Translate

Friday, 24 June 2016

Mitsubish MC8000 audio system repairs.

Sadly, my friend Richard's dad passed away a while ago...

"There's some stuff here Andy, would you like it? I'd rather it went to a good home."

So it's now my duty to the man, to get it all going.....

This interesting audio unit was amongst the gear. It's a Mitsubishi MC-8000, originally sold by my old employer, B.V.Harrod (sadly long gone), and has it's original speakers and cabinet.

 ... and yes, that's the right way up, it has a vertical linear tracking turntable.


After some cursory checks, I give it some mains. There's a motor running somewhere, the turntable doesn't work, neither does the cassette, but the radio works fine!













Off with the back, and it's immediately obvious why the turntable doesn't work .... the belt's missing!

Actually it's not... Some of it is in the bottom of the cabinet, and some has stuck to the turntable flywheel. I quickly clean it up, with some wipes and a bit of IPA. Sizing of these things can be a pain, but it's easy really. Get a piece of string, and wrap it round the motor shaft and flywheel, where the belt would run, and cut the string. This will be the approximate circumference of the belt. Now belts are sold in dimensions of diameter, width and thickness, so divide the length of your string by Pi... in this case it's 200mm, and about 5mm wide.

The arm is driven by two other motors too. One raises and lowers the arm, and the other is used to track the arm across the record.

The belts that drive these functions are also in a bad way... just touching them leaves a nasty sticky black mess. A bit of IPA to clean up, and some replacement belts see the turntable working....













... now the motor continuously running is the motor in the cassette deck.... probably another belt!  It's buried right in the bottom of the cabinet. See that brown, spotted thing lying across the circuit board? That's a bit of turntable belt!







... the motor nicely dates the unit from 1980...












Getting the transport out requires a lot of disassembly, and quite a considerable amount of cussing....


















... but eventually yields ... I will not be beaten by mere machinery!












... sure enough the capstan belt has gone the same way as all the others! I'll change the lot...



















The tape transport is carefully disassembled to gain access to the belts..












..which involved removal of the record switch actuator lever. Capstan flywheel is removed to clean the remains of the belt off...










... and some suitable replacements found from the belt box. The capstan belt measures in at 71mm. There's a 2.8mm wide belt which will do nicely.










The deck is repaired, and time to contemplate re-uniting it with the rest ... look at all those screws!











Finally back into the lower part of the cabinet!


























... and that reunited with the top...

Thankfully, all the plugs are nicely labelled...


















... and once the transformer is re-fitted, speakers connected, it's tested...




A new stylus is fitted, and the turntable works a treat. Sounds far better than I had expected... unfortunately there's nothing but a nasty hum from the cassette deck. It appears either the wiring to the tape head, or the head itself is open circuit.... I dread having to remove the transport again. Closer inspection reveals the wiring to the head is broken, and it's been repaired before.. there's some evidence of a poor soldering job, and the wires have been left very short. Thankfully, access, although difficult, is possible through the front, after removal of the door, and the repair is completed.








Here's a quick video of the turntable in action....

And, finally, a few photo's of the original dealership who supplied the unit. These were taken on the last day of trading, back in November 2005.. a sad day.

Shop front...














Interior... looking sadly empty :(






























and the workshop...
















2 comments:

  1. I hear that they had a brilliant 1st class service technician working there...

    ReplyDelete
  2. I have an MC-8000 as well. It will play 45RPM singles very well, but it refuses to play 33RPM longplay recored. Any idea what might be wrong? Easy to fix?
    Many thanks, Louis

    ReplyDelete