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Bought my first oscilloscope

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david77:
Yes, I finally put my hands in my wallet and bought my first oscilloscope last week.
It's nothing special, just a 2 channel 40MHz scope but it really is the first scope I paid for myself. My Hitachi scope was a gift from a well meaning family friend, an EE himself, who recognised my interest in electronics and my Philips scope was rescued from the trash and fixed with some help from some guys on here.


Here it is fresh out of the box:


Yeah, all right.  ;D It is an old banger, I'll admit it. It cost me all of 35,00 euros, straight from ebay. I like ebay.
It is a Siemens Oscillar M07107 analogue storage oscilloscope. I did not know Siemens ever made scopes until I stumbled across this beauty, but apparently they had a small line up of scopes in the 50ies, 60ies and 70ies.
I'm a bit of a sucker for everything with the word Siemens on it, so I wanted it. Luckily nobody else wanted it as much as I and I won the bidding.

There's even the service manual available. The internet is a good thing, isn't it?
http://www.rainers-elektronikpage.de/SM-SIEMENS/SIEMENS-M07107.pdf
Only German, sorry.

The seller advertised it as defective, he claimed the screen showed a green flash after turning it on but nothing else happened.
So, at least there was a chance of the tube & HV section still working.
Postman Pat hauled the thing to my front door today, the box looked like it had been shoved and kicked around in the depot for a week. I had horrible images in my head what I would find inside...
The seller did a reasonably good job at packaging it, though. Lots of bubble wrap and paper and - oddly - an old T-Shirt protected the scope.

Something was loose inside, though. There were parts rattlig around inside the case. Not good.
At this point it was time for Dave's motto so off we went to the man cave lab to crack her open.

The rattly bits turned out to be small screws, I think from the hinges of the missing carry handle.

There is quite some dust accumulated inside the unit as you can see in the following pics, most of it around the 8kV HV section, obviously. The back of the unit is also dented, no idea if that is Pat's fault or if that happened earlier.

The scope is made up of three modular sections. The display unit contains the PSU, the tube and all the storage circuitry.
The deflection unit is bolted to the display unit using four thumb screws. It contains the timebase and trigger circuits and controls. The third unit is the 2 channel amplifier that slots into the deflection unit. There was also a 4 channel amp available, will have to look out for that.











It was becoming obvious that this scope will require some major work to become usable again. A first quick visual inspection showed no obvious signs of damaged components, so I decided to power it up to see what's what.
And would you believe it? The damn thing still basically works! After a bit of fiddling with the controls and minor adjustments to focus, astigmatism and trace rotation I got this on the display:



Now I will have to start cleaning it up and fixing what's broken.
The trace could be a bit sharper and I think I can see a bit of ripple in the trace, dead caps probably.

I will update this thread as I go along and I'm sure I'll have some questions for you guys.
If anyone has got some good advice for me don't hesitate I'm all ears. There are after all several guys on here who have rescued old beauties like this.

hammil:
That's a beautiful piece of kit.. Fantastic score there :D I wish I had such luck

I'll have to do a little 'teardown' of an old valve scope my granddad gave me. Love old analogue circuitry

elgonzo:
Ohh... that lovely old Siemens logo...

(EDIT: Siemens & Halske, to be precise)

Hydrawerk:
Well, this scope is probably 40 years old.  :) Does the waveform storage function work?

david77:
You're right it is probably exactly 40 years old, the newest date stamps on the electrolytics are from February 1973.
The storage function seems to work as far as I can make out. Never used a storage scope before.

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