1. TekScopes@groups.io
   Date   
Re: 2445A Sweep and Other Questions

Lawrance A. Schneider
 

Hi,

Fix it and tell us about it.

How large is the ripple? Everyone seems to recommend changing the caps in the power supply. You say after warmup, then the problem starts. CAPS??

The manual is online. 2445 and 2465 are very similar. On EEVBlog, another fella is working na 2465.

Larry

On Aug 14, 2019, at 3:04 PM, Paul Gallimore <paulmk22@gmail.com> wrote:

Hi,

I acquired a 2445A a few years back and never switched it on until now. I am now starting to look at it for the first time and there are a couple of issues, but I have no scope fixing experience. Plus it's been a while since I did any fault finding on anything truly electronic.

So, I am trying to assess whether I should sell this on Ebay (UK) as a broken item, or whether I should take a shot at fixing it up.

I have powered it up and there are no reported faults, plus the scope traces appear as they should, as well as on screen characters. However, after a warm-up period (5-10 mins) the sweep stops and I am left with just a vertical trace. Using the J119 test points I can see that the supplies all look good with a DVM, but using Pico scope (laptop based scope) I can see some ripple on the supplies. I have yet to determine whether the ripple is in spec. (Though, I know where the info for that is in the manual)

Where do you think I should start with this? Should I just do a bulk capacitor swap out an ask questions later, or are there a few particular ones I should go for?

I should also say that some of the on-screen characters seem to get corrupted after a while as well.

Any opinions on where I should go with this would be appreciated.

Thanks

Paul
Need help troubleshootingTektronix PS280 Power supply

daven9ooq <daven9ooq@...>
 

Hi everyone: This is my first post since the group changed to IO.

I been in need of a good Dual Voltage variable power supply for my bench, I been looking around on line for awhile when I came across a Tektronix PS 280, up to that point all that I was seeing is cheap Chineese PS , I already own lots of Tek TM 500 equipment , So I thought the Tek PS280 would fit right in.

The PS280 is around late 70's early 80's vintage It was advertised as working on ebay, I but I had my duoghts, I felt I could probably fix it , having built many of my own, I looked up the schematic and manual in advance, I found it on W140.com Tekwiki, I found all the semiconductors were still available ,even the Intersil meter chips.

For the money , you couldn't even build one for the hundred bucks + shipping!

Although it has the Tek name, it doesn't look like a Tek products that I'm used to seeing, Was after Tek sold out you can tell it was built with a budget in mind, but is of fairly good quality, the two varabile supplys are 0-30volts @2amps they can be run independently or in series or
parallel, Neither of the variable sides worked properly, there was some low voltage but nowhere near the range it should have and not a smooth adjustment but very choppy. I ordered the electrolytics and replaced all the caps except for the 5 volt supply that was still working havent checked the ripple yet.

Since the board was difficult to remove and I'm working one handed due to a stroke also wanted something I could depend on well into the future.

After the recap things were a lot better voltage wise but still not working right to my surprise.

The boards looked pristine , no one had their fingers in before me I did find a cold solder joint on one of the 470uf electrolytics , the boards were waved soldered.

Upon visual inspection nothing else looked bad ,burnt or smelled bad,
I have not been able to find any obvious bad components .
There has been many revisions and the schematic is somewhat correct on the general circuitry but not the leadgonds for the connectors, there are many interconnects and wire jumpers on the board but the numbers on the connections don't jive, which makes me think I don't have the correct schematic for the revision.

Looking at Tek wiki the one that I have looks like the latest version.
The serial number is TW 50125 the main board is marked
GPC- 848A-1 B

The supply looks like it was farmed out and built under many Brands
But has a legit looking Tek Serial number tag.

This power supply is unusual to me having built many of my own over the years, it is dual tracking and constant voltage and current that uses a bunch of Asian transistor logic and 4 relays, but uses none of the usual regulator designs like LM317 or LM723 but it does have some of the usual regulators but used only for reference, it starts with a 7815 as a reference that goes into LM741 op amps and LM301 then another 741 to a driver transistor then to the usual series pass transistor a 2N3055.

Most of the 7800 series regulators and op amps are bulit proof which makes me think the culprit probably has to be a cold solder joint or a bad zener, or transistor.

I only had one basic course of electronics in college the rest is self taught.
I'm not able to follow a signal through a maze of transistors and op amps, but I know enough to be dangerous!

I would really like to gain a better understanding of this power supply
And get it working of couse. Many thanks! in advance.
Dave N9OOQ
2445A Sweep and Other Questions

Paul Gallimore
 

Hi,

I acquired a 2445A a few years back and never switched it on until now. I am now starting to look at it for the first time and there are a couple of issues, but I have no scope fixing experience. Plus it's been a while since I did any fault finding on anything truly electronic.

So, I am trying to assess whether I should sell this on Ebay (UK) as a broken item, or whether I should take a shot at fixing it up.

I have powered it up and there are no reported faults, plus the scope traces appear as they should, as well as on screen characters. However, after a warm-up period (5-10 mins) the sweep stops and I am left with just a vertical trace. Using the J119 test points I can see that the supplies all look good with a DVM, but using Pico scope (laptop based scope) I can see some ripple on the supplies. I have yet to determine whether the ripple is in spec. (Though, I know where the info for that is in the manual)

Where do you think I should start with this? Should I just do a bulk capacitor swap out an ask questions later, or are there a few particular ones I should go for?

I should also say that some of the on-screen characters seem to get corrupted after a while as well.

Any opinions on where I should go with this would be appreciated.

Thanks

Paul
Re: Is an early 7A26 a keeper?

John
 

Ron, that is what I figure too. U1350 is the probable culprit as the signals match on channel 1 & 2 up to that point. The readout is OK so it is basically in the gain channel. As I say one day;-))

John Proctor
VK2DLP
Re: non-gumming oil

Ken Eckert
 

It really works well in the task removing label glue. Paper labels I just
let it soak into the label, let it sit and pell off the label, remove the
glue then your favourite IPA to remove the WD-40. One thing about WD-40 I
have not found a material that it "attacks"

Ken

On Wed, Aug 14, 2019 at 1:36 PM greenboxmaven via Groups.Io <ka2ivy=
verizon.net@groups.io> wrote:

I have seen some lively discussions about WD-40 in switches, pots and
bearings. I have never had any problem using it as a PART of the
cleaning process. It will often cut loose crud that nothing else will,
but must be completely flushed out once it has done it's job or it will
soon become a residue far worse than the original.

Bruce Gentry, KA2IVY


On 8/14/19 1:09 PM, Greg Muir via Groups.Io wrote:
WD-40

Spent a couple of years working in the tropics with extremely high
humidity. I used to protect tools from rusting by wiping them with WD-40
then storing unused tools in plastic bags. What I found after coming back
after several months to use them was that the light hydrocarbons used in
the product had evaporated leaving behind a petroleum based product with
the consistency of something between 90 weight oil and Cosmoline.

From this I learned that it is only good for a very few purposes (aside
from the original intent of the product for coating the outsides of
missiles to prevent corrosion) is to protect items from rust and corrosion
(with some subsequent clean-up effort), a penetrent and, on occasion, a
gummed label remover. When I hear of someone using it to lubricate
potentiometers, switches and such, I wince.

A footnote: while at the project it was interesting to find that all of
the local outlets sold WD-40 in gallon cans, an indication that I was
probably not the only one facing rust and corrosion issues.

Greg
Re: non-gumming oil

greenboxmaven
 

I have seen some lively discussions about WD-40 in switches, pots and bearings. I have never had any problem using it as a PART of the cleaning process. It will often cut loose crud that nothing else will, but must be completely flushed out once it has done it's job or it will soon become a residue far worse than the original.

Bruce Gentry, KA2IVY

On 8/14/19 1:09 PM, Greg Muir via Groups.Io wrote:
WD-40

Spent a couple of years working in the tropics with extremely high humidity. I used to protect tools from rusting by wiping them with WD-40 then storing unused tools in plastic bags. What I found after coming back after several months to use them was that the light hydrocarbons used in the product had evaporated leaving behind a petroleum based product with the consistency of something between 90 weight oil and Cosmoline.

From this I learned that it is only good for a very few purposes (aside from the original intent of the product for coating the outsides of missiles to prevent corrosion) is to protect items from rust and corrosion (with some subsequent clean-up effort), a penetrent and, on occasion, a gummed label remover. When I hear of someone using it to lubricate potentiometers, switches and such, I wince.
A footnote: while at the project it was interesting to find that all of the local outlets sold WD-40 in gallon cans, an indication that I was probably not the only one facing rust and corrosion issues.

Greg
Re: non-gumming oil

Chuck Harris
 

Hi Richard,

I tend to use Oilite as a generic term for sintered bronze.
It seems to be a common usage among older mechanics and
machinists... Oilite kind of rolls off the tongue better than
sintered bronze.

I am pretty sure that Oilite didn't invent sintered bronze, but
rather were the first to market oil infused sintered bronze, and
claim it was a lifetime lubricated bearing... it most certainly
isn't... unless you gauge lifetime to be the devices working
life.

I am certain that you are right, Oilite is a pre-oiled product,
and in light duty, slow speed applications it is used that way
quite often... A turntable fits that description.

However, in higher speed, heavier duty applications it is all
but unheard of to use it that way. Things like blowers that
need to be quieter than ball bearing will allow, furnace blowers,
bathroom ventilation fans, ... Tektronix 500 series scope fans...
In these sorts of applications, an oil reservoir is used. It
may be only filled by the motor's manufacturer, but it is a
reservoir none the less.

Turbine oil has a slightly more noble purpose, being intended
for pressurized lubrication systems in jet engines... but that
is exactly the same sort of bearing as is serviced by automotive
motor oil. Turbocharged engines have turbines that spin faster
than 100KRPM, and use a synthetic motor oil, such as mobil 1.

Turbine oil, and light weight motor oil work equally well for
these lowly light duty motors.

I have both on my bench, and which I use is more dependent on
which container will fit the motor I am oiling.

My 5W30 synthetic motor oil has a 16ga blunt needle, and the
turbine oil has a 6" long 3/16" wide straw...

...Very scientific!...

-Chuck Harris

Richard Knoppow wrote:

Look at the Oilite web site. They state that the oil is infused via vacuum. This
is what I always understood about how Oilite bearings were made. There are sintered
bearings that are meant for an external oil reservoir but the Oilite type is
lubricated during manufacture and is not supposed to need any other lubrication
although the web site describes the use of a light wax to eliminate break-in.
In the past I was involved in rebuilding sound recording equipment with Oilite
bearings. They were not easily replacable. I used turbine oil of a type recommended
by the lab of one of the larger oil companies. He gave us a sample, about a quart, I
never used it up. Turbine oil is a very highly refined oil.
Re: Is an early 7A26 a keeper?

ron roetzer
 

Dennis
I should have been more precise, I didn't mean to imply that the 7A26 had differential inputs but that the internal signal path was differential. If you look at the block diagram in section 7 of the manual the signal becomes differential after U1350 (U2350) and continues differentially to the vertical signal output. If either side of the differential pair is not functioning then the output would be 1/2.

Ron

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Dennis Tillman W7PF
Sent: Wednesday, August 14, 2019 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Is an early 7A26 a keeper?

Hi Ron,
This is not what is causing the 1/2 gain in one of the two channels but not the other. The 7A26 is not differential. It has two separate input channels.

In certain cases the 2nd channel can be inverted and added to the first channel to make a "primitive" difference, but not differential, amplifier. Tek generally makes no claims about the performance of their vertical amplifiers when the signal goes off screen. While the signal is on-screen it is in the linear region of the vertical amplifier and you can expect the bandwidth of the amplifier will meet its stated specs.

Provided neither signal by itself goes off screen, and the addition of both signals stays on screen, you will probably remain in the linear region of both channels. If you invert Ch 2 and add both signals together you will get the difference between them provided you use the same probes on each channel and you are careful to calibrate their response as closely as possible. You will also need to calibrate the gain of each channel.

Even if you did all this it would be misleading to assume that the on screen result was what a true differential amplifier with matched probes, matched inputs, matched phase response, matched offsets, etc would give you.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of ron_roetzer@comcast.net
Sent: Wednesday, August 14, 2019 5:42 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Is an early 7A26 a keeper?

although I have no specific knowledge of the 7A26, in differential amplifiers if one side is dead then the gain is exactly 1/2 what it should be.





--
Dennis Tillman W7PF
TekScopes Moderator
Re: 2440 deal

Bob Albert
 

Wow good news!  I hope one of those will end up here.  Keep me informed.
Bob818 894-2887

On Wednesday, August 14, 2019, 09:29:00 AM PDT, Robert Simpson via Groups.Io <go_boating_fast=yahoo.com@groups.io> wrote:

Snagged two, one already gone. Got a reply from seller and my daughter was able to pick up two. I will get to see them next time she comes up (from SF South bay area). Was excess inventory from the seller's company.
Bob
Re: Is an early 7A26 a keeper?

Dennis Tillman W7pF
 

Hi Ron,
This is not what is causing the 1/2 gain in one of the two channels but not the other. The 7A26 is not differential. It has two separate input channels.

In certain cases the 2nd channel can be inverted and added to the first channel to make a "primitive" difference, but not differential, amplifier. Tek generally makes no claims about the performance of their vertical amplifiers when the signal goes off screen. While the signal is on-screen it is in the linear region of the vertical amplifier and you can expect the bandwidth of the amplifier will meet its stated specs.

Provided neither signal by itself goes off screen, and the addition of both signals stays on screen, you will probably remain in the linear region of both channels. If you invert Ch 2 and add both signals together you will get the difference between them provided you use the same probes on each channel and you are careful to calibrate their response as closely as possible. You will also need to calibrate the gain of each channel.

Even if you did all this it would be misleading to assume that the on screen result was what a true differential amplifier with matched probes, matched inputs, matched phase response, matched offsets, etc would give you.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of ron_roetzer@comcast.net
Sent: Wednesday, August 14, 2019 5:42 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Is an early 7A26 a keeper?

although I have no specific knowledge of the 7A26, in differential amplifiers if one side is dead then the gain is exactly 1/2 what it should be.





--
Dennis Tillman W7PF
TekScopes Moderator
Re: 5xx 'Scopes

Dennis Tillman W7pF
 

EVERY Tek curve tracer, except for the limited plugin versions (7CT1N and 5CT1N) have two "sockets" to do A/B comparisons. This includes the 570 (vacuum tube curve tracer), 575, 576, 577, and 370. The 576 and the 577 have similar basic capabilities such as their maximum voltage (1,600V at 100mA, and 1,500V at 200mA respectively), but differ significantly in other ways.

The 576 has an optional 176 high current "front porch" capable of testing power transistors. The 576 has readouts (not on-screen) which assist casual users in avoiding mistakes when making basic device measurements.

The 577 comes in a non-storage (577-D2) and storage 577-(D1) CRT version. It has an optional 176 "front porch" which can test single, dual, or quad OpAmps, SCRs, 3 Terminal Positive and Negative Voltage Regulators.

Both the 576 and the 577 were designed to make the majority of semiconductor measurements that any circuit designer would be interested in quantifying. I once asked Deane Kidd, when I was in his lab, which he recommended, 576 or 577. His answer was definitive: the 577 hands down. So that is what I found to replace my 575 10 years ago. I have had both the 577-D2 and 577-D1 over the years since and there is no question that the 577-D1 (storage) version has more capabilities although the storage is tricky to adjust and is sometimes annoying.

I am now fortunate to own both a 576 and a 577 and all the optional "front porches" so I can test just about anything.

Sean: I believe you are thinking of the low cost adapter board I designed to test vacuum tubes on a Tek semiconductor curve tracer. My adapter is not limited to the 576. It works on ANY Tek curve tracer (575, 576, 577, 7CT1N, and 5CT1N). Contact me OFF-LIST at "dennis at ridesoft dot com" if you would like a copy of the paper I wrote about testing vacuum tubes on Tek curve tracers.

Dennis Tillman W7PF

-----Original Message-----
From: Chuck Harris
Sent: Wednesday, August 14, 2019 5:17 AM

I would have to beg to differ, the 577 has the same left/right sockets, left/right lever switch, and as such, comparison capability as the 576.
It even uses the same dual transistor plugin adapters.
It (with the right option) even has a split screen storage capability.
What it doesn't have is any form of on screen readout display of the settings.

-Chuck Harris

sdturne@q.com wrote:
On Tue, Aug 13, 2019 at 07:59 AM, Mlynch001 wrote:

One of the best finds of mine was a very nice Type 576 Curve Tracer
(at a great price). The 576 has indeed helped me repair other
equipment. More importantly, it has greatly increased my
understanding of all these little pieces of black plastic with various wires protruding from the sides.

Michael Lynch
Dardanelle, AR
That's exactly the model I would like to find. The 577 is smaller but lacks the ability to do A-B comparison testing. The 576 can do vacuum tubes too, with the right test fixture if I'm not mistaken.

Sean



--
Dennis Tillman W7PF
TekScopes Moderator
Re: non-gumming oil

Richard Knoppow
 

Look at the Oilite web site. They state that the oil is infused via vacuum. This is what I always understood about how Oilite bearings were made. There are sintered bearings that are meant for an external oil reservoir but the Oilite type is lubricated during manufacture and is not supposed to need any other lubrication although the web site describes the use of a light wax to eliminate break-in.
In the past I was involved in rebuilding sound recording equipment with Oilite bearings. They were not easily replacable. I used turbine oil of a type recommended by the lab of one of the larger oil companies. He gave us a sample, about a quart, I never used it up. Turbine oil is a very highly refined oil.

On 8/14/2019 10:45 AM, Stephen Hanselman wrote:
Sorry Chuck,
My only experience with these type of bearings is with ones that were already oiled, sorry about that. One thing I like about this list is the plethora of new information.
Steve
--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL
Re: non-gumming oil

Stephen Hanselman
 

You're right it was, I saw this on a Science channel show.

S

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jim Ford
Sent: Wednesday, August 14, 2019 10:41 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] non-gumming oil

The WD stands for Water Displacing, by the way. 40 is presumably because it was the 40th substance the manufacturer tried.Jim FordSent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: "Greg Muir via Groups.Io" <big_sky_explorer=yahoo.com@groups.io> Date: 8/14/19 10:09 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] non-gumming oil WD-40Spent a couple of years working in the tropics with extremely high humidity. I used to protect tools from rusting by wiping them with WD-40 then storing unused tools in plastic bags. What I found after coming back after several months to use them was that the light hydrocarbons used in the product had evaporated leaving behind a petroleum based product with the consistency of something between 90 weight oil and Cosmoline.From this I learned that it is only good for a very few purposes (aside from the original intent of the product for coating the outsides of missiles to prevent corrosion) is to protect items from rust and corrosion (with some subsequent clean-up effort), a penetrent and, on occasion, a gummed label remover. When I hear of someone using it to lubricate potentiometers, switches and such, I wince.A footnote: while at the project it was interesting to find that all of the local outlets sold WD-40 in gallon cans, an indication that I was probably not the only one facing rust and corrosion issues.Greg
Re: non-gumming oil

Stephen Hanselman
 

Sorry Chuck,

My only experience with these type of bearings is with ones that were already oiled, sorry about that. One thing I like about this list is the plethora of new information.

Steve

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Chuck Harris
Sent: Wednesday, August 14, 2019 10:39 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] non-gumming oil

Hi Stephen,

I don't recall saying anything about the original infusion with oil. I generally receive sintered bronze bearings that are bone dry from a distributor, such as MSC.

I don't recall ever getting one that was pre-oiled, except perhaps as a bagged replacement part.

I am not sure how the manufacturer of the sintered bronze would know what parameters your oil needed to survive your use.

Oil is not meant to be added to the shaft/oilite interface, it is intended to be done through oil contact with the outer surface of the oilite The oil then diffuses through capillary action into the sintered bronze, just like a common sponge does when it comes into contact with water.

Very few high reliability users of oilite do not provide an oil reservoir... usually in the form of an oil soaked piece of wool felt that is in contact with the oilite. This is what tektronix has in the fan motors for the old vacuum tube scopes. Often, these motors find themselves with their oil holes upside down, so if you find one that way, be kind and restore it to the upright position. Gravity, and all that...

Getting the oil out of, and back into the oilite is easy. To remove it, set it on a rag, and bake it to 212F. As soon as the oilite gets hot, the oil will leave due to expansion. And to put it back, soak it in hot oil, then allow the oil to cool.

Generally, if the bearing isn't worn out, all that is needed is to remove the gummy oil from the outside of the bearing, and shaft, and put some fresh oil in the wool felt.

If you have to keep adding oil to the shaft/oilite interface, to keep the peace, the bearing and shaft are worn out.

-Chuck Harris

Stephen Hanselman wrote:
Chuck,

You’re right on all your points, except the original oiling was when the bearing structure was made and the oil was “infused”(??) into the material (oil-lite bearing)where our added oil is applied to the bearing surface-spindle interface.

Really it gets down to use what works for you. I’ve also had good luck with WD-40 which isn’t ever a lubricant.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@datagatesystems.com
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
On Aug 13, 2019, at 14:22, Richard Knoppow <dickburk@ix.netcom.com> wrote:

I am not so sure about what additives there are in engine oil. One can get good quality SAE 20 machine oil at many hardware stores. 3-in-one puts it up in a blue can (red can is something else). Also as Kano Microil, very highly refined petroleum based oil, wax free, and does not gum. Most of these blower bearings are so called "life time lubricated" meaning it works until it doesn't. They are made from sintered bronze with oil held in the spongy metal. You can't really re-lubricate them in any easy way but they will hold oil for a reasonable time.
Hewlett-Packard used blowers with a rubber seal at one end. They could be re-lubricated using a syringe to poke through the seal and inject some oil. I have no idea if the Tek blowers are similar. Unfortunately, once the bearings run dry they will become galled and run rough despite having new lubricant.
I agree with you that mixing silicon oil or grease with petroleum lubricant is not a good idea.

On 8/13/2019 2:03 PM, Chuck Harris wrote:
Why?
Silicone oil isn't miscible with the original oil, and you are not
going to make the motor become maintenance free, no matter what you
do with oils.
Just give it some motor oil, thin like SAE5 or 10 is fine.
Detergent isn't like the stuff you wash your clothes in, it will not
cause any problems, in spite of its suggestive name.
The synthetic doesn't oxidize as quickly as the old oil did, but
then any modern oil is much better in that regard.
The last time anyone lubed your scope fan was likely 40 years ago
and yet, it still works. Give it a couple of drops of oil, and move
on... be happy!
-Chuck Harris
Stephen Hanselman wrote:
I've read some of the answers and wanted to add my two cents. We
use marvel mystery oil which seems ok so far. I was thinking about
using silicon based gun oil though

steve
--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL
Re: Is an early 7A26 a keeper?

ron roetzer
 

although I have no specific knowledge of the 7A26, in differential amplifiers if one side is dead then the gain is exactly 1/2 what it should be.
Re: non-gumming oil

Jim Ford
 

The WD stands for Water Displacing, by the way.  40 is presumably because it was the 40th substance the manufacturer tried.Jim FordSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "Greg Muir via Groups.Io" <big_sky_explorer=yahoo.com@groups.io> Date: 8/14/19 10:09 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] non-gumming oil WD-40Spent a couple of years working in the tropics with extremely high humidity.  I used to protect tools from rusting by wiping them with WD-40 then storing unused tools in plastic bags.  What I found after coming back after several months to use them was that the light hydrocarbons used in the product had evaporated leaving behind a petroleum based product with the consistency of something between 90 weight oil and Cosmoline.From this I learned that it is only good for a very few purposes (aside from the original intent of the product for coating the outsides of missiles to prevent corrosion) is to protect items from rust and corrosion (with some subsequent clean-up effort), a penetrent and, on occasion, a gummed label remover.  When I hear of someone using it to lubricate potentiometers, switches and such, I wince.A footnote: while at the project it was interesting to find that all of the local outlets sold WD-40 in gallon cans, an indication that I was probably not the only one facing rust and corrosion issues.Greg
Re: non-gumming oil

Chuck Harris
 

Hi Stephen,

I don't recall saying anything about the original
infusion with oil. I generally receive sintered
bronze bearings that are bone dry from a distributor,
such as MSC.

I don't recall ever getting one that was pre-oiled,
except perhaps as a bagged replacement part.

I am not sure how the manufacturer of the sintered
bronze would know what parameters your oil needed
to survive your use.

Oil is not meant to be added to the shaft/oilite
interface, it is intended to be done through oil
contact with the outer surface of the oilite The
oil then diffuses through capillary action into the
sintered bronze, just like a common sponge does when
it comes into contact with water.

Very few high reliability users of oilite do not
provide an oil reservoir... usually in the form of an
oil soaked piece of wool felt that is in contact with
the oilite. This is what tektronix has in the fan
motors for the old vacuum tube scopes. Often, these
motors find themselves with their oil holes upside down,
so if you find one that way, be kind and restore it to
the upright position. Gravity, and all that...

Getting the oil out of, and back into the oilite is
easy. To remove it, set it on a rag, and bake it to
212F. As soon as the oilite gets hot, the oil will
leave due to expansion. And to put it back, soak it
in hot oil, then allow the oil to cool.

Generally, if the bearing isn't worn out, all that
is needed is to remove the gummy oil from the outside
of the bearing, and shaft, and put some fresh oil in
the wool felt.

If you have to keep adding oil to the shaft/oilite
interface, to keep the peace, the bearing and shaft
are worn out.

-Chuck Harris

Stephen Hanselman wrote:

Chuck,

You’re right on all your points, except the original oiling was when the bearing structure was made and the oil was “infused”(??) into the material (oil-lite bearing)where our added oil is applied to the bearing surface-spindle interface.

Really it gets down to use what works for you. I’ve also had good luck with WD-40 which isn’t ever a lubricant.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@datagatesystems.com
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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On Aug 13, 2019, at 14:22, Richard Knoppow <dickburk@ix.netcom.com> wrote:

I am not so sure about what additives there are in engine oil. One can get good quality SAE 20 machine oil at many hardware stores. 3-in-one puts it up in a blue can (red can is something else). Also as Kano Microil, very highly refined petroleum based oil, wax free, and does not gum. Most of these blower bearings are so called "life time lubricated" meaning it works until it doesn't. They are made from sintered bronze with oil held in the spongy metal. You can't really re-lubricate them in any easy way but they will hold oil for a reasonable time.
Hewlett-Packard used blowers with a rubber seal at one end. They could be re-lubricated using a syringe to poke through the seal and inject some oil. I have no idea if the Tek blowers are similar. Unfortunately, once the bearings run dry they will become galled and run rough despite having new lubricant.
I agree with you that mixing silicon oil or grease with petroleum lubricant is not a good idea.

On 8/13/2019 2:03 PM, Chuck Harris wrote:
Why?
Silicone oil isn't miscible with the original oil, and
you are not going to make the motor become maintenance
free, no matter what you do with oils.
Just give it some motor oil, thin like SAE5 or 10 is fine.
Detergent isn't like the stuff you wash your clothes in,
it will not cause any problems, in spite of its suggestive
name.
The synthetic doesn't oxidize as quickly as the old oil
did, but then any modern oil is much better in that regard.
The last time anyone lubed your scope fan was likely 40
years ago and yet, it still works. Give it a couple of
drops of oil, and move on... be happy!
-Chuck Harris
Stephen Hanselman wrote:
I've read some of the answers and wanted to add my two cents. We use marvel
mystery oil which seems ok so far. I was thinking about using silicon based
gun oil though

steve
--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL
Re: non-gumming oil

Greg Muir
 

WD-40

Spent a couple of years working in the tropics with extremely high humidity. I used to protect tools from rusting by wiping them with WD-40 then storing unused tools in plastic bags. What I found after coming back after several months to use them was that the light hydrocarbons used in the product had evaporated leaving behind a petroleum based product with the consistency of something between 90 weight oil and Cosmoline.

From this I learned that it is only good for a very few purposes (aside from the original intent of the product for coating the outsides of missiles to prevent corrosion) is to protect items from rust and corrosion (with some subsequent clean-up effort), a penetrent and, on occasion, a gummed label remover. When I hear of someone using it to lubricate potentiometers, switches and such, I wince.

A footnote: while at the project it was interesting to find that all of the local outlets sold WD-40 in gallon cans, an indication that I was probably not the only one facing rust and corrosion issues.

Greg
Re: 5xx 'Scopes

Jason A.
 

I have a 535A that I just finished mostly refurbishing I would part with. It's got all new tubes, almost all the capacitors replaced, one broken resistor replaced in the vertical amp, and calibrated up (mostly) to the "B" plugin inside it. I can attest the frequency and voltage displays are in-line with reality, but may need some geometry true-up and probably wouldn't hurt to adjust the delay line. I would also be willing to include a 1A1 plugin (probably needing at minimum new capacitors and a calibration). I am in the Atlanta area. The downside is that with all the parts I've just put into it, I'll have to have what I have sunk into it for acquisition cost and parts. I will even write off the labor as a labor of love keeping something as cool as an old 5-series running.
Re: 2440 deal

Robert Simpson
 

Snagged two, one already gone. Got a reply from seller and my daughter was able to pick up two. I will get to see them next time she comes up (from SF South bay area). Was excess inventory from the seller's company.
Bob
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