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Re: Those funny 311-0603-00 pots

snapdiode
 

According to the MSDS, etching cream is actually ammonium bifluoride and some other weird chemicals. This has a "severe effect" on Nylon and Delrin.

http://www.edhoy.com/pdf/5303_53003_53004_msds.pdf http://www.edhoy.com/pdf/5303_53003_53004_msds.pdf

I wouldn't go near HF with 15 space suits on.


Re: Timebase and CRT Issues on Tektronix Type 545A

Alex Brinister
 

@Albert: I ran the sawtooth signal through both Timebase A and B. There is still nothing on Timebase A. On Timebase B, it shows up nice and clear (albeit still on half the screen). However, when I change the time division on Timebase A, the sawtooth signal gets very badly distorted, sometimes to the point where it stays distorted. The working sawtooth and distorted sawtooth: Imgur: The most awesome images on the Internet http://imgur.com/a/HHKOT

http://imgur.com/a/HHKOT

Imgur: The most awesome images on the Internet http://imgur.com/a/HHKOT Imgur: The most awesome images on the Internet.



View on imgur.com http://imgur.com/a/HHKOT
Preview by Yahoo




I took out the CRT out of its socket to see if there were any bad connections and whatnot. I also looked at the CRT circuit to see if there was anything going on there. Everything seemed to check out. Looking at the circuit diagram in the manual, it seems there is a very high number of oil paper caps in the CRT circuit. Perhaps one or multiple are dead and need replacing?


Alex Brinister


Re: Those funny 311-0603-00 pots

 

Hi Mitch,
It is not clear which message you are responding to about melting points -
Snapdiodes or mine.

Teflon won't melt with any soldering iron I have ever had in my 45 year
electronics career. I have Thermal Wire Strippers that melt the Teflon
insulation off wire but the blades on that wire stripper glow cherry red.

Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, March 22, 2016 7:01 PM
Subject: RE: [TekScopes] Those funny 311-0603-00 pots

That would depend on how "Butch" the soldering iron is... ;-)
Mitch
N4MF
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Posted by: n4mf_sc@...
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Re: Those funny 311-0603-00 pots

David DiGiacomo
 

On Tue, Mar 22, 2016 at 7:48 PM, <snapdiode@...> wrote:
It melts quite nicely at a temperature that Nylon melts at. I wonder who told me it was Delrin.
Anyhow, I'll try glass etching cream, there's a local store that has it in little bottles.
I'm sure Chuck Harris will be posting any minute, but that's the last
thing I'd use. The active ingredient is HF, which will etch glass and
your fingers, but not most plastics.


Re: Those funny 311-0603-00 pots

n4mf_sc
 

That would depend on how "Butch" the soldering iron is... ;-)

Mitch
N4MF


Re: Those funny 311-0603-00 pots

snapdiode
 

It melts quite nicely at a temperature that Nylon melts at. I wonder who told me it was Delrin.
Anyhow, I'll try glass etching cream, there's a local store that has it in little bottles.

The idea is still to etch the surface so epoxy will grab it.

Chromic acid will etch Delrin and Nylon, but I don't see how I can make the acid easily locally.

The grey end cap is glued to the white part, so I'd guess it isn't Teflon...


Re: Those funny 311-0603-00 pots

 

Hi Snapdiode,
There actually is a glue or adhesive (I'm not sure what the difference is in
the terms) for Teflon. I have a roll of Teflon tape with glue on one side of
it that I can stick down on a surface. It is the only time I have ever seen
something stuck to Teflon.

Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, March 22, 2016 5:46 PM
Subject: RE: [TekScopes] Those funny 311-0603-00 pots

I'll try... I'll also try ammonium bifluoride, if it won't touch it, it's
Teflon...

Of course the paradox is, what keeps the grey end cap glued to the pot?
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Posted by: snapdiode@...
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Re: New guy with a 2225 vertical deflection issue

Steve Cozart <stvn.czrt@...>
 

Hi All,

Just wanted to share my victory repairing my 2225. Using a bamboo skewer, I was able to locate a spot that induced the failure at will, when I pressed on the printed circuit board.



It ended up being the final output transistors in the vertical deflection amp. (Q256 and Q257).

These transistors have neat little heat syncs attached to the frame, and I noted that when the board slightly flexed under the mechanical pressure of the bamboo skewer, the transistor did not budge. I suspected a broken leg or solder joint, and indeed that was the case. The collector pin of BOTH transistors were broken off at the can of the transistor.





I assume heat induced mechanical stress over the years caused the metal to crack. I had to remove the big 7W 330 Ohm resistors to access these two transistors, but that was still easier than removing the whole pc board from the frame. Plus it made testing those resistors a piece of cake, and they were good.

I purchased a pair of 2N3866A off eBay and the scope is now working like a champ!

Thanks for helping me isolate the circuitry based on the symptoms. I don’t know if this is a common failure mode for this model ( 2225 ) but it was definitely the reason my scope was acting up. And I hope this post is useful to someone else facing a similar issue.


Cheers,

Steve









On Mar 9, 2016, at 1:30 AM, stvn.czrt@... [TekScopes] <TekScopes@...> wrote:

Hi Dave, I don't see any discoloration in that corner of the board. It kinda looks like some of the rosin flux hasn't been cleaned fully.

Tonight when I powered it up, it was in failure mode for a short while. Probing with my Rigol scope shows the the voltage at the node that connects R272, R266, and Q256 at roughly 35v DC (flat, not much ripple).


The schematic states "+12.5v Centered" and sure enough, later, when the scope had magically fixed itself, that same node was at roughly 12v with copy of my input waveform on it (roughly 3v peak to peak).


If memory serves me, the node that connects R267, R273, and Q257 was at roughly 12v with in inverted copy of my input waveform on it while the scope was in both failure mode and operational mode.



So I know I'm in the right ball park. And this seems to rule out a failure inside the CRT, and the wiring from the main board to the CRT deflection plate. Like you mentioned earlier, it could be an intermittent open in one of those big 7watt 330 ohm resistors. I wish I had measured them before powering up.


So I gotta start working my way back.



Using a bamboo skewer (thanks for the idea) I poke and prodded the area. I can make the waves jump a bit, but not go into serious failure mode. No spot seem to be extra sensitive to light pressure or tapping with the bamboo skewer.


Will try agin tomorrow. I have my Rigol, and multi meter all ready to go. Just need the 2225 to fail again.


[Non-text portions of this message have been removed]




[Non-text portions of this message have been removed]


Re: Those funny 311-0603-00 pots

snapdiode
 

I'll try... I'll also try ammonium bifluoride, if it won't touch it, it's Teflon...

Of course the paradox is, what keeps the grey end cap glued to the pot?


Re: 7A22 Differential Amplifier Calibration

 

Can you make a measurement of the rise and fall times (check both just
to be sure) in the working configuration and non-working
configuration?

I do not remember what mainframe and timebase you are using but a 100
MHz mainframe like a 7603 and 100 MHz timebase like a 7B53A are more
than fast enough to do this. You may need to use the fast rise or
fall output from your PG506; I do not remember if the other outputs
are fast enough. The square wave output on my 3 MHz function
generator was not quite fast enough but only contributed like 10%
error.

My 7A22 measured very close to 350 nanoseconds which equates to a 1
MHz bandwidth. I am hoping that asymmetrical rise and fall times or
something about the difference between working and non-working reveals
something.

On Mon, 21 Mar 2016 18:54:14 -0000, you wrote:

...

I am attaching two photos which hopefully show the traces that I see. A 50mV
1KHz square-wave from a PG506 is connected to the +ve input of the 7A22 with
DC coupling in both cases. The photo “Input+ve_Input –ve GND” is what shows
when the –ve input coupling switch is at “GND”. It seems like pretty good
square-wave to me. The photo Input+ve_Input-ve DC” is what appears when the
–ve coupling switch is set to “DC”. A rounding of the upper leading corner
can be seen. According to the Service Manual, the aberration should not
exceed ±1%. Is this so in my case and how can one estimate or measure that
anyway? If the 50mV 1KHz square wave is connected to the –ve input, there
is no perceptible change when the +ve input coupling is changed between
“GND” and “DC”.

I haven’t adjusted C241 at all. It has occurred to me that some insect may
have crawled into the zone where C241 and C141 are located and died close to
C241, changing the capacitance just enough…..

Colin.


Re: Those funny 311-0603-00 pots

 

Hi Snapdiode,
There is a slim chance it might be Teflon which is white and almost
impossible to glue. One way to tell if it is Teflon is that it will feel
extremely slippery to the touch. Another way to tell is that Teflon has a
very high heat resistance. If you hold a soldering iron to it nothing
happens.

Dennis Tillman W7PF

-----Original Message-----
Sent: Monday, March 21, 2016 6:25 PM
Subject: [TekScopes] Those funny 311-0603-00 pots

I thought the white part is made of Delrin, but so far it has shrugged off
every glue and solvent I threw at it.
MEK, dichloromethane, hot glue, cyanoacrylate, plastic bonder epoxy,
nothing affects or sticks to it.

How can I be sure the material is Delrin, and not say, Nylon?
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Posted by: snapdiode@...
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Hoard of gear for sale in NYC

Paul
 

Hi Folks -

Those in the NYC area may want to check this out. I picked up a 7854 (needs work), but he's still got a room full of scopes, meters & gak. Lots of 7603s, some 7k series plugins, a few 475s, fluke meters, etc...
He's hosting an open house this Saturday from 12pm-5pm @ 562 west 162ND street. His name is Will, and he's reachable at (347) 688-3051

No affiliation, just helping out. He really just wants to get rid of it, so head on over & make a reasonable offer! I took some pics for him, that he'll be putting on the Craigslist post shortly.

http://newyork.craigslist.org/mnh/atq/5500135099.html http://newyork.craigslist.org/mnh/atq/5500135099.html
Cheers,
Paul


Anybody have a Xantrex XT-series schematic?

 

These are great power supplies, the XT series started out as Xantrex, then became Sorensen, and were private labeled to at least one other company. The manual for them is all over, BUT the schematic is removed.

I'd really like to fix and adjust two I have, but need the schematic, all models have the same print, the manual (which I HAVE) explains the parts changes. Does anybody have the missing schematic? I could really use a copy.

all help appreciated,
all the best,
walter (walter2 -at- sphere.bc.ca)


11K frame power supply and other boards

 

In our pile of 11K stuff (for stuff day), there is a complete 11401/402 power supply assembly (known good), a universal 11K PSU regulator card, an 11402 memory card, a waveform compressor card and two big system cards, plus the rear IEEE488 interface panel and board. All look good, anti-static wrapped, and should be a big help to anybody with 11K stuff to support. Like to sell it all as one cheap lot. We used to have a bunch of 11K frames, but all gone now, so these spares can leave too.

Let me know if any interest, I can give you all the 670 assy. number and pics if required.

all the best,
walter (walter2 -at- sphere.bc.ca)
http://www.sphere.bc.ca/test/


Tek 7D01/DF2 Logic Analyzers and P6451 pods

 

If anybody is looking for 7K compatible logic analyzers, I have two 7D01's, one with a DF2 formatter, and 4ea. of the wickedly hard to find P6451 pods.
These were all working when I pulled them from frames last year, but have to say as-is now, since I don't see the pod leadsets anywhere. I have some other leadsets and grabbers that might work, but don't know the Tek p/n of the intended one, or exactly what it should look like.


Anyway, these will go out for stuff day, there is a way to get them back to the USA with no shipping with Larry to the Oregon area. Let me know if anybody is interested in them, we don't have a lot of dollars tied up in them so the whole batch (2 ea. 7D01, 1 ea. DF2, 4ea P6451) can go for $120 if anybody wants them. Appearance is excellent on all items.


all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
http://www.sphere.bc.ca/test/


Re: X-Y mode for Tektronix 2465A

cmjones01
 

On Tue, Mar 22, 2016 at 4:46 PM, ballen4705@... [TekScopes] <
TekScopes@...> wrote:

Chris, that was the answer, thank you very much! It's obvious once you
realise that all four channels by default are modulating the Y position.
Problem solved. Cheers, BruceOutlook, AOL and more) in one place. Never
delete an email again with 1000GB of free cloud storage.
You're very welcome! I'm glad to hear it worked for you.

Chris


Re: Those funny 311-0603-00 pots

Ed Breya
 

For anyone needing to glue polyethylene or other tricky plastics, I think there are special adhesives meant for that. I bought some a while back at an auto parts store, but haven't tried it, so don't know if it actually works. As I recall, it had an extra bottle of a surface-activating chemical that had to be applied before the adhesive. It should help to roughen up the surface too, with an abrasive.

Ed


Re: 475a, no trace

satoperator@...
 

Thank you Tom, Dave and Raymond for your suggestions. I did check the 15V bridge last night and it's ok so I likely will swap out a few of the IC's and see what happens as I'm getting some wacky voltage readings around them. I will keep the group posted on my progress or lack of.

Gary


Re: Tek 485 - Intensity at Max, Cannot Adjust Down

EB4APL
 

Hi,

It smells like a DC restorer problem. The best test is to replace the diodes unless you have facilities to test the leakage at high voltage, the circuit is very sensible to diode leakage and a DMM test usually is not enough. Since anyway you have to remove them, it is safer to replace them. Another suspects are the restorer's capacitors.

Regards,
Ignacio


Re: X-Y mode for Tektronix 2465A

ballen4705
 

Chris, that was the answer, thank you very much! It's obvious once you realise that all four channels by default are modulating the Y position. Problem solved. Cheers, Bruce