Portable Mini Tektronix Scope Teardown Please

[German_EE]

A long time ago a mini Tektronix scope arrived in the mailbag, any chance of doing a teardown on this rather than new stuff such as the power analyzer?

[Andy Watson]

What are you expecting to see? It will be much like a big scope, ... only smaller ! 

Here is a wee teaser. This is a 222A, the digital cousin of the mailbag Tek.  The board at the back, with the 5 pin edge connector is the processor board - not much to see - it is standard processor stuff.  The board that lies parallel contains the power supply inverter/converter - it supplies all the low voltage rails, the heater for the crt and the high-voltage (via a tripler) for the cathode. (I really should have taken more photos whilst it was naked). Both of these boards sit on the mother board - some of which can be seen under the crt. The mother board regulates the primary power supply, the battery supervision and provides isolated power and control signals for both acquisition channels.

The acquisition board, which is lying flat on the table in the photo, is quite interesting. To the front is an FPGA that performs some sort of overall care-taking function. The remain of the board, from the label onward, contains two identical acquisition channels. The two PLCC devices perform timing and control for the data transfer (to the mother board). At the very back, the blue and white units are the infamous Tek hybrids - ceramic substrate, DIP package, containing attenuator and (I think), the white square chunk is the ADC. Hidden under the hybrids are several relays which complete the attenuator and perform AC/DC coupling.

Down the centre of the board are five grey blocks retained with spring clips. These are data transformers for communicating the data back to the mother/processor board. The grey blocks are the ferrite cores of the transformers, these puncture the PCB and mate with identical blocks on the other side. The windings of the transformer are etched as part of the PCB. This side is channel 1, the reverse side in channel two. A third winding, for collecting the data is etched in the middle layer of the board (these are multi-layer boards and the channels share the data transformers.)

If there's enough interest I'll post some more details of the repair/tear-down, although, it's probably another thread.

[T3sl4co1l]

That tube shield is so hot.  Like a vacuum tube latex suit.