Oscilloscope MPU: Trio-Kenwood MTM-5010

[shimniok]

Hi, all. I have a bit of a challenge for you -- one which I've so far utterly failed despite all my attempts -- is the mysterious Trio-Kenwood MTM-5010 MPU in my oscilloscope by any chance a well-known device under a different guise? The story behind this? well...

My BK Precision 1590A started behaving oddly. The scope has buttons instead of switches to select mode, timebase, trigger. (I knew I'd one day regret this "new fangled" technology -- I want my Hitachi V1050F back, dangit)

For example, when you press the SINGLE trigger button, it selects X-Y timebase. If you press the A timebase button, it selects QUAD mode. DUAL timebase selects ALT timebase and ADD selects CH1. That's what I mean by odd. It struck me as a logic problem and after looking at the schematic, I see that all the buttons are set in a keyboard matrix and all the problem buttons correspond to two lines in that matrix which in turn connect to two MPU pins. The MPU is capturing the button press, but mis-reading its source (A and QUAD share the same matrix line).

I was curious to find info about this MPU, labelled Trio-Kenwood / MTM-5010 / 8851 294M / 8422 Z03. The parts list shows "MTM-5010". I've uploaded a detail portion of the schematic. Does it by any chance look familiar?

Usually I'm much better at digging up info like this and wouldn't have to ask. I've searched the web for a number of relevant keywords associated with the problem, the MPU, the scope, etc. I've reviewed datasheets for some of the well known CPUs/MPUs with which I'm only vaguely familiar (6502, 68xx, etc), I've searched for subsets of the pin names (EXTAL, XTAL, IRQ, STBY, SC/TO, TC) and I've searched for the numbers on the IC in hopes of finding any correlation but I'm coming up with nothing. Not even a hint.

The MPU looks relatively generic to me. It's a 0.6" 42-DIP package. Four GPIO ports (K[0..3], R[0..14], O[0..7], P[0..3]), some control lines, power.

While it'd be swell to replace the MPU with its equivalent, I think the reality is that I'll need to replace it with a modern MCU. The MPU, along with button polling duties, drives LEDs through transistor arrays (AN90B20), and controls the vertical and horizontal boards through, based on a quick review, TTL logic. If I can prove to myself that it's all logic level, then I can start developing the circuitry and software. Because, hey, I don't have enough projects to work on so why not add this to the list?

Thanks, all.
Michael

 

[rumpfy]

Hi shimmy,
Not sure that I can help directly, BUT!
I never cease to be amazed at the number and complexity of I/C's used for remote controls on domestic TV/VCR/Audio stuff. It maybe a microprocessor related to this kind of function. I am not certain but it is possible you are looking for a standard product rather than a generic microprocessor. If a microprocessor, if you can get the device, you will still have to program it, IF you have the program. I recently tried to identify a device which is used on the control panel of a Fisher and Paykel washing machine. The IC has a paper label attached which suggests the IC is specially programmed. The IC is a 64 pin DIP package. It has, I think, an 8x8 matrixed output, to drive all the LED's on the control panel. I totally failed to identify the base device.

I had an experience with a CD / tape /radio player, where the central micro was supplying data to the 1 out of 4 function selector. The micro was not supplying the strobe pulse, so the unit was constantly only able to select the radio function. I was able to get round this fault by using other bits of information from the front panel of the unit and also to select some information from the led readout display. The job was OK, but i had to use about 30 transistors to get all the logic functions needed to get thing working.
What I might also suggest, is you check which functions you are able to correctly select, and to see what functions are actually selected. From this you may be able to come up with a fix.
Obviously I cant do much else.
Hope you succeed cos when you lose your right arm, things get hard.

 

[shimniok]

All good points and info, thanks!

I may be able to add-on something to hack it into working. Or just replace the whole board.