Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: dartvader on December 19, 2015, 02:50:06 pm
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Hi im just starting do do this stuff so im fairly new my grandpa was in the army and he was a tech on fixing radios and such.. so he gave me some of his tools he has used over the years. So now you know i need to get all the pieces too make them work right I am a guitar player (ive won a couple of contests) and now im wanting to learn more about these electronic part. like how what tube makes what sound and things like that. Probably the thing i would like to make work is his old oscilloscope eico 460. We may of gotten the wrong test leads but it dont seem too be working right but we aren't sure. i took a few pictures of the filter caps and some of them look kind of bubbly. It does turn on you can move the knobs it works its just the wave forms on it dont look not right. but like i said it may be the wrong test leads we bought (they are just some regular test leads we need to get the right ones!) Anyway what im looking to do with the oscilloscope is i have a pedal that isnt working and would love to learn to how to tracedown a circuit and try and fix the solder joint and such or if i need to order a part and figure out which part is the failure! i just need to know what all i need to fix a guitar pedal like certain equipment and such :) I do have this one guy that local and he does a lot of repairs maybe he can show me a thing or two Thanks guys for reading this would love the help (also ive been soldering for awhile now so im getting quite good hehe modded a boss ds1 :P) thanks!
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Do you have manual?
http://bama.edebris.com/manuals/eico/460/ (http://bama.edebris.com/manuals/eico/460/)
The 460 does not need magic leads; whatever stray wire works.
Take a half-bad guitar cord, cut the bad end off, strip the good end, connect to the V-input posts. This should give a clean wavy-wave that matches what you hear.
I had a slightly older 427, and at this point in time I would expect these low-price 'scopes to need significant repairs. With asian-made LCD sillyscopes selling for $50 on eBay, you may ask if it is worth it.
> i have a pedal that isnt working
Perhaps start a new thread in the appropriate section. Much pedal-repair is done with voltmeter and listening probe.
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thanks for the reply what exactly is a listening probe and i do have a multimeter but i dont really understand how too test a circuit in the pedal could you give me an example of how to find a problem within the pedal with a multimeter thanks :)
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http://el34world.com/schematics.htm#Helpful info items
Good place to start your knowledge.
There's also a forum search at the top of the page.
how to find a problem within the pedal with a multimeter thanks
a scope or listening amp, is about required for anything not *dead* but a schematic is 1st.
the basic steps;
test switching, test - inspect all the connections, look for *the obvious*
make sure all the DC volts are where they should be - if so;
plug in a good signal that you know what it looks like or sounds like, then probe the signal path till you find the *bad* spot.