Beogram 4004 (5526): Return to Bench with Blown Fuse - Replacement of Solenoid Transistor

A Beogram 4004 (5526) that I restored in April 2019 just returned to my bench with blown fuses. I was told that "it died as I was lowering the tone arm and is now totally non-responsive".

This suggested an issue with 1IC4, the Darlington transistor that is responsible for regulating the current through the arm lowering solenoid. This solenoid is the largest current 'hog' of the Beogram and puts quite a bit of strain on this IC whenever the solenoid is activated.

But first I installed two tabs on the power entry plug for convenient connection of a bench supply for testing the board:

Then I extracted the TIP125 that was installed as 1IC4 and plugged it into my transistor tester. It gave me a strange reading with an additional forward direction diode between emitter and collector, while still showing a reasonable turn-on voltage of 1.09V for a Darlington.

I think this shows the limitations of transistor testers...the new TIP107 replacement showed a normal reading:

I installed it 

and tested the deck with the bench supply providing power. All went normal and the arm dropped normally at the LP run in groove position.

I decided to also replace the other two power transistors that run the platter motor (1TR2) 

and the 24V rail of the Beogram (1IC1)

with a TIP120 and a TIP31, respectively, to be on the safe side.

I stuck a cartridge on the arm and put a record on the platter (Eberhard Weber Colours "Little Movements"  (ECM 1-1186), and it played as it should. So I think this Beogram may be fixed. I will give it some more play and then it will be time for it to return to its owner!