Pioneer MD435 and MD450 - Neither one will recognize CDs

Discussion in 'Pioneer Audio' started by Nickib, Jan 11, 2019.

  1. Nickib

    Nickib New Member

    Messages:
    9
    When we merged households we ended up with two Pioneer 6-CD cartridge changers. They have both sat unused for several years. We recently got a tuner and plugged one at a time in hoping to use these on the auxiliary setting of the tuner. We didn't even get that far. Neither of them will recognize ANY CDs! It doesn't matter if the magazine is full, or one in any of the slots, CD right side up or upside down. Both of the units go to each CD, check it and then move on to the next one. Originally I just thought one of them was just beyond repair, but with both of them doing the exact same thing, I wonder - can this be resolved? Thanks for any insight!
     

     

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  2. quaddriver

    quaddriver 120 What's per channel Subscriber

    the ribbon cable from the main board to the cd, does it have a real tiny VR on it? if so, mark, spray, work it. that is laser power attenuation and oft it suffers the same fate as volume controls. also, work the head indexer motor (check any belts) and perhaps D5 the 'inner limit' switch..if it does not cycle then the thing defaults to 'load next cd'

    So far, I am like 5 for 5 on fixing them doing just those items.

    if you fail, dont ditch em, the cartridges are worth $15 on ebay any day...
     
    Blue Shadow likes this.
  3. wormhole

    wormhole New Member

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    Since I also have an MD-435, I will have to keep this info in mind if it ever goes silent on me. I bought mine new and, so far, it has played flawlessly.
     
  4. Nickib

    Nickib New Member

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    Thank you for the info. I don't mean to be stupid, but I haven't taken the "hood" off - I assume that once I get that off that will make sense? going for the screwdriver now . . .
     
  5. Nickib

    Nickib New Member

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    AA435F7C-73BA-48A7-82C6-35101ECC2660.jpeg
    Attached is what I see. Are you referring to the orange cable? I am not seeing a small “vr”. ????
     
  6. quaddriver

    quaddriver 120 What's per channel Subscriber

    yes that orange cable, there isnt a tiny little knot in it down where the thicker copper strips are? which model is that?
     

     

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  7. Nickib

    Nickib New Member

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    33B12A53-6C66-4496-8D8D-F306CB773354.jpeg
    435. Here’s a close up. Again my apologies but even if this is what I’m looking for I am not sure what exactly I’m to do.
     
  8. quaddriver

    quaddriver 120 What's per channel Subscriber

    couple more things come to mind...make sure the lens is in the pickup...I had one where the lens fell out prolly due to a wicked shock and it would never focus to read the vsn track.

    next, see the can motor on its side? is that the head indexer? they typically have a small belt that connects that to a wheel on a shaft with a worM gear and the back and forthness moves the head assembly...make sure the belt is there, not slipping or sticky. then work it back and forth by hand by turning the wheel, another thing you can do is move it to the center, load a CD and see if it does go to the center all the way, then come out a wee bit. that tells us if the indexing function is working. (there is a crap load can do with the service manual and a scope by putting it into test mode and then getting a display of the track signal, but my opinion is that is worthless cuz even if you identified a bad chip you cannot replace it, hence the brute force method of mechanical failures)
     
    Last edited: Jan 11, 2019
  9. quaddriver

    quaddriver 120 What's per channel Subscriber

    ok that pic is in fact the VR = variable resistor. mark where it is 'pointing' fairly closely...there is a good bit of allowed error in here. then spray with F5 and work it back and forth gently, then set it back to where it was originally. check the indexing belts etc and try it out

    eta: are those burnt traces in the ribbon cable or just ink? can you test for continuity?
     
  10. Nickib

    Nickib New Member

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    Ok the can motor does indeed have a belt/gear. They appear to be working smoothly and not sticky. I still don’t understand “moving” the vr- to where? What is F5 or D5? Is they WD-40?
     
  11. Nickib

    Nickib New Member

    Messages:
    9
    Ok the head indexer does not move back toward the center when I put the cd in. The cd clearly loads and then that’s it. Nothing.
     

     

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  12. quaddriver

    quaddriver 120 What's per channel Subscriber

    aha, D5 is deoxit contact cleaner 5%, F5 is the same but cleans fader controls with a lube in it - you want this for the VR

    so the VR has like a 270 degree arc it can be in. one way goes to '0', the other goes to 'max' - whatever it is rated for. when this was set up, there was factory test that in effect measured the laser scatter and some value was what they set it at. but the laser-y thing itself does degrade and the VR gets corroded so less or no power goes to the laser..the machine ASSUMES the laser is working and the track is read. but no power = no read so it grabs the next disk.

    if you load ANY disks in it, do they at least spin for a moment? there are 2 things here, it sends a laser beam and looks for a reflection, if it has one it says 'ooo I got me a disc' and then spins it and reads. but if that shot has no reflection then it says 'bonehead owner didnt put a disc in this slot, next!' and so it goes.

    if it just cycles 6 disks then that says no laser at all. I have never had one where the laser didnt EVER work. so lets get a red light.

    and no, Im not sure I would use wd40 here....if you have no deoxit, a local guitar shop should have at least d5 on the shelves as it brings back foot switches and controls on tube machines...
     
  13. Nickib

    Nickib New Member

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    Ah, good thing I didn’t “assume” - I don’t have the right lube. I see you’re near Pittsburgh. We are also. Would I be better off just taking both of these to a repair shop? I know they’re old but I don’t think they were cheap when purchased. I just don’t know if they’re worth fixing. All I wanted to be able to do was play multiple CDs and the radio on occasion. My dear husband bought me a pretty cool tuner for Christmas that appears to work with auxiliary pieces like these. It’s a Keiid which I had never heard of but sounds pretty good. What do you think?
     
  14. quaddriver

    quaddriver 120 What's per channel Subscriber

    well I could fix them, but Im jammed up, try Mr Vince at Galaxie on murray ave in squirrel hill. BUT, the labor cost might exceed the value...I cannot shamelessly plug any stores up north which may or maynot have some in stock, but use a local craigslist (or call mr vince) and keep the 6 disc cartridges if you decline to try to fix them up.
     
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  15. quaddriver

    quaddriver 120 What's per channel Subscriber

    btw - this is a dumb question, but did you put the discs in the catridge label DOWN? shiny side up? it does make a difference..
     
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  16. Nickib

    Nickib New Member

    Messages:
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    Not a dumb question. I tried both but the cartridge states putting them in upside down. I also did not see any movement whatsoever when I put the cartridge in other than it loaded the disc and stopped. No spinning, no laser, nothing. Thank you for trying to help! Hope you’re enjoying Pittsburgh!
     

     

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  17. kydog

    kydog AK Subscriber Subscriber

    The lens in these players tend to dislodge and fall out. See if it’s still in place. As stated CDs load shiny side up only. Good luck
     
  18. Nickib

    Nickib New Member

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    Thank you. Any idea how I find that??
     
  19. kydog

    kydog AK Subscriber Subscriber

    I actually “ Shook” the player slightly and turned it upside down & shook it. Sure enough I heard it rattle around, took the case off & it fell out. Plastic white lens.
     
  20. onwardjames

    onwardjames Hoardimus Maximus Subscriber

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    For the budget-minded, these are great cd players. Hoping you get it fixed. They tend to run forever, but the lens thing is a common failure point.
     
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