Sony Discman D-350 CD Player CD Not Being Seen

[DMcMahon]

Been looking at a Sony Discman D-350 for a friend that no longer will play (after being dropped a short distance) any CD and just errors with "CD not found".

It powers up OK (tried it on batteries and AC/DC adapter). As far as I can see the motor that spins the CD never rotates, the sledge motor that drives the laser assembly does rotate. It looks like the laser does not light up (assuming it is a visible light laser).

Took it apart to get access to the sledge assembly with the aim of cleaning the laser lens and seeing if there is a laser gain adjustment pot on the associated litte PCB, there being lots of web reports of fixing "CD not found" by tweaking the laser gain on many CD players.

On this unit I cannot see a small PCB at the sledge motor assembly.

Even though I very carefully disassembled it (everything is very delicate of course) I found there were 2 short wires on the main PCB that appeared to be broken off at the opposite end of the wires on the other side of the PCB.

As far as I can see these 2 wires are not shown on the service manual documentaion, so at the moment are a big mystery. I have tried to see where the wires may have broken away from the PCB but nothing really obvious.

So wondering if anybody has come across similar on the D-350 ?

David

[Uncle Bulgaria]

They probably won't be shown as wires on the diagram - have you gone through every connection where they spring from and ticked off on the diagram as you do so? I bet you'll find two that aren't PCB tracks. The only white wires I can see in your photographs look like they go to a small motor.

If it played before being dropped, I don't think you should fiddle with anything to do with the laser - surely the more likely culprit is the wires (perhaps they go to the motor and were broken off by the fall?) or a fractured connection to do with the CD motor. My Walkman spins the disc as soon as it starts, with the sled then winding back and forth to read the ToC. I can imagine that if the disc isn't spinning, it'll never find the CD because as far as it's concerned it's not there. Can you run the disc motor externally and see if it reads?

[DMcMahon]

Thankyou Uncle Bulgaria, I agree with everthing you say. The little wire in the second photo I think is actually violet. The white wire on the first photo does not connect to a motor.

Some of the wires that connect to the PCB are shown in the documentation but not these 2 link wires.

I need to find time to check it more thoroughly.

David

[DMcMahon]

Thought I was onto something. In the Service Manual it lists some Focus/Tracking Gain adjustments using a piece of electrical test equipment with a keyboard (called CD Jig) that connects to the PCB via 5 wires, 1 being white and it connects to the area where the mystery white wire is connected.

But by enlarging the PCB artwork many times and viewing on laptop (then is somewhat blurry with my eyesight) and using a strong magnifying glass to view the actual artwork can now see that the white wire from the CD jig connects to a different piece of the artwork nearby. I was thinking possibly that the mystery white wire was a left over from a previous CD jig test, but obviously now know that this is not the case, so back to the drawing board.

David

[DMcMahon]

Have traced where the solder jumper connection on the artwork (that the end of the white wire is soldered to) connects to. The nearest artwork component connection is the junction of C507 (33uF) -ve to C508 (0.1uF).

Looking at the PCB schematic this connects out to loads of components particularly resistors and capacitors as well as IC connections, nearly all minute surface mount devices. It looks this this connection is maybe a DC voltage rail as in a couple of places it is designated VC and shown as 1.7 on some ICs.

The likelyhood of me being able to check out all the large number of connections realistically is very slim (continuity wise) due to the difficuty of locating and being able to get a meter lead connection on these tiny components, especially with relatively poor eyesight at this size of components but will try.

David

[DMcMahon]

The attached photo was taken before the PCB was hinged up. This shows the mystery white wire going over the edge of the PCB (2/3 down the left hand edge) and presumably connecting somewhere on the underside of the PCB.

Currently difficult to clearly access/view that underside area of the PCB without disconnecting some wires and a ribbon cable, but it looks like there are only a few areas there where there is a solderable connection point and there is probably no more than 10mm of wire to reach the solderable area. So should just be a case of identifying whereabouts on the circuitry the solderable areas are and by looking at the schematic seeing if any of those connection areas should connect to the 1.7V VC connection. If one should and does not measure continuity back to VC 1.7 then solder the end of the white wire to that connection point. Sounds a good plan to me.

When that is sorted then do similar exercise for the mystery violet wire.

David

[Techman]

And if you can get in there close enough with a strong magnifying glass and a good light you might be able to see the glint of copper indicating where the wire has broken off flush with the solder.

[Uncle Bulgaria]

Yes, logic says that a wire can't be soldered to the same tiny pad as a surface mount component, so they must be a) within the radius of the available wire length, and b) connected to a pad of sufficient size to be soldered without destroying or moving a tiny component.

Have you got a microscope? I bought a 'dissection' microscope (probably 1960s) from a local school clearout recently. Binocular with some add-on Greenough lenses, the working distance is enough to solder underneath while looking through. It's been completely fabulous for tiny things like this. On one of my Uher boards it was vital to spot some wire strands that were causing problems. I've attached a (poor) photo taken through one of the eyepieces to give an idea of what one can see. There's one of a very similar type for sale near me for £80, but they might take less. If you're interested send me a PM.

[DMcMahon]

Thankyou Uncle Bulgaria, good input about microscope use.

I have 2, an old fashioned small microscope for small slides, do not think there is any practical way of getting the PCB to be viewed by that, also have a larger one with USB output, once again probably very difficult to get PCB into this for viewing, but it is something I must have a look at sometime.

After hinging the PCB further open I could see that there actually is only 1 solder pad in that immediate area (below the bottom right corner of the flat cable connector in the photo), the other solder pads that I previoulsy thought I had seen are tiny surface mount devices. And no obvious sign of a wire having broken away from that solder pad.

Also the white wire would not stretch to it. Actually the white wire is taped down in a loop on the other side of the board and there is extra length available that would enable the white wire to reach that solder pad, however the wire was firmly stuck down with the tape, so I think that the white wire could not have originally been connected to that solder pad. I have yet to determine what this solder pad connects to in the circuitry

There is a blob of solder on the copper covering of the flat ribbon cable as can be seen in the photo and possibly a small dink on it that might be where a wire has broken away.

Do not yet know what the purpose of the copper (looking) covering is on the flat ribbon cable, screening, protection ? and why a 1.7V VC supply might connect to it ?

As can be seen in the photo the mystery violet wire also resides in this area and can easily reach the solder blob on the flat cable, so maybe both wires broke away from the copper covering ? I have yet to determine what the other end of the violet wire connects to circuitry wise.

David

[Uncle Bulgaria]

That solder blob looks a very good candidate. It looks from the photograph as if there could be two darker flux smudges opposite each other where the wires could have broken off from the same blob. If you melt it carefully, you might find two sets of fractured strands which would aid the hypothesis.

I think the key word is 'dissection' microscope, as they're for working under rather than looking at prepared slides with greater magnification. My one has a working distance of about 15cm, so soldering during use is a doddle.

[DMcMahon]

PM sent ref dissection microscope.

After much studying of the complex schematic and tracing the artwork, can now see that the solder pad on the artwork near the flat cable connector connects to pin 9 of that connector (CN501). This is a 0V connection, so doubly proving that the white wire connecting to VC 1.7 supply at its far end definately does not connect to the solder pad.

But possibly the mystery violet wire should connect to the solder pad (pad does not look like anything has broken away though), still need to determine what the violet wire connects to at its far end.

David

[DMcMahon]

The copper looking covering over one side of the flat ribbon cable definately looks and feels like copper/metalic and is conductive when checked with a resistance meter.

The other end of the mystery violet wire was very close by and connects to a solder pad on one edge of the PCB as per photo. This solder pad is part of the 0V main artwork so now it would make sense that the open end of the violet wire should connect to the solder blob on the copper on the flat ribbon cable. Although still do not really know what the function of the copper covering actually is, maybe for screening.

However if the violet wire connects 0V to the solder blob then it would not make sense that the mystery white wire also should connect to the solder blob.
The white wire is designated VC 1.7 so I assumed a supply or control voltage, so need to check out further what VC 1.7 actually is.

David

[Keith956]

David, if I'm not mistaken, the white wire is part of a group of 5 (brown, red, orange, yellow, white) that is shown in the manual in the 'CD Jig Connecting procedure'. And this wire goes to a point on the PCB labelled 'VC'.

Earlier it mentions VC (1/2 Vcc) as a connecting point for connecting to a scope. It's also connected to pin1 of IC503 and pin21 of IC501, plus several others, so its obviously part of the supply network. So it doesn't look like it should connect to the copper shielding. But what it should connect to is eluding me.

[DMcMahon]

Thank you for that Keith.

Earlier at post 5 I had initially thought that the white wire might have been a leftover (i.e. not disconnected after doing a test with the CD Jig) but after checking concluded it was not the white wire shown for the Jig because it connects to an area a little way from the solder pad that my white wire is soldered to. Then I did not notice that the white wire from the jig connects to point VC.

So I need to look at this again to see if my white wire that does connect to VC from my previous checks is the same electrical connection as the VC that the jig white wire connects to. If it is then it is still a bit of a mystery why it is connected to a different solder pad than shown for the jig and maybe was just left connected when jig testing completed ?

David

[DMcMahon]

Yes the VC solder pad for the white wire connection to the CD jig is the same VC connection as per the mystery white wire solder pad as per Posts 4 and 5, i.e. the junction connection of C507 (33uF) -ve to C508 (0.1uF) as well as connecting to numerous places also connects to pin1 of IC503 and pin 21 of IC501 as per Post 13.

David

[DMcMahon]

The 5 wires connecting to the CD jig appear to be shown going into a connector that plugs into the jig. So presumably the CD jig comes with this cable and the ends of the 5 wires are soldered to the respective places shown in the manual as per Photo attachment 1.

The VC solder connection is shown in photo attachment 2, it is above the 2nd 0 in the 105706 serial number label, it is not designated VC on the PCB but is designated VC on the PCB section drawing showing the CD jig connections.

As already stated the VC solder connection is not close to the actual solder connection that the end of the mystery white is soldered to, as can be seen at Photo 1. But as already stated both solder connection points are electrically connected together.

The floating end of the mystery wire looks like it has been soldered somewhere, but there appears to be no obvious home for it so I will insulate the end and leave disconnected.

My friend is keen to get the unit back, so that he can sell it, believes that he can get good money for it even though not working.

So apart from reassembling it all, I doubt if I will do any more work on this.

David

[DMcMahon]

All reassembled, no change of course to the fault.

David

[Techman]

Originally Posted by DMcMahon

The floating end of the mystery wire looks like it has been soldered somewhere, but there appears to be no obvious home for it so I will insulate the end and leave disconnected.

My friend is keen to get the unit back, so that he can sell it, believes that he can get good money for it even though not working.

There's got to be a logical explanation as to where this wire is supposed to go.

Your friend needs to give an honest explanation as to what work has been done so far when he advertises this unit for sale, as the internet is a very public place and it's almost guaranteed that the new owner will research the unit and end up on this forum thread, which could lead to trouble if the unit has not been described honestly

[DMcMahon]

Originally Posted by Techman

There's got to be a logical explanation as to where this wire is supposed to go.

Yes, totally agree but it is not easy to determine, it does not really make any sense.

David