Tektronix 5111A Problems

[JPeitzman]

I recently picked up some test equipment at a recent surplus sale, including a Tektronix 5111A Storage Oscilloscope. It has a 5B10N Time Base module and a pair of 5A22N Differential modules. I've been having the following issues with this unit and am wondering if there are any fixes worth pursuing:

1. The mainframe seems to work fine, except that the center bay doesn't seem to send power to the module which is plugged into it. I haven't really torn into the mainframe yet to see if anything is simply loose or if any parts have released any magic blue smoke.

2. When the inputs are grounded and nothing is hooked up to the modules there seems to be some noise.

3. This is the biggest issue, I have hooked the modules up to both the mainframe calibration (which does work, on my other scope it's a beautiful square wave) and my B&K 3020 feeding in square, sines, and saw-tooth waves. One of the 5A22N modules displays more or less junk, the other 5A22N displays really poor (I mean really poor, nearly garbage) squares on the positive input. On the negative input this module displays a square, but it's rounded. Plus every once and a while it will just flake out, turn to garbage, then pop the rounded square wave back up on the screen.

I know the 5111A is a bit dated and slow at 2Mhz, but I would really love to get this scope going. The scope came out of a student lab at a local university so who knows how it was treated before I acquired it. If anyone has any advice I would be all ears and very appreciative!



P.S. I have operation manuals for the mainframe and the modules, but if anyone has any service manuals or schematics I would be appreciative for copies if possible.

[jackinnj]

artek media probably has the service manuals -- check in with the Tekscopes group on yahoo.

clean the 5A22n switch contacts ONLY with isopropyl alcohol -- you can get the high test version from various suppliers. the 5A22n is a great plug in.

these 5xxx series scopes are very low noise --

[thaumaturge]

Bama has the 5110 mainframe, should be close. I remember the 5000 series basically as a bunch of dogs. The likely source of your problems is on the mainframe edge connectors. Also those dang push button switches on the modules. I also recall some channel switching problems. I seem to recall tek used a troublesome hybrid to do the channel switching. I've seen some other Tek specialty sites that covered the 5000 series. I'll check my bookmarks and see if I can find something. On the Edge connectors, try wrapping a piece of heavy bond paper around the plug in edge connector and use it as a wiper may help. Also recall using thin tongue depressors with slightly abrasive paper on the ends to clean the mainframe connectors.
Doc

[thaumaturge]

Okay, found at least mainframe manual. Second link is mostly just description and pics. First link leads to mainframe manual and -some- plugins.
Doc
5000 Series

Index of /tektronix/tek5000

[JPeitzman]

Thanks guys! Come this weekend I'll crack it open and give it a thorough cleaning and inspection. Hopefully that will clear some or all of the issues up.