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 Post subject: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 4:49 pm 
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Hello, all; Lot of good info on this forum!
I've identified all the old capacitors, and most of the the resistors, but then run into this. 2 silver mica capacitors that don't look too good. It's not recommended to replace these, as it would throw off calibration a lot. Should I just call it quits on this signal generator and find another? Thanks in advance for your advice.
-Simon
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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 5:57 pm 
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Joined: Jan Tue 16, 2007 7:02 am
Posts: 2851
Location: Lexington, KY USA
I don't see anything that resembles a silver mica capacitor in the first picture. Neither picture shows any capacitors that are obviously "bad" by appearance in the photos.

The mica caps in the second picture look pretty OK to me, though you can't tell by the appearance. These are often not silver mica. Silver mica caps cost extra, and were seldom used in service grade equipment.

There is a pretty good chance that both the mica and ceramic caps in the pictures are still good. Both tend to fail much less than electrolytic and paper capacitors.

Be careful about turning any of these capacitors on their leads, it can break the connections to the leads.

There should be no fixed capacitors in this unit that can't be replaced by modern components. You may have to substitute different types, and get the values you need by using two or more in parallel (or series, or series-parallel).

Do you have a schematic and parts list for this unit that you can link? If not, perhaps someone on ARF can find one. Forum members will help you evaluate what you might need to do, but the advice can be much more specific and useful if everyone has the same schematic. The documentation can help determine the correct value for any replacement parts. The old mica caps with the dots are always an adventure when you try to read the value.

Ted


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 6:21 pm 
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Location: Portland, TN, USA
The E-200C is a very robust and useful generator and worth your effort to refurbish. You'll likely need to tune it up in any case, a fairly easy process.

There are at least a couple different schematics and the applicable one will be dependent on your serial number. I can probably supply a pdf once we know your S/N.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 7:27 pm 
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If you use the common silver micas with 5% tolerance, there should be no problem tuning up for the correct dial reading. Except for electrolytics and paper/wax, don't bother replacing unless there is a problem.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 7:50 pm 
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Thanks for responding! In the first picture I assumed is C2 'HI-Q 15mmf 10%', and second picture C3 'HI-Q 4.7mmf 20%. But then, maybe the domino-looking ones are the silver micas? Anyway, the two I'm talking about have pooped out of the ends (technical term), and look really used up....maybe there is hope for this thing?
hope this schematic is clear enough......
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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 8:10 pm 
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Joined: Aug Tue 24, 2010 8:56 pm
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Location: Northeast Florida
Even if you have to replace the mica capacitors, they are readily available. In fact, you can go even more precise than the originals if you want by going with 5% or even 1% tolerance

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Thu 10, 2019 11:40 pm 
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Those white tubular ceramic caps look fine to me. The goop on the ends looks like wax. Does the signal generator work with those caps? If so, I'd leave them be.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Fri 11, 2019 1:43 am 
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stevebyan wrote:
Those white tubular ceramic caps look fine to me. The goop on the ends looks like wax. Does the signal generator work with those caps? If so, I'd leave them be.

Thank you stevebyan! I should have known better, but was thinking those ceramic capacitors were the mica capacitors.

And, thank you Usually lurking, I have not touched or turned any mica or ceramic capacitors; What I have done is identify, and cut one lead of all the paper capacitors so as to test the resistors, so now I have list of caps and resistors to replace.

Thanks Chuck TN; tuning up will be a new adventure for me!

And, Pixellany, I’m not going to touch any but the electrolitic and paper/wax for now.

I do have another question


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Fri 11, 2019 1:46 am 
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The variable air C1 capacitor is 0 ohms. Shouldn’t it be open?


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Fri 11, 2019 3:02 am 
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It is in parallel with a coil, unless you disconnected it.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Fri 11, 2019 4:40 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Hartford, KY
I have an original manual for the E-200-C if you need it. If that would help. I had one many years ago and sold it but ended up with a spare manual.

LLOYD SPIVEY


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Fri 11, 2019 2:50 pm 
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Spivey wrote:
I have an original manual for the E-200-C if you need it. If that would help. I had one many years ago and sold it but ended up with a spare manual.

LLOYD SPIVEY

Very kind of you, but I think I got the original manual with this unit. It looks original, is stapled like a book, and in it there are 3 schematics to cover 3 ranges of serial numbers. Mine is serial 30848 with 5Y3 rectifier (which tests marginal on my tester)


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Fri 11, 2019 4:04 pm 
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stevebyan wrote:
It is in parallel with a coil, unless you disconnected it.


Ahh, that would explain that! I think your right!

So, what I'm going to do is proceed with replacing paper caps and toasted resisters, put it back together and see what happens.


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sat 12, 2019 9:02 am 
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Location: Tucson, Arizona U.S.A.
Quote:
with 5Y3 rectifier (which tests marginal on my tester

The current drain of this instrument is far below the capability of a 5Y3. If after you are ready to test it, the B+ is OK, then use the tube you have. The 5Y3 in mine tests weak on a tube tester but works fine.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sat 12, 2019 9:20 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Tucson AZ
Spivey wrote:
I have an original manual for the E-200-C if you need it. If that would help. I had one many years ago and sold it but ended up with a spare manual.

LLOYD SPIVEY


I've got an E-200-c I'd love to get a manual for.


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sat 12, 2019 5:27 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Hartford, KY
Xwarp, just sent you a pm.

LLOYD SPIVEY


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sat 12, 2019 7:07 pm 
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Location: Sayreville, NJ 08872
FYI: the E-200/E-200C first schematic I have is dated 5/40 and evolved with slightly different designs, components, and tubes to the last schematic I have which is dated 12/57. There were several schematics in between. Don't know if there were any additional schematics issued after 1957. The basic manual with its features and functions probably had changed little over those 17 years.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sat 12, 2019 7:48 pm 
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My mistake, I thought you were looking for a correct diagram. Nevermind. Posted in error.

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Last edited by Bugman on Jan Sun 13, 2019 1:47 am, edited 1 time in total.

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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sun 13, 2019 12:48 am 
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Joined: Nov Wed 28, 2018 2:29 pm
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Jim Mueller wrote:
Quote:
with 5Y3 rectifier (which tests marginal on my tester

The current drain of this instrument is far below the capability of a 5Y3. If after you are ready to test it, the B+ is OK, then use the tube you have. The 5Y3 in mine tests weak on a tube tester but works fine.


Ok, Thanks Jim; will try the one I have, and will test the B+. Thanks!
-Simon


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 Post subject: Re: Precision E-200-C Signal Generator
PostPosted: Jan Sun 13, 2019 2:07 am 
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I just restored one of these of the same vintage. As mentioned above, there are modern equivalents of everything you would need to restore this unit. I doubt you will find one much better unless you buy a restored one (which will have the same components you will install). This is a great generator and easy to calibrate. I also restored an e200d and an e400 to go along with it. I use it with a Precision 98VTVM. I really like the Precision instruments. Don't give up on them to quickly. I've restored some instruments that looked like they were ready for the scrap heap and they turned out working perfectly. When I get to that frustration point, I just let them sit a few days and come back to them. BTW, when you get it on a scope don't be put off by the ugly wave forms. These units produce harmonics by design. Good luck. Doc


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