Electronics Forum > Electronic videos
My first YouTube video HP 8640B signal Gen
The Radio Shop:
https://www.youtube.com/watch?v=ZQrnKrwrBqE&feature=youtu.be
This is my new HP signal generator I purchased from a very nice fellow up in Pikeville. He bought it 2 years ago and was going to fix it but never got around to it. The unit is well used. And would not power up. While checking switched I noticedthe fine tune switch is stuck and I broke the FM mode switch. That can be fixed no worries.
I addressed the no power up issue and found that one side of the power switch did not work. Removed the switch, drilled out the rivits, and found a spring out of posistion on that side. Put it back together and the unit powers up.
Next was to remove the range select unit so I could address the cracked gear issue. It is simple to remove but I nned to take the front panel off also to repair the broken slide switch and do some needed cleaning. While looking at the cracked gear I noticed one of the contact fingers were missing on the front rotory switch. I cut up an old relay to make the fingers out of, took me 2 tries to get it right.
After I get the unit cleaned up I will put everything back together and start testing to see where it is. I do know it put out some signal but with the fingers missing nothing was right.
The Radio Shop:
I was able to fix the range selector gear. Maybe it will hold up till I can find a repalcement.
What I did was remove the brass insert. Then put epoxy in the crack and clamped it back together. I then drilled very tiny holes in the back side of the gear. Then rough it up with sand paper. Nylon is hard to glue together!.
I cut a piece of perfboard to fit the rear of the gear. epoxed everything and clamped it together. After 3 hours of trying time it seems to have done the trick. After the epoxy dried I heated up the insert on a flat piece of steel. Then pushed the gear down over it and cooled it with water. Just had to align the 2 set screw holes then clean them out.
BTW, make sure you mark the location od all moving parts. I had the rear contact disk in the wrong location and had to disassemble everything.
On the broken FM switch there was not enough material to hold when glued together. I then cut a piece of very thin steel and formed it to the underside of the switch lever. I then drilled holes in all pieces and epoxed it together. Seems to work fine.
The Radio Shop:
Part 2 is now posted:
https://www.youtube.com/watch?v=Ym3X7VNS0uw&feature=youtu.be
The Radio Shop:
more pics
The Radio Shop:
Part 3
https://www.youtube.com/watch?v=ecminz1S3Qw&feature=youtu.be
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