McIntosh 1900 Recap and Restore

Discussion in 'McIntosh Audio' started by CohibaJoe, Jul 24, 2012.

  1. MikeRam

    MikeRam AK Subscriber Subscriber

    Messages:
    183
    Location:
    Portland Oregon
    Awesome! That helps a lot. I'll skip replacing the films.

    One more question, did you replace the two multi capacitor cans? Did you stuff the new ones in the cans?

    Thanks,

    Mike
     

     

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  2. paulram

    paulram Well-Known Member

    Messages:
    809
    I keep kicking myself when I see threads like this cause many years ago I let go a 1900 for next to nothing due to one channel not working. At the time I didn't know better and sent it to Rat Shack where it was unable to be fixed. So they say. Wish I had it today .Great job on the overhaul!!!
     
  3. jas2400

    jas2400 New Member

    Messages:
    2
    Do you have a cap / resistor / part list in the excel sheet you were talking about? I am beginning the same project and would very much appreciate it if you did.
     
  4. perryinva

    perryinva IS it vintage????

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    2,276
    Location:
    Richmond, VA
    Did anyone ever get a cap/resistor/part list from cohiba joe?
     
  5. perryinva

    perryinva IS it vintage????

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    2,276
    Location:
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    Bump. Still looking for that parts list for my 1900. It would be a nice winter project now that I have the replacement power/volume pot....
     
  6. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    I might have something.
    If you don't hear back soon , pm me.
    Honestly I don't remember how well I documented
     

     

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  7. captouch

    captouch AK Subscriber Subscriber

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    I have a cap list. I’m not replacing my resistors, so I don’t have a list for those. Will post within the hour.

    But realize that there are at least 3 different service manuals based on different serial numbers. I have a late model with the 4ohm impedance switch. And even my service manual had deviations from actual.

    I’d recommend you not rely on a service manual or list from another owner, but actually open up your unit and log the values yourself. You’ll have to get in there to do the recap anyway and this will avoid your having to place a second order due to differences.
     
  8. perryinva

    perryinva IS it vintage????

    Messages:
    2,276
    Location:
    Richmond, VA
    Thank you nj phoenix & captouch! Oh, yes, that is exactly what I do. I absolutely don't expect a "this is the easy answer list" and especially with the 1900, know that there are WAY too many iterations to trust any ones list as being absolute. (And I will not be replacing resistors, either). A parts list is helpful as a check against current inventory for any unusual components..like the 150mFd film caps, mentioned, and the cross references for the transistors can be very useful. Things like a Mouser product number will show correct physical sizes, to avoid, say a too tall power filter cap, ands often show caps that will fit in a multicap can for an OEM look. I would not perform the mega upgrade that Cohiba performed here..to each their own, and while I appreciate the effort and especially the posts, I have neither the time nor the desire for THAT kind of mega build. I've owned this 1900 for about 12 years, and it had already gone to Terry before I started servicing my own gear. He did a mild warmover, (maybe a dozen caps) and FM alignment, and it worked well enough for about 6 months before the volume pot started acting up, and loud pops on turn on and off occurred. Static appeared in some selections, and sometimes a channel would just become a loud hum, as well. So I know it really needed a major clean & ground trace verification and overhaul, as well as replacement of all electrolytics and probably tants as well. I'm not fooling myself in to thinking that I will get this done without more than one parts order, but minimizing the loss of momentum, because of too many re-orders, during the process is important to me. I have well over $2000 in caps, resistors, transistors, op amps, SS components etc spare parts, so even a first cut of "sure don't have those", like the output transistors, is worth it. No rush, and thank you very much for responding!!!
     
  9. captouch

    captouch AK Subscriber Subscriber

    Messages:
    4,680
    Location:
    Bay Area, CA
    Here's the list as it applies to my late serial # 1900. This excludes can caps. Four of the caps are ROE caps, designated as such in the list. I don't know if/how they're any different.

    Axials:
    4 x 150uF/63V
    1 x 100uF/40V
    1 x 470uF/35V

    Bipolars:
    2 x 10uF/40V (ROE)

    Radials:
    2 x 2.2uF/50V (signal path!)
    1 x 3.3uF/50V
    2 x 10uF/50V
    2 x 10uF/63V (ROE)
    6 x 100uF/16V
    1 x 100uF/25V

    On the preamp board, there are multiple mylar caps in the signal path. I bought Wimas MKP4's to replace those. What I'll likely do is replace one preamp board, play something mono, and compare between mylar and Wima caps to see if I can hear any difference. I believe the mylars are all 250V rated

    6 x 0.47uF (22mm lead pitch)
    4 x 0.22uF (15mm lead pitch)
    4 x 0.1uF (15mm lead pitch) (in my service manual, it said these were 0.22uF, but I found them to be 0.1uF, so am replacing with what was already there).

    Here are some internal pics of the underside and individual boards. It looks me me like one of the underside caps (the one vertically oriented at the 9'oclock position) and two of the caps on the FM board might have been replaced as they look like more modern caps.

    IMG_2251.JPG IMG_2256.JPG IMG_2258.JPG IMG_2260.JPG IMG_2261.JPG
     
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  10. perryinva

    perryinva IS it vintage????

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    2,276
    Location:
    Richmond, VA
    WOW. That's all? I haven't been inside mine in at least 10 years, but even without the can caps, I thought there would be more. Looks now like sooner rather than later! Thank you!
     
  11. ukfan4sure!

    ukfan4sure! Expert Smoke Releaser

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    Location:
    Louisville, KY
    Here is part of the Service Manual. Not helpful except for values....
     

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