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Philips CD160 not working

Discussion in 'd.i.y.' started by a.palfreyman, Jul 31, 2017.

  1. Mike P

    Mike P pfm Member

    It's known to be rather value specific, it must be 33uF, don't be tempted to uprate it.
     
  2. a.palfreyman

    a.palfreyman pfm Member

    Oh, rather interesting. I used 47uF caps of circa 1 ohm ESR and have had no real issues except skips / jumps etc on discs which are damaged, although I admit both CD160s are more "sensitive" to poorer discs than my Micromega stage 3. I have bough two 33uF, 40V BC axials which were NOS but late '82 so circa 37 years old. I have reformed them and they now measure circa 38-40uF, 0.5 ESR and have about 1-2µA leakage current (they "loose" about 1V in 30secs by self discharge i.e. only 10 megaohm voltmeter connected across them). What do you think, try them or leave the others in place as I suspect that the much newer 47uFs will not be that much different in value?
    Cheers,
    AP
     
  3. chartz

    chartz pfm Member

    Just get fresh new BC/Vishay 33µF axials. New old stock caps are a no-no in my opinion. That some people might sell them beats me.
     
  4. a.palfreyman

    a.palfreyman pfm Member

  5. chartz

    chartz pfm Member

    Keep us posted then please.
     
  6. a.palfreyman

    a.palfreyman pfm Member

    I get them next week so will fit, run in and trial versus #2 machine with 47uF 1ohm ESR in that position, versus a Micromega Stage 3 (which is less sensitive to surface damage) and report back. Could be a few weeks tho'.
    Best,
    AP
     
  7. a.palfreyman

    a.palfreyman pfm Member

    Caps turned up Sat which was good because I was assessing the damaged discs to see how they behaved in the three machines and making some notes. Took a new 33uF at random and measured it: 46uF and 1.5 ohm ESR so well within spec (-10/+50%). Took out the 47uF that was fitted which measured 47uF and 0.8 ohm ESR. Was sceptical that it would make any difference, but fitted one and ran it for a short while before working through the damaged tracks I had assessed earlier in the day. Made no notable difference TBH. Got me thinking though as my #1 machine was clearly as bad (on discs with small pits / scratches) or worse (on a disc with a 3mm wide circumferential damaged zone) than my #2 machine whilst the Drive 3 sailed through the lot with no problems. I had removed the swing arm from the #1 machine a few months ago to clean / grease the bearings and despite trying to accurately align this with visual markers, it is clear that I can't have got it in the original position. I made a 5" square disc out of perspex and put a 16mm hole in the middle so I could check the optical alignment. The reflection in the lens (compared to that from the disc) was found to be about 2mm off-centre (outwards WRT the radial arm and at 90 degrees it was radially inwards WRT the disc) so I adjusted to get this down to about 1mm in both. Massive improvement, especially on the circumferential defect. Readjusted to get both offset values as close to zero as possible and this was clearly worse so have gone back to about the mid point. Not quite as good as the first adjustment but still better than it was. This also seems to have improved upper mid-range detail retrieval and image focus / depth.
    Is there a method for optimising the optical alignment using the four diodes used for tracking / focusing as the service manual says to get the lens reflection within 4mm of the disc reflection, but it is clear from my results above that this would clearly not be optimal at +/-4mm in both planes when a much smaller adjustment has such a profound effect?
     
  8. a.palfreyman

    a.palfreyman pfm Member

    Two weeks ago I tried soldering four wires to the back of the ribbon socket (#2 CD160) but made a hash of it. Damaged one of the traces to the chip, so removed the wires, replaced the trace with a wire and put it back as is; thankfully all OK. Last weekend, used a piece of strip-board which I thinned the backing down and placed over the chip so I could tack-solder to the legs of the chip and scoped the four diodes. D1 had a lower output than the other 3 (about 2/3) near the inner of the disc but this evened out with D2 (both about 80% of D3 and D4) towards the outside of the disc and making an adjustment to the lens alignment made no visible difference on the scope.
    Had a good listen to both the CD160s and compared to my Arcam Delta 170 transport (as this has the SAA7220 same as the CD160s, but the B variant rather than the A) with Bushmaster ii DAC and my conclusion was that there was little difference between the three. In fact I confirmed my previous suspicions that there was more difference from changes of seating position than from the three players and suspect my comments from above are due to this rather than alignement. Confirmed this with headphones (DT990 driven by a Ion Obelisk 3). I must admit though that my hearing starts to tail off about 6kHz and I can't hear test tones of 10kHz so I suppose it is possible that there are HF differences that I can't hear.
     

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