Beogram 4002 (5501): Return of an Old Friend from Australia - Dead Solenoid Transistor and a Carriage Motor with a Corroded Lead

Sadly, recently I received a well-worn Beolover Beogram shipping container from Australia. Contents: A Beogram 4002 (5501) that I restored in 2016. Type 5501 Beograms are special since they represent a briefly made transitional version when B&O went from Beogram 4000 to 4002. While the 5501 already has the analog control system characteristic of the 4002 series (the 4000 had a more advanced hard wired digital logic system, which was unfortunately (IMO) downgraded for the 4002), it still has mechanical carriage position switches like the 4000. It also has an exciting rotary encoder for the detection of the end groove. You see the Beolover is a bit love with the 5501, but seeing it for a third time caused a bit of a heart ache...;-).

Anyway, the reason it needed to visit my bench again was that it stopped working. The indication was that upon plugging it in the solenoid immediately became activated, while the deck was unresponsive to any keypad entry except 33/45 RPM changes.

So I removed the hood and the aluminum panels to have a look:

After a bit of poking around I found that the TIP41 that drives the solenoid had a short circuit:

After replacing it with a new one, the solenoid started working properly and it again responded to pressing the arm lowering key. This shows the new type implemented:

I also replaced the browned 8.2 Ohms solenoid resistor (4R1)

With a modern 2W rated unit:

This shows the voltages measured across the activated solenoid

and the resistor:

This means that the resistor runs at about 1.2W. The original types are rated 1W, i.e. a bit too low.

After this repair, the deck still did not respond to any of the 4 keys that control the carriage motion. After checking some of the transistors in the electronic switch it finally occurred to me that the carriage motor itself did not work anymore. I extracted it and opened it up. I found that one of the flimsy wires had disconnected from its tab on the motor due to corrosion. The other wire also came right off when I moved it slightly:

I cleaned the terminals and soldered 22AWG wires to them. I also replaced the completely deteriorated sound proofing with a cut to size self-adhesive piece of neoprene rubber:

Then I installed the motor again:

and everything was fine. At this point the deck's functions had been restored. I decided to do some preventative maintenance since I learned since 2016 that the AC motor driver transistors (found underneath the main PCB) often have issues in the AC motor type Beograms. This shows the original transistors 0TR2 and 0TR3:

I also found a hood attachment bolt spring near the transistors (which explained the absence of said spring when I removed the hood..;-). This shows one of the original transistors, the PNP TIP32 (0TR3, on the right):

I replaced it with a modern BD438. Note the reversed emitter and base leads on these types:

I also replaced the NPN TIP31 with a complementary BD437 (also with reversed wiring). This shows both new transistors installed:

I will now test this Beogram for a while, and if nothing else comes up it will travel back across the big pond to Australia!