I perform some simple maintenance on the scope then retest it with a signal to check the sweep function and general operation of the scope….(read more)
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I loved this scope when I was starting out in 1956.
I do enjoy your videos very much and agree with your philosophy of troubleshooting for the purposes of education. In a real money making shop you would be fired for you production numbers. However elsewhere like teaching your skills would be appreciated by staff and students. Keep up the good work Jim!
These Dumont scopes were made for educational purposes and Radio / TV service for signal tracing waveforms.
Ive seen WD40 cause fires in switches that have higher voltages being switched, especially 125 VAC.
Dumont used quality components. If it ain’t bad don’t change it.
I saw your lazy Susan years ago and liked it, so I built one or about $20 for the race and $15 for the cut wood circle from The lumber yard. A good tip Jim!
Don’t Forget to lube the bearings in the detent mechanism.
The wafer switch construction also has front of wafer and back of wafer rotating contacts.
Add another thumbs-up. I covet that lovely gal; good to see she's healthy!
When you were comparing the gain against your DMM, did you have the Y vernier gain set to the CAL position?
Second the pencil eraser tip. And not just the eraser on the end of the pencil. You can get the type where the eraser takes the place of the lead. Works very well. Mine came from Faber-Castell.
Jim
Alcohol is best for those silver contacts, but I think a pipe cleaner would do a better job on those hard to get at contacts. It is more flexible, and will hold the shape you bend it in.. I have cleaned many rotary switches in thos manner over the years.
dumont has been out of business since the late 1950's when another company bought them out. i believe it was emerson that bought them. dumont also had a television network in the usa in the 50's but it never really could compete with abc nbc and cbs. dumont was the first company to make the large rectangular crt. they also pioneered improvements in tv cameras and magnetic recording of tv programs.
i know it sounds weird but it will work if you can get a pencil eraser in there and rotate the switch against the eraser and it does remove gunk without causing harm. this is what was used on really dirty rotary tuner contacts. i see no reason it wouldn't work on a wafer switch. unfortunately you may have to take the switch out to give it a good clean. if you do that make sure to make a diagram and label each wire or component so you know where it goes back.
alcohol may be ok but wd40 isnt really a contact cleaner. since carbon tet is no longer available i have heard deoxit is a good contact cleaner. deoxit is available from http://www.radioshack.com
a dumont is top of the line and deserves all the love it can get. good luck getting this working.
one more thing pipe cleaners will work to clean contacts with alcohol and dont leave all the residue that a cotton swab will
the nickname you're looking for, for those moulded caps are either black beauty or bumble bee caps
the nickname you're looking for, for those moulded caps are either black beauty or bumble bee caps