Wavetek 116 VCG function generator teardown photos

[radioFlash]

I picked up a Wavetek 116 that was sold as not working. I replaced the output ground binding post, which had broken off, and the BNC jacks which had corroded. It generates signals, although there is a noticeable ringing in the signal. I'm not sure if this is because I haven't properly terminated the output--I've just connected the output to the scope probes.

The schematics in the manual are dated around 1966. Some components seem to have date codes around 1968, although some other components seem to have date codes around 1987/88. It could be that it was refurbished or repaired sometime in the 80's.

The inside top of the case had a strip of foam to cushion the boards in place, but the foam disintegrated which is what the black dust on the boards is.

The mechanical construction is interesting. There are four hexagonal bars with grooves cutout that run from front to back which hold the boards in position.

Frequency Range: .005 Hz to 1 MHz (mine actually tops out at around 800 kHz)
Signals: Sine, Square, triangle, ramp

Manual: http://bitsavers.informatik.uni-stuttgart.de/pdf/wavetek/112_115_116_Oct69.pdf

[radioFlash]

Photos of the front panel, sub panel, main, trigger, and VCG boards.

[radioFlash]

Photos of the power supply, output panel, and motherboard.

[radioFlash]

And some sample output signals.

[c4757p]

Wow, look at the ringing in the sine and triangle!!

No, that's not because you've not terminated it. Something's funny in the generator, probably around the current steering network (assuming it works like most analog function generators; I haven't looked at the schematics).

[krivx]

It almost looks like clock noise - could the square output be pulling hard on the power supply during transitions?

[SeanB]

Probably the decoupling capacitors on the 6V rail have died, and seeing as there are only 2 100uF capacitors that have to do this work a replacement will solve the noise issue. Replacing all the electrolytic capacitors in this will be a good idea as well.

[radioFlash]

I've now replaced the electrolytics on the power supply rails. The noise/ringing is smaller in amplitude but still quite obvious. The pulled caps all measured fine. Here are the before and after traces for a 500 kHz sin and square wave.

[andymouse]

Hi there, I know it's been some time but I am trying to find the gold PCB connectors that are used in these wavetek Sig Gens in order to build a riser card to calibrate my model 112 do you know where I can get them please ?

Andy