开云体育

Hi!

I got a dead 172B wave form generator for cheap. The unit is equipped with the options 001 (Front panel operation) and 002 (5,5 Digit Synthesizer).

It does "light up" and I checked all voltages to be in tolerance. Unfortunately the frontpanel only shows "00000000000000000000" and that is all. Pressing keys results in a beep.?
I have the schematics and figured that the keyboard is beeping on it's own. As the display is controlled by the CPU of the unit, the 0000 tells me that it at least tries to do something. However there is no "Self Test..." or "Wavetek 172B" logo showing up as described in the manual.

While the manual contains all schematics, it is very dumb on fault finding. If the display is not correct, but the keyboard beeps on keypress, exchange the CPU module... That is not what you want to read ;)

Checking a bit around on the CPU board, I see that there are only two ROMs. One is soldered in and another "gold capped" one is in the first left socket. On the other hand the schematic shows 4 ROMs placed and a few others marked as "not populated". However it may be plausible for having only two, as above the ROMs only two of the capacitors are installed, one for each. The other caps related to the empty sockets are not placed.

So my question is, if this symptom is already known, or if there are common fails on that unit I should check first. And there is the question if someone may have copied the ROM content for backup? Just in case these are dead.

Thanks in advance!