I'm always suspect of the the surface mount electrolytic capacitors in these vintage units -- especially if they haven't been used for a long time (years).
Also, voltage regulators can get hot. With time and use the solder connection can get unstable and even break. This situation happens because the of the expansion and contraction of the connections due to heat and subsequent cooling down of the regulator.
The break may not visually apparent. With *any* vintage solid state equipment, a "touch-up" of the voltage regulator connections would be good preventative maintainence.
I know that this post may be a bit off the subject, but I'll ask anyway. See, I just got a Sony D-211 which works intermittently. Mostly of the time, it has trouble tracking and won't find the first track till the 3rd attempt. I actually got the pcdp to track on the first attempt by messing with pot 502 on the circuit board. However, everytime I pop in a new CD, it seems like the tracking gets thrown off again. In fact, every time I put open the lid and shift the CD, the player has trouble tracking, and have to go and reajust the pots.
Chances are, any adjustment to any one pot isn't going to solve all the tracking problems. I don't have the manual, but the focus and tracking work together. As the adjustments are made while the unit is playing, listen to the mechanism: there should be a point where it sounds like it is working less hard (less noise). Basically, that's the correct point of adjustment.
Try working the head transport mechanism by repeatedly seeking the first and last track of a long (70+ minutes) disc.
I have a D25 with a periodic distortion issue….. There are certain bass frequencies that cause a static/distortion-type noise, primarily in the right channel. It's only on certain cuts that I can hear it, and usually only if bass (and maybe vocals) is playing. The beginning of Bullet Proof Soul by Sade is a perfect example. It's possible that higher volume tracks in the right channel are drowning out this slight distortion and it's still there, just covered up by other sounds.
The noise sounds most like that of a cracked speaker cone; follows the bass beat, and not very audible. Definitely an electronically induced sound as opposed to motor noise. It's not dependent on high volume like something is being over driven because I can reproduce it at somewhat lower volume levels.
What's weird - In other songs that have equally strong bass, this unit is clean and powerful in all frequencies. Janie Runaway and Negative Girl off Steely Dan's Two against Nature have some serious bass chops that reproduce perfectly (or as closely as possible for a pcdp). All of Johnny Lang, Lie to Me, which has some mean bass, is clean and mean through and through with no hint of static or distortion.
Diags so far - I swapped RCA inputs and it appears in the left channel, so it's definitely in that one channel circuit. HP out and line out give the exact same results, so the problem is upstream of the internal amp (conjecture on my part, of course). Same results using a wall wart or 8-cell ni-cad pack.
I read 555's mention of an electrolytic cap failure that caused one channel to go out in his D555, and that this was a reoccurring issue in this model. Since the D25 is from the same era and practically a little brother, I'm wondering if this might be the case. I've already replaced the two PS caps and the two 100uf caps at the headphone output. Still I'm hoping this is just an issue of chasing down and replacing a discrete component or two.
History - I recently modified this D25 by stacking two DACS, in addition to a few other changes. After stacking the DAC, I believe I might have amplified a glitch that was already present. Prior to the mod, I played a channel integrity test track and could hear very slight static in the right channel during the left channel only test, but nothing visa versa. I was playing through the line out into a Headsave Tempo and using Shure E5s (the stethoscope of portable audio.....). It was not motor noise I was hearing, but more like a slight electronic distortion.
Everything else about the Turbo mod and the overall sound blows me away every time I listen to it. Currently, I'm using HD650 (200+ hrs), ZU Mobius (~100 hours), ZU Pivot (15 hrs) and an XP-7. Again, for most songs, i.e. 98% of the time, this unit in many ways at least matches my Onkyo 717, which has a fairly decent CD section.
I'd appreciate any thoughts from the electronic gurus out there, especially those with a D25 schematic. I can publish small sections of the schematic if this would be helpful.
If it's at the line out then it is probably "upstream" from the headphone amp IC as you say. Not only are the coupling caps between the stages suspect, the power supply filtering capacitors for the line out IC may be bad.
If you are able to post the amplification stages after the DACs then that would be helpful in pointing out possible culprits.
I'm not familiar with the mods but to me if there are DACs being stacked I would think that there would be some additional requirements on the power supply to those ICs, thus a change at the DAC power supply filtering cap (increase of filtering) might be necessary. Maybe that increase is already part of the mod?
Thank you so much for posting, was actually hoping you would.
I posted a few screencaps of the schematic at the Yahoo address where I'd posted a few pics of the mod itself: http://photos.yahoo.com/davidp01503 Hopefully these are legible enough; thought larger zooms would be too unwieldy.
Given that several folks have performed this mod with success, I assume that for my unit, there is a cap or other discrete that's a little less than spec, as you mentioned. However, I think your email points to that one final tweak needed to make this mod rock solid. There is a slight change in gain if I understand the dynamics, one that my particular unit is having difficulty with on some passages, or maybe it is with songs that have higher initial recording levels. On a solid unit, I think your suggestion would further improve the already much-improved performance.
Amen on the extra coupling caps!!! I've been studying the concept of stacked DACS and searching where I can. In the original thread at DIYAudio, there was question and mention of extra caps being needed due to voltage changes. I was trying to compose an email to pose this exact darn question, so your post is very timely.
To answer your question, no discretes were added at the new chip's location. Larger caps were added at the PS, with one bypass cap. I just need to know what and where to solder…8~)
Thanks again, I would appreciate any thoughts or suggestions.
Btw - I have a D555 on the way so will soon be joining the ranks. I just hope I never need any of the related info you've posted in this thread….. 8~)
Ahhh.... As originally built: The line out and the headphone amp utilize the same output IC so the headphone/line out amp cannot be ruled out (yet).
The headphone amp and the D/A converters utilize the same voltage line.
I need to read more on the mod to get a better idea of what the current state of the player is but some capacitors that have my attention are:
(The schematic is a bit hard to read (on my screen anyway) )
C304: 47uf @ 10v?
C307: 22uf @ 6.3v?
Both are attached to the IC's power supply line and might have something to do with distortion on both channels.
C102: 2.2uf @ 6.3v
Right channel coupling capacitor between the D/A converter and audio amp (it is probably tantalum).
Did this problem develop over time or did it suddenly happen?
Looking at the picture as to how the DAC's are stacked, it would appear that the signal from the original DAC is the signal having the problem. That is, both DAC's right output are being utilized. The original DAC is for the 'real' right channel while the new, stacked DAC's right channel is being utilized for the left.
Just to be sure, have the stacked DACs been revisted and the connections checked, perhaps reflowing the solder to a make sure there are no cold solder joints?
I know it would involve some surgery but I wonder if the DAC's outputs could be switched? (right DAC output now in the left channel audio output) If the sound is OK then the problem would most certainly be with the amp. In theory, the left audio (now in the right channel) would now sound bad. If the audio is bad in the left channel then the issue would be the DAC or further upstream.
Paul - Can't thank you enough for your thoughts and effort.
Yup, the caps and values are as you read them. I can also enlarge and publish any section you'd like. Not crazy about soldering chiclets, but what the heck….
To answer your question, the right channel noise did not appear until after installing the second DAC. As mentioned in an earlier post, there was a tiny bit of static (or leakage) in the right channel during a channel integrity test track (using E5s and wicked high volume). I had performed the op-amp mod and cap mods beforehand, while waiting for the DAC, and all was peachy. But then, I do not remember playing the cuts on which I can hear the slight distortion.
Solder joints - My first attempt did leave two cold solder joints; I reflowed these, and for the heck of it, just opened the unit and reflowed pin 10. Additionally, I've ohm'd out the connections and viewed through ~15x magnification. I do hope that in resoldering I did not overheat anything. But then, if I had, I assume that it would be very obvious.
In the original Turbo Thread, PeterR wrote about a possible rewire of the DAC that seems related to your thoughts. Here it is, followed by the submitted graphic:
"In the D25, the DAC works in Dual Channel mode, i.e. the chip handles left and right channel alternately and the outputs aren't in phase. By using a second DAC, it is possible to use them in Single Channel mode, so that each chip is dedicated to one stereo channel, giving in phase output. To achieve this, you would have to connect the second DAC a little differently than mechanoplastik describes. As far as I think to have understood, it would need to look like below (modified detail from the D25 schematic, see toro_bull's thread - second DAC in red, additional connections and cuts in blue)."
I'd have to feel confident that it would be the best design change, before cutting traces, but in conjunction with additional coupling caps, this might elevate this mod to the next level. Again, as is, it's pretty damn amazing.
I found a D-4 hidden away in my basement and it powers up but it won't read discs. It will spin the disc(I think) but then it just makes a clicking noise and displays track 00.
Need Sony D-4 Help!
Linear Mode
