Re–Riveting Rotary Wafer Switch Contacts?

[Chris55000]

. . .I have just come across a case of Audio Instability on a Truvox R54 Series Tape Recorder due to a smashed R/P Switch Wafer – the wafer used for Speed Equalisation on the Thorn DC432 Stereo Tape Recorders will fit the Truvox Deck but the contact arrangement is wrong – I need 4 poles, each two–way, but the DC432 switch is 4 poles, 3 way, but the rotary centre of the DC432 switch won't slide over the operating shaft on the Truvox Deck!

. . .Is there a method of removing the centre rotor of the DC432 Switch and substituting the rotor from the broken Truvox Switch, and if so, is it possible to re–rivet the contacts in different positions to make a 4 Pole 2 Position Switch?

Chris Williams

[Station X]

I've never tried re-riveting as I thought there was too much risk of cracking the Paxolin. Instead I substituted small brass screws, washers and nuts locked with solder.

[G6Tanuki]

I have done likewise, with tiny brass nuts and screws from a model making shop after dremelling out the original rivets.

I just couldn't see myself getting the right amount of clench had I tried to install new rivets, and was worried about cracking the switch base, which was WWII era ceramic.

[Ed_Dinning]

There used to be available in dev labs a Plessey switch kit that allowed all sorts id wafer switches to be made up, including rear shorting wafers. Included in this kit was a special pair of parallel jawed pliers (with indents for the rivets) that closed the small tubular jaws precisely. I have one of the kits but never managed to get a pair of the pliers

Ed

[Radio Wrangler]

It might be possible to drill through and tap both jaws of a pair of the more commonly seen Singer sewing machine mechanic's parallel motion pliers, and turn up a suitable pair of anvil inserts to screw into the jaw faces for setting switch rivets.

David

[Ed_Dinning]

Hi David, the parallel pliers all appear to have jaws that are too hard, probably needs spark erosion and a bonding agent in the cavity for the anvils
Anvils could be a mini version of the ones used on eyelet pliers

Ed

[Trigon.]

I have a little RS toggle press for such duties, but on checking it seems they're now rather expensive! Looking around for something with a similar function I came across this:-



https://www.amazon.co.uk/SHRJ-Setting-Machine-Decorating-Clo...p_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

It looks to be a decent cast metal frame, and it would hopefully be fairly straightforward to make new anvils out of bolts of the appropriate thread. I'm not sure if the supplied pearls will be very useful though...

Cheers

[G6Tanuki]

RS also did their "Maka-Switch" kits that might provide an updated solution - I used plenty of them in applications where there was only a few hundred Volts or a couple of Amps involved.

[Radio Wrangler]

Thanks, Ed, I didn't know those things were so hard. I'm the sort of idiot who would blow a hole in them with the plasma cutter then fill the hole with mild steel weld, drill and tap, or just weld a mild steel extension onto ground down originals, but this is too elaborate for a few rivets of the sort you can set with an automatic centre punch if you're careful.

Plan B might be easier: Find a whole switch with the right electrical format and replace the entire thing. This would not need to be compatible on the wafer and contact level.

David

[knobtwiddler]

TW Alpha make a 2-pos / 6-pole rotary switch:

105-SR2511F-62S

If you think it will fit, Mouser have them.