Date   

Re: Tektronix 7104 and 7D20 showstopping?

Don Black <donald_black@...>
 

That and the Columbia were very sad events that shouldn't have happened. They were perfect examples of Murphy's law.

Don Black.

On 08-Apr-13 6:43 AM, Dave Daniel wrote:
 


On 4/7/2013 12:25 PM, Craig Sawyers wrote:
 

[snip]

But as you say - there is no possibility of doing a service visit! Once the
rocket goes - it either works perfectly 100%, or it is a complete and utter
failure. There is a price for that degree of confidence.

Craig

Slightly off topic:

We used to watch the space shuttle launches from the StorageTek parking lot in Palm Bay, FL. I remember one time when I was working through a MIL-217-based reliability assessment of one of my processor board designs and we went out to see a launch, my boss remarked to me something like, "Now those guys need to understand reliability!".

We watched the Challenger disaster in '86 from the parking lot. Not much got done in the engineering building for the rest of the day.

DaveD





Re: Curve Tracer vs. Octopus

Don Black <donald_black@...>
 

Well, I'm an old fart but definitely interested.

Thanks, Don Black.

On 08-Apr-13 6:13 AM, magnustoelle wrote:
 



Hello again,

well, somehow I got inspired again and I have pulled out and played with my component tester over the weekend.

If the subject is of general interest, I am happy to post some more pictures and a write-up of setup-details on the usage beyond Alan's excellent video. I have used it to test Germanium- and Si-Diodes, a LED and as a very simplified transistor tester. I do not have the time or equipment to create videos, but I surely have the time to create some write-ups.

While all this is an old hat for most senior group members, it might be of interest for some beginners among us. Just let me know...

Cheers,

Magnus



Re: Sad story - scrapping old Tek scopes for the gold

teamlarryohio
 

"Alex" <alexeisenhut@gmail.com> wrote:
We live in a poor world, people do what they can to survive.
If you have time watch the BBC doc "welcome to india 2012", you don't
want to know where they find their gold.
Scrapping a scope for gold is luxury.
I watched a friend's kid (copper reclaimer) nearly cut the cable off a
brand new A6302 current probe. Less than maybe a penny's worth of
Cu or a $300 probe. Go figure. He gave it to me intact, along
with a working Halli SX-25 :-)
-ls-


Re: Sad story - scrapping old Tek scopes for the gold

Alex <alexeisenhut@...>
 

We live in a poor world, people do what they can to survive.
If you have time watch the BBC doc "welcome to india 2012", you don't want to know where they find their gold.
Scrapping a scope for gold is luxury.

--- In TekScopes@yahoogroups.com, "keithostertag" <keitho@...> wrote:

At the Timonium (Baltimore) Hamfest this past Saturday I talked with a seller briefly about a 465M he had on a shelf. It was badly damaged- looked like it had dropped or crushed, though the CRT wasn't cracked. When I asked him how much he was asking for the 465M he said "What's that?"

Turns out he was just one of those guys living on the get-free-sell cheap plans. Didn't know where it came from or what it was. He told me he could get $15 or so just from scrapping it for the gold on the circuitry.

I was tempted to save it, but really I have too many projects as it is and I don't have the expertise most of you have.

I am amazed that with all the labor and energy and time it takes to store, transport, and extract the tiny bit of gold in the scope that it could fetch $15 (or more). I guess with gold at the prices it is today all kinds of things are possible...

What would you have done? Do you think you might have been tempted to save it or part it out, even if you don't yourself need those parts?


Re: Sad story - scrapping old Tek scopes for the gold

bonddaleena@...
 

Keith, reminds me of a sad story back when I worked for IBM in Lexington, Ky....

One of my buddies who was on a smoke break, came into my office and said,: "Ron, you have GOT to see this!".
He knew I was a ham and showed me a huge dumpster next to the building we were in. The whole bottom of the dumpster was filled with Tek scopes and carts. Seems the lab was 'upgrading' to newer models and just trashed them. IBM had a strict policy against 'dumpster diving', but I was sorely tempted.
In later years, this surplus equipment was given to the local schools, where I heard, the students, parted them out for components!!!
Near the end of my career, the stuff started showing up in the local surplus junque shoppes........

ron
N4UE



-----Original Message-----
From: keithostertag
To: TekScopes
Sent: Sun, Apr 7, 2013 7:15 pm
Subject: [TekScopes] Sad story - scrapping old Tek scopes for the gold

 
At the Timonium (Baltimore) Hamfest this past Saturday I talked with a seller briefly about a 465M he had on a shelf. It was badly damaged- looked like it had dropped or crushed, though the CRT wasn't cracked. When I asked him how much he was asking for the 465M he said "What's that?"

Turns out he was just one of those guys living on the get-free-sell cheap plans. Didn't know where it came from or what it was. He told me he could get $15 or so just from scrapping it for the gold on the circuitry.

I was tempted to save it, but really I have too many projects as it is and I don't have the expertise most of you have.

I am amazed that with all the labor and energy and time it takes to store, transport, and extract the tiny bit of gold in the scope that it could fetch $15 (or more). I guess with gold at the prices it is today all kinds of things are possible...

What would you have done? Do you think you might have been tempted to save it or part it out, even if you don't yourself need those parts?


Sad story - scrapping old Tek scopes for the gold

keithostertag <keitho@...>
 

At the Timonium (Baltimore) Hamfest this past Saturday I talked with a seller briefly about a 465M he had on a shelf. It was badly damaged- looked like it had dropped or crushed, though the CRT wasn't cracked. When I asked him how much he was asking for the 465M he said "What's that?"

Turns out he was just one of those guys living on the get-free-sell cheap plans. Didn't know where it came from or what it was. He told me he could get $15 or so just from scrapping it for the gold on the circuitry.

I was tempted to save it, but really I have too many projects as it is and I don't have the expertise most of you have.

I am amazed that with all the labor and energy and time it takes to store, transport, and extract the tiny bit of gold in the scope that it could fetch $15 (or more). I guess with gold at the prices it is today all kinds of things are possible...

What would you have done? Do you think you might have been tempted to save it or part it out, even if you don't yourself need those parts?


Re: Tektronix 7104 and 7D20 showstopping?

Dave Daniel
 

Absolutely mind-numbing.

Most people went home at mid-day. Most people brought back TVs. The afternoon was spent trying to get work done, and (universally failing that), wandering around and watching the various news stations' coverage.

On 4/7/2013 4:17 PM, Craig Sawyers wrote:
 

=====================

We watched the Challenger disaster in '86 from the parking lot. Not much got done in the engineering building for the rest of the day.

DaveD

 

Jeeze.  We all stood still that day.  I cannot imagine what it must have been like to have been right there.

 

Craig




 







Re: Tektronix 7104 and 7D20 showstopping?

Craig Sawyers <c.sawyers@...>
 

=====================

We watched the Challenger disaster in '86 from the parking lot. Not much got done in the engineering building for the rest of the day.

DaveD

 

Jeeze.  We all stood still that day.  I cannot imagine what it must have been like to have been right there.

 

Craig




 






Re: 7854 firmware

Dave Daniel
 

AND ... What was the last revision?

DaveD


On 4/7/2013 11:44 AM, kngtron wrote:
 

does anybody know how many versions of 7854 firmware there are ??
i did get my 2 7854's up and running with 1.03 and no patch rom needed



Re: Tektronix 7104 and 7D20 showstopping?

Dave Daniel
 


On 4/7/2013 12:25 PM, Craig Sawyers wrote:
 

[snip]

But as you say - there is no possibility of doing a service visit! Once the
rocket goes - it either works perfectly 100%, or it is a complete and utter
failure. There is a price for that degree of confidence.

Craig

Slightly off topic:

We used to watch the space shuttle launches from the StorageTek parking lot in Palm Bay, FL. I remember one time when I was working through a MIL-217-based reliability assessment of one of my processor board designs and we went out to see a launch, my boss remarked to me something like, "Now those guys need to understand reliability!".

We watched the Challenger disaster in '86 from the parking lot. Not much got done in the engineering building for the rest of the day.

DaveD




Re: Curve Tracer vs. Octopus

magnustoelle
 

Hello again,

well, somehow I got inspired again and I have pulled out and played with my component tester over the weekend.

If the subject is of general interest, I am happy to post some more pictures and a write-up of setup-details on the usage beyond Alan's excellent video. I have used it to test Germanium- and Si-Diodes, a LED and as a very simplified transistor tester. I do not have the time or equipment to create videos, but I surely have the time to create some write-ups.

While all this is an old hat for most senior group members, it might be of interest for some beginners among us. Just let me know...

Cheers,

Magnus


Re: Vacuum? ESD fixes....

petertech99h
 

Lang,

If you are lucky, some surplus outfits that pick up factory equipment close-outs may be sitting on
a pile of ionizing blowers.  They can cost $600 + new,  I got 8 for $100 each!  When you
buy, turn on, check for HV discharge noise and use the invisible tape test, pull a 6 inch length fast,
observe that it wants to jump to you hand, etc, then hold it in the air flow, should be limp and
discharged in seconds.  My fav is the Simco Aerostat XT with a plug in probe, it speeds up and slows
down depending on sensed static in the work area!!

see ya



From: langlv56
To: TekScopes@...
Sent: Sunday, April 7, 2013 8:05:47 AM
Subject: [TekScopes] Re: Vacuum? ESD fixes....

 
Hi David,
I don't think that so unreal to have 60% of relative humidity. I think that we use to live in an air conditioned room which is quite dry. A good HVAC should maintain in the range of 40..60% relative humidity for wellness, but it's often about 30..40% (on what I saw where I live). It is particulary dry in airplane, around 10..15%, as in a desert.
Simply open the window, there are much more humidity outside (and also dusts...). Per example: currently at San Jose: 82%, Houston=88%, London=40%, Lausanne=61%, Geneva=41%. In my basement (my home lab), it's currently around 65..70% humidity and 5..8degC (40..47degF) Brrrrr.
The humidifier I use is just a poor man solution, but my next purchase in a long wish list will be an ionizing blower.
Bests
Lang

--- In TekScopes@..., David DiGiacomo wrote:
>
> It's not so easy to keep the humidity that high. If you have hard
> water, you don't really want to use an ultrasonic humidifier in the
> lab, and the other types are very noisy and hard to keep clean. I
> think an ionizing blower is simpler.
>
>




Re: 7854 firmware

 

My 7854 has firmware version 2.00 with the combined memory board that
replaced the SRAM and ROM boards.

Based on the service manual and change information I have, it looks
like the old ROM board had:

2 Mask ROM versions
3 FPLA versions
3 Patch EPROM versions

But if the development units up to serial number B010100 had firmware
version 1.00, then that makes for 3 released firmware versions from
1.01 to 1.03 so yours would be the latest before they changed the
hardware.

On Sun, 07 Apr 2013 17:44:08 -0000, "kngtron"
<KNGTRON@worldnet.att.net> wrote:

does anybody know how many versions of 7854 firmware there are ??
i did get my 2 7854's up and running with 1.03 and no patch rom needed


Re: Mild OT question – Checking diodes

PA4TIM
 

They can be tested that way, the Vf is just to high for most meters, but with a CT or octopus, or current limmited voltage source and a multimeter it can be done. I made a 1-25 mA currentsource that has an unoaded voltage of 35V and reads the voltage over the Dut. I use it for testing zeners, HV diodes en leds. 

Fred PA4TIM

Op 7 apr. 2013 om 15:10 heeft bonddaleena@... het volgende geschreven:

 

Hi. In regards to the front/back diode test... the diodes used in microwave ovens won't test that way, either. I guess there are several end-to-end inside the package....

ron




-----Original Message-----
From: Pa4tim <fredschneider@...>
To: TekScopes <TekScopes@...>
Sent: Sun, Apr 7, 2013 4:15 am
Subject: Re: [TekScopes] Mild OT question – Checking diodes

 
There are rare occasions the diod test is not good enough. Also when testing transistors. For instance while reparing a HP4260 the scope showed me where it went wrong. I desoldered that transistor, but I love testing components so i start doing all kind of tests on bad components.

The multimeter diode ceck and it was good on several of my (30) multimters, took my peak component tester, also good. Took a few of my transistortestster ( collect them too) all good. Took my trusty 576 curvetracer and this transtor gave the most funny traces. It was like looking at a capacitor that reacted to steps. A sort of varicap transistor ;-) 

Placed a new transistor and probem solved so the transistor was indeed the problem. Found thanks to ( in this case) my trusty 547 ( most times I use my Hameg DSO for repair, but sometimes I use the 547 because I'm head over heels In love with that scope, would love to have a 556 but my 547 is very beautifull and good on a nice scope mobile and I have no room for a 556. Only have room if it is placed on a ( even more rare) 556 mobile and then instead of my 547.
 
I also found transistors that had a good hFE on the peak component tester and one of my many transistortesters, also diode test OK but in the 576 they showed all curves on the same trace. So hFE was OK for the first base bias current step or better in this case it had a hFE that could be right, but hfe was bad because increasing bias current, that is each next step of the CT, did not increase collector current. A very strange fenomen that I now have seen about 5 times and in Tek and HP silicium tranistors from the 1966-1972 area. Like it is "rusted" in one position and only behaves like a switch, but with very limmited collector current.

Talking about problems from that area and Tek ( and in this case also Guildline and General Radio, not yet found it on HP) i found a lot of cases of tin-rot. In the case of my 1S2 using a microscope  with top and under light, I could see a halo of light around the pins of some transistors and the sample bridge so those pins where complete loose. In a guildline a solder joint just fell fell apart when I probed it with. multimeter. These Solder joints are recognized by a more dark grey matt color as the rest.

Did the USA used other solder around that time ( maybe by law. like everybody  now has to use leadfree solder) on later gear I have not seen this problem ( yet) 

Fred PA4TIM

Op 7 apr. 2013 om 03:45 heeft Bob Albert <bob91343@...> het volgende geschreven:

 
Like anything else, the test is worth something as long as you know the parameters.

The DMM test sends a current through the diode and measures the voltage drop.  It's not a complete test by any means.  If you want something better, you need to do a more sophisticated setup.

For me, almost always, a simple ohmmeter test with a VOM, first one polarity and then the other, serves very well.  If it's a high frequency signal diode, that may not be a good test.  If it's a zener, one needs to break down the junction with a specific current and measure the voltage.

No substitute for knowing what you are doing.

Bob


--- On Sat, 4/6/13, Robert <go_boating_fast@...> wrote:

From: Robert <go_boating_fast@...>
Subject: [TekScopes] Mild OT question – Checking diodes
To: TekScopes@...
Date: Saturday, April 6, 2013, 12:38 PM

 
Had this thought reading Craig Sawyers 7844 repair work:

Recently working on a 485, I used a simple diode curve trace set up. One of the diodes clearly showed bad, probably leaky. Initially that diode would still show some forward reverse difference on a DMM diode test. Does this seem reasonable? I am beginning to doubt the DMM diode test, or if I use the DMM test correctly.

Bob


Re: 7912 Jittery Display

Craig Sawyers <c.sawyers@...>
 

So what caused the jittery display?
Failure in through hole plating on a 6-layer board, on a buried layer. It
was where the characters were added to the y data stream. Once located it
was a matter of wire bypassing the flakey internal layer plating failure.

Craig


Re: Mild OT question – Checking diodes

Craig Sawyers <c.sawyers@...>
 

======================
Craig,

Let me apologize for any suggestion that you aren't knowledgeable. My comment was composed based on the electronics, not on anything to do with your background. I didn't mean to denigrate your abilities. In fact, it was partly meant to inform the lurkers who are here to learn.

Bob
======================

Check. For my part I likewise apologise for knee jerking.

All the best

Craig


Re: Tektronix 7104 and 7D20 showstopping?

Craig Sawyers <c.sawyers@...>
 

================
That's nice he's being recognized for his life's work. I guess that
developments since the 7104 days must have improved the reliability and long
life without deterioration for space work, you can't just take a bus up to a
satellite to change the MCP. Perhaps we can wonder what the latest Tektronix
scope using MCPs would be like if development continued to the present day.
The email cut the link in half, I think this should work OK
<http://www.labcompare.com/617-News/844-University-of-Leicester-to-Bestow-Ho
norary-Doctorate-of-Science-on-Ray-Fairbend-of-PHOTONIS/>
Thanks for the link, interesting it's still leading edge technology.

Don Black.
================

Hi Don

Ray is a really nice guy, and the main man in anything MCP related. The
space applications are quite different and distinct from anything else. In
MIXS there are two curved micropore MCPs (4m radius and 3.3m radius of
curvature) with holes 6um square (the 7104 was 25um, and flat) coated with
iridium. Basically there is a 1:1 correspondence between a dual curved MCP
and a Wolter Type 1 reflective X-ray imager - but at 200g rather than 50kg.
There is no bias voltage in that application.

But as you say - there is no possibility of doing a service visit! Once the
rocket goes - it either works perfectly 100%, or it is a complete and utter
failure. There is a price for that degree of confidence.

Craig


Re: Mild OT question – Checking diodes

iglesia_cristiana_arpas_eternas
 

Hi Bob and all fellows, what is very cheap and usefully , is a small power transformer (in my case 220/12Vac) and inject signal on 12V side 1Khz or less, put a 470K in series with 220V side and apply to a diode or DUT.

Putting the scope probe on DUT, and you will easily see direct and reverse voltage, also the breakdown voltage in some case, I use this to find avalanche transistors for replace in my Tek high level avalanche pulse generator.

Also at the time to repair my Vector Voltmeter HP8405 sample probe, I find that the Avago schotty bridge HSMS-282x rated @15V, work very fine to 25V .

Just a silly tip on check unknown transistor pin lay out, which one is the base or the emitter?

The base emitter acts as a low voltage zener near 7,5 volts in npn, and could rise to 10V in pnp.. the base collector are a full voltage diode
Gabriel.

--- In TekScopes@yahoogroups.com, "Robert" <go_boating_fast@...> wrote:

Had this thought reading Craig Sawyers 7844 repair work:

Recently working on a 485, I used a simple diode curve trace set up. One of the diodes clearly showed bad, probably leaky. Initially that diode would still show some forward reverse difference on a DMM diode test. Does this seem reasonable? I am beginning to doubt the DMM diode test, or if I use the DMM test correctly.

Bob


7854 firmware

kngtron
 

does anybody know how many versions of 7854 firmware there are ??
i did get my 2 7854's up and running with 1.03 and no patch rom needed


Re: Planning 2467B LVPS re-cap

vdonisa
 

Hi Patrick,

Thank you! I took a second look at the circuit. C1350 was an original green cap installed by Tek, and it measured OK. However as can be seen here:

http://groups.yahoo.com/group/TekScopes/photos/album/1314606778/pic/1650565509/view 

it was C1330 that went bad at a certain time in the past and was replaced with the black Chong in the pic.

Now I'm not sure how exactly what happened but assuming that C1330 shorted you would had ground connected to the -8V output (via CR1331 which would conduct) and also to the group R1351/CR1351 (I'm too dizzy right now to follow what it would do when applied there).

Anyway I will check all components there for good health and do the test as you suggested to confirm that the transistor is not overheating anymore.

Thanks,
Valentin VE3VDO


--- In TekScopes@..., "Patrick Wong" wrote:
>
> Hi Valentin,
>
> Regarding the 3 vs. 2 capacitor count: that is an example of why I had earlier posted that you cannot rely 100% on any capacitor list that you might find.
>
> Regarding Q1351, I looked at photos of the regulator boards installed in my 2465A and 2467 and do not see any circuit board discoloration. That transistor is in the -8V regulator circuit and I would not have expected a high current draw there.
>
> While you have the regulator circuit board out, maybe you might:
>
> 1) check the resistors surrounding Q1351, Q1354 and U1270D and
>
> 2) use a couple of lab power supplies to feed -13V to the input, and +10V to the reference point in the circuit, to verify that you get -8V at C1350.
>
> If C1350 was leaky, that might cause excess current flow through Q1351.
>
> Patrick Wong AK6C
>
> --- In TekScopes@..., "vdonisa" vdonisa@ wrote:
> >
> > More trouble: I found out my A2 board has 3 x 1uF/50V unpolarized while the manual I have mentions only 2.
> >
> > ...In addition I noted that the area around Q1351 has a brown coloration from heat. Is this common or should I investigate for something defective there? If it's common, can that transistor be helped with some small heatsink? Anyone that has done such mod?
>

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