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Registered Member #157
Joined: Sun Feb 12 2006, 08:00PM
Location:
Posts: 76
I have two oscilloscopes a Heathkit labortaory oscilloscope model0-12 and a Tektronics Model 442.
The heathkit i got for fifteen cents (from salvation army) because it was missing a tube which i replaced. I dont quite know how to calibrate it. The terminals are AL on steel and have corroded together and are going to be made into BNC connectors. When i turn it on there is a scratchy looking waveform already present without anything plugged into the test connections, somewhere between a squarewave and a sine wave. When i touch the case or any of the ungrounded terminals the waveforms amplitude increases. there is a few knobs i dont quite understand. And when i go to a particular mode i get what looks like a flattened lissajous pattern almost like its in an x-y mode.
The tektronics has a broken intensity knob and about a quarter of the white phophorescent(sp) material has fallen off the inside of the screen. It is also out of calibration. it so far is connected to a speaker so my friends little brother can "see" his voice. he loves it.
Registered Member #139
Joined: Sat Feb 11 2006, 11:01AM
Location: Perth, Western Australia
Posts: 358
Your IO-12 has another blown tube, probably in you vert. amplifier.. It'll be one right up the front panel, check the "getter" and any tube thats white and not metallic, replace. Also, the increase in amplitude is an earthing/leakage problem, I would check everything inside and replace/resolder all suspect joints. Also check the quality of soldering on the bottom of the tube mounts, mine where exceedingly dodgy. Don't forget these where kit units, so you can't vouch for the quality of the soldering in a 40+ year old home constructed item. I had (Still have in bits) an IO-12, it took some abuse before the Xfmr decided it had had enough. Here's a link to the IO-12 Schematic ftp://bama.sbc.edu/downloads/heath/io-12.bmp/ Google for "IO10.DJVU" That's the manual. the 10 and 12 are the same item, just different sized CRT's. you will need the DeJaVu viewer as well. http://www.djvuzone.org/
Registered Member #157
Joined: Sun Feb 12 2006, 08:00PM
Location:
Posts: 76
Dr Desmo wrote ...
Your IO-12 has another blown tube, probably in you vert. amplifier.. It'll be one right up the front panel, check the "getter" and any tube thats white and not metallic, replace. Also, the increase in amplitude is an earthing/leakage problem, I would check everything inside and replace/resolder all suspect joints. Also check the quality of soldering on the bottom of the tube mounts, mine where exceedingly dodgy. Don't forget these where kit units, so you can't vouch for the quality of the soldering in a 40+ year old home constructed item. I had (Still have in bits) an IO-12, it took some abuse before the Xfmr decided it had had enough. Here's a link to the IO-12 Schematic ftp://bama.sbc.edu/downloads/heath/io-12.bmp/ Google for "IO10.DJVU" That's the manual. the 10 and 12 are the same item, just different sized CRT's. you will need the DeJaVu viewer as well. http://www.djvuzone.org/
The soldering on mine is really good and the wires are all neatly bundled in a paper tubing material. Ill check the tubes as you say. I get a request for a name and password when trying to access the ftp link you supplied.
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oscilloscope problems
