Hello Gentlemen
I am a longstanding Beogram owner going back 30+ years. My Beogram 1000 was the first 'decent' turntable I owned and I still remember how I swallowed and gulped at the purchase price when I needed to purchase a new SP14 cartridge for it around year 1976. During the following years, I purchased two 1900 turntables, as well as two series 4000 which were in total disrepair and beyond resque or so the seller said.
A few years later, I bought a 4002 series 5511 which is in superb condition cosmetically and I briefly used it a few times but I always had issues with the platter speed and various other functions.
A few weeks ago and after years of having it in this non-functioning condition, I decided to troubleshoot the problems although I know virtually nothing about electronics.
The first fault was easy to spot. The arm leadscrew pulley was cracked in half. I repaired the problem by using a pulley from one of my 4000's, centre-drilled it in my lathe to make it fit on the thinner leadscrew shaft of the 4002.
Next up, I attended to the non-functioning 3V dc motor and traced its problem to an open coil on the rotor. I carefully fished-out the joint on the rotor's underside, cleaned it and re-flowed fresh solder on the joint which restored the faulty coil. I also re-soldered one of the varistors around the coils as the joint had also desoldered.
The motor brushes were almost completely gone as these had arc'ed, making them unserviceable. I then managed to make new brushes for it, cleaned the commutator segments and reassembled the motor with a fresh drop of Elna sewing machine oil at each shaft end.
I tested it out of the deck with a powersupply set at 3.4V and the motor spun perfectly and silently.
My last repair took almost an entire day's worth of testing and cleaning the control panel switch contacts and testing them repeatedly with my multimeter set to "continuity" to ensure all controls were now reliable.
By this time, almost a week over the Easter holidays had elapsed after continuous work on the 4002. I was dead-tired and should have stopped there but I thought "Victory is within reach".
And this was where it all went wrong. I once more tested all controls and functions with the mains plugged in. All controls worked, the motor spun the platter instantly to speed, the carriage worked and so on.
I went to fetch a record, a strobe disc and its cartridge. One minute later when I returned, I found a smoking motor and the top left corner of its pcb where the 4 diodes are located, also severely burned.
For some incredibly stupid reason, I didn't look properly where I plugged the motor into the board. It went into socket P2 instead of P1 and the motor got far too many volts.
So, back to square one. It took many, many hours to clean the burned wires and remove the fried varistors from the motor. And the newly replaced brushes.
I found replacement coil wire - almost identical - and re-insulated the rotor, preparing for a motor rewind. Fortunately, I had measured the coils' dc resistance before and counted the number of windings when I removed the old wire.
So, I rewound the motor. The original measured resistance for each coil with the wires removed from the commutator tags was 23 ohms and the new windings measure 25 ohms. In the pic, you can see what I did to replace the now fried varistors. I used 1 diode and 1 zener between each commutator segment.
The motors spins instantly and quietly but I haven't yet tested if the speed is right.
My apologies to all about this very long post.
Also found was a real mess on board 8, under the control pad. It looks as if the previous owner had a mono switch installed, bridging the + of the left and right channels.
Another mistake on my part. Before cutting away the non-standard tone arm wires at the 6-pin connector, I should have taken photographs of the correct sequence and colours of the wires going into this connector.
The circuit to this connector underneath the board is untouched. I have removed the non-standard armwire and I want to rewire the male plug going into the 6-pin socket but my measurements from the other multipin connector to the left, doesn't make any sense.
Tracing the wires from there, it looks like the earth return wires of the L&R armwires had been commoned. All I now is that the wire from pin 6 must be earth, going to the earth tag at right back of the 4002.
Even though all connections or circuit traces between the two multipin connectors are original, I measure continuity between some of these pins on both connectors , which I don't understand at all.
So, now I have only a single "certainty" for re-wiring the 6-pin male connector: Pin 6 (extreme right) is earth which goes to the earth tag at the rear of the turntable, leaving 4 more wires to account for in their correct positions - Left channel earth return (blue), Left Channel (white) +, Right channel earth return (green) and Right Channel + (red).
If the earth return wires of the two channels are commoned as it appears at the connector to the left of my pic, I have even more troubkles to understand this wiring as all this leaves two extra connector pins free and unaccounted for?
i have in the meantime cleaned and repaired the board at top left, as well as replacing all four burned diodes with new items. All functions work again, including the motor.
I measured the voltage at socket P1 on the board and its output measured 3.4V initially. Later on, I measured just below 8V there, which indicates a fault. Nothing is smoking but the large soldered surface near socket P1 feels too warm for my liking so something here is also not right.
Please, can any member here come to my assistance to get this turntable working properly again - especially with the correct wiring of that 6-pin connector on board 8.
Any replies or assistance with these problems will be much appreciated. I have jpegs of the problem areas but don't know how to upload them.
Regards
dauphine
