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My first YouTube video HP 8640B signal Gen

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The Radio Shop:

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:


The Radio Shop:
more pics

The Radio Shop:
Part 3



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