Date   

Re: 91% Isopropyl Rubbing Alcohol to clean potentiometers?

Roy Thistle
 

Hi:
I think that high concentration IPA might... but only after prolonged contact (like soaking a part in it, in a closed container) partly dissolve some of the binders, or plasticizers, in rubber or plastic parts (Some of those are to a degree soluble in IPA.) . IPA is, to some extent, going to attack natural shellacs, varnishes, and lacquers (IPA might be similar to the solvents they use.). So caution might be advisable with old electronics, that might have used these in their manufacture.

Most of the chemicals that Bob mentions are de-greasers. As Bob points out acetone (in some nail polish removers) is a strong degreaser (Usually used on bare metal because it can dissolve, or weaken, some plastics, and paints.) Of all the strong degreasers Bob mentions, acetone is available, and is not very toxic (though good ventilation is necessary, and no sparks or flames).

There are also chemicals that are de-oxidizers, anti-oxidants, and lubricants (usually just being one of those kinds of things.) Some "cleaners" claim to be all those things. In other threads there were discussions about the different kinds of Deoxit, for sale. I don't use it. And, I don't know about it. So, I am not saying it works, or it doesn't... I don't know. But, I am listening and researching. The main things that turn me away from "cleaners" is I don't usually know what is in them (So, I don't know what I am using.) That and, the amount of woo around them. They are expensive too. And some of that might be just because people might not know how cheap and available, the chemicals that they use, are (because we don't know what is in them.)

WD40 is a different thing. I think it is mostly a water displacement compound... and, it is very good at that... for driving water, or moisture, out of closely fitting parts. It does clean, or dissolve too. And it will lubricate (at least temporarily... the liquid lubricant (low viscosity petroleum distillates and very fine mineral oil?) evaporates fairly quickly, and leaves a white residue (not sure if the white stuff has lubrication properties.) I have used it to free really stuck potentiometer shafts, where they pass through the bushing... the WD40 runs easily into the busing, and some mechanical force frees up the shaft. I don't like to use penetrating oil. It is kind of a last ditch thing to try, if other methods fail to unseize the shaft... and sometimes nothing seems to work too.

As Bob mentions.... I've had good success with "exercising" a "scratchy" pot too.
Regards


Re: 91% Isopropyl Rubbing Alcohol to clean potentiometers?

Bob Albert
 

It looks like the link has been filtered out.  Just google the title.
Bob

On Wednesday, March 6, 2019, 11:55:07 AM PST, Bob Albert via Groups.Io <bob91343=yahoo.com@groups.io> wrote:

For the general information of the group, here is a link to determine characteristics of various solvents, etc.  It provides more information than you will ever want to have.
The Most Complete Free Material Safety Data Sheet (MSDS) list of chemical information on the Internet


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The Most Complete Free Material Safety Data Sheet (MSDS) list of chemica...

Looking for MSDS information regarding the chemicals in a commercial product or a material safety data sheet (MS...
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    On Wednesday, March 6, 2019, 11:16:45 AM PST, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

Hi:
Lots of companies sell it. I see it on Amazon for 13.00 U.S. a gallon (4, 1 quart plastic bottles.) It is very hydroscopic (absorbs water from the air readily)… so unless you store it over a drying agent, it will tend towards 90%, as it picks up water, from the air that gets into the bottle.
The main advantage of IPA is it is cheap (really cheap compared to proprietary cleaners, like Deoxit). But, another significant advantage is that it is a pure (other than the little bit of water)… it is a pure chemical. So, you know what you are using, and can find out what it will do to what you are using it on (That part needs some research, or advice.). You can get (download) the Material Safety Data Sheet (MSDS), so you can determine how it will affect you, how to use it safely, and how it will affect the environment. The MSDS for many proprietary cleaners don't significantly identify what's in them (it's proprietary).
Regards


Re: 7834 with bad HV transformer free to good home

 

Sorry, Craig Sawyers got there first!

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Roger Evans via Groups.Io
Sent: 06 March 2019 20:37
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7834 with bad HV transformer free to good home

David,

I have a 7934 which is in good health apart from some damage to the storage meshes at the front of the CRT, works fine in non-storage mode. I have been hoping for some time to find a good CRT from a 7834 or 7934 as a replacement. I would be delighted to come and collect. You can contact me at r.g.evans@talk21.com to minimise clutter on the list.

Many thanks,

Roger Evans


Re: 7834 with bad HV transformer free to good home

Roger Evans
 

I see the e-mail address has been anonymised, the missing bit is talk21.com
Roger


Re: 7834 with bad HV transformer free to good home

Roger Evans
 

David,

I have a 7934 which is in good health apart from some damage to the storage meshes at the front of the CRT, works fine in non-storage mode. I have been hoping for some time to find a good CRT from a 7834 or 7934 as a replacement. I would be delighted to come and collect. You can contact me at r.g.evans@talk21.com to minimise clutter on the list.

Many thanks,

Roger Evans


Re: Uncooperative 7834

Ed Breya
 

Before totally giving up on it, you may want to check the HV filter caps and rectifiers in the cathode circuit. I don't recall if these use the old ceramic type, or plastic caps - ones typically rated for a few kV. I've had a few of the ceramic ones go bad here and there over the years. To properly test them, besides measuring the C, you should also juice them up to a fairly high voltage, comparable to where they operate, and make sure they don't break down or leak excessively. Usually the 1500 V peak, in DC-mode, on a 576 or 577 is enough to show problems with them - if they can't handle that, then they won't make it at twice that. For testing them without doubt, they should have the full cathode voltage applied, if you have a convenient HV source.

Ed


Re: 91% Isopropyl Rubbing Alcohol to clean potentiometers?

Bob Albert
 

For the general information of the group, here is a link to determine characteristics of various solvents, etc.  It provides more information than you will ever want to have.
The Most Complete Free Material Safety Data Sheet (MSDS) list of chemical information on the Internet


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| |
The Most Complete Free Material Safety Data Sheet (MSDS) list of chemica...

Looking for MSDS information regarding the chemicals in a commercial product or a material safety data sheet (MS...
|

|

|

On Wednesday, March 6, 2019, 11:16:45 AM PST, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

Hi:
Lots of companies sell it. I see it on Amazon for 13.00 U.S. a gallon (4, 1 quart plastic bottles.) It is very hydroscopic (absorbs water from the air readily)… so unless you store it over a drying agent, it will tend towards 90%, as it picks up water, from the air that gets into the bottle.
The main advantage of IPA is it is cheap (really cheap compared to proprietary cleaners, like Deoxit). But, another significant advantage is that it is a pure (other than the little bit of water)… it is a pure chemical. So, you know what you are using, and can find out what it will do to what you are using it on (That part needs some research, or advice.). You can get (download) the Material Safety Data Sheet (MSDS), so you can determine how it will affect you, how to use it safely, and how it will affect the environment. The MSDS for many proprietary cleaners don't significantly identify what's in them (it's proprietary).
Regards


DC508 HELP with PHOTOS option 7

Miguel Work
 

Hi, I had bought a DC508 option 1 for my TR502 7L14. I need to install option7, TM503 is option7, manual is very clear, but It will be very useful a detailed photos from cables and connector. Has some body one and can post some photos?
Thanks
Regards

Miguel


Re: 91% Isopropyl Rubbing Alcohol to clean potentiometers?

Roy Thistle
 

Hi:
Lots of companies sell it. I see it on Amazon for 13.00 U.S. a gallon (4, 1 quart plastic bottles.) It is very hydroscopic (absorbs water from the air readily)… so unless you store it over a drying agent, it will tend towards 90%, as it picks up water, from the air that gets into the bottle.
The main advantage of IPA is it is cheap (really cheap compared to proprietary cleaners, like Deoxit). But, another significant advantage is that it is a pure (other than the little bit of water)… it is a pure chemical. So, you know what you are using, and can find out what it will do to what you are using it on (That part needs some research, or advice.). You can get (download) the Material Safety Data Sheet (MSDS), so you can determine how it will affect you, how to use it safely, and how it will affect the environment. The MSDS for many proprietary cleaners don't significantly identify what's in them (it's proprietary).
Regards


Re: Wanted 7B15

Albert Otten
 

Wait a minute Fred. At least one of those 7A29s should have the variable delay option... Still happy=;)?
Albert

On Wed, Mar 6, 2019 at 04:48 PM, Fred S. wrote:


----
Now my 7104 is complete: 2x7A29, 7B15 and 7B10, I am very happy!!!


Re: still trying to track down 2216 manuals

Jim Olson <v_12eng@...>
 

Colin, thanks that was my thought also. Checked with the site nothing there. I did send him an email letting him know that Q service had a complete service manual with schematics for the 2212 on CD it is also on ebay.

Jim O

On March 6, 2019 at 3:48 AM "Colin Herbert via Groups.Io" <colingherbert=blueyonder.co.uk@groups.io mailto:colingherbert=blueyonder.co.uk@groups.io > wrote:


Jim,
My post was relating to Bill K7WXW's earlier post (see below). I don't own a 2216; I was just trying to help. I don't know if your suggestion has possibilities or not....
Colin.

-----Original Message-----
From: TekScopes@groups.io mailto:TekScopes@groups.io [mailto:TekScopes@groups.io mailto:TekScopes@groups.io ] On Behalf Of Jim Olson
Sent: 05 March 2019 20:18
To: TekScopes@groups.io mailto:TekScopes@groups.io ; Colin Herbert via Groups.Io
Subject: Re: [TekScopes] still trying to track down 2216 manuals

Colin, have you tried the Vintage TEK Museum in Beaverton Oregon? they have a good collection of original Tek manuals.

Jim O

> > On March 5, 2019 at 10:42 AM "Colin Herbert via Groups.Io" <colingherbert=blueyonder.co.uk@groups.io mailto:colingherbert=blueyonder.co.uk@groups.io mailto:colingherbert=blueyonder.co.uk@groups.io mailto:colingherbert=blueyonder.co.uk@groups.io > wrote:


I don't know whether this is at all valid, but after doing a bit of searching with Bing, I found this:

http://www.jetecnet.com/others.html

It claims to be Tektronix 2216, 4 Channel digital Storage Oscilloscope Service Manual for $20 and is 332 pages. Oddly, they state that the Operator's Manual is "Not Available" which we know is untrue. Since the User Manual is 328 pages, I'm inclined to think it is that.
Is it worth a punt?
Colin.

-----Original Message-----
From: TekScopes@groups.io mailto:TekScopes@groups.io mailto:TekScopes@groups.io mailto:TekScopes@groups.io [mailto:TekScopes@groups.io mailto:TekScopes@groups.io mailto:TekScopes@groups.io mailto:TekScopes@groups.io ] On Behalf Of bill K7WXW
Sent: 04 March 2019 20:03
To: TekScopes@groups.io mailto:TekScopes@groups.io mailto:TekScopes@groups.io mailto:TekScopes@groups.io
Subject: [TekScopes] still trying to track down 2216 manuals

I've search through the archives here and saw the 2014(?) discussion on the 2216 service manual. I have copies of the partial manuals for the 2216 and 2212. Alas, no schematics. Yet.

I am surmising that the manuals' unavailability is related to the fact that both the 2212 and the 2216 were designed in Heerenveen. I would guess that they were only manufactured in Holland and repaired at the Benelux Repair Center. Since Benelux was closed in 2000 as part of the Tek breakup, who knows what happened to the stock of manuals? I am hoping that they all didn't end up in the tip.

Unfortunately, I am now in "dog chasing bone" mode now wrt to finding documentation. Does anyone know if there's a European-based Tek fan or alumni club? I want to see if I can track down anyone that worked in Benelux. So as not to inflict my obsession on others, I can be contacted off list, my call sign at arrl dot net.






>




7834 with bad HV transformer free to good home

 

I've reached the end of my repair efforts on this 7834. I'd hoped to fix it
and sell it, but I'm not equipped to rewind the transformer and I need the
space it has occupied.

So if anyone in the UK wants it then they are welcome to collect it from
Kenilworth.

If no-one wants to take the whole thing, then I'm happy to remove boards or
other parts that people want but you'll need to collect them or pay postage
and packing costs.

I need to have it gone within a week or so - it goes to the local recycling
centre after that :(

I will be keeping one piece of the metal work from the PSU as I need that
for a 7854 ... unless one comes my way!

PS if anyone needs CRTs for 7633 or 2564 I have to clear those out as well.

David


Re: Help with 465 repair - no signal on 50mv/100mv/200mv ranges

bbortnick@...
 

Hi Tom,
Thanks for putting me on the right path. Indeed, there was no continuity between the pads of the x10 fingers. Redid the IPA thing, and now I have a signal at all settings! On to the timing switch - it's quite crusty, not sure if that is repairable. May post a question on that one here later.
Thanks again!


Re: Help with 465 repair - no signal on 50mv/100mv/200mv ranges

Colin Herbert
 

My guess also would be the X10 attenuator. These attenuators can develop a connection fault inside the module. It *can* be fixed with a small soldering-iron and a steady hand, once the top has been popped off, but it is tricky and could ruin the attenuator module. If you haven't already tried this, swap the X10 attenuator modules between the channels and see if the problem goes with the module or stays with the channel.

Cleaning of these cam-switches has been discussed in some detail on a recent thread titled " Help with 7A18 problem". Whatever you do, don't get anything other than IPA or any other cleaning product anywhere near the attenuator assembly circuit-boards - it is likely to ruin them.

Good Luck, Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tom Gardner
Sent: 06 March 2019 17:38
To: TekScopes@groups.io
Subject: Re: [TekScopes] Help with 465 repair - no signal on 50mv/100mv/200mv ranges

On 06/03/19 17:12, bbortnick@2bcool.ca wrote:
The fingers are gold plated and looked very clean before I IPA'd them. Is there anything else in the circuit that could be causing the problem? Here is the relevant page from the service manual:
https://groups.io/g/TekScopes/album?id=86337
If the 5V/div range is also faulty, my guess would be the *10 attenuator.

Have you tried applying a signal to the faulty channel's input, and using the
/other/ channel to follow the signal forward until it disappears? That could
indicate whether the attenuator or the switch was faulty.

If you then suspect the attenuator, remove it and /cautiously/ replace it with a
wire jumper. If the signal then "gets through" (albeit at the wrong amplitude
and possibly distorted due to the wire and poor connections), then the
attenuator is faulty.

Alternatively, you can use an ohmmeter to measure the contact resistance of the
switch fingers.


Re: TEST MESAGE. "Fw: You have been removed from TekScopes@groups.io"

Brendan
 

This happened to me a week or so ago. Like you I accidentally marked a message as spam in yahoo mail.

On Wed, Mar 6, 2019 at 11:08 AM, Daniel Koller wrote:


Hi Folks,
    This is a test for me to make sure I am re-subscribed, and a warning to
others to be careful.
    I use Yahoo mail to read my tekscopes group messages (perhaps I should
not use Yahoo Mail).  This morning I *accidentally* clicked on a message and
reported it as spam, then immediately restored it to my inbox realizing it was
the wrong one.  It seems groups.io is on a hair trigger because it sent me
the message below.  This must be a new setting because...
...I have accidentally reported messages from Tekscopes as spam before, and
this has not happened, and some Tekscopes messages regularly end up in my spam
folder anyway, and I have to check there from time to time.   So, wonder if
Yahoo is now reporting when you move a message to spam, or groups.io is now
recording when yahoo sends such a report.  
   Either way, heads up to everyone that the system is sensitive!
  Dennis, is there a way to set up the groups.io system so that it takes 3 or
so reports of spam before groups.io unsubscribes a user?  Thanks,
  Dan

   
----- Forwarded Message ----- From: TekScopes@groups.io
<TekScopes+owner@groups.io>To: "kaboomdk@yahoo.com" <kaboomdk@yahoo.com>Sent:
Wednesday, March 6, 2019, 10:23:58 AM ESTSubject: You have been removed from
TekScopes@groups.io
Hello,
Because your Email Service Provider reported to us that one or more messages
sent to you from TekScopes@groups.io has been marked as spam you have been
automatically removed from the group. We suggest that you check your spam box
as soon as possible to see if your Email Service Provider has diverted
legitimate messages into it.

You will receive no more emails from that group. If this was a mistake, you
can resume your subscription within the next 7 days by clicking the following
link:

Resume Subscription

Groups.io groups offer several options for controlling how much and what types
of emails to receive. See this Help Center article for more information.

If this happens repeatedly please check with your email service to learn about
how they decide to send feedback reports to list services (such as Groups.io
groups).

Cheers,
The Groups.io Team


TEST MESAGE. "Fw: You have been removed from TekScopes@groups.io"

Daniel Koller
 

Hi Folks,
    This is a test for me to make sure I am re-subscribed, and a warning to others to be careful.
    I use Yahoo mail to read my tekscopes group messages (perhaps I should not use Yahoo Mail).  This morning I *accidentally* clicked on a message and reported it as spam, then immediately restored it to my inbox realizing it was the wrong one.  It seems groups.io is on a hair trigger because it sent me the message below.  This must be a new setting because...
...I have accidentally reported messages from Tekscopes as spam before, and this has not happened, and some Tekscopes messages regularly end up in my spam folder anyway, and I have to check there from time to time.   So, wonder if Yahoo is now reporting when you move a message to spam, or groups.io is now recording when yahoo sends such a report.  
   Either way, heads up to everyone that the system is sensitive!
  Dennis, is there a way to set up the groups.io system so that it takes 3 or so reports of spam before groups.io unsubscribes a user?  Thanks,
  Dan

   
----- Forwarded Message ----- From: TekScopes@groups.io <TekScopes+owner@groups.io>To: "kaboomdk@yahoo.com" <kaboomdk@yahoo.com>Sent: Wednesday, March 6, 2019, 10:23:58 AM ESTSubject: You have been removed from TekScopes@groups.io
Hello,
Because your Email Service Provider reported to us that one or more messages sent to you from TekScopes@groups.io has been marked as spam you have been automatically removed from the group. We suggest that you check your spam box as soon as possible to see if your Email Service Provider has diverted legitimate messages into it.

You will receive no more emails from that group. If this was a mistake, you can resume your subscription within the next 7 days by clicking the following link:

Resume Subscription

Groups.io groups offer several options for controlling how much and what types of emails to receive. See this Help Center article for more information.

If this happens repeatedly please check with your email service to learn about how they decide to send feedback reports to list services (such as Groups.io groups).

Cheers,
The Groups.io Team


Re: Help with 465 repair - no signal on 50mv/100mv/200mv ranges

Tom Gardner
 

On 06/03/19 17:12, bbortnick@2bcool.ca wrote:
The fingers are gold plated and looked very clean before I IPA'd them. Is there anything else in the circuit that could be causing the problem? Here is the relevant page from the service manual:
https://groups.io/g/TekScopes/album?id=86337
If the 5V/div range is also faulty, my guess would be the *10 attenuator.

Have you tried applying a signal to the faulty channel's input, and using the /other/ channel to follow the signal forward until it disappears? That could indicate whether the attenuator or the switch was faulty.

If you then suspect the attenuator, remove it and /cautiously/ replace it with a wire jumper. If the signal then "gets through" (albeit at the wrong amplitude and possibly distorted due to the wire and poor connections), then the attenuator is faulty.

Alternatively, you can use an ohmmeter to measure the contact resistance of the switch fingers.


Re: Uncooperative 7834

 

When the EHT transformer is connected to the 25kHz HV drive, then pin 13 on the control IC hits 0V pretty much immediately after the inverter starts causing a shutdown after 10mS. Anything below +50mV on this pin indicates a fault condition (inverter current > 5A).

I tried disconnecting the HV Multiplier, but that wasn't the problem. My suspicion is shorted turns in the EHT transformer.

With the EHT transformer disconnected the supply also ticks, but not because of over-current, but because Bal-Sense (pin 2) is just over +200mV when the 10mS timer expires. From what others have said this is pretty much normal behaviour.

Ho-Hum

Who needs some 7834 spares (including a working PSU)?

Dave


Re: Help with 465 repair - no signal on 50mv/100mv/200mv ranges

bbortnick@...
 

The fingers are gold plated and looked very clean before I IPA'd them. Is there anything else in the circuit that could be causing the problem? Here is the relevant page from the service manual:
https://groups.io/g/TekScopes/album?id=86337


Re: still trying to track down 2216 manuals

bill K7WXW
 

Thanks for the help, all. I have a lead on the 2216 service manual. The 2216 operators manual is at the vintage tek museum website. It will be interesting to see how much the 2212 and the 2216 have in common. Cheers, bill

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