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Anyone have a READABLE schematic for an Eico 320 Signal Generator?

I picked up an old tube type Eico 320 Signal Generator. I'm tracing it and checking stuff. There was a disconnected paper (.5mf 450V) capacitor. The tube filaments and pilot light work. There is B+ voltage, The voltage from the 6X5 tube at the filter cap, is around

140VDC. (That seems low). The AC volts on the transformer secondary is about 450V (or 225V each side of the center tap). There is a 2watt 5000 ohm resistor which comes from the power supply, which feels warm, so apparently there is a voltage draw.

Anyhow, I have found three schematics in PDF format, an one as a .GIF. They are probably all from the same source, and are very hard to read. The parts symbols are ok, but where it says the cap and resistor numbers (such as is that C8, C6 or C3), I can not make out the numbers. They are blurry. I've tried several pairs of reading glasses, enlarge and shrunk the diagrams on my screen, and they are just plain poorly scanned.

Does anyone have a decent schematic? And one that shows the voltages at the tube contacts would greatly help too.

I intend to recap this thing, but first I need a useable schematic.

Thanks

Reply to
oldschool
Loading thread data ...

** This is probably the same one:

formatting link

The filter electro is 16uF.

R8 connects to the 6X5 cathode.

140V on the first electros is about right, due to the large value feed resistor.

Lines that cross with no loop ARE connected.

.... Phil

Reply to
Phil Allison

BAMA has it in djvu format.

Reply to
Tom Biasi

Thanks, but I dont have any software that will read that format.

Reply to
oldschool

Are you looking at it in your browser, or a PDF reader? A lot of PDF files look like crap in a browser, but they are fine in a real PDF program.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

formatting link 

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

This is the internet where "information yearns to be free." This means one person will publish something, and everyone else will copy it and claim it as their own.

This _may_ be a clean scanned copy. Or it may just be the same copy of a copy of a copy.

--
Jeff-1.0 
wa6fwi 
http://www.foxsmercantile.com
Reply to
Foxs Mercantile

PDF - XChange Viewer. Version 2.5. Works in Windows 98se, which is the OS I use.

I have other schematics, even some for other Eico stuff. Those are in PDF and can be read. This one for the 320, was written to small to start with and the scan is lousy too. I downloaded a few more PDF versions sonce my post. They are all identical, just have different file names. The GIF version is also lousy and looks the same as the PDF.

By the way, I downloaded that DJVU reader. I wont install in Win98se. Considering the file size, I'd think the DJVU files are worse quality anyhow. There has to be a lot of loss of detail to compress a file that small.

Using Paint Shop Pro, I tried some filters and made size changes to the GIF version. I saved it as a high quality BMP, but with no luck. I guess a person cant fix what was lousy quality to begin with. At this point, all I can do is spend hours trying to determine which parts are which, and modifying the schematic in my paint software with BIGGER numbers.

That still wont tell me the correct voltages though.

I was evn willing to pay for a Sams Photofact, but it looks like they dont have this one.

Reply to
oldschool

This URL looks promising....

Reply to
oldschool

Sadly, it is the same scan and resolution as the PDF file. It is typical of the quality of what Eico supplied with their kits

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

So you looked and saw the same thing. Thank You. It seems that from what you said, the original was a lousy print job, and I'm sure scanning it just made it worse. A few of them numbers look like nothing but an ink blob. Those numbers should have been larger right from the start. There is plenty of white space to have made them larger.

Fortunately there are only 12 caps and 9 resistors. (The other part numbers are not important and are obvious). The good thing is that it seems that C3 is near C4, near C5 etc. I'm just redoing the (GIF version) of the schematic using my paint software, and putting in bigger numbers. When I finish, I will have a better schematic. And I am checking each one against the actual circuit.

For those of you who work on a lot of this tube equipment, does it seem that 140V B+ is low? It does to me, with 450V AC coming from the power transformer, but it's been many years since I worked on this stuff. The 'lytic cap is not shorted according to my VOM. I checked that before I plugged it in. I will have to check the tubes too, but I dont have any tube tester yet. (I have one somewhere). [whatever happened to the good ol' drug store testers] :)

At least there has not been any smoke!!!

I'll have to order all new caps as soon as I confirm the numbers are correct. Just curious, what would you use for that filter cap "lytic? The schematic says 16mf or over (weird). I'm thinking 20 to 30.... (I cant read the original, since it's numbers are not visible, and it's in a spot making it hard to rotate without removal.

Either way, it feels good getting into a tube device again.....

Reply to
oldschool

A 22 uF will work just fine.

--
Jeff-1.0 
wa6fwi 
http://www.foxsmercantile.com
Reply to
Foxs Mercantile

snip

Probably bad electrolytics, at least for the first guess. If this had been a receiver, there would be a loud hum.

snip

I will have to check the tubes too, but I dont have any

snip

There's one here:

formatting link
but it is hidden by other things in the picture in "About Us". It's probably out of your driving range too :)

--
Jim Mueller wrongname@nospam.com 

To get my real email address, replace wrongname with dadoheadman. 
Then replace nospam with fastmail.  Lastly, replace com with us.
Reply to
Jim Mueller

** Please read the thread.

  1. There is a baby size transformer that put out 250-0-250 with no load.

  2. The AC voltage peaks are clipped under load so the peak value is about 270V.

  1. There is a 6X5 rectifier that drops 50V off as well.

  2. Then there is a 5000 ohms resistor before the filter electro that causes another a large voltage drop.

A voltage of 140V on the electro about right, the trick of being that it allows just one 16uF part to do the job.

..... Phil

Reply to
Phil Allison

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