Recently I've got a Nakamichi CD Player 3, the MusicBank kind. The seller said it was not opening the tray and thus playback was untested and they were giving it away for a decent discount. "Aight just a few new belts right?" — the famous last words before I turned my desk into a lab first time in a decade again.
Linking the service manual right here for those kindly playing along at home: ElektroTanya
So, indeed, first I went ahead and swapped the belts and lubricated all the plastic parts. One of the cogs in the optics lifter mechanism had some crud somehow make its way onto the rod so that had to be reseated.
Then it turned out the lever of the home position sensor of the stacker assy was broken off — so I bent the spring beneath it to account for that, finicky, but it works most of the time for now.
Powering it on revealed that sometimes it would glitch out, showing garbage on the screen or trying to spin the disc in reverse up to takeoff speeds. Tapping the +5V logic supply voltage regulator often fixed that by triggering a reset. So, reflowing that and the two transistors generating the ±5V supply for the DAC got the voltages steady and spot on within a few hundred mV of the designed value. (Those components went hot enough to slightly brown their surroundings on the board)
I took out a few caps at random on both the main and RF boards and they all matched the label, albeit I have to admit I didn't look at the ESR too much.
(Cue the Benny Hill chase soundtrack and footage of myself spending a whole day looking for the transistor shaped "turns-out-it's-a-fuse" that I've blown by shorting one of the caps by accident)
Then I plugged in my speakers and put in a pressed album and... the sound was absolutely trashed, as if only one bit of the DAC was working.
I assumed the DAC is broken, so I recorded a CD-R with a few sinewaves and a silent track, 30 seconds each.
And here's how the 1kHz sinewave, 50% FS looks like on the output:
Not quite 50%, not quite sinewave, but at least both channels are the same, so it's not like the DAC is faulty — I doubt both sides of it would've developed an exact same failure. It's more like something is loading garbage into it.
So I went on to play silence, and:
Definitely not silence either!
So, going on the path from the rear jacks backwards I traced along the following symptoms while playing the silence CD-R:
Easier done than said, I go ahead and try to look at the eye diagram on the RF input of the main board (while realizing the afterglow mode on my scope doesn't clear itself up over time), and this is what I see on a pressed CD:
Then I go onto a quest of re-lubricating the spindle motor bearing (a drop of IPA [not beer] into it, followed by some power tool oil), cleaning up the clamps, and attempting to make the eye diagram a tad better by spinning the EF SIGNAL knob, resulting in this on the pressed CD — that's as good ad I could get it:
But if it ain't broke, I fixed it! It won't really lock onto a CD-R anymore:
(in case of track 5-6, so 2.5-3min into the disc, it sometimes does play, but intermittently)
So now, the questions:
Thank you very much for your help!
Linking the service manual right here for those kindly playing along at home: ElektroTanya
So, indeed, first I went ahead and swapped the belts and lubricated all the plastic parts. One of the cogs in the optics lifter mechanism had some crud somehow make its way onto the rod so that had to be reseated.
Then it turned out the lever of the home position sensor of the stacker assy was broken off — so I bent the spring beneath it to account for that, finicky, but it works most of the time for now.
Powering it on revealed that sometimes it would glitch out, showing garbage on the screen or trying to spin the disc in reverse up to takeoff speeds. Tapping the +5V logic supply voltage regulator often fixed that by triggering a reset. So, reflowing that and the two transistors generating the ±5V supply for the DAC got the voltages steady and spot on within a few hundred mV of the designed value. (Those components went hot enough to slightly brown their surroundings on the board)
I took out a few caps at random on both the main and RF boards and they all matched the label, albeit I have to admit I didn't look at the ESR too much.
(Cue the Benny Hill chase soundtrack and footage of myself spending a whole day looking for the transistor shaped "turns-out-it's-a-fuse" that I've blown by shorting one of the caps by accident)
Then I plugged in my speakers and put in a pressed album and... the sound was absolutely trashed, as if only one bit of the DAC was working.
I assumed the DAC is broken, so I recorded a CD-R with a few sinewaves and a silent track, 30 seconds each.
And here's how the 1kHz sinewave, 50% FS looks like on the output:
Not quite 50%, not quite sinewave, but at least both channels are the same, so it's not like the DAC is faulty — I doubt both sides of it would've developed an exact same failure. It's more like something is loading garbage into it.
So I went on to play silence, and:
Definitely not silence either!
So, going on the path from the rear jacks backwards I traced along the following symptoms while playing the silence CD-R:
- Output filter OpAmp: just repeats the noise that the DAC sends into it, once the DAC shuts up there's no noise, so it's ruled out
- DAC: sends out the abomination on the second picture above on the L and R outs, and the input data line gets some blips of '1' bits at times, while I assume silence should be all '0'? Sure enough, shorting the data in to ground makes it shut up. The output waveform is somewhat like this:
- Digital filter / Resampler: Gets 1-2 of '1' bits every now and then on the data in line. Shorting the data in line to ground makes the whole downwards chain shut up, so I assume the Resampler is getting garbage data on the inputs.
- Sony DSP chip: the CRC incorrect flag line raises 1-2 times at a similar timing to those 1-2 '1' bits. (I don't have a second probe on the scope to compare)
- All the other frequencies seem to be spot on, aside from the PLL — it's constantly 0.2MHz too high, but locks on to the specced 4.2ish MHz just fine once the CD is spinning.
Easier done than said, I go ahead and try to look at the eye diagram on the RF input of the main board (while realizing the afterglow mode on my scope doesn't clear itself up over time), and this is what I see on a pressed CD:
Then I go onto a quest of re-lubricating the spindle motor bearing (a drop of IPA [not beer] into it, followed by some power tool oil), cleaning up the clamps, and attempting to make the eye diagram a tad better by spinning the EF SIGNAL knob, resulting in this on the pressed CD — that's as good ad I could get it:
But if it ain't broke, I fixed it! It won't really lock onto a CD-R anymore:
(in case of track 5-6, so 2.5-3min into the disc, it sometimes does play, but intermittently)
So now, the questions:
- Am I right in the assumption that the DF/DAC/OpAmp are likely all good?
- Could the Sony DSP chip fail in a way that it reads out the data fine but sends out garbage on the audio out? Are chips even likely to fail in the first place?
- Could it be the playhead having some crud get inside it and ruining the read out signal and should I replace that?
- ...Or am I dumb and those graphs just scream "I NEED A RECAP" about the main board? (The ESRs on the RF board were in spec as well so that's not it)
Thank you very much for your help!
More hilarity ensues... My wife's been a champ at reverting all the damage I do, and this time is no exception — after she had a few hours to tweak the optical knobs and things the CD drive now even reads the cheapest CD-Rs it wouldn't want to before. The sound, however, is still trashed.
Looking at the input bit clock of the SM5840CP, the resampler, it looks kinda funny? But overall stable:
The input data line also has some weird things from time to time:
Not sure if as a result of that, or due to the resampler itself being faulty, it's output clock to the DAC doesn't make any sense at all
Looking at the input bit clock of the SM5840CP, the resampler, it looks kinda funny? But overall stable:
The input data line also has some weird things from time to time:
Not sure if as a result of that, or due to the resampler itself being faulty, it's output clock to the DAC doesn't make any sense at all
It's been decades since I have owned a Nakamichi 3 CDP. What I do remember about it that I hated the sound and sold it soon after I got it.
Depending on the chipset, the optimal RF eye pattern value is 1.2 to 1.5Vpp, + and - 0.3V.
I have that Burosch CD, which I used for the adjustments and fault-find the broken CD players.
I see from the service manual, that this particular CD player requires adjustments of focus, sled, spindle, tracking... trim pots.... so it appears that someone before you had a go at turning the trim pots without proper measuring gear and service manual...
I have that Burosch CD, which I used for the adjustments and fault-find the broken CD players.
I see from the service manual, that this particular CD player requires adjustments of focus, sled, spindle, tracking... trim pots.... so it appears that someone before you had a go at turning the trim pots without proper measuring gear and service manual...
@Extreme_Boky
Yeah it does, but we've went through all those adjustments already.
The eye diagram had different amplitudes depending on which CD I used, some plants better some worse, and CD-R the lowest.
The subcode is being read perfectly (nearly no CRC error signal aside from when moving tracks, time code and TOC display on the first spin after loading the disc).
Moreover, the weird clocks I posted above were due to me using the scope at the 1x probe setting. Changing it to 10x showed me fairly decent discontinuous clock that's the norm for those upsampling converter players.
And the weird noisy data bits edges are aligning with the clock edges. So something is making the DSP send high pulses to the DAC for no reason. Given the DSP has RAM in it and a bunch of other things, I suspect whatever part of it that extracts the audio data from the bitstream just went out of whack?
I'll try to source a replacement somewhere
Yeah it does, but we've went through all those adjustments already.
The eye diagram had different amplitudes depending on which CD I used, some plants better some worse, and CD-R the lowest.
The subcode is being read perfectly (nearly no CRC error signal aside from when moving tracks, time code and TOC display on the first spin after loading the disc).
Moreover, the weird clocks I posted above were due to me using the scope at the 1x probe setting. Changing it to 10x showed me fairly decent discontinuous clock that's the norm for those upsampling converter players.
And the weird noisy data bits edges are aligning with the clock edges. So something is making the DSP send high pulses to the DAC for no reason. Given the DSP has RAM in it and a bunch of other things, I suspect whatever part of it that extracts the audio data from the bitstream just went out of whack?
I'll try to source a replacement somewhere
Ok, I had a better look now, seeing that you adjusted the trim pots...
Check U501 pin 51... see what happens there when the CD player misbehaves. One of the RA504 resistors may also be an open circuit, which will prevent the U501 from properly switching Vcc to produce the correct pulse train.
It seems that both the U501 and U505 can request data from RAM (U503).... but I don't get it... why would 2 different ICs be allowed to request data from RAM on the (via the) same PCB track... I could not find the U505 pin designation with the function description in the service manual... Anyway, I'd be looking at this track HIGH... in relationship with what the CD player is doing... I would cut the track at point "x" and see which IC is the master.
Check the ceramic oscillators X501 and 502 for correct operation. They like to fail.
Good luck.
Check U501 pin 51... see what happens there when the CD player misbehaves. One of the RA504 resistors may also be an open circuit, which will prevent the U501 from properly switching Vcc to produce the correct pulse train.
It seems that both the U501 and U505 can request data from RAM (U503).... but I don't get it... why would 2 different ICs be allowed to request data from RAM on the (via the) same PCB track... I could not find the U505 pin designation with the function description in the service manual... Anyway, I'd be looking at this track HIGH... in relationship with what the CD player is doing... I would cut the track at point "x" and see which IC is the master.
Check the ceramic oscillators X501 and 502 for correct operation. They like to fail.
Good luck.
@Extreme_Boky
If you mean U503 the RAM, that is for the system firmware only (display, drawer, all that stuff).
The chain in charge of audio from what I can tell is: laser diode -> U201 (RF amp) -> U102 (they call it DSP, but it basically decodes the EFM signal from the laser) -> U801 (audio resampler/filter) -> U802 (DAC) -> U803 & friends (filter/buffer) -> line jacks and whatnot
U201 is likely fine since the discs read out and show the timecodes; U102 decodes them so it's at least semi-fine?; U801 onwards seem to be fine but maybe not?
It doesn't help there's no decent datasheet for the DAC (with the tables of how the binary codes and the voltages relate to each other), otherwise if I can get a ±5V power source I'll desolder it and try to build a test rig to output known voltages...
If you mean U503 the RAM, that is for the system firmware only (display, drawer, all that stuff).
The chain in charge of audio from what I can tell is: laser diode -> U201 (RF amp) -> U102 (they call it DSP, but it basically decodes the EFM signal from the laser) -> U801 (audio resampler/filter) -> U802 (DAC) -> U803 & friends (filter/buffer) -> line jacks and whatnot
U201 is likely fine since the discs read out and show the timecodes; U102 decodes them so it's at least semi-fine?; U801 onwards seem to be fine but maybe not?
It doesn't help there's no decent datasheet for the DAC (with the tables of how the binary codes and the voltages relate to each other), otherwise if I can get a ±5V power source I'll desolder it and try to build a test rig to output known voltages...
@Extreme_Boky oh indeed, thanks.
Now that I think of it if the bitclock is 44100 x 2 x 18 = about 1.6MHz, I could probably stuff the DAC inputs into my 16MHz saleae clone and try to see if the data being fed into the DAC makes sense. If it does, swap the DAC end of story, otherwise go up one step to U801, if the signal sent to that doesn't make sense either replace U102.
My gut tells me this is something all too simple I might be overlooking.
Once I record the (digital) waveforms for that I'll post them
Now that I think of it if the bitclock is 44100 x 2 x 18 = about 1.6MHz, I could probably stuff the DAC inputs into my 16MHz saleae clone and try to see if the data being fed into the DAC makes sense. If it does, swap the DAC end of story, otherwise go up one step to U801, if the signal sent to that doesn't make sense either replace U102.
My gut tells me this is something all too simple I might be overlooking.
Once I record the (digital) waveforms for that I'll post them
That would be U801.
You mentioned before that you did some re-flow, which stabilised the Clock X801. Make sure it is still stable.
The Clock should become active as soon as you turn the CD player ON, and it should stay stable. Check what happens with the RESET signal at that time....
I can not find this main PCB (2/2)...?
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Found it... make sure that U403 is working correctly... check R420... check Q410. By the way, how the heck is this the Main PCB..??
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I'll have a look at it, thanks.
Previously I think it was pretty clean, but it makes sense that there might be some ripple on it that isn't enough to throw the mechacon/microcontroller off the rails but semi-reset the audio filter or the DSP.
Also a friend of mine who used to work at a service center in the 90s says the CXD series chips of that era failed out of the blue in enormous quantities, so I'll try to source a replacement as a first safe enough bet.
Previously I think it was pretty clean, but it makes sense that there might be some ripple on it that isn't enough to throw the mechacon/microcontroller off the rails but semi-reset the audio filter or the DSP.
Also a friend of mine who used to work at a service center in the 90s says the CXD series chips of that era failed out of the blue in enormous quantities, so I'll try to source a replacement as a first safe enough bet.
That's been done this morning as well, they made audible "clack" sounds while reflowing as if they were tensioned. But no dice otherwise.
Maybe a tensioned pin could've damaged the internal wire between the die and the pin but we'll never know...
Maybe a tensioned pin could've damaged the internal wire between the die and the pin but we'll never know...
Alrighty, now that I've sorted out my scope issues (and gave it a firmware update), time to dump all the waveforms in the chain I've mentioned previously and try to source the replacement chip, as well as point out any obvious weirdness. How they say — It's the Final Rundown!
1. RF output after the amp, measured on the RF testpoint (CN-105:3) while playing a pressed CD
2. EFM output from the amp as seen from the U102, taken at R170, with a pressed CD
3. The PLL clock, CN-109:2 (~PLCK signal), must be 4.2MHz as per the manual
4. Bit clock IN U801:17 (2.?68MHz in the manual) and Word clock IN U801:16 (44.1kHz in the manual): 24 bits per word, isn't it too much for 16 bit CD? or am I reading it wrong?
5. Bit clock IN and Data In (U801:18) while playing a silence track on a CD-R, to hopefully highlight the problem. We can clearly see 10 clock cycles are in a logical 1, whereas silence should be 0? Or is it some weird different format?
6. Bit clock IN and Data In while playing a music track on a pressed CD
7. Oscillator out (U801:4) to the DSP, 6.9244MHz in the manual
8. Data Left (U802:12) and Data Clock (U802:13) on the DAC while playing a silence track on a CD-R. This is data for the DAC so it clearly should be zeros (see datasheet) and yet!
9. Data Right (U802:16) and Data Clock (U802:13) on the DAC while playing a silence track on a CD-R
I was about to take some power voltages and the DAC outs as well but while I was at it the -5VD rail went, and the fuse seems intact so I'm puzzled. Either way without it the DAC is completely silent. Duh, will look into it later.
I have a feeling that otherwise these waveforms either makes it clear that either the U102 is toast or I'm totally lost 😛
P.S. It might be worthy to note that during the pauses between tracks there is (was) no noise from the DAC
1. RF output after the amp, measured on the RF testpoint (CN-105:3) while playing a pressed CD
2. EFM output from the amp as seen from the U102, taken at R170, with a pressed CD
3. The PLL clock, CN-109:2 (~PLCK signal), must be 4.2MHz as per the manual
4. Bit clock IN U801:17 (2.?68MHz in the manual) and Word clock IN U801:16 (44.1kHz in the manual): 24 bits per word, isn't it too much for 16 bit CD? or am I reading it wrong?
5. Bit clock IN and Data In (U801:18) while playing a silence track on a CD-R, to hopefully highlight the problem. We can clearly see 10 clock cycles are in a logical 1, whereas silence should be 0? Or is it some weird different format?
6. Bit clock IN and Data In while playing a music track on a pressed CD
7. Oscillator out (U801:4) to the DSP, 6.9244MHz in the manual
8. Data Left (U802:12) and Data Clock (U802:13) on the DAC while playing a silence track on a CD-R. This is data for the DAC so it clearly should be zeros (see datasheet) and yet!
9. Data Right (U802:16) and Data Clock (U802:13) on the DAC while playing a silence track on a CD-R
I was about to take some power voltages and the DAC outs as well but while I was at it the -5VD rail went, and the fuse seems intact so I'm puzzled. Either way without it the DAC is completely silent. Duh, will look into it later.
I have a feeling that otherwise these waveforms either makes it clear that either the U102 is toast or I'm totally lost 😛
P.S. It might be worthy to note that during the pauses between tracks there is (was) no noise from the DAC
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Wanted to edit the post to avoid flood but I could not, if mods could stick this message into the last one that's much appreciated.
The -5VD is back, I was looking at the wrong fuse — likely shorted something while measuring, the probes from GW Instek aren't the most convenient in the world.
Since I don't feel comfortable bridging yet another fuse I've ordered a 10-pack from a local vendor, and a U102 from some guy on ebay (albeit mine and the docs say it must be a 1167QZ while I couldn't find it anywhere online and thus ordered 1167Q, they seem to be the same package and chip in general).
Will post back once those are swapped.
The -5VD is back, I was looking at the wrong fuse — likely shorted something while measuring, the probes from GW Instek aren't the most convenient in the world.
Since I don't feel comfortable bridging yet another fuse I've ordered a 10-pack from a local vendor, and a U102 from some guy on ebay (albeit mine and the docs say it must be a 1167QZ while I couldn't find it anywhere online and thus ordered 1167Q, they seem to be the same package and chip in general).
Will post back once those are swapped.
So, today I received the 1167Q, and fitted it into the U102 spot.
What has changed:
I'll probe around more later this week, but it's weird... I don't think I could've killed the laser diode by putting the whole mech assembly into a plastic bag to keep it from dust while waiting for the chip?
It's as if some command or something isn't coming through.
What has changed:
- The 5MHz clock is on PCLK pins, so the insides of the chip are at least somewhat true to the label
- Otherwise the player won't even try to spin the disc... The laser seems to come on but no focusing takes place, no spindle action either.
- Then the player just gives up on reading the disc and ejects it
I'll probe around more later this week, but it's weird... I don't think I could've killed the laser diode by putting the whole mech assembly into a plastic bag to keep it from dust while waiting for the chip?
It's as if some command or something isn't coming through.
Hello, I have a Nakamichi MB2 and a Nakamichi CD Player 3, both with the same issue: they need a long warm up (1-2 hours) unti they play a disc. Seems to be a typical fault. I resoldered and recapped the CD Player 3 ( incl. the rf amp pcb ) but there is no success. Is there any experience with this fault?
Thanks for support!
Thanks for support!
Hello Audience, I repaired several players CD 1-3. Most common failure is the RF AMP pcb, did you exchange them all? Otherwise you have to replace the laser, but you can tweak the current a bit according to the service manual. BR Wolf.