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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 10, 2019 1:50 am 
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Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

No problem. If I had $5 for every time I typed up a page of reply only to discover what I said had already been covered, I would be able to afford some of that new test equipment I have been drooling over. :D

Regarding the Amazon stuff... I note that your product is for a laser printer. There is a different plastic formulation for ink jet printers.... be sure you get the right stuff for whatever printer you have. Ask me how I know.... I have an ink jet printer and I tried to print on the laser stuff.... it smeared and ran all over. However, after a second trip to Office depot, I found the ink jet equivalent and that worked well.

Regards,

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 10, 2019 6:04 am 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 713
Location: St. Louis, MO
Here, I'll release this to everyone. I basically remade a graticule template from the cover of the Construction Manual. It's got 0.2" divisions with 1" larger divisions. It's centered on 6 full 1" divisions, so it should be large enough for even 7" tube scopes.

I still need to wait for my transparency films to come in the mail though.


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graticule.xlsx [13.33 KiB]
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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 10, 2019 9:15 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
Find online page 7-42 of Encyclopedia On Cathode Ray Oscilloscopes And Their
Uses, and read:

" Whatever may be the length mentioned in the specifications, it is
that dimension which should afford a linear sweep. We assume this
to be the length stated, although in the final analysis it is determined by
the screen diameter.
"

From the graticule design, the use of darker and lighter quadrant
lines should make the eye path as easy to read as possible.

X rate assumed constant Y is where the interest may be.

Will your wave from have an expected aspect ratio ?
Attachment:
Wiki Scope.JPG
Wiki Scope.JPG [ 40.19 KiB | Viewed 1661 times ]

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 10, 2019 8:32 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 713
Location: St. Louis, MO
What are you suggesting exactly, radiotechnician? I only have a black and white laser printer, so I can't differentiate lines by color. I just recreated the pattern from the manual cover and from pictures I've found online. For every round tube oscilloscope I've seen, the graticule used square divisions.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sun 11, 2019 3:25 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
These thoughts came to me when I downloaded your spread sheet and saw a sheet of equal
squares and dark lines. It doesn't look like the graticules on my scopes.
Attachment:
Excel.JPG
Excel.JPG [ 86.44 KiB | Viewed 1641 times ]
Attachment:
Graticule D61.jpg
Graticule D61.jpg [ 135.1 KiB | Viewed 1641 times ]

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sun 11, 2019 6:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3603
Location: Seattle WA US
Another possible approach: Take the graticule from a 5-inch oscilloscope (often found next to the dumpster after a hamfest) and scan it with a flatbed scanner.
Then you can extend that graticule pattern to 7 inches or greater using a program like Photoshop or Gimp.

If you don't have access to a scanner, I'd be willing to do a few scans for you.

-Chuck


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sun 11, 2019 8:45 am 
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Location: Lincoln City, OR 97367
Greetings to Steve and the Forum:

That graticule may not look much like a modern scope, but it was a fairly common style in the 1950's and on service grade scopes into the early 60's. I seem to remember at least one graticule that looked exactly like that except the lines were red.

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sun 11, 2019 10:01 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
The scope is a Telequipment D61. I bought 11 of them from a university
surplus sale about 40 years ago. They served well and all worked hauled around to
where my electronics classes were.

Sadly, they were solid state, and almost all need a complete refurb now. They
are heavy.

Time marches on.

If I can sell enough seats in the Fall my students will learn basic on some tiny
handhelds. I can stuff six of them into my jacket pockets. They are good for 5 Mhz.

The Telequipment D61 was good for 10 mHz in 1975.

The 5 Khz comes from a $25. 6000 count DVM from Banggood.
Attachment:
Scope Hyjjinks.jpg
Scope Hyjjinks.jpg [ 187.97 KiB | Viewed 1635 times ]

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Mon 12, 2019 10:50 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 713
Location: St. Louis, MO
I got a graticule in, first try! 8)

Is my trace supposed to be curling on the left like that with nothing hooked up?

Jthorusen, I was looking up your post about how to calibrate this scope beyond this step and I have some questions. Do you have a recommended way to set the voltage on 60 Hz AC? This sounds like putting a big fat pot on a cord and plugging it in.





Oh come on... I just discovered that this weird spring I found on my desk is one of the rotors from S101. It fell out because the disc section holding it broke off. Now I need a 4 position 2 pole rotary switch.


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graticule in.jpg
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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 12:47 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
Trace should be a straight flat line.

Turn vertical gain to zero and short circuit the vertical input to ground.

That used to be east to do when the vertical input was a binding ppst
and so was the ground.

Also make sure the front panel of scope, and the grounding washer/lugs with
the BNC connectors are grounded.

Are the resistors under that door at the rear of scope jumpered out ?

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 2:43 am 
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Joined: Nov Mon 02, 2009 7:01 am
Posts: 4629
Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

First, the scope should show a flat line with no input, as Steve says. However, with the vertical attenuator switch broken, you will not be able to proceed until you get that replaced.

If you can post some photos of the old switch with a ruler in the picture for measurement comparison, perhaps someone may have a suitable switch lying around in his junkbox. I have a number of rotary switches lying around, but without knowing how much room there is around the switch (which determines maximum diameter of the wafers), the wafer spacing (necessary to accommodate the inter-wafer components gracefully), bushing diameter, etc. it will be impossible to know if any given switch will do the job.

Regarding the calibration, you are looking for millivolts, not volts. Perhaps the best way would be to get a known accurate AC true RMS voltmeter. Rig up a filament transformer so you have a safe, isolated source of low voltage AC. Connect a pot across the filament transformer (1 K should do fine) and then connect the wiper of the pot to the scope vertical input, with one end of the pot connected to scope ground. Bridge the scope connection with your accurate AC voltmeter. Set the pot across the transformer so that 177 mV is read on the meter. Set the scope controls for 500 millivolts full scale on the graticule (50 mV per division). Change the vertical input selector to the "CAL" position and then adjust R108 for a display of the same size. You are done.

Arithmetic: Cal circuit puts approximately 500 mV peak-to-peak on the S-101 "CAL" contact. 500 mV peak-to-peak is 250 mV peak. Converting peak to RMS (multiply by .707) gives 176.75 mV. 177 mV is probably as close as you can read your meter and close enough for a service grade scope.

Regards,

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 4:35 am 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 713
Location: St. Louis, MO
radiotechnician, I didn't use the washer lugs that came with the BNCs. I was just relying on the aluminum face plate being screwed to the steel frame. The original ground lugs were (badly) soldered to the steel brackets spot welded to the front plate. I may just wire up black wires for the new ground lugs. And yes, the resistors under the back panel are jumpered.

Jthorusen, I got a Fluke 87V and an isolation transformer. The Fluke says right on top "true RMS multimeter". I'm going to stop by my local electronic supply store tomorrow. They have a surprising amount of old electronics components. I might get lucky. Maybe they'll still have that signal generator I had my eye on...


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 5:39 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
There are voltages in the Eico 470 that exceed the safe operating range of
the Fluke 87.

Consider keeping it in a drawer and getting an expendable DVM, available
for under $20.

Remember, there were no nice DVMs when the 470 was made.

Attachment:
Fluke probe.jpg
Fluke probe.jpg [ 288.72 KiB | Viewed 1605 times ]


https://www.instrumart.com/assets/80K-6-instruction.pdf
Attachment:
Flike probe.JPG
Flike probe.JPG [ 303.64 KiB | Viewed 1605 times ]

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 6:26 am 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 1662
Looks like it takes $150 or so to buy one of those probes.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 7:09 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
Many of the classic multimeters had 6000 volt jacks on them.

It the meter was 20000 ohms per volt then the load would be
12 meg ohms on DC AC would be lower.

Warning: these methods and meters are only for low energy
applications

They are not for testing power distribution or utilization systems.
Attachment:
Triplett 630 NA.jpg
Triplett 630 NA.jpg [ 207.46 KiB | Viewed 1604 times ]
Attachment:
Triplett 630 na ii.jpg
Triplett 630 na ii.jpg [ 139.68 KiB | Viewed 1604 times ]

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 9:44 am 
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Joined: Nov Mon 02, 2009 7:01 am
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Location: Lincoln City, OR 97367
Greetings, All!

Please note that the voltage being measured is EXTERNAL to the 470, is a calibration voltage, and is in the range of 177 millivolts or .177 volts or roughly one tenth of the voltage of a common AA dry cell.

This is what ZombieElvis is using his meter for. I do not think that he is intending to use it to poke around in the CRT circuits of his scope. In order to get the best calibration results possible, a 4 1/2 digit or even more high accuracy true RMS meter is called for. Sounds to me like that's exactly what the fellow has.

Regards,

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KB6GM


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 13, 2019 3:50 pm 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 1662
I have one of those Triplett 630-NA meters with the 6 kV scale, as well as an old Simpson 260 with a 5 kV scale so I'm good with high voltage measurements. Maybe I don't have high accuracy but I do have very minimal circuit loading and certainly accurate enough for any of my usual measurements.

I can improve the accuracy of the VOMs by measuring say, 1000 Volts and comparing with my accurate meters. I eyeball the error and that gives me a clue how far off it might be at full scale. This doesn't take into account the voltage coefficient of the multiplier resistors but it's close enough. I can measure the voltage coefficient up to 1 kV with my megohm bridge and extrapolate from there, especially after seeing how said coefficient changes below 1 kV.

All this stuff is just a hobby so if I screw up there isn't that much lost.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Thu 15, 2019 7:00 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 713
Location: St. Louis, MO
Hey, they had a switch that worked at my local shop! It's a 3 pole too, so I got a spare pole to use if another rotor decides to break off in the future. The position turn angle even matches the marks on the face plate. Better yet, R108 actually does something when I turn it now!

Jthorusen, let me see if I understand this what you said. Basically I need a really low voltage transformer that I can use a pot with to get line voltage down to millivolts, set it at 177 mV, hook that up to V input, set the vertical gain for 10 divisions, get an idea for the amplitude of that, then switch the vertical attenuator over to CAL and try to match that amplitude? I assume you mean matching the 1X attenuation setting?


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Thu 15, 2019 7:25 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12437
Location: Powell River BC Canada
Your scope already has a low voltage transformer winding (6.3 volts).

Just connect to the un grounded side of the pilot light, or point W on the schematic.

Recommend not using R313 (phasing pot) as the variable resistor.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Thu 15, 2019 7:32 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 713
Location: St. Louis, MO
True, but then it's not isolated, right? Am I going to fry this thing after doing so much work on it?


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