From: Chin Siang Lim
Subject: Re: [TekScopes] Question on what to do with 4 pallets of scopes...
To: "TekScopes@..."
Date: Monday, February 18, 2013, 3:00 AM

?

Hi chuck,?

Walter of is doing a brisk business clearing his pallets of tek scopes and accessories.?

Active marketing does create sales.?

Maybe?you want to consider scrapping scopes??below 100 MHz and all those 5000 series but hold back on those 7000 series and 100 MHz and above scopes. And list those 100 MHz and above scopes for sale ? By showing s few photographs. Thatway some monies are flowing in plus?more to come.?

Selling at scrap plus is attractive for people like us.?

Cslim

On Monday, February 18, 2013, wrote:

?

Hi Chuck

To be honest if I had four pallets of TEK scopes I would break them up for spares as I don't think anyone is going to buy this stuff especially the tube scopes.

The only buyers for old TEK scopes are hobbyists and collectors and those who want a realtime wide bandwidth CRT scope. Technology has moved on, scopes are digital these days with A-D converters sampling at N GHz and all in a cute little box.

I want a scope that works when I switch it on, not with a power supply that goes bzzt, bzzt, tick, tick because some cap has gone short circuit or some corroded part in a socket isn't making contact.

In short, there really isn't much of a market for old TEK scopes.
They were great in their day but not so good 30 or 40 years later.

Best regards
Chris

--- In TekScopes@..., Chuck Harris wrote:
>
> Here's the thing:
>
> I have 4 pallets of tektronix scopes taking up space in my
> warehouse. One pallet is mostly 7000 series, with a few
> 5000 series mainframes, another is a mix of 7000 and 5000
> series rack mount scopes, with a 564. The third is mostly
> 453's, 454's, and a few odd 434, 464, 465, 466, 475, and 485's.
> And the fourth has a 585A, 545A, and 535A on it... the '45
> and '35 were beautiful before the tube whores stripped them...
> but recycler's don't get the luxury of judging, they just take
> what they get.... ixed in with all of this are several large
> boxes of plugins... nothing sexy, but the usual 7B53A's, and
> 7A16, 7A26, 7D14, kind of stuff...
>
> I love cleaning, fixing, calibrating and restoring scopes
> into good working condition. I have all of the Tek specified
> gear for doing this, but judging by ebay sales, buyers don't
> seem to value that effort at all.
>
> To give you an example. I found a DOA 434 in my stash, and
> because it was so cute, I cleaned it up, fixed a power supply
> problem that stumped the original owner, replaced a tantalum
> on one of the boards, fixed a really nasty trigger problem,
> that was caused by the power supply problem, lubed all of the
> pots, cleaned and lubed the panel switches, and fan, cleaned
> the attenuator contacts, and did a complete calibration. It
> took me a week of evenings to do the work. When it was put on
> ebay, as cleaned, calibrated, and guaranteed, it got a couple
> of $15 offers, and it remains unsold... as does its twin that
> I did in hopes of a better result...
>
> At current US scrap prices, I can get $17 per pound for gold
> plated circuit boards, which is the standard price recyclers
> are giving these days... I work with a recycler, so I am very
> sure of these prices... There is easily 2 pounds of circuit
> boards in a 434 [vertical, horizontal, storage, preamps, and
> power supply are all gold plated]. The 453's and 454's have
> easily 5x more...
>
> Considering how much you folks are yipping and yapping about
> tunnel diodes, and how hard they are to find, I could have
> gotten more than $15 if I simply removed the two diodes in
> this 434, and sold them on ebay. And I would still have a
> good CRT, the aluminum from the chassis and can, the gold
> plated circuit boards, a bunch of special IC's, etc... I have
> gotten $5 just from a knob, and $15 from just selling one CRT
> filter!.... to sell.
>
> What's the answer? I keep hearing about how much you guys
> love Tektronix and their scopes, but when one sells for less
> than a tankful of gas, I have to wonder if it is all just
> dreamy nostalgia talk. When a couple of days worth of cleaning,
> repairing, and calibration is worth less than you would pay
> for a dinner out with someone you don't even like all that
> much... Where is the love?
>
> What's it to be? Do I fix them, or Do I scrap them?
>
> What shall I do with these scopes?
>
> -Chuck Harris
>

"Rob" <rgwood@...> wrote:

I do not think the person selling this in knowingly doing something wrong.
However, (correct me if I am wrong it is why I posted) the ends do not
appear to me to belong together. Other than the obvious I discarded
prior..Any ideas as to why someone would do this?

Hmmm...the label on the comp box says P6022, but it's not like any P6022
or P6022 termination I've ever seen. I wonder if the 010-067 number
would turn anything up.

-ls-

The +87 is from a doubler and added to the +42. I would take a close look

Since you recapped this unit, don't overlook the fact that bad capacitors

Regards,
Tom

Hi all,

I have a TDS684A scope that has a problem on the CRT driver board. I've noticed that R294 is discolored. Can anyone tell me what the value of this component is? It measures 2.7K ohm, and it might be correct because I can see the color band is red-purple-????. The 3rd color band is too discolored to tell what it is. If it's red then the value is correct, but I can't tell due to the burn discoloration.

Can anybody tell me what value R294 should be?

Does anyone have schematics for these CRT driver boards? The TDS520B component service manual only has the B&W display schematic :(

Thanks,
Mike

Hi all,

I have a TDS684A scope that has a problem on the CRT driver board. I've noticed that R294 is discolored. Can anyone tell me what the value of this component is? It measures 2.7K ohm, and it might be correct because I can see the color band is red-purple-????. The 3rd color band is too discolored to tell what it is. If it's red then the value is correct, but I can't tell due to the burn discoloration.

Can anybody tell me what value R294 should be?

Does anyone have schematics for these CRT driver boards? The TDS520B component service manual only has the B&W display schematic :(

Thanks,
Mike

I have a 475 scope, but pretty much a beginner in its use. I want to measure RF frequencies in a ham tranceiver that could be as high as 800 VDC, and up to 30 Mhz. My question has to do with the proper type of probe. Is anything special needed to measure RF frequencies that could be generating significant power other than a common probe? Does the scope need protection from high power RF? I want to at least see what is going into the grids of the final amplifier tubes.

----- Original Message -----

From: Richard

To: TekScopes@...

Sent: Sunday, February 17, 2013 11:53 PM

Subject: [TekScopes] Basic Probe Question

?

I have a 475 scope, but pretty much a beginner in its use. I want to measure RF frequencies in a ham tranceiver that could be as high as 800 VDC, and up to 30 Mhz. My question has to do with the proper type of probe. Is anything special needed to measure RF frequencies that could be generating significant power other than a common probe? Does the scope need protection from high power RF? I want to at least see what is going into the grids of the final amplifier tubes.

Hi Walter,
Will take 6 of the hp 848x sensors at 7 dollars if that is ok with you?
Cslim

Those unregulated supplies all look good. I would concentrate on the +87 first since all the others are dependant on it. You might check the drop across R1221, the current limit shunt. At least check the resistance.

Tom
----- Original Message -----
From: Chris
To: TekScopes@...
Sent: Sunday, February 17, 2013 8:39 PM
Subject: [TekScopes] Re: Tektronix 2465 capacitors etc.



All voltages measured in the scope with everything hooked up. I just got done checking the voltages pre-regulator.

At J233A I get:
pin 5 (87v unregulated) 97.6v
Pin 3 (42v unregulated) 49.0v

And at J234A I get:
pin 5 (15v unregulated) 18.94v
Pin 4 (5v unregulated) 6.64
Pin 2 (-5v unregulated) -6.92v
Pin 1 (-15v unregulated) -18.54v

Based on the unregulated values, I believe the issue must lie in the regulator portions, and since I'm getting the 97.6v pre-regulated it would seem to me the voltage doubler is working. I also double checked and verified the 10v reference voltage at the test point on the main board as well as the J121 connector that feeds the main board. (I figured this was important to double check as the regulators all are based off the 10v reference as I read it). Of course this is where I wish to learn more - I understand what the individual components do but I still somewhat struggle to see what the assembly as a whole is doing, which is why I'm trying to get into all this, so maybe my understanding is skewed. :)

At any rate, it would seem to me that with the unregulated voltages where they're at, that the issue would have to lie within the follow area:

Yes? No? I mean I have the correct voltages on the left side of those three groups, and the wrong voltages on the right side, so it would seem that's where I should look next?

Thanks for helping this newb out!

Chris

--- In TekScopes@..., "Tom Miller" wrote:
>
> The +87 is from a doubler and added to the +42. I would take a close look at the three 10 uF caps and all the diodes in that area. Be sure to only use fast diodes for any replacements.
>
> Since you recapped this unit, don't overlook the fact that bad capacitors can come from the factory new. Did you measure all these voltages in the scope or on an external load?
>
>
>
>
> Regards,
> Tom
>
>