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I’ve got an old Weston standard cell that sits on my bookshelves and I check the DVMs against that. I’ve never calibrated it but it seems close enough. I don’t really ask much of my calibration, within two or three decimal places is fine.

Robin

Hi Vincent,

I've read your thread on eevblog, which was helpful. The reason I focused on the horizontal amp is that unlike the situation with your 317, the traces are still there after warm-up, just in the wrong position and malformed. The caps in the horizontal amp section are all dogbone-shaped ceramic or mica. It's possible they've gone bad, but IIRC ceramic and mica caps last longer than paper or old electrolytic.

All the paper caps in this serial # are Good-All rather than Sprague. I've replaced the paper caps on the chassis, but still need to get to the paper caps on the rotary switches.

I hope the flyback transformer isn't damaged! Besides the two paper caps I replaced in the HV circuit there is an electrolytic (C807, 8uf, 450V). I've never seen a single-lead cap like it before. It's held to the chassis with a clamp. Looks to be body-negative. Another one is C154 (500uf, 6V) in the preamp. Are these still available outside of fleaBay, or will it suffice if I get modern two-lead caps and route the negative leads to the chassis?

I have an Eico 950B cap bridge I can test the caps with. I do need to get pictures and measurements from the LV rails, but right now I don't have the scope in front of me. I'll be sure to post back here with my findings.


Hi Barry,

It's actually the chassis code for my favorite car, the Mitsubishi Lancer Evolution 10.

Regards,
John - CZ4A

What I do is periodically take my voltage transfer standard to a lab, and get it measured. I then
take
my now known transfer standard, and use it as my shop standard when calibrating all of my meters
and calibrators.

I've done precisely the same thing. I had my old Cropico DC 10V voltage standard traceably calibrated.
And it was within the last decimal place (7 of them) as it was when it was originally calibrated by
the manufacturer in 1987.

Why did Cropico (the Croydon Precision Instrument Co) exit the voltage standard business? I talked to
them about that - actually the original designer: "Fluke entered the market, and as a small company we
could not compete"

So I've stopped worrying or getting paranoid. I'm going to assume the voltage is what it says it is on
the tin.

Craig

I have calibrated everything I could with what I have. This scope is a mashup of several scopes. 2 different attenuators a vertical amp from another 485 and all new capacitors. I would like to clean up the square waves. Pictures are of the scope calibrator 5V 1khz. 50mV and .1V are both using a 5x attenuator and 50ohm cable the 1V is just the 50 ohm cable. I dont know if this is able to be done with what I have.

50Mv /g/TekScopes/photo/37195/8?p=Name,,,20,1,0,0
.1V /g/TekScopes/photo/37195/0?p=Name,,,20,1,0,0
1V /g/TekScopes/photo/37195/1?p=Name,,,20,1,0,0

this is another scope at 1V /g/TekScopes/photo/37195/7?p=Name,,,20,1,0,0

Thanks for the info.. I am no radio amateur so it didn't make any sense to me I must admit...

I guess I am old fashioned but I prefer to call human beings via their real name, feels more natural and fitting to me ?!
It's also easier to remember a real name than a call sign, at least for the average human being that I am.

Anyway, looks like he is not far from a diagnosis on his Tek 317, though would be nice to have a few piccies showing the problem, and/or uploading a little video on Youtube maybe ?


Vincent Trouilliez - VT7760... err no, just made that up, just Vince, that will do fine :-)

Hi Kevin,

Absent a calibration, or comparison of your meter's readings
to a standard value, how will you even guess if it is right?

What is often called calibration is really verification and
documentation of your meter's performance as compared to what
the manufacturer claimed its performance would be.

Is it worth it? I cannot know what you value. Some just buy
new meters whenever they suspect that their old meter may be
performing incorrectly. Others repair and calibrate the old
meter. Still others don't really need a meter that can do much
more than verify that a D cell is about 1.5V, so for them,
calibration is just a new D cell away...

What I do is periodically take my voltage transfer standard to
a lab, and get it measured. I then take my now known transfer
standard, and use it as my shop standard when calibrating all
of my meters and calibrators.

Is it truly right? No. My transfer standard starts to change
the instant I stop comparing it to the calibration lab's
transfer standard, which started to change the instant that
NIST stopped comparing it to NIST's standards, and every time
UPS went over a bump...

OBTW, your thermocouple calibrator is not even in the same
league as your 5.5 and 6 digit DVM's... it is kind of like
comparing a pro baseball game to the toddlers playing T ball.

-Chuck Harris

Kevin Oconnor wrote:

This auction includes some funny-looking 160-series modules? Are they clones or are they Tek?



thanks, -Kurt

CZ4A is most likely an amateur radio call sign (Canadian).

Thanks,
Barry - N4BUQ

Forgot : the caps you actually need to worry about are not the electrolytics (at least not at first), but rather all the paper caps, the black and red "Sprague" ones. You already have replaced the two from the CRT/HV section... maybe there is one causing trouble in the horizontal section...

Hello anonymous ! :-) I guess "CZ4A" is not your real name ;-)

Well I am hardly an expert with tube stuff, as I only have one of these beasts.... yes, a Tek 317 just like yours.
Got it last summer, fixed it a few months ago, learned some stuff along the way... thanks to the people on here obviously.

My first thoughts :

- Don't lose sleep on the big electrolytics... it so happens that they were top quality and more often than not, they are still good today ! Mine certainly are, and my unit is even older than yours (SN# 2369). All power rails were spot on, and ripple on all f them was negligible.

- You say that the trace brightness is good at power up, but dims a bit once fully warmed up (an indication of how much time that actually means, might be useful : 2 minutes, 30minutes ?). I guess that can only mean that there is still some issue in the CRT/ HV section that needs sorting out. You already replaced the two paper caps in the CRT section (I did too, that fixed the dimming trace issue on my scope, would dissapear after only 60 seconds), but I gather that another common problem on these scope is the HV transformer which becomes lossy once, precisely... warmed up). So maybe you need a new tranny. The issue is so common, that there is someone on here who used to wire them by the dozen to help others fix their scope...

- As I understand you, you already have narrowed it down to the horizontal section of the scope... so well, just keep trouble-shooting it further, thanks to the comprehensive service manual, and your existing experience working on tube stuff... shouldn't take you too long I would think ! :-)


I understand this is your first scope... however it's gonna be difficult checking ripple and waveforms at various points, without... a second scope. Just pick the cheapest/crapest basic old analog scope you can find locally. Even if just single channel, even if just 1MHz B/W... that would still be night and day to assist you in trouble shooting your 317. Obviously you will need to use x10 probes, given that voltages can go up to, IIRC, 400+ Volts (for the CRT circuit). A HV probe would be nice too, to check what voltage you actually get on the CRT anode... I picked a decent 40kV one for 75 Euros shipped. You can find cheaper since here you only need a 10kV probe.

But at first, you can start by checking all DC voltage levels indicated on the schematics (in the area of interest), using a simple digital multimeter...
Of course start by checking all the voltage rails. You can use your DMM in AC mode to get a first taste for ripple levels, short of a scope at the moment.

Keep us posted on your progress :-)


Regards,

Vincent Trouilliez

Very good explanation Fabio. It’s as if I was there. Thanks
Raymond C?té
KD9CCZ

Heaven goes by favor.
If it went by merit, you would stay out and your dog would go in.

-Mark Twain

Oilite is a registered tradename for a sintered bronze
bearing material.

Oilite bearings need to be precharged with oil. This
is done by heating the bearing, and then placing it in
a container of oil. When the bearing cools, the fresh
oil will be drawn into the bearing. It doesn't have
to be real hot, probably about 100C... don't want to
ruin the oil.

When an oilite bearing is put into service, it is
common to put the oilite into contact with an oil
soaked felt pad. The worn out oil will be replenished
with fresh oil from the pad.

Oilite is more abrasive than the steel shaft (usually),
and when wear happens, the steel usually does the
wearing.

The oilite can get damaged through being run dry.
The little bronze lined cells... sort of like a sponge...
get smeared, or hammered, shut by the friction, and
rattling that happens when the oil runs out. They
can sometimes be cleaned well enough by heating them
to get the old oil (and dirt) out, and allowing fresh
oil to charge the bearing.

Usually, a bearing that has been run dry will not wick
oil adequately, and will just throw the oil you add,
and again go dry.

Also, it is imperative that oilite be run with close
tolerances. It works by meniscus action of the oil
in the oilite against the shaft, forming a film of
oil that supports the shaft... The shaft isn't supposed
to rub against the oilite.

-Chuck Harris

Fabio Trevisan wrote:

On Fri, 16 Mar 2018 12:41:47 -0700, you wrote:

Hello Brasscat,
What a world of experts and specialists this is.
In my small world, I never thought there were different kinds of bronze bushings... To me, there was sintered bronze bearings, for cheapo, less demanding applications, and ball bearings for serious stuff.

There's also sleeve bearings, which may or may not be lubricated (and
likely ought to be).

I've got to do some research to answer your question, since I didn't have a guess of what "Oilite" meant.
Now I know there's plain sintered bronze bushings, often (but not always) made of phosphor bronze, and there's Oilite, which I understood as being a specialized type of sintered bronze bushing... one that's auto-lubricant (e.g. that doesn't require additional oil, IF I got it right).

I think you do. Oilite is a sintered bronze, made up of tiny little
welded together bronze spheres. As such, it has a lot of internal
space. It's oil impregnated to "avoid" the need for continuing
lubrication. It is supposed to be permanent lubrication.

Cleaning them with a solvent may require them to be re-lubricated.

Sleeve bearings are a shaft running in a tube, I think there's no
question about lubrication, they have to be.

Never having seen an Oilite bearing or, at least, not knowing that I saw one, I can only offer an assumption.
This fan has 2 very generous lint pads (say 1" x 3/4" x 1/8th") that surrounds the bronze bushing... So I THINK it's not Oilite.

I think you're right.

Harvey

Rgrds,
Fabio

On 2018-03-16 3:10 PM, lop pol via Groups.Io wrote:

It is so darn close. It's very hard to tell. /g/TekScopes/photo/37195/4?p=Name,,,20,1,0,0

Looks great. I'd like to know if anyone has experience fabricating the
panels. I may be receiving a machine with missing panels and would want
to re-create. Recommendations or suggestions welcome.

Metal... or acrylic? :-)

--Toby

Hello Fabio, oilite is a sintered bronze bushing which is impregnated with oil
while under vacuum. The sintered bronze is full of cavities. They are not un-
common. Reoiling oilite will not last that long, after the internal oil supply has
exhausted or hardened. Plain bearings need a means to supply oil. If it has
felt pads, then I would suspect it to be plain bearings. The felts need to be oiled.
Wikipedia has a nice article on oilite.

Stan

Hello Brasscat,
What a world of experts and specialists this is.
In my small world, I never thought there were different kinds of bronze bushings... To me, there was sintered bronze bearings, for cheapo, less demanding applications, and ball bearings for serious stuff.
I've got to do some research to answer your question, since I didn't have a guess of what "Oilite" meant.
Now I know there's plain sintered bronze bushings, often (but not always) made of phosphor bronze, and there's Oilite, which I understood as being a specialized type of sintered bronze bushing... one that's auto-lubricant (e.g. that doesn't require additional oil, IF I got it right).
Never having seen an Oilite bearing or, at least, not knowing that I saw one, I can only offer an assumption.
This fan has 2 very generous lint pads (say 1" x 3/4" x 1/8th") that surrounds the bronze bushing... So I THINK it's not Oilite.
Rgrds,
Fabio

It is so darn close. It's very hard to tell. /g/TekScopes/photo/37195/4?p=Name,,,20,1,0,0

Hello the thread, question about these fans:

Do these motors use plain sleeve bearings,
do they use oil felts to supply oil? Or are
they using oilite bearings??

Thanks, Stan KO6YB

I`m sure there will be plenty of opportunities Lop,
Next question about this kind of fan is yours!
Rgrds,
Fabio

Bleh, I was afraid you'd say that! Two of the can caps look hard-to-access. They all look to be original, and even if one or more were replaced during the last calibration in '77 you are right that they are old enough for replacement to be considered.

For the smaller-value caps I can likely get away with mounting pencil caps under the chassis and keep the cans in place for appearance's sake.