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My preference is for denatured alcohol. It's ethanol that had methanol added so you won't drink it. When I worked for the government we used high proof alcohol because we didn't have to pay tax. If you have access to high proof alcohol don't drink it at higher than 195 proof. They use benzene to remove the last bit of water, and benzene is carcinogenic. I haven't messed with the pure stuff since 1964, in case anyone is worried about my liver. These days I stick with moderate quantities of beer and wine.

On Thu, 21 Feb 2019 13:36:03 -0800, you wrote:

Yeah, Tom, it's a good idea to have at least a second unit of any of this old equipment.? For comparison and for parts.? Now if I could just sell my wife on that idea....Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

Hmmmm.....

You spent X dollars and Y amount of time fixing this up.

What happens if the power transformer goes? what of the CRT? Where
do you get spare parts a few years down the line?

Best to get a spare now, if you can. They just don't make the parts
any more.

(Owner of two 7904s and 3 parts units...; we'll just cut the
discussion short at that....)

Harvey

-------- Original message --------From: fiftythreebuick <ae5i@...> Date: 2/21/19 1:21 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek 555 K601 contacts chattering and sparking Hey Matt, you are NOT a pest!? :-)Whatever you do, don't quit on it.? There's nothing else like a 555!? A real pleasure to operate and extremely versatile!? When you consider the range of plug-in units that are available and the fact that you can have two totally different ones in play at the same time (a spectrum analyzer and a standard vertical, for instance), it's just a wonderful instrument.I would be surprised if you'd get much useful info from running the power supply without an indicator connected.? Hey, that's just a good reason to get a second 555, so you can mix and match indicators and power supplies for troubleshooting!? ;-)Please don't hesitate to contact me off list if I can help...Tom

jim, are you talking about the 2 tiny wires on the side of the crt

For contacts and switches we use a product called Cramolin, could be de-o it by another name but I don’t think so. This is fairly slippery liquid. We put it on with a que-tip and scrub a bit then wipe off all excess. In the end there is clean gold with a layer of lubricant.

An aside about alcohol, one of the Systems we support is a missile test set used in several countries and the US. Installations range from 20 to 30 years and we have seen an interesting problem come up in the cannon connectors. These have been cleaned for years w/isopropyl and in humid environments have shown nearly 150 mV across the face of the connector. That is voltmeter applied to the rubber insulator on each side of a connector face. Needless to say this messes up sensitive readings, so I would use caution when cleaning with Isopropyl

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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I have worked with Tek scopes since these “blue beauties “ were being manufactured. But for many years I didn’t actually own, or even want to own, one. But one night, perhaps 15 years ago, I dreamt about a Tek scope. When I woke up, I was hit with the thought “I bet there are some of them on eBay.” Share enough I found an RM502 for 50 bucks. So I bought it. I was smucked with amazement when I plugged it in and it actually worked. Six months later I realized I now had 50 of the things. So be careful what you wish for, right?

But to return to the topic of acquiring another one. Prices on eBay have gone through the roof. There is a power supply on there the guy wants $399 for. Plus shipping. So eBay is pretty much a wasteland for big blue these days. If any show up. Flea markets, Craigslist, yard sales, that kind of thing may be more productive. From Maine I wonder if places like MIT and other universities might have flea markets like cal tech has once a month.

Then there is shipping. I have received a 555 packed in one box! The cost of ups or fedex could be $400+ Just to show you what global shipping has done to prices, I recently purchased a scope on eBay that global shipping wanted $170.00US to ship. I talked to the seller and he shipped it by fedex for $106.00US. So this program has significantly increased the cost of shipping which was already too high. And I won’t even go there to shipping damage.

Thanks Siggi, I'll try and have a look at it once again after this weekend. I know it's probably something simple.

That's the technique I used to clean seriously oxidized contacts on a 60 year old tube tester. DeOxit is great stuff. - Jim

Chiming in on ad-hoc variable AC supplies.

We were building an automated mastering console that used 8080 processors. Development was done on an IMSAI 8080 computer and we needed a printer to printout the assembly language source code. All we had was an ASR 33 tele-type that refused to print properly. In abject frustration I hooked up a Tektronix 465 scope (Notice how I’m keeping this on topic.) and looked at the letter ‘A’ coming from the computer and the letter ‘A’ coming from the tele-type. It was then I noticed a 20% difference in the overall timing of the character. I pulled off the cover and in big letters on the tele-type motor was 50Hz. I went to the shop and got a Crown DC300 amplifier, transformer, and an HP 3310A function generator that I set to 50 Hz. Everything now worked. My memory is good because I took a picture of this screwball setup.

George

Hello there: Just an update: On 2465B,

RE: Cover off CAL cooling: During HOR CAL 01, about 2 hrs total, all IC, Hybrid HS and U800 temps just slightly warm, did not need an external fan.

RE: CAL 01: Good instructions, just a few that I puzzled over the routine.

I used TM501, and 2467 as bench scope. Only 3 steps hit limits, fixed by the repeat of those steps.

Checked HOR timing afterwards, really spot on!

Next for CAL 02. Many thanks to Chuck and others for their fine CAL notes!

Enjoy!
Jon

I have one of these Q service shows zero so not sure how much to charge say $15.00 and I can mail it in a padded envelope?

Jim O

thanks guys! if you guys know of any 555 that anyone will part with and sell to me and be happy to ship to the great ole state of Maine keep me posted please! I have been bitten by the bug and I can not atop thinking about these blue beauties!!lol
you all have a great night!

p.s. also if you can think of any really good books or downloads with good information in them I would also appreciate that asa well!

Thank you all for the insights and advice (by the way, I'm from Belgium). This evening I went over to the seller to test it. I'm proud to announce that the Tektronix Oscilloscope Owners Club has received a brand new member! It really is a beauty and more compact than I anticipated.

The scope triggers nicely (tested up to 8 MHz square wave). The screen is still bright enough even on the fastest sweep. Beam focuses OK. All important controls and LEDs work as expected, as far as I could tell. Apart from the aforementioned issues, I noticed that the graticule illumination pot did not have any effect, the bulbs seem to be fully on. The delay time position control is a bit stiff but works, probably just needs cleaning and lubrication. Right handle hinge cap and bottom feet are missing, but that's not a big deal. I didn't notice any other problems, so next steps will be to create an equivalent for the front cover to enable servicing.

Kind regards,
Alexander

On Thu, Feb 21, 2019 at 10:45 AM, Fabio Trevisan wrote:

open the worn out tubes

Hi Fabio:
There is a guy, of maybe more than one, that fixes old irreplaceable television CRTs... but, I've never heard of anyone doing CRTs for scopes. Maybe part of it is because the phosphor, and the phosphor suspension, and the process for processing that in the tube face is not sufficiently known. Another thing is though people might have high vacuum technology, the sufficient skills for working with glass, and the equipment needed, seem to be almost non-existent. Recovering of CRTs...It's doable, I think; but, its not trivial in terms of skill, or investment in the equipment needed.
Regards
Roy

Hi Jim-

Yes sir, one parts unit is a necessity and several would be better! :-) The problem is that so many of these 500 series scopes are either fully functional or nearly so that it always hurts me to cut one up for parts! <laughing> I seem to frequently wind up fixing the parts unit and then having to find ANOTHER parts unit, etc, etc, etc....

Tom

On Thu, Feb 21, 2019 at 10:45 AM, Fabio Trevisan wrote:

space charge

During thermionic emission... where electrons are "boiled off" the filament, or the heated cathode.. they form a cloud in the space around those elements. Literally, it is a cloud of charged particles (electrons), suspended in space, around the cathode, or filament. Hence, the term "space charge."

Hi:
I am looking for a 475, 475A, rear bezel.... the plastic plate (with cutouts) that fits under the rear feet. One from other models might fit too. (If people need the part number, I'll look it up and post it.)
Regards
Roy

Still chasing a working copy or original of the Diagnostics Tape for the
4041.
DaveB, NZ

I once had an RM35 with double-peaking. The beam stayed focused across the initial peak and dip, and only broadened when I cranked Intensity to max.

YMMV,
Dave Wise
________________________________________
From: [email protected] <[email protected]> on behalf of Albert Otten <aodiversen@...>
Sent: Thursday, February 21, 2019 1:48 PM
To: [email protected]
Subject: Re: [TekScopes] Mechanism of CRT Double Peaking

On Thu, Feb 21, 2019 at 07:45 PM, Fabio Trevisan wrote:

Hello Albert,

I don't see the rationale behind this. With rising grid voltage larger rings
on the cathode disk take part in the cathode current. Moreover, the increasing
electric field strength in space just outside the already exposed smaller
rings makes it easier for electrons there to escape from the cathode. So I
would still expect a monotonically increasing intensity (or better, cathode
current).

Yep, as I mentioned... my rational may be (and probably is) flawed.
Back when I was still struggling with that 464 and romancing the chance there
could be some level of recovery to that CRT, I read a lot of things in a lot
of places... In many of them I encountered widespread use of the term "Double
Peaking" but in none of them I found explanation about the mechanism that
originates the behavior.
I agree that by my own rational, the intensity should always increase (maybe
not at an even, or linear fashion, but always increase).

Hi Fabio,

I searched around here and via Google and must say that nearly always cathode degradation is mentioned as the cause of double peaking. I hink now the explanation could be as follows.
The phenomena you describe lead to a quick increase of aperture when intensity is increased. Then the beam gets de-focused and that might produce a decreasing brightness for the observer, despite a monotonically increasing beam current. As soon as the aperture is at its maximum, the brightness might start to increase again.

Albert

The 1A contacts and the 10B contact are also closed in those positions.? I don't have a PG506 with me now to check further.

Bob.

Hello--

I have a Tek 555 manual as part of a bundle of Tek manuals (see below).

I'm offering all of these manuals as a group to free some shelf
space-- hence the bundle costs $26.00, or if you're only interested
in the 555 manual, that's also $26.00.

The price includes USPS media-mail shipment to U.S. locations.
***
Tek RM35A (also marked "535"-- probably shares most of the circuitry)--
in very good condition; no serial number
***
Tek 555/21A/22A, serial no. 11455; in good condition, but plastic comb binding
is breaking up, and rear cover is detached. Front cover is partially detached
and the front (title) page is partially torn.
***
Tek 453A-1/2/3, s/nB70383; in very good condition.

Scope-mobile 200-1 062-0870-00, May 1969 (R), 8 pp. double-sided. (For 475-size scopes)
*
4957 Series Graphics Tablet Instruction Manual, 070-4784-01, Product
Group 15, Nov.1986 (revised); approx. 72 pp., in 9-inch by 7-inch three-ring
binder.
*
TDS 200-series Programmer Manual, 071-0493-01, approx. 220 pp., wire-bound,
in as-new condition.
*
11401 and 11402 Programmers Quick Reference, 070-6255-00, Product Group 47,
1988 first printing. approx. 80 pp., wire comb-bound (9-inch by 4-inch format),
In very-good-minus condition (front cover creased).
*
DSA 601A and DSA 602A Digitizing Signal Analyzers Quick Reference, 070-8183-00,
Product Group 47, 1991 first printing. approx. 60 pp., wire comb-bound (9-inch by
4-inch format), In good-plus condition (front cover creased, wire comb? slightly distorted).
*
P6231 10X Active Probe, DC to 1.5 GHz, Instruction Manual, 070-6027-00 Product
Group 60, revised 1987, (8 1/2 inch by 5 1/2 inch plastic comb binding) approx 40 pp.
In very good condition (front cover slightly faded)
****
Questions welcomed, PayPal honored.

Thanks, and 73--

Brad AA1IP
--
Sent from Postbox <>