enjoy your trip! seems like you're having a good time checking out some local places. one day i'll make it over there to visit my friend in Kobe (and also go to like 1 million different shops of all different kinds...)

I've never seen this with Philips HPI lamps.

None of these are actually swelled believe it or not 😎, that black shadow is on the inside of the tube as yours is, if you zoom into the picture you can see it clearly.
It’s also got the halides sat on it, showing which way the lamp has been running in horizontal position 🤔

I think that in your case, the arctube of the Philips HPIs, swelled, hence the appearance.

I wonder if this is the same thing on these Philips HPIs?

I’m just saving anything HID now, even if they’re used and no longer in use!, I won’t see what we still have at work put in a skip🧐

Nice little lanterns Olav. 

These will be tricky to repair without the original replacement parts. As the ballast compartment is very restricted and takes only one certain type of ballast meant for this fixture. Also the lamp socket might be of a shorter type? Any other type will be too long in conjunction with HgL 125W I guess?

For such open rated fixtures 125W lamps with hard glass were available as any other bulb with soda- lime glass will crack when exposed to rain/ snow. Were such special bulbs available in DDR?

Here's a photo of me with the owner of Koto Electric.   

We are stocking up with CPO 45W and SDW-T 50W lamps as these are the only HID lamps left in use in our city and will most likely remain past 2027 till about 2032.

Thank you @James  and @joseph_125 !!

Currently in Akihabara Electric Town- I will look out for all of those places.