Info on wavetek 114 sweeping sig gen.

[dr pepper]

I just got a wavetek 114 sig gen on ebay.
It has a couple of issues, mainly with the sweep side of things.
I got a 111 manual off bama no problem, however the 111 doesnt have sweep, and its the sweep thats the issue.
I know its a long shot but I wondered if anyone has a schematic or a link to one.

 

[tunedwolf]

I think you'll need to pony up a few quid for it. **broken link removed**

 

[dr pepper]

Well found I'll see if they'll ship to the UK.

 

[KeepItSimpleStupid]

I found the 112, 115 and 116 SM. One manual for all. I didn't download it.

 

[dr pepper]

Yes I found that and printed it, unfortunately it doesnt mention sweep, only the pll version.

 

[HiTech]

Start by checking all tantalum caps in the sweep section. Is the PCB marked off with lines that identify each section of the circuitry? I think that vintage may have been. ..... wait I just noticed that's an old, old model.... it might predate tantalums!

 

[dr pepper]

There are very few electrolytics, I think in just the supply.
I think the sweep is a seperate plug in board, it has modular boards and a motherboard.

 

[HiTech]

yeah, being an earlier model, that's a very different construction line of Waveteks than what I originally was thinking of.

 

[dr pepper]

Using my component curve tracer I found a dead 2n3046, replacing it didnt bring back the sweep function, but it did bring back the square wave o/p I didnt know I didnt have.
I need to do some serious taking apart to get to the front pcb, but it looks like that is where the sweep generator comes from, there is on this unit a voltage input to control the freq, that works so I'm assuming the osc board is ok.

What would be a good replacement for a 2n3046, I've used a bc327.

 

[dr pepper]

So after buying this thing when the owner said all transistor no custom Ic's, I have tested just about every component with my comp checker and found just 2 parts left, philco pa71239, if that isnt an odd ball ic what is, I've been duped.

I guess its a very early op amp, google doesnt even bring any hits, if I had some idea of what it was I'd have a look at stuffing something else in maybe on a bit of veroboard, 741's probably werent out when this thing was put together.

Might even be a nuvistor, that would be fun to replace.

 

[dr pepper]

Got it working again.I got the manual for $8 off the net.
The 8 pin can device is a ua302 op amp, the ones in must be philco versions.
Turned out the fets that buffer the ramp generator output for the sweep had gone wayward, 2 are glued together as a thermally matched pair, I chaged them both for 2n3819's from the same batch, maybe not perfectly matched but the gen now works well.

 

[large_ghostman]

nice one!!!! what curve tracer do you use? and where abouts northwest uk? (roughly)

 

[dr pepper]

It'll be back on ebay soon, I decided to build a better one.
The tracer is a hameg, grey box doofer, it has 3 different current settings and a transistor socket, my boss bought it for me to use in the early 90's, I won it after I'd started working somewhere else after doing a couple of favours.

At the moment I'm in Garstang, just south of Lancaster.

 

[large_ghostman]

what would be needed to make a curve tracer? i assume a old oscilloscope (analogue) might be a good place to start??????

 

[dr pepper]

If you want to make one they are dead easy, just a transformer, couple of resistors and a pot, there are quite a few designs, some ridiculously complicated, yes an old analogue 'scope does the trick, I had a beckman years back that had one built in, I saw one that had even been bashed out of a mini tv, have a look at this one:



This one:

https://www.experimentalistsanonymous.com/ve3wwg/doku.php?id=simple_diode_tracer

An advanced cool version:

https://www.changpuak.ch/electronics/Curve_Tracer_advanced.php

Anyone who's repaired telly's or domestic electronics will be well versed in component checkers, there is some skill involved in using one, but you soon get the hang of it, I found it helped me understand components a little better way back when I first used one.
The thing to watch out for is a slope when reading a semiconductor junction or a straight vertical line.

 

[large_ghostman]

maybe i am over ambitious but i would love to have a bash at building one that gives you transistor curves like you see in datasheets! where the measurements are taken over different ranges but so fast that the screen shows them all at once if you see what i mean!
i will start small tho and do a simple one!

 

[dr pepper]

The last version does that, but only one curve.

You could do that with a digital 'scope with the persistance set to infinite, but it would take intervention between traces.

If you really want multiple lines, then you could do that with a microcontroller rapidly switching between curve test points.

From what I've seen you could accomplish a task like this Lg.