not have a knob, it's a plastic slotted screwdriver adjustment.3.) I think the main one, the CRT bezel is quite different. Attaches via a plastic release. Also no TEK model plate. Also scratched where someone removed a sticker.4.) The serial number is A01, not a production serial number, such as Bxxxxxx.5.) The CRT. No distinguishable TEK part numbers, and also appears to have some kind of ceramic coating.6.)The Interface Module (rear) only one connector. No other wiring inside for other connectors.7.)No photos, but all the internal wiring is not bundled at all. I assume for quicker wiring changes. Also found unused wires taped at ends.Let me know if you see other differences!The bezel glass and blue filter had what seems like soda pop splled into the Filter sandwich. Etched the glass a bit. Some was still slightly liquid. Was able to remove most of the etching.My other 576 has a very weak CRT with double peaking. Swapped the tubes. The prototype tube seems to have very low hours. Extremely bright, withonly mild burns at 0Vert 0Horiz. After I swapped the tubes, I thought wait, I need to photograph it for you 576ers out there, so out it came again, for photos.A B&K 467 CRT restorer should be here soon to see if I can bring the dim tube back, it is a -05 CRT, which I think was the last version made.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 10, 2023, 03:25:10 am
content: Almost forgot... what looks like possibly the biggest adapter find yet that I know of, also from Virgil. Wipe up all that messy drool.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 10, 2023, 04:05:06 am
content: I have a question for anyone highly knowledgeable on the 576, and in particular the CRT. It almost looks like what I thought were burn marks, may not be at all. Anyone know about the graticule etching process they did on these tube faces?

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 10, 2023, 05:55:07 pm
content: I see now why they did not implement this ceramic prototype CRT build into production models. Too expensive to build!If you have a real interest, here is how they manufactured ceramic CRTs. Takes a bit of dedication to watch this film, and the kooky music that plays!https://vintagetek.org/building-a-ceramic-crt-1967/

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 10, 2023, 06:01:15 pm
content: As the old Master Card ad would say: “priceless”.

author: Testtech
author_rank: Regular Contributor
timestamp: July 12, 2023, 12:49:47 am
content: All the 576 instruments have ceramic funnel tubes.By the time the 576 came out in the late 1960's I think most if not all Tek CRT's used the ceramic funnel technology.As for the internal graticule, these were silk screened on.The tube in the photo does not seem to have any burns, but it does have some broken corners from rough handling. Be careful with this very hard to find CRT!

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 14, 2023, 04:05:30 am
content: Quote from: Testtech on July 12, 2023, 12:49:47 amWell then! Not sure where you are getting your information on the 576 CRTs. I have two 576's... the Early Prototype, and a much later production version. The later production unit came with the -05 CRT the last version as far as I am aware. It is all glass. No ceramic. (I made a correction to these statements in a later post)Can you give any links that substantiates your claim they were ALL ceramic CRTs? I saw that corner of the CRT in the photo. I didn't actually notice it looking at it. The person that shipped this 576 to me had no idea how to pack it. It barely fit into the box, and a thin layer of bubble wrap. So pretty sure it happened then. Amazing there wasn't severe damage.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 14, 2023, 05:28:18 am
content: Quote from: Testtech on July 12, 2023, 12:49:47 amThe internal graticule on the 576 CRT was not "silk screened on" it was actually etched right into the inner front glass plate. That seems to be fairly common information.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 14, 2023, 01:59:08 pm
content: Because the Production CRT is painted blue on the funnel it threw me. You can see the ceramic unpainted at the fusion of glass to ceramic. So I stand corrected.These are photos of the -05 CRT. No blue paint or raised logo evident on the prototype tube.