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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Sun 20, 2019 12:18 am 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 225
Location: St. Louis, MO
radiotechnician wrote:
The Heath and Eico products of the past have no great value in this century.

However the potential for learning electronics from the restoration theory issues
cannot be easily be found by googling.


You mean how electronics can instantly "behave" as soon as you attach your test gear, and then you have to juryrig them so that it appears like that test gear is always attached? :lol:

In other news, square waves on this Eico look weird. There's a spike off screen after each peak and valley. I'll post a picture when I got time. Is that spike normal on these old tube scopes?

Jthorusen, definitely check out MLCCs! They can take the place of lower spec electrolytic caps now and eliminate those parts from having lifetime replacement issues. I used them in restoring that B&K E-200D signal generator I was talking about earlier. I got it down to only 2 electrolytics, the smoothing caps in the power supply section. I know that there's a shortage of them right now, but that should improve over time.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Sun 20, 2019 1:29 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11816
Location: Powell River BC Canada
Quote:

You mean how electronics can instantly "behave" as soon as you attach your test gear, and then you have to juryrig them so that it appears like that test gear is always attached?

Your phrasing is very interesting and dives deep into the heart the universe itself.

I would use a clumsy metaphor and wonder how important is having confidence in
believing the light in the refrigerator goes out when the door is closed.

But seriously, back to your square wave issue. In the Rider oscilloscope book there are
pages and and pages of wave forms and discussions about causes.

To quote some wise person who spoke before, perhaps an old scope is the
"Huntron" of square waves.

When you couple anything together in electronics involving a change of rate
signal (e.g. AC) there exists a conjugate match. This may look like a 3 + j4 source
ideally wanting to transfer power to a 3 - J4 load.

In the case of the wonky Eico 470, something has crept in that triggers instability
without the 30 uuFd load.

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Amateur Radio Literacy Club. May we help you read better.
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 Post subject: Instruction manual for an Eico 470 oscilloscope
PostPosted: Oct Tue 22, 2019 3:59 am 
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I had no idea that was a feature on the M70 deck. Yeah, having the manual makes a big difference. Damn shame there arent manuals for all radios. Almost none for Lasonic and few for Toshiba. Damn lucky there is an M90 service manual though

<a href=https://prom-electric.ru/>.</a>

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Sun 03, 2019 10:23 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 225
Location: St. Louis, MO
After recovering from illness after illness (kids started school) and work, I finally have time to get back to this stuff.

Here's those square waves. Is this normal for square waves on this old tube scopes? I couldn't get a good view of them on screen at lower frequencies.


Attachments:
470 square waves.jpg
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square waves.png
square waves.png [ 42.22 KiB | Viewed 336 times ]
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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Mon 04, 2019 10:20 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11816
Location: Powell River BC Canada
It is good that you are feeling better.

The Eico 470 does not have the bandwidth to display a 50 kHz square wave correctly.
The vertical band width is 10 cycles to 1 megacycle +/- 2 dB.

Overshoot is caused by circuits that may have drifted over time and checking L101 and
L102 associated parts may aid in correction in your oscilloscope. Read the math and look at the +/-
which means these circuits can have have 2 ideal frequencies.

Attachment:
Rider and Uslan sect 6.jpg
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Attachment:
Heavyside op calc W B Coulthard Pitman 1941  i     university of british columbia.jpg
Heavyside op calc W B Coulthard Pitman 1941 i university of british columbia.jpg [ 375.12 KiB | Viewed 327 times ]


edited out whoops multiple images.

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
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Last edited by radiotechnician on Nov Wed 06, 2019 8:51 am, edited 1 time in total.

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Mon 04, 2019 6:38 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 225
Location: St. Louis, MO
Huh. Come to think of it, I replaced nearly every component in this Eico except for the tubes and their sockets, switches, pots, 4 or 5 resistors and the inductors. I didn't even test the inductors. I just assumed they worked. Back to testing!


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Tue 05, 2019 10:03 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11816
Location: Powell River BC Canada
Inductors of that era were sometimes coils wound on resistors.

In TV sets, the inductor winding sometimes went open circuit. It also
failed due to corrosion where the coil wire was soldered to the resistor.
These were called video peaking coils, and when bad,the picture on
the screen had tell tale symptoms (washed out fine detail).

Attachment:
L101 L102.JPG
L101 L102.JPG [ 37.91 KiB | Viewed 312 times ]

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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: Nov Wed 06, 2019 5:52 am 
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Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

If you observe the rise and fall times as shown on the Rigol display, it looks to me as though the fall time is very fast... quite a bit faster than the rise time. This fast transition is probably well outside the bandwidth capability of the Eico scope and is causing ringing somewhere in the vertical amplifier. You could look for where it is occurring with the Rigol and try to add some correction, but you would likely cause other problems at lower frequencies.

As the old saying goes, you can't make a silk purse out of a sow's ear. The Eico is what it is... and it actually looks pretty good with that waveform.

Regards,

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Sun 10, 2019 10:33 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
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Location: St. Louis, MO
I just did a resistance test on those inductors out of circuit. One measured 27.1 ohms and the other measured 26.6 ohms. From what I've read, that's a little high... Should I replace them?


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Mon 11, 2019 1:40 am 
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Greetings to ZombieElvis and the Forum: Resistance measurements are a poor way to evaluate inductors. If you have a way of measuring the actual inductance and know what it is supposed to be, you can try that. Otherwise, let well enough alone... they are unlikely to be bad unless abused in some manner.

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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Mon 11, 2019 8:43 pm 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Resistance is in order, ( e. g. a 2.5 mHy coil is 22 ohms in period catalogue).

There is test you might try.

Connect a resistor in series with the coil and and then apply a square wave to the
combination, and see what the coil wave form looks like on your new scope.

Do both coils act in the same way? A few shorted turns may not affect resistance
but will affect Q.

(That is how shorted turn testers work.)

Then convince yourself that two resistors only will not affect a square wave that way.

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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: Nov Tue 12, 2019 11:53 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
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Location: St. Louis, MO
I used this method and got 5.07 mH for one and 3.94 mH for the other. Do the units on inductors go up or down with shorts?

Jthorusen wrote:
they are unlikely to be bad unless abused in some manner.


This thing has had quite the life. There are 4 original resistors left that weren't out of spec, I just checked. The tubes are a mix of GE, RCA and Sylvania. The 6J5 definitely isn't original since the 6J5 is an all metal tube. It's even in the illustration in the construction manual. Mine came with a 6J5GT, a glass variant.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Wed 13, 2019 6:58 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
No, the inductor range of values values you found are fine.



The measurement of the inductance of a coil using AC is affected by the resistance
and a coil with a short circuited turn becomes a transformer with at least two
windings.

The frequency critical resistances calc were posted before
and show that shorts can affect the value of measurements.

I have a General Radio 160 Q meter that allows measurement of
the inductance of coils over a wide variety of frequencies.

With the resistance and the inductance you have tested, calculate the Q
of your coils at frequencies your scope will be used at.


Also, find out which direction the coils were wound. Then mark a
dot on the end to signify polarity. This will allow you to swap ends
to make the two adjacent coils have the same or different polarity.

Do you think that alter any thing ?

You could measure one coil using the way shown in the article. Then
see if the inductance changes if the second coil is shorted out, and
moved adjacent the one under test.

Read up on mutual inductance.

A bad coil will show up with a low value of Q.
Attachment:
Boonton 160 Q meter.JPG
Boonton 160 Q meter.JPG [ 13.55 KiB | Viewed 220 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: Nov Wed 13, 2019 8:02 am 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 819
The nice thing about Q meter measurements is that they can be done at nearly any frequency. I have two Boonton units, one HF and one VHF. They are great for measuring coils or capacitors or even resistors. I have one giant coil that measures a Q over 500. That impresses me.

I can measure coils or capacitors or resistors with my VNAs. I have an HP and an Advantest and the new nanoVNA. They also measure transmission lines, antennas, and all sorts of interesting things. In fact they are a lot of fun to play with and make random measurements of whatever parts I find in the junkbox. I can measure the length of a transmission line or its characteristic impedance.

I also plotted a curve of a diode with a function generator and a resistor. The scope was in xy mode and I could see the forward curve of the diode after around a half volt. Just power the diode via a series resistor. Sweep the scope with the function generator and use the other channel to look at the diode voltage. Use either a sine or triangle wave. The frequency is unimportant; too low and the pattern flickers. Too high and the two traces don't coincide. A hundred Hz is good.

All these toys are great teachers of electronics.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Wed 13, 2019 11:27 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11816
Location: Powell River BC Canada
Electronics can be fun. Especially when you can look at something
that may actually be something else. 8)

From Google.

The Thing, also known as The Great Seal Bug, was a passive covert listening device, developed in the Soviet Union and planted in the study of the US Ambassador in Moscow, hidden inside a wooden carving of the Great Seal of the United States. It is called a passive device as it does not have its own power source.

:lol:

_________________
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: Nov Wed 13, 2019 11:43 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 225
Location: St. Louis, MO
Oh forget it. My numbers don't match online calculators for L now. It's cheaper to replace them than deal with the headache.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Thu 14, 2019 10:06 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11816
Location: Powell River BC Canada
ZombieElvis wrote:
Oh forget it. My numbers don't match online calculators for L now. It's cheaper to replace them than deal with the headache.


Find one of these I have used for 60 years.

And the dough stashed from back then will buy my Win 10 laptop soon.
Attachment:
HP2.jpg
HP2.jpg [ 312.75 KiB | Viewed 199 times ]
Attachment:
HP2 i.jpg
HP2 i.jpg [ 279.6 KiB | Viewed 199 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: Nov Fri 15, 2019 8:57 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 225
Location: St. Louis, MO
How useful are those Q meters? My local shop has a Boonton 160-A for sale for $35 and that's negotiable. It will definitely need work. The cord was horribly dry rotted and the calibration sticker said it was last calibrated in 1972.


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 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Nov Sat 16, 2019 2:59 am 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 11816
Location: Powell River BC Canada
I would grab The Boonton 160A Q meter for $35. My 160A was presented
to the University of British Columbia, by the B.C. Telephone Company.

Eventually it got to the assets disposal division, where the bright young
clerks sold it to me for a song. The clerks were totally knowledgeable
about the vast quantity of first generation PCs they were selling.

The electronics instructor at the college I was interning at for a teaching cred
went on vacation. When he returned, his lab was cleaned out. They dropped
the program. So he had to go back to teaching biology, which he had done
when the need for electronics was added to the physics department.



But be very careful with any restoration. Forget calibrating it.

I use mine by sniffing the frequency with a tiny digital counter
sitting on top.

Any readouts are as precise as the printing on the dials .

Change the cord, don't recap it quickly, if at all.

The fatal part of the unit is the thermocouple, blow that and
you are done.

If you get it working, keep it under a bell jar, and seek out a Heathkit
Q meter for daily use.

Also you said your numbers didn't work with online calculators.
Entering numbers correctly is very important.

I bought a HP-28C about 30 years ago. I needed it a couple of weeks ago
but forgot how to use it precisely. Had to hit the instruction books for it,
(four came with it). But I'll never forget how to use the RSR-1 slide rule.
Attachment:
HP1.jpg
HP1.jpg [ 339.41 KiB | Viewed 170 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: Nov Wed 20, 2019 5:53 am 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 225
Location: St. Louis, MO
Umm, I only buy stuff that I can use...

Man, this Mouser order is taking forever to get here.


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