TDS3034B rotary encoder repair

[dmuntz]

I'm working on a TDS3034B that looked like it was treated like the printer in _Office Space_. The external trigger BNC is now a D-shaped connector, and the force that cause it bent the chassis to the point that the case almost didn't come off, but my main sticking point at the moment is that the horizontal rotary encoder for scale is broken off, flush with the base of the switch. If it were one of the "smooth-turning" encoders, I might just attempt a mechanical fix, but the scale encoders have a tactile effect that I suspect would put too much stress on anything I could rig up to attach the knob. I read another thread here with a great deal of information about these encoders, but there wasn't a clear solution other than trying to find an identical replacement. I'm curious if anyone has come up with any replacement alternatives since the prior thread. I have 3 out of the 4 channels working so far, so the scope is definitely worth some further work. Also, if anyone has any advice regarding pitfalls I may hit when replacing the external trigger BNC, that would be appreciated.

[Teichhermelin]

I bought replacement decoders. The circuit board already has the vias for it. So simply drill out the plastic nipples and pull off the decoder. Solder in new and done. I can send you the exact designation tonight.

[dmuntz]

Awesome! Thanks!

[Teichhermelin]

Here is the Link:

https://www.mouser.de/ProductDetail/Bourns/ECW1J-B24-BC0024L?qs=Ulw2Wvwv5HrI2ExiO9lNLA%3D%3D&gclid=Cj0KCQiAosmPBhCPARIsAHOen-Osoxa9Fbxys9Z58_RKbSoM1Q69IfB9aigJqIm44jFjGqghNEGOymQaAvU_EALw_wcB

[dmuntz]

Some notes on how it's going so far. Encoder dial was easy to remove: melted the 4 posts from the back first with a cone-tip to making drilling out the rest very easy. If I couldn't find a replacement part, this could almost be reparable. I'd cut a slot where the knob broke off, and insert a strip of firm metal (e.g., a piece of a AA battery clip and create a form around that with some epoxy. Shape to fit into an appropriate external knob.

The external trigger BNC is a bit of an odd-ball (to me, anyway). On the internal side of the connector, the cable isn't soldered on--it plugs in with a "harness" making it very easy to remove, but possibly difficult to find a replacement (pic attached).

The chassis is remarkably flexible. I assumed it was aluminum, but it seems softer. Was able to straighten most of it by hand, and pliers were sufficient to work out sharply-bent places (e.g., around where the external trigger BNC was smashed in sideways).

A loose screw may have been responsible for channel 4 dysfunction, but will have to wait until some reassembly to test.

[MarkL]

...
The external trigger BNC is a bit of an odd-ball (to me, anyway). On the internal side of the connector, the cable isn't soldered on--it plugs in with a "harness" making it very easy to remove, but possibly difficult to find a replacement (pic attached).
...

That's a Peltola connector in the back of the BNC:

  https://w140.com/tekwiki/wiki/Peltola_connector

According to the TDS3000B service manual, it's Tek part #131-1315-01.  Qservice Electronics has some additional info on it, but unfortunately no stock:

  https://qservice.eu/shopexd.asp?id=10151

Maybe search around for "Peltola BNC bulkhead connector", or something like that.

[dmuntz]

> That's a Peltola connector in the back of the BNC

Thanks! Knowing the name and part number helped tremendously. Based on your info, I found one.

Also decided to try a rotary encoder repair as long as I can get a replacement if it goes South. I cut a sliver off of a AA battery connector, but rather than cutting a slot for it, I just marked a depth on it, heated it up, and pushed it in (pic attached). The metal tab is strong enough to turn the switch, but next I'll probably blob some epoxy on it and shape to fit the standard knob. Alternative suggestions welcomed

[dmuntz]

Using epoxy to create a new place to attach the knob worked very well, and Amazon carries nylon bolts that are perfect for reattaching the switch to the PCB.