Since it looked like my new Kontron counter needed only a little cleaning, I started doing that. No way I can live up to the marvelous pieces of restoration some of you perform, but at least get rid of most of the grime, especially on the front. Which means, of course, disassembly to allow decent cleaning.
Pic from above with cover removed:
My high repute I held for Kontron got a slight setback when I discovered that the brackets that held the PCB to the side panels where not threaded. My fault, unscrewing the PCB first would have given me access to the nuts. Next blunder: Int/Ext oscillator switch is soldered to the PCB and riveted to the back panel. I simple didn't notice this until it was brought to my attention - the switch was now the only thing holding the backplate, or, more precisely, not holding it any longer:
Please take a close look: The layout guy placed the switch too close to the trimmer cap. What did they do? Make a new layout with a little more room? No! They just cut off one mounting flange of the switch and let it be.
Oh Kontron.
The disintegrated switch wasn't too bad, though. I often did that on purpose, they can easily be cleaned then. With well stained contacts, that's just what I did here. But I scratched the back badly getting that #*&$! rivet out.
On to the front. Here it was where my trust in Kontron workmanship suffered the most. Looking at the inner plate, no more words are needed. Some of the holes where not even chamferred at the back.
When opening a counter, it is my wont to look at the oscillator. But I couldn't see any of the usual suspects. My best bet is this: An 8-lead TO-5 can labeled '0800 7000'. Pin 5 goes to the clock input of a 74LS196. Never seen a crystal oscillator in such a case.
Closing time. To test the prescaler input (>50 MHz) I built an oscillator with a shorted 74F14 for a quick check. Apart from the disappointing mechanical engineering of the thing, it works quite nicely.
Hope I didn't overdo with all those pictures.