Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jan Sun 19, 2020 9:36 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 141 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8  Next
Author Message
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 24, 2019 12:00 am 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 3968
Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

Well.... you know what a square wave is supposed to look like. You adjust the trimmer for the closest approximation. Ideally, it will bend the last part of the horizontal top and bottom of the square wave up and down. You adjust for the flattest top and bottom. Usually, the adjustment bends the horizontal part of the waveform starting at a different place that the hook that you see, so you will end up with a "wrinkle" in the top and bottom of the waveform. If the wrinkle is severe, you may wish to compromise with a bit of a spike as you have now in exchange for a flatter top.

You will just have to play with the adjustment and see. Fortunately (or unfortunately, depending upon your point of view) you have only one adjustment available, so it should be fairly easy to arrive at an optimum setting.

Good Luck,

_________________
Jim T.
KB6GM


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 24, 2019 1:06 am 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
Well that was easy enough. My problem now is a blurry trace and it's deformed on the left side. The blurriness happens on higher sweep frequency settings. As for lower settings, the trace won't stand still. Here's a higher setting triangle wave.

Where do I go from here?


Attachments:
o scope triangle output.jpg
o scope triangle output.jpg [ 274.81 KiB | Viewed 599 times ]
Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 24, 2019 3:09 am 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 3968
Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

You asked:
Quote:
Where do I go from here?


Well.... where you go from here is to beg, borrow or steal another scope. You will need to look at the horizontal sweep waveform, which is supposed to be a sawtooth. Your sweep waveform is obviously distorted. This can be due to a number of causes and can be happening in any stage from the horizontal oscillator (V301) all the way to the horizontal deflection plate driver (V203). You will need a scope to look at the various stages to see where the distortion arises.

Good Luck,

_________________
Jim T.
KB6GM


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 24, 2019 3:59 am 
Member

Joined: Jan Tue 10, 2012 8:39 am
Posts: 911
Don't rule out a bad CRT. If abused (dropped) the deflection plates can move out of place and cause effects like that.

Observation of the horizontal wave will tell the story. If the horizontal wave looks a bit odd near the start, then the CRT is probably okay. If it looks good, then no.

What CRT does it use? I have a spare that I got from a Dumont unit that may be similar.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sat 24, 2019 7:19 am 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 11910
Location: Powell River BC Canada
Your scope does not have an astigmatism adjustment. However some scopes use a
trace rotation coil to correct effects similar.

Show Hor. set to 60 ~, and Vert set to cal. Try various lissajous circles,
big and small, set by V and H gain, made by adjusting phasing control at places
on the screen to show aberrations .

Attachment:
Eico 470 trace rotate.jpg
Eico 470 trace rotate.jpg [ 15.98 KiB | Viewed 589 times ]
Attachment:
Eico 470  Astig and B rotate study.jpg
Eico 470 Astig and B rotate study.jpg [ 143.3 KiB | Viewed 589 times ]

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


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sun 25, 2019 7:34 pm 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
bob91343 wrote:
What CRT does it use?


7JP1.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Sun 25, 2019 10:27 pm 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 3968
Location: Lincoln City, OR 97367
Greetings All:

The Eico scope is very basic. Trace rotation is accomplished by loosening a neck clamp and physically rotating the CRT. There is no trace rotation coil.

Regards,

_________________
Jim T.
KB6GM


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Mon 26, 2019 12:38 am 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 11910
Location: Powell River BC Canada
OP quote. "I need to align mine after recapping it."

Perhaps all these issues explored will be moot when this is done.

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


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Mon 26, 2019 5:06 pm 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
Jthorusen wrote:
This can be due to a number of causes and can be happening in any stage from the horizontal oscillator (V301) all the way to the horizontal deflection plate driver (V203). You will need a scope to look at the various stages to see where the distortion arises.


radiotechnician's most recent post inspired me. Could another part out of spec in the section you mentioned be causing this problem just like my earlier horizontal sweep problem? Earlier it was one resistor 1000 times too big.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Mon 26, 2019 9:30 pm 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 3968
Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

Quote:
Could another part out of spec in the section you mentioned be causing this problem <snip> ?


For any given piece of electronics equipment which is exhibiting a failure, if we make the assumption that it worked properly at one time, then we may safely say that the problem is due to one or more components which no longer meet their original specifications.

Unfortunately, this actually tells us nothing more, really, than the statement "it's broke." If one were to systematically remove all parts in that given piece of equipment (including insulators) and subject them to original equipment manufacturer quality control tests, one would almost certainly find the problem. However, this is not cost effective, either in terms of time or money.

Therefore, we employ test equipment to narrow down the fault to a specific circuit or circuits and hopefully down to a specific component. In most cases, the test equipment required to do this is less expensive and elaborate than that which would be required to perform the OEM quality control tests on all the components in the equipment.

By all means, you can go through the entire horizontal sweep circuit with an ohm meter and see if you can find one or more resistors out of tolerance. Bear in mind that you will have to do a lot of lifting and re-soldering of leads to do this accurately. When you get done, you will still have evaluated only about half the components; there are still capacitors and tubes.

I would try substituting known good tubes into the sweep section. If you have them, replace all at once. See if this fixes the problem. If it does, then put the old tubes back one at a time until the problem re-appears. That tube is the suspect. You may find that more than one tube contributes to the problem.

If not tubes, then try measuring the resistors. If you can't find any problems there or if replacing out-of-tolerance resistors does not fix the problem, then you are back to my original suggestion, which is to get another scope and trace the problem that way.

Since you run a good chance of needing the scope anyway, I'd start there. Of course, I own four scopes, so I don't have any difficulties in whipping out another one to fix one if I need to.

If you plan to work on oscilloscopes or anything else where waveform analysis is key to trouble-shooting (vintage TV, some types of test equipment, digital logic, etc.) then it would pay you to buy another scope.

Regards,

_________________
Jim T.
KB6GM


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Tue 27, 2019 6:56 pm 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
This is starting to sound like the "chicken or the egg" problem.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Wed 28, 2019 5:15 am 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 11910
Location: Powell River BC Canada
Somehow owning a Fluke 87 and diving back 70 years into a scope
that was morphed from an electrostatic TV set is interesting.

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


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Wed 28, 2019 3:20 pm 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
The Fluke was a gift.

Say... Labor Day is coming up. I don't suppose oscilloscopes are considered tools and included with the usual Labor Day tool sales, are they?


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Aug Thu 29, 2019 4:41 am 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 3968
Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

There are lots of scopes on eBay right now. You can probably do much better than even these prices if you can find a ham swap meet near you. There is a Tektronix 465M on there now for $80 plus shipping. Condition unknown, however,

There is a nice B&K scope (B&K 2160A) there (tested and in "good working condition") for $111 and includes free shipping. This is a 60 MHz bandwidth dual-trace scope with delaying sweep. These are nice features and more than you would probably ever need for radio servicing, but sometimes I find them handy. The delaying sweep feature could actually be handy in trouble-shooting your Eico scope. My go-to scope is a Tektronix 465DM which is virtually the same thing except it has a DVM built in and has 100 MHz bandwidth.

You just have to shop around.

Good Luck,

_________________
Jim T.
KB6GM


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Sep Wed 04, 2019 2:14 am 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
I got a Rigol DS1054Z coming in the mail soon. Apparently everyone has been raving about them online.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Tue 01, 2019 8:32 pm 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
So I got an oscilloscope. Now what?


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Tue 01, 2019 8:50 pm 
Member

Joined: Jan Tue 10, 2012 8:39 am
Posts: 911
The wave you show isn't that far from what I'd expect from a typical scope sweep without feedback. The feedback will make it much more linear but without it, you have nothing more than an RC charge, which isn't linear but exponential. That will make the display crowd toward the right as you show.

If it's crowded too much, perhaps there is a power supply problem. Too low a charge source voltage will make the wave much less linear.

These old scopes are worth more as curiosities than tools. Not that they can't be useful, but when you don't have good tools you have to think harder and work harder to accomplish your task.

A good scope is worth its weight. I have too many of them but can't resist a bargain. All my 'extra' scopes are Tektronix and it would be painful to get rid of any, but space has become a problem. So I have two digital scopes and four analog scopes.

I remember when I had none and couldn't justify buying one. But that was a long time ago.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Tue 01, 2019 9:08 pm 
Member

Joined: Jul Mon 01, 2019 4:42 pm
Posts: 360
Location: St. Louis, MO
Don't care, still fixing it!

I misspoke earlier. I got a brand new scope, a Rigol DS1054Z which has been invaluable.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Tue 01, 2019 9:33 pm 
Member

Joined: Jan Tue 10, 2012 8:39 am
Posts: 911
Nice unit, good brand. So the EICO has become a fun project, not a struggle to get a scope working.

Big CRT can be nice if you have the space.


Top
 Profile  
 
 Post subject: Re: Instruction manual for an Eico 470 oscilloscope?
PostPosted: Oct Wed 02, 2019 2:18 am 
Member
User avatar

Joined: Nov Mon 02, 2009 7:01 am
Posts: 3968
Location: Lincoln City, OR 97367
Greetings to ZombieElvis and the Forum:

OK, now you need to use the Rigol to scope the sweep ramp in the Eico. You might start at the grid of V201A. See what the ramp looks like. Move toward the CRT or away from it until you find the cause of the non-linearity. Do be careful not to allow more voltage to be applied to the Rigol than it can handle. Solid-state scopes are fussy about this!

Good Luck,

_________________
Jim T.
KB6GM


Top
 Profile  
 
Post New Topic Post Reply  [ 141 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: Tony Wells and 23 guests



Search for:
Jump to:  


























-->


Privacy Policy :: Powered by phpBB