My DM502A OPTION 2'd itself!

[BlownUpCapacitor]

So I have this DM502A that has a sticker on it that says it has option 2 installed, but looking at the circuits and the front panel, it clearly does not.

Option 2 is an option available for the DM502A that omits all temperature measurement related functions. Mine still had all the circuits and front panel layouts for this function. It even worked in temperature measurement mode.

After a while though, the function buttons got jammed. I opened the unit up and concluded that the temperature function button had failed!

After the factory's failed attempt to properly option 2 the unit, after almost exactly 40 years after it's manufacure (chip dates say mid 1984), the unit decided to option 2 itself. 

I find this story of mine to be quite hilarious and wanted to share.

Now I have the issue of finding a replacement button or maybe fix the old one...

Makes me wonder why Tek used such poor quality switches for these? They don't even align correctly with the front panel.

[BlownUpCapacitor]

One more photo for the failed switch

[Warsp]

I also have a option 2 DM502A that for some reason still has temperature functionality. Seeing that the free service manual is from when the DM502A was originally released, maybe Tek decided to change what option 2 did later on.