Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: JerkStore on November 27, 2018, 09:16:44 am
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Hello everyone. I recently acquired a heathkit IO-21 General Purpose o-scope and would like to make it functional again. I have a good understanding of electronics, but not a lot of experience with tubes. I found an older thread on this site concerning the same scope and everyone was very helpful. I am heading out soon to get a copy of the schematic made, and would appreciate any help I can get. Thank you in advance.
I did plug the unit in and it does power up. I get an oval-ish dot in center of screen and no response from any knob turning.
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here's the schematic;
http://www.nostalgickitscentral.com/heath/schematics/heathkit_schema_io21.pdf
standard troubleshooting, physical inspection, DC volts,.....
only real difference between sand n glass is how bad it hurts when you put your fingers where they shouldn't be :icon_biggrin:
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http://www.antiqueradios.com/forums/viewforum.php?f=8&sid=2c6d7b6063eacf13abd9c4af2514a802
Right there is the site to visit. Do a good search first, that will answer many of your questions, and keep the guys from getting aggravated off the bat. ;)
Be careful poking around in there, I believe you'll find 1600 or so VDC. At least I did, while testing one that "didn't power up".