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...
















57 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
    Replies
    1. Hi. You need to replace all 3 bulbs on the back of arm.

      Delete
  3. Good job on your mc-8000

    I have the x-10 here in the states and also have the repair manual. I got the turntable working great after finally figuring out that the 12v bulb in the tone arm needed replacing. That was no fun!

    The cassette player needed 4 new belts so I’m tackling that now. I think I got everything back correctly. I’d like to test the deck before putting it back in. I’m concerned that when I push the play button(no power) the pinch roller doesn’t move and when I push the stop bottom it won’t make the play bottom pop up.

    I hot wired the red and black wires from the power supply to the cassette motor but only got a hum without the motor turning.

    Any suggestions?




    ReplyDelete
    Replies
    1. Cocked up the reply, Jim... it's below... ;)

      Delete
    2. Hi. Don't suppose you could help me locate an output module for my MC, Andy. I'm in the UK. cHEERS.

      Delete
    3. Likely to be made from purest unobtainium. If it were mine, I think I'd be mounting one of those small class-D amplifier modules in there, and finding a suitable supply. Audio will (obviously) be available where the original amp module fitted.

      Delete
    4. Motor control unit inside the motor is faulty. Remove end cap of the motor, replace electrolytic capacitors and AN6610, or use external motor control.

      Delete
  4. Hi Jim,
    I'd see if the mech is free first, by gently turning the motor pulley with the end of a screwdriver. If the mech has jammed for some reason, you'll need to strip it again to see what's stopping it from turning. I didn't have the manual, but it all seemed straight forward... except getting it in and out of the case!!!

    Good luck, and keep us posted!

    Andy Doz.

    ReplyDelete
  5. Thanks for your thoughts, Andy.

    Nothing seems to be jammed so I took a chance and put it all back together. What a nightmare but I got it.

    Well the pinch roller comes up when play is pushed but tape does not move. After about 3 seconds the play lever pops up and the motor turns off. Same happens with fast forward/rewind.

    I think I may have found the problem by looking over the mechanism before I put it back in. There is pulley just to the left of the motor(the belt motor goes right in front of it). A belt goes to it from the flywheel. BUT, the pulley only turns on it’s shaft! The shaft does not turn! I can move it on the shaft. That just doesn’t seem right. There is no washer/keeper on it either. I was thinking at first maybe it was just for balance. In the parts list, I can see other stuff on the other end of the shaft but I can’t tell for sure what’s what as the diagram is small.

    After tying this, I am more convinced that the pulls should be attached to the shaft.

    I was hoping someone reading this could verify that the pulley IS attached to the shaft by looking at their unit.

    If so, I’ll have to try to glue it on. All ideas are welcome!

    Thanks for your time.

    Jim







    ReplyDelete
    Replies
    1. Sadly Jim, I passed my unit on... The pulley hasn't got a felt pad underneath it, has it? To form a slipping clutch to provide some low-torque to the take-up spool? I somehow doubt it from your description. Sounds like you've hit the nail on the head!

      Good luck!

      Delete
  6. Getting ready to tackle repairing an X10 that wandered into the record shop I work at. Same issues as yours; weird motor running in cassette section when powered on, turntable belts are gone. I just wanted to say thanks for posting everything on here, it's been EXTREMELY helpful in giving me the courage to (as a young amateur) try to repair this unit.

    ReplyDelete
    Replies
    1. Congratulations Alan! Another saved from landfill! You are now officially a hero.

      Delete
    2. Happy to report that my X-10 turntable is working like a champ! I re-wired the incandescent sensors to LED, replaced the belts, and I'm back in business. Tape deck is still out of order, but I'll tackle that beast at a later date. Thanks again for the help!

      Delete
  7. Good going Alan!

    I got mine repaired also, both the record player and the cassette. Yep, I was right that that pulley on the tape deck was suppose to be attached to the shaft. It took JB Weld and some thinking on how to do it. Plus getting the cassette unit in and out 3 times was no fun.

    I also had to replace the light sensor bulbs including the one in tnr tone arm. I opted to use incondescences as I really didn’t know how to sub LEDS.

    If you get a chance and the time, I’d be interested in what you had to do to use LEDs.





    ReplyDelete
    Replies
    1. My friend, Andy at North Hill audio had one with a failed lamp. He used a yellow LED, and with a 1K current limiting resistor in series. You'll need to work out the polarity, or it won't light (just reverse it, if it doesn't)

      Delete
    2. Hi Jim! Like Andy said, polarity is key :) I ended up having to wire mine up twice to figure that out. Looking top down at the main circuit board on top of the tonearm, you'll see a red wire soldered to the left, with one leg of each incandescent going to a pad connected to the red wire. That's the negative side. What threw me for a loop was the fact that I didn't realize I can wire a resistor to either side of an LED leg, anode or cathode, and it'll still put the resistance on the circuit. I just assumed you have to put the resistor on the positive side, and I also assumed the side with the red wire was positive, leading to me having to wire the LED's up twice.

      SO, all that said, what you'll want to do is wire from the pad on the left, to one leg of a resistor (I used 1/4w 470 ohm), the other leg of the resistor goes to the cathode (negative) side of the LED, and the anode (positive) side of the LED goes to the pad on the right that corresponds to where the incandescent leg was soldered. You'll want to use 3mm LEDs as 5mm won't fit, and I don't think color really matters as long as light is emitted (I used red). Hope that helps, let me know if you have any more questions!

      Delete
  8. Hey there, I have an X-10 and it has a grey wire coming from the E part of the power switch PCB. I always take pics but I didn't take one of where that one goes. Any help?

    ReplyDelete
    Replies
    1. Sadly I've never seen an X-10. It wasn't available here :( Sorry...

      Delete
    2. I went back and looked at my pics from earlier in the year when I repaired my X-10. I think the gray wire is a chassis ground; here's a pic I took that shows it: https://imgur.com/a/D9Fshpe

      Hope that helps!

      Delete
  9. I have the schematics for the X-10 and I don’t see any gray wire coming off the PS-41 power switch. It shows only 2 white wires coming off of it and going to the power transformer. I don’t know what you mean be the “E” section.

    ReplyDelete
  10. GOOD AFTERNOON,I HAVE A MITSUBISHI MC- 8000 VERTICAL MUSIC SYSTEM IT DOES NOT WORK AT ALL, I AM LOOKING FOR SOME TO FIX IT BY SENDING IT TO APPROPRIATE MECHANIC TO FIX . CAN YOU ASSIST PLEASE TO HELP ME TO GET IT FIXED , LOOK FORWARD TO HEARING FROM YOU , RERARDS ROB

    ReplyDelete
    Replies
    1. Hi Rob,
      Where are you?
      BTW There's a button marked caps lock on the left hand side of your keyboard. Give it a press... ;)

      Delete
  11. hello. when i moved inyo my house about 3 years ago, it was completely empty....but for one of these. Didnt work. Spent nearly a year and a half rebuilding it. Finally, it cut it on and she purred like a kitten. the kittke speamers i had didnt do it justice, so left to go buy someyhing more fitting. When i got homme, my girlfriend described some kinda power issue in the house. all elwctronics plugged in got fried. including,the mc8000. the mic4owave STILL only heats 1 minute at a time. turns out it was the power line spur from the street. byt boy, i cried.... all that for nothing.

    the cavinet is now repurposed, as i love the etched logo on the glass. The turntable itself survived my temper tantrum, as did the heavy psu. Id like to now give it new life, but cant find the primary or secondary wire schematic i once had, the total output, nothing. can you help me out there? This is really important to me. and id appreciate any help

    ReplyDelete
    Replies
    1. This comment has been removed by the author.

      Delete
    2. This may help https://www.vinylengine.com/library/mitsubishi-diatone/mc-8000.shtml

      Delete
  12. Hi everyone were could I get all the belt spares for the Mitsubishi MC-8000 thanks in advance.paul

    ReplyDelete
  13. I got all the required belts from CPC. https://cpc.farnell.com/

    ReplyDelete
  14. Hi Andy. I managed to get mine fixed locally. For some reason the speed of the turntable is slightly too fast. Is there a way of calibrating this?

    ReplyDelete
    Replies
    1. Yes! Beneath the motor, to the right of the flywheel, you'll see a small PCB with two skeletal pots on it. One adjusts 45RPM, and one 33RPM. Adjust as required with an insulated tool. It quite visible on the second picture down..

      Delete
  15. Hi I have one of these as with yours the belts have turned to sludge .Luckily the tape deck still
    Turns . I had a few belts and changed The three . Everything moves now but the arm just lifts up and goes to the middle of the record . And doesn’t lower onto the disc . It lowers when returning to the cradle . Any ideas thanks .

    ReplyDelete
    Replies
    1. Is the little lamp at the end of arm lit OK?

      Delete
  16. There is a lamp lit it’s a square above the disc cheers steve have you got an email

    ReplyDelete
    Replies
    1. I'm not willing to publish my email here, sorry.

      Delete
  17. Question on the 3 lights at the end of the arm: is it called PH 101? Looks like they stopped selling them. Which did you get?

    ReplyDelete
    Replies
    1. Long since obsolete. Use a yellow LED, and a 1K resistor in series.

      Delete
  18. Wish I could help but once I got my unit fixed- like 3 years ago- I just don’t remember much about the repair. Wish Zi could help more.

    ReplyDelete
  19. Hi Andy. My cassette player in The MC8000 its making odd noises permantley. To be honest id like to just disconnect it as I only use it for vinyl. Best way of doing? Snip wires to motor ? or a clip of sort?

    ReplyDelete
    Replies
    1. Just unplug the casette deck milti-pin plugs... easy to put it back if you ever fancy fixing it!

      Delete
  20. Hi, I have a MC-8000 that use to work perfectly but will now only play 7" and not 12". The tracking arm picks up the fact that the 7" has loaded, but the 12" doesn't pick up, the arm tracks across but it doesn't drop and play - any ideas? Thanks

    ReplyDelete
    Replies
    1. Hi Dan,
      I would start by looking at the optical sensors that are located behind the platter. Does it attempt to play the 12" as if it's a 7"?

      Delete
    2. Hi. Thanks for responding. No the arm simply tracks across to the centre of the record and then tracks back and stops. With the 7" it lifts and drops perfectly and plays, but 12" it's almost as if it doesn't recognise its there. The arm also won't lift up and down using the button when loaded with 12" record. Out of interest is replacing the optical sensors are hard job? Cheers.

      Delete
    3. Not sure, never done them! I'd just remove the platter and examine them, it may be as simple as a dirty sensor.

      Delete
  21. I have one of these and was able to restore it back by replacing the belts and bulbs with LEDs. however, the radio/tuner does not work (very faint), and was that way when I received it. I am not sure where to start on repairs for it. Do you have any suggestions?
    thanks!

    ReplyDelete
    Replies
    1. You have got an aerial connected??

      Delete
    2. I think it has a built in AM antenna but not one for FM so you would need one for for FM.

      Other than that I don’t know why it’s faint.

      Delete
    3. That's why it's faint. You'll need both! It would have originally had an am loop antenna, and an FM ribbon antenna. Try a length of wire, about 2m long in the centre pin of the fm socket. Am loop antennas can be obtained from a scrap hifi, or maybe eBay... it attaches to the binding posts on the rear. You will be an improvement with a longer piece of wire on the am... try it out!

      Delete
    4. Check white wire from antenna/connector-panel is soldered into receiver module. Mine was loose because of bad soldering.
      You can see it when you remove back plate.

      Delete
  22. Keep up the good work guys!!! You just gave me the courage to start on mine.

    ReplyDelete
  23. Hi Andy, I know the blog is old and you repaired a MC 8000 some year before. I also own such a device now. Do you know what I have to do that the tonearm is running back and stop the motor when the vinyl ends ? My device is not switching of after end of record :-(

    ReplyDelete
    Replies
    1. Check LA103 (download a copy of the service manual fro somewhere.. or drop your email here and I'll send you a copy). LA103 is the end sensor lamp.

      Delete
    2. Will do, Thanks from Germany, I have the service manual and test it next weekend

      Delete
  24. Hi There - Theo here from Wembley, I have an MC-8000 - wow what a great bit of Hi-Fi. I've done the lamp to LED swaps for the turntable - all working really well. The lights on the selector (Tape / Phono / Radio) and the digital read-out do not normally come on on power-up but eventually do come on. Any ideas what causes this - it is sort of intermittent, but the selector switch is working at all times for operation. Many thanks, Retro - Theo - theoparadise@msn.com

    ReplyDelete
    Replies
    1. Hello Theo. Download the schematic, and start checking supply rails to that bit of the circuit. Electrolytic caps in their later years often give this kind of symptom! That's where I'd start. You may find some freezer spray on the electrolytic will cause the fault to occur once the displays are working. Use the search button above for "Freezer spray on the cheap"

      Delete
  25. hi, i have got a mc800-, but it is missing the motor for the arm, i think in your pictures it is no 2 and number 3 it is black by going by your photos any ideas where i could get one or a modern eqivilant of it, i have looked on ebay and facebook, thanks

    ReplyDelete
    Replies
    1. I would think a scrap unit for parts is your only hope there.

      Delete
  26. Hi, I have one of these to fix. Capstan belt has completely deteriorated so I want to replace the lot. I fixed these back in the day but not touched one in many years (cough), so great to see this teardown. I do not have a workshop so it will be a kitchen table repair so would like to have all the belts to hand. I definitely dot want to leave it ' on the bench' for too long as it looks complex with plenty of parts to remove. so, any idea what the belt sizes are so I can pre order? Thanks, great work.

    ReplyDelete