Wobbulator Woes

[Geaney]

I got this for not much money but it looks like it was stored somewhere for a long time and there is evidence of corrosion in the (sealed) wafer switches - green discolouration where th contacts show at the edges.   I suspect there may have been something toxic in the way of fumes at some stage.  It took ages to get the gunk off the front panel so at least I can work on it without coming over all quesy.
I powered it up and got a sort of distorted triangle wave out but nothing changed it regardless of how I moved the controls.  The only exception is even this dies if I wiggle the controls - obviously those wafer switches are a major concern.   Long way to go on this one.  At least I found a decent enough manual for it.
Cheers,   John


    

[Mark Hennessy]

Looks like a nice bit of gear. Not a brand I'd heard of before. The switches and pots look a lot like the ones in my Wavetek 162 - they've been pretty reliable over the years. Do you have a link to the manual?

[ppppenguin]

I've not heard of that make either. Here's a spec sheet: https://www.valuetronics.com/Manuals/IEC_F40SERIES.PDF


This seems to be the company: http://www.vault.com/company-profiles/ae...rview.aspx

And their main business now seems to be the defence sector: http://www2.l-3com.com/iec/index.htm

[pamphonica]

I have had success on green-corroded battery terminals with a stiff solution (even a paste) of baking soda in water. It eats most of the corrosion and can be washed off afterwards.
Inevitably some of the plating will have been damaged by the corrosion, but DeOxit can both clean and protect contacts once they have been de-gunked.
Others may know of downsides to this approach!

[Terry]

I think the downside to Jeremy's idea is that there is no open access to the wafer switch contacts.

I'd get a large hypodermic syringe - think in terms of vet rather than doctor as regards size - and, if the protective guards are flexible, use the needle to punch a hole at an oblique angle so that maximum coverage of the contact area is possible then use the syringe to liberally spray any available switch cleaner into the switch. Be careful if it is a disposable syringe to empty it of any remaining switch cleaner immediately afterwards if it is solvent based!

Is the guards are solid or particularly tough, use a very fine drill to make an access hole for the needle.

[Geaney]

Thanks for all the useful info guys.  Alas I don't have a link to the manual.  Having searched extensively I finally found an outfit that sold it on CD so I splurged $15 figuring I'd need it.

Great tip re using a syringe - I'll give that a shot - might save a lot of open heart surgery!

After running it for about half an hour the heatsinks on the back were certainly nice and toasty.   I read one article where the author mentioned that tantalum caps from this era are problematic so I guess I'll need to look into that - there's a little forest of them in it!.

More to come.

Cheers,

John
   

[Refugee]

I think you will have quite a few tantalum capacitors to change. I can also see what looks like an axial Callins that will also need looking at.

[Geaney]

Some hopefully positive news after a few hours messing with it last night.  The wafer switches are not sealed after all.  I removed the easiest one and found there are holes each side so I can squirt plenty of contact cleaner in there.  Just as well since there are about twenty of them in total.  Also, the one I removed did not have much corrosion inside on the contacts so hopefully I can move on to the caps.  Overall I'm really impressed with both the design and the build quality of the device.  It probably cost quite a lot back in the day.

Cheers,  John


   

[boater sam]

I see plenty or red polyps o that board. Looks to be a good construction, lovely switches.

Its a very complex unit, is it just a wobbulator?

[Geaney]

Yes there are 27 tantalum caps according to the parts list - that's the bad news.   However, slightly better news is 24 of them are the same value so a wholesale replacement will be that bit easier.  Caps on order.

Cheers,   John