Date   
Re: NEW to the group

Michael
 

Eric, I am not optimistic about our chances of not using nukes again. There are groups in the world who would not hesitate to use a nuke if they got their hands on one. I believe the USA would use nukes in retaliation for an attack on America without really knowing who set off the nuke that attacked America. Even an angry president could go ahead and start something like this. Our world without nuclear war is on a tenuous footing

I prefer to try not to think about this. Much more fun using my Tek Scopes to repair old stereos and transceivers. I am old and fix these things just for fun. I charge what it costs for parts and other supplies. I don't charge for labour. I have more work than I can handle. I was amazed how many people are still using stereos and hf transceivers from the 60s 70s and 80s. Some of them have been kept in absolute pristine condition on the outside. I have 2 465s and 2 22something scopes. I actually only use two scopes at a time on my bench. I just like having spares. The 465s are my favourites to use, the 2200 series is may favourite to repair. Taking apart a 465 is not easy. I repaired one for a friend and a simple capacitor change on a power supply line was somewhat difficult. I love it when the using the motto, (always check the power supply first) actually works. It is a method of repair that is used by me religiously. I don't of course just check voltage, I also check ripple. I have a new digital scope (not Tek) that will immediately give me the voltage and amplitude and frequency of the ripple with one button push. Still love my 465s best. I hope it never takes offence at my little indiscretions with that new (younger and sexier) Hantek babe. It was never for love, just physical.

Re: Tek 7a13 mechanical to LED display conversion ? / 7ct1n user notes ?

 

On Sat, 09 Jun 2018 19:11:48 -0700, you wrote:

a) Is there a way to convert the 7a13 mechanical ( "veeder root" type ) display to the LED display ?
Did Tektronix provide any field Tech notes for doing such ?
Does someone have the schematic & parts list for the LED module ?
( does anyone have that module from a dead 7a13)
Could it be transplanted into a 7a13 that has the older mechanical module ?
Tektronix never did this but I think someone on the list may have done
it so a search through the archives may reveal something. I know we
discussed various options for the ADC and display because I was part
of that.

The biggest problem is finding a small enough LED display. One of
those tiny OLED graphic displays could work but would be more complex
to drive.

b) I am trying to understand how to use the 7ct1n Curve Tracer in a 7704 with the 7a13.

Does anyone have a set of simple notes written up for this ?
The 7ct1n manual seems a tad confusing ...
The 7CT1N works with the 7A13 like it does with any vertical amplifier
set to 100mV/div.

Re: NEW to the group

EricJ
 

I should hope that no one ever forgets about Hiroshima. Or Nagasaki. It would seem difficult not to know about the places hit with the most deadly and indiscriminatory bombs in the history of the world. Although they seemed necessary at the time, hopefully they will never be used again.
--Eric
Sent from my Samsung Galaxy S8.

-------- Original message --------From: Joel R Kist <joel-kist@...> Date: 6/13/18 10:28 AM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] NEW to the group
About (Hiroshima)-- I would not say everyone at least in the USA; most do not know who are presidents past of the USA !!

Hi, my name is Joel and I have been reading the group messages for some time now and enjoy them. I was a sonar technician (Submarines)in the US Navy sometime ago, very early (1970's). Now retired I am drawn back to playing with the "TRONS". It is easy to see there is a abundance of knowledge here. I look forward to being guided by the group on some projects.

Joel

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ancel
Sent: Wednesday, June 13, 2018 10:17 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Upgraded, stub tuned, Tektronix SG-504 leveling head back online for a last run

BTW, one went to Hiroshima. First time shipping there....I guess everyone knows where that is.
Ancel




---
This email has been checked for viruses by AVG.
https://www.avg.com

Re: What removes sticker residue without hurting the blue paint?

ki6bge
 

Goop works well on all surfaces i've used it on.

On Wed, Jun 13, 2018, 11:06 David Hess <@DWH> wrote:

Not necessarily at the same time. A hot air gun works well for
initially trying to peel the label up and also works with new tape to
try and pull up any adhesive residue.

And I don't now that naphtha is any worse than acetone or lacquer
thinner or alcohol as far as danger due to flammability. Back when
rebuilding carburetors was a thing, I always had a laugh at the
warning on the carburetor rebuild kits about not using gasoline as a
cleaner and solvent because of flammability when acetone and such were
even more so.

On Wed, 13 Jun 2018 10:58:10 -0700, you wrote:

I would assume you do this outside ? My insurance provider would frown on
doing something like this within 50 feet of the house or garage. I'm
almost
tempted to try it and cause a spark and see what happens :-)


Re: What removes sticker residue without hurting the blue paint?

 

Not necessarily at the same time. A hot air gun works well for
initially trying to peel the label up and also works with new tape to
try and pull up any adhesive residue.

And I don't now that naphtha is any worse than acetone or lacquer
thinner or alcohol as far as danger due to flammability. Back when
rebuilding carburetors was a thing, I always had a laugh at the
warning on the carburetor rebuild kits about not using gasoline as a
cleaner and solvent because of flammability when acetone and such were
even more so.

On Wed, 13 Jun 2018 10:58:10 -0700, you wrote:

I would assume you do this outside ? My insurance provider would frown on
doing something like this within 50 feet of the house or garage. I'm almost
tempted to try it and cause a spark and see what happens :-)

Re: NEW to the group

Joel R Kist
 

About (Hiroshima)-- I would not say everyone at least in the USA; most do not know who are presidents past of the USA !!

Hi, my name is Joel and I have been reading the group messages for some time now and enjoy them. I was a sonar technician (Submarines)in the US Navy sometime ago, very early (1970's). Now retired I am drawn back to playing with the "TRONS". It is easy to see there is a abundance of knowledge here. I look forward to being guided by the group on some projects.

Joel

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ancel
Sent: Wednesday, June 13, 2018 10:17 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Upgraded, stub tuned, Tektronix SG-504 leveling head back online for a last run

BTW, one went to Hiroshima. First time shipping there....I guess everyone knows where that is.
Ancel




---
This email has been checked for viruses by AVG.
https://www.avg.com

Re: What removes sticker residue without hurting the blue paint?

Pete Lancashire
 

I would assume you do this outside ? My insurance provider would frown on
doing something like this within 50 feet of the house or garage. I'm almost
tempted to try it and cause a spark and see what happens :-)

On Wed, Jun 13, 2018, 10:11 AM David Hess <@DWH> wrote:

A hot air gun and naphtha (lighter fluid) are my first choices.
Lighter fluid and hardware store naphtha may have contaminates so
purer options are heptane or Bestine Solvent and Thinner which is used
for rubber cement and commonly available. Plastic safe contact
cleaner for switches is another source.

I had problems with hot water causing the Tektronix paint to peel in
some cases.

Ha! Amazon's page for Bestine even says:

"EASILY REMOVE LABELS – Using this solvent, you will be able to
effortlessly remove stickers, labels and decals without leaving behind
and messy residue."

https://www.amazon.com/BESTINE-Solvent-Thinner-Rubber-Cement/dp/B004O7HM38

On Tue, 12 Jun 2018 00:14:35 -0400, you wrote:

Naptha, or lighter fluid does a good job, and is
mild on paints and plastics.

Hot air will often allow you to peel off a sticker
more or less intact, but will usually leave the
stickum behind... which you will still have to
remove with something like lighter fluid.

-Chuck Harris

Dennis Tillman W7PF wrote:
A far too common problem I have no solution for yet:

What will remove sticker residue on Tek blue paint without harming the
paint
finish?

...

Would boiling water soften the sticker residue and leave the paint
alone or
would it siften the paint as well.

Suggestions are welcome.


Re: What removes sticker residue without hurting the blue paint?

 

A hot air gun and naphtha (lighter fluid) are my first choices.
Lighter fluid and hardware store naphtha may have contaminates so
purer options are heptane or Bestine Solvent and Thinner which is used
for rubber cement and commonly available. Plastic safe contact
cleaner for switches is another source.

I had problems with hot water causing the Tektronix paint to peel in
some cases.

Ha! Amazon's page for Bestine even says:

"EASILY REMOVE LABELS – Using this solvent, you will be able to
effortlessly remove stickers, labels and decals without leaving behind
and messy residue."

https://www.amazon.com/BESTINE-Solvent-Thinner-Rubber-Cement/dp/B004O7HM38

On Tue, 12 Jun 2018 00:14:35 -0400, you wrote:

Naptha, or lighter fluid does a good job, and is
mild on paints and plastics.

Hot air will often allow you to peel off a sticker
more or less intact, but will usually leave the
stickum behind... which you will still have to
remove with something like lighter fluid.

-Chuck Harris

Dennis Tillman W7PF wrote:
A far too common problem I have no solution for yet:

What will remove sticker residue on Tek blue paint without harming the paint
finish?

...

Would boiling water soften the sticker residue and leave the paint alone or
would it siften the paint as well.

Suggestions are welcome.

Looking to buy or trade a simple XY monitor

Pete Lancashire
 

Either the old 602 or one of the newer models. Only need one or two
megahertz bandwidth. Plenty of older Tek gear to trade or cash. Could
entertain an HP but being it retired from tektronix I have a preference :-).

-pete

Re: Tek 2445 - No Power

 

I will start with some general advice about the 24xx LVPS.  What you describe (start stop cyclng) we call "tick mode" because it often makes ticking sounds as it cycles.  You may have a short or the inverter is unable to start.
Safety first.  The input side of the inverter is directly connected to mains power.  You cannot probe around there with grounded instruments and you cannot safely touch most of the electronics.  Using a grounded meter on the input side will create more faults because it creates a direct short.  I suggest an isolation transformer if you have one.
A common fault.  All PCB layouts for the 24xx LVPS have an error.  This error creates a short if you recap the supply by following the documentation (most do).  Specifically, on the PCB layouts, they have interchanged the positions of C1115 and C1132.  So if you follow the document you end up with a 35 volt capacitor in an 87 volt circuit.
You must have a load to run.  But trying to run without a load does not usually create more faults.
R1071 and C1072 are part of the start up circuits and will overheat in tick mode operation.  The inverter needs a load to run.  R1071 and C1072 form a load on the inverter for a short time until C1072 is charged.  This is enough time for the inverter to start.
My first guess is you have C1115 connected to the 87 volt line and C1115 has failed short.  That may have created other faults (such as a shorted CR1132).
Good luck.

On ‎Wednesday‎, ‎June‎ ‎13‎, ‎2018‎ ‎07‎:‎19‎:‎06‎ ‎AM‎ ‎CDT, ElectroKid via Groups.Io <liv_electro=yahoo.com@groups.io> wrote:

[Edited Message Follows]

Hi all,

My first post here :)
I got this 2445 and upon 1st examination the power supply was clicking - no power at all, no light on front panel.
Replaced all e-caps on the inverter board A3, The fan is the early version ('mouse wheel') and it was moving upon finger help...not enough current.
At one point some self test lights on the front panel came on for a second or two - but that's the only time it happened,
Not much later had another fault where a resistor with a wire wrapped on it LR1060 got burnt gave quite a smoke.
I replaced it with a new resistor and wrapped it with fine lacquered wire (taken from a small transformer) based on the number of turns of original burnt coil LR1060.
Along with it I also checked the power FETs attached to heatsinks, and one was faulty, so I replaced them all.
Power supply is till clicking, I noticed an overheating resistor R1071 gives up smoke and getting charred gradually as the power is on.
Note: I have the 2445 inverter version with two 18K resistors (R1073, R1069) 'standing' to form one 36K  (unlike one 36K R1069 in the Tek 2465).
I decided to replace charred R1071, and near that point the clicking stopped and now there is no sign of life... I hope the x-formers are still ok though.
Worth noting is that I did my live tests without load connected which I now found is not the way to run these SMPS... I wonder what can go bad in that case.
I don't see any voltage to the Pre-Regulator section (13.2V)
Further details:
I have replaced the RIFA caps although they were intact.
I checked incoming voltage to the inverter board is twice 155V on the connecting pins so apparently the bridge is well.
The big reservoir caps were not replaced, I don't think they are bad.
I check the thermal cutout device is ok.

So basically what looked like a simple re-cap job turned into a more complicated fault finding.
Would like to hear your suggestions on how to proceed based on the above.

Re: Help with a TEK 502 scope

Siggi
 

On Tue, 12 Jun 2018 at 13:20 Dave Wise <david_wise@...> wrote:

Thanks for the URL, Siggi. The last picture in the album is my assistant
performing a thermal stress test. :)
A CAT scan is always useful after a repair :D.

Re: Tek 2445 - No Power

Harvey White
 

On Wed, 13 Jun 2018 05:13:32 -0700, you wrote:

Hi all,

I got this 2445 and upon 1st examination the power supply was clicking - no power at all, no light on front panel.
Replaced all e-caps on the inverter board A3, The fan is the early version ('mouse wheel') and it was moving upon finger help...not enough current.
could be low voltage.

At one point some self test lights on the front panel came on for a second or two - but that's the only time it happened,
Not much later had another fault where a resistor with a wire wrapped on it LR1060 got burnt gave quite a smoke.
That's a filter on a low voltage line. Overcurrent through that
resistor indicates a shorted (likely tantalum) capacitor downstream. A
typical value would be 5 or 10uf, just as a guess.

I replaced it with a new resistor and wrapped it with fine lacquered wire (taken from a small transformer) based on the number of turns of original burnt coil LR1060.
Along with it I also checked the power FETs attached to heatsinks, and one was faulty, so I replaced them all.
Power supply is till clicking, I noticed an overheating resistor R1071 gives up smoke and getting charred gradually as the power is on.
Then something is drawing too much current, I'd suggest checking for
shorted capacitors or bad transistors.


Note: I have the 2445 inverter version with two 18K resistors (R1073, R1069) 'standing' to form one 36K (unlike one 36K R1069 in the Tek 2465).
I decided to replace charred R1071, and near that point the clicking stopped and now there is no sign of life... I hope the x-formers are still ok though.
Then without clicking, the inverter isn't trying to start, typically.

Worth noting is that I did my live tests without load connected which I now found is not the way to run these SMPS... I wonder what can go bad in that case.
Not sure here.

I don't see any voltage to the Pre-Regulator section (13.2V)
Need to figure out why....

Further details:
I have replaced the RIFA caps although they were intact.
Ok, was not the cause of the supply failure, but can be good
insurance.

I checked incoming voltage to the inverter board is twice 155V on the connecting pins so apparently the bridge is well.
The big reservoir caps were not replaced, I don't think they are bad.
I check the thermal cutout device is ok.
Ok.


So basically what looked like a simple re-cap job turned into a more complicated fault finding.
Would like to hear your suggestions on how to proceed based on the above.
Check supply to see if the bulk supply is ok, then check to see if the
oscillator/control is running. Check for good/bad determination made
by comparators in the power supply, that can shut down the regulators.

Smoking resistors indicate excessive current flow, can be something
shorted or simply plugged in the wrong way.

Orange drop tantalums (dipped epoxy) frequently fail and should be
checked. They don't have to be orange in color, I've seen blue,
orange, and brown.

Harvey


Re: Upgraded, stub tuned, Tektronix SG-504 leveling head back online for a last run

 

BTW, one went to Hiroshima. First time shipping there....I guess everyone knows where that is.
Ancel

Tek 2445 - No Power

ElectroKid
 
Edited

Hi all,

My first post here :)
I got this 2445 and upon 1st examination the power supply was clicking - no power at all, no light on front panel.
Replaced all e-caps on the inverter board A3, The fan is the early version ('mouse wheel') and it was moving upon finger help...not enough current.
At one point some self test lights on the front panel came on for a second or two - but that's the only time it happened,
Not much later had another fault where a resistor with a wire wrapped on it LR1060 got burnt gave quite a smoke.
I replaced it with a new resistor and wrapped it with fine lacquered wire (taken from a small transformer) based on the number of turns of original burnt coil LR1060.
Along with it I also checked the power FETs attached to heatsinks, and one was faulty, so I replaced them all.
Power supply is till clicking, I noticed an overheating resistor R1071 gives up smoke and getting charred gradually as the power is on.
Note: I have the 2445 inverter version with two 18K resistors (R1073, R1069) 'standing' to form one 36K (unlike one 36K R1069 in the Tek 2465).
I decided to replace charred R1071, and near that point the clicking stopped and now there is no sign of life... I hope the x-formers are still ok though.
Worth noting is that I did my live tests without load connected which I now found is not the way to run these SMPS... I wonder what can go bad in that case.
I don't see any voltage to the Pre-Regulator section (13.2V)
Further details:
I have replaced the RIFA caps although they were intact.
I checked incoming voltage to the inverter board is twice 155V on the connecting pins so apparently the bridge is well.
The big reservoir caps were not replaced, I don't think they are bad.
I check the thermal cutout device is ok.

So basically what looked like a simple re-cap job turned into a more complicated fault finding.
Would like to hear your suggestions on how to proceed based on the above.

Re: Tek 7623A - Source of 151-0271-00 transistor (A5T4261) or a currently available equivalent.

tinkera123
 

Hi Fabio,
I appreciate your time taken for this response .... I have got the “gist” of this, although I will ponder a few of the issues further ... eg. I am assuming that the top part of the rise time response curve was being driven by the ‘troubled’ transistor .... and bottom section driven by the ‘good’ transistor ... Push Pull??
And I don’t yet understand the HF compensation circuitry.
Anyway, another brick in the wall ...
Thanks,
Ian

Hello Ian, in response to your message further down...

I've got busy in the past couple of days which prevented me from answering
you.

First of all, please don't expect too much... because I think that, in the
end, it had a 50% of plain luck...

On this 7623A, .as I got rid of the gross issues that it had, and could focus
on doing a careful HF step response, I noticed that no matter what I would do,
be it on the Vert. Output Amplifier, or on the Vertical Plugin, I couldn't get
a clean step response in the whereabouts of 3.5ns.
If I would push too much on the HF compensation adjustments, I would
eventually get 4.5ns at best, but with a lot of ringing on the step corner.
If I would adjust it to tame the ringing, the step response would worsen even
more to - say - 5.5 to 6ns (this is a 60MHz scope, not a 100).
But what was puzzling me was that the step was not really like a slow
transition, but it was really fast up to about 2/3rds of the amplitude, and
then it would turn into a really rounded shoulder... So, I thought there were
2 superimposed time constants at play and that maybe, only maybe, I would be
able to spot which stage was not keeping up, by probing the vert amplifier at
different nodes.
It crossed my mind, for instance, that local power supply decoupling could be
lacking at some spot and that the slower last third could be due to a
decoupling having depleted its stored charge during the first part of a hi
speed transition and then, the stage would be running on "lean" mixture and
dragging.
So I started looking at places where there should be a more or less steady
voltage value, either the power to each stage, or the biasing networks.
So I went on to probe the +15V (dcpl) that feeds the Q2405 and Q2505 (this is
the NPN pair that precedes the PNP 151-0271-00 tranny I found guilty) and also
the bias to the bases of the very stage where the 151-0271 trannies were. This
is a common base stage, that has about +8V bias, coming from the Thermal
balance adjustment voltage divider, and decoupled by a 1nF capacitor.
While probing the bases of the transistors looking for the base pin (I didn't
know it by heart), I eventually probed both emitters (of the two PNP
transistors) and noticed they were markedly different... much different than I
would expect from two complementary sides that were being driven with a nearly
symmetrical square wave, swinging in AC around the center point...
The signal at the base of one of the transistors had something like x mVpp,
while at the other emitter, if was like 4x.
Well, the bases are not tied together, but from the bias voltage, through 100R
resistors into each base, so I thought that the markedly different signals
would also be different from one base to another... but not... The bases had
pretty much the same signal (almost no signal in fact, since it's a decoupled
bias)... only the emitters were remarkably different.
So, I thought... well, either this is caused by the transistor themselves, or
it's the signal coming into them...
So I swapped the transistors, and the signal at the emitters swapped along...
So I knew the transistors were the cause for the difference... leaving only to
discover if they were just too different (un-matched) or if one of them was
faulty.
So I ran them through my AVR transistor tester, which is far from being a
curve tracer, but would be able to tell me of any gross differences they might
have...
While one of the transistors tested like a normal PNP transistor, with about
40 of gain (hfe), the other, despite showing an increased hfe of about 70
(almost double), tested like if it had an anti-parallel diode connected across
the emitter-collector, and this anti-parallel diode with a Vf of 3.5V... the
whole thing being completely unusual for a regular silicon transistor (not
being a mosfet, a darlington, or a power device).
Testing them with my DMM in diode test mode showed no differences between
them.
So, despite they test equal on the DMM, I concluded that transistor could only
be faulty.
To confirm my theory, I needed a pair of small signal transistors that were -
at least - reasonably fast and I was lucky enough to find a couple of BFQ241
in my parts bin, which are high voltage, 1GHz TO-92 transistors used as video
amplifiers of CRT computer monitors.
In the moment that I shuffled them in, not only the signals at the emitters
became similar (as they should), but I immediately got a strong overshoot on
the square wave...denoting that the HF response of that stage started
contributing a great deal to the overall response.
After readjusting the HF compensation trimmers, I managed to get a risetime
about 2ns faster than it was, with a nice top almost free of ringing or
aberrations.
At this point, it's almost at the performance we would expect from a 100MHz
amplifier but, I decided to bring the subject to the group, and see what could
come out.
A fellow member of the group contacted me off-list to tell he has one original
151-0271-00 in spare and was so kind of offering it to me... so I`m now
awaiting for it to arrive, which will still take a while, as I`m in Brazil.

Hope this illustrates well how I got there...

Rgrds,

Fabio

Re: Tektronix 2465. Odd wave pattern superimposed on waveforms.

John Osborne
 

Greetings from South East London.
My Thanks goes to Chuck Harris who very kindly took the time to reply to my plea for help. As he stated (I hadn’t noticed) the issue was only evident on inputs 1 and 2. I had incorectly assumed that the issue was on all. However channels 3 and 4 are actually perfect?

He stated
*****
“If this wave only travels on CH1 and CH2, but not on CH3 and CH4, it is probably a problem with the external garbage that Tektronix hung on the CH5+ and CH5- inputs of the U400 channel switch to handle the readout display. I had a 2465 that had this condition, and I was tearing my hair out, until it was suggested to me that the CA3049 transistor arraysU485, and U475, were put there to prevent this problem. The issue is that the channel switch doesn't have the internal hardware to disable the readout from being displayed... it can only select the vertical channel. So, Tektronix put the transistor arrays U475 and 480 on the CH5 input to select and deselect when the readout can be displayed. Note that the readout can only be displayed during CH1 and CH2.”
******
I am off on holiday so any further investigation will have to wait 3 weeks. My thanks to Chuck Harris who so very kindly pointed me in the right direction.
I will post a cure once the issue has been solved. If by chance any one can add any further info I would be grateful.

Many thanks

John.

-----Original Message-----
From: Chuck Harris <cfharris@...>
To: TekScopes <TekScopes@groups.io>
Sent: Tue, 12 Jun 2018 15:43
Subject: Re: [TekScopes] Tektronix 2465. Odd wave pattern superimposed on waveforms.

Hi John,

If this wave only travels on CH1 and CH2, but not on CH3 and CH4,
it is probably a problem with the external garbage that Tektronix
hung on the CH5+ and CH5- inputs of the U400 channel switch to
handle the readout display.

I had a 2465 that had this condition, and I was tearing my hair
out, until it was suggested to me that the CA3049 transistor arrays
U485, and U475, were put there to prevent this problem.

The issue is that the channel switch doesn't have the internal
hardware to disable the readout from being displayed... it can only
select the vertical channel. So, tektronix put the transistor
arrays U475 and 480 on the CH5 input to select and deselect when
the readout can be displayed. Note that the readout can only be
displayed during CH1 and CH2.

I can't remember which array was bad, but they are cheap, and you
can test all of the transistors fairly easily in circuit.

-Chuck Harris

John Osborne via Groups.Io wrote:
Greetings to all.
I have recently purchased a non-working Tektronix 2465 (not A or B). Having carefully recapped the power supply which was blowing fuses due to leaky mains input filter capacitors I am left with an unusual fault.

The scope displays a good sine wave on all inputs. But superimposed on the perfect sine wave is a rippling wave that travels from right to left in quick succession. Perhaps 6 waves per second. It does not distort the sine wave in any way but travels along the wave on both the top and bottom edge of the trace. The wave is much lower in intensity than the sine wave displayed but is very noticeable.
Perhaps a common issue so please excuse me as I am new to this group.

Many thanks and best wishes to all.

John

Re: What removes sticker residue without hurting the blue paint?

Mark Mathis
 

Lemon Oil Furniture Treatment.

I have used Lemon Oil for over 30 years with great success on countless materials and finishes. With sufficient elbow power Lemon Oil always removes the adhesive without damage. Bear in mind, a slight difference in shading underneath the sticker can result from the difference in UV exposure. Exposed surfaces tend to darken over time, especially with older paints and plastics. This common also with woods such as Pine, Oak and White Ash.

Good day to all,
Mark

-----Original Message-----
From: Chris Elmquist
Sent: Tuesday, June 12, 2018 10:47 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] What removes sticker residue without hurting the blue paint?

This butyl cellosolve sounds like it can wreck more stuff than it fixes. I wanted proof that my beloved 409 should now be considered a member of the problem set and went searching. I found this NIH site that lists stuff with particular ingredients,

https://hpd.nlm.nih.gov/cgi-bin/household/search?tbl=TblChemicals&queryx=111-76-2

And it looks like it was “old” 409 that had it. But of note is that there are other things suggested in this thread that do still contain it that might be a risk. Simple Green (of several flavors) as one example.

Be careful out there...

Chris
--
Chris Elmquist N0JCF

On Jun 12, 2018, at 9:58 AM, Chuck Harris <cfharris@...> wrote:

Over the years, I have had a wide variety of
equipment with vinyl coated aluminum panels.

I used to cuss quite a bit when I got something
that was gorgeously pretty, but was sticky like
you were touching the sticky side of a piece of
tape. Virtually nothing would clean off the
sticky, and if you did, it would come back in a
little while... I wondered what had happened to
the vinyl.

Then I found it happening to equipment that I had
brought in my lab that was good, but dirty, then
cleaned with formula 409... my go to cleaner.

I read the ingredient list and saw the butyl
cellosolve... and stuck it away in my memory
somewhere.

Years passed, and more and more of my equipment
was getting sticky, when I bought a new truck.

The owner's manual had a warning about using window
cleaners containing butyl cellosolve, on the
instrument panel's windows. They said that it
would soften the plastic over time and make it fog.

A lightbulb went on, and I did some research on
butyl cellosolve, and found it was a super solvent
capable of soaking into almost all grease, dirt,
pitch, tar, and plastics. It cleaned by getting
inside of the dirt, expanding, and breaking it
apart so that it could be removed with a little
scrubbing... With plastics, it was to displace the
incredibly sticky stuff called plasticizer that is
used to make ridged PVC into flexible PVC... which
is what the stuff on the panels was.

A lot of pressure sensitive adhesives are very
similar chemically to plasticizer. And a lot of
the permanently affixed ID tags use a killer solvent
to bond them to plastic, vinyl, and painted panels.

-Chuck Harris

Kevin Oconnor wrote:
from Chuck:
"Goo gone is not aqueous. It is more like terpene,
made from the citrus, with mineral oil added to
prevent re-adhesion of the stickum."

Yes, oils seem to passivate the glue surface adhesion bond mechanism. Same as pouring Canola oil on a snake stuck in a glue trap. Slowly the glue is rendered ineffective and the snake squirms away none the worse for the experience! Not sure the atomic mechanism going on though.

I have seen some stickers on vinyl covered aluminum that seem to have modified the underlying vinyl by flattening out the orange peal surface. You can remove all trace of the adhesive, but you can do little regarding the latent outline of the sticker. The adhesive, when first applied, must react with the vinyl in some way. Any one else encounter this?

Re: Help with a TEK 502 scope

jrodriguezcsb@...
 

Sisi, thanks for the link. Pretty useful as I still do not navigate very well by the forum

Re: Help with a TEK 502 scope

jrodriguezcsb@...
 

Wow Dave,

just by looking at the pictures it seems both quite interesting and feasible!

Pease, give me a bit of time to read it carefully and undertand it and then I will come back here.

Thanks a million for that source!!

Anyway, any other source is still welcomed : )

Re: What removes sticker residue without hurting the blue paint?

Ed Breya
 

I too have a number of sticky-finish instrument cabinets (especially HP), and have tried without success over the years, to wash it off with some common solvents and detergents. Something that occurred to me, is instead of trying to remove the stuff, to maybe bind it with something, or to counteract the stickiness with an oil or wax finish. One possibility is to use a drying oil, like linseed, which would perhaps bind to the surface materials, and harden over time, to make a new finish (but slightly yellower than original). I have not tried this, so have no idea if it would work, or make things worse, but it may be worth looking at.

Ed