@Mooly, Hello, I would like to ask you a question about a JVC mini system, the laser pickup is a SOH-AAN -04H, at least that's what the label says.It's strange what I found, at least for me, I notice that it takes a lot of work to read the TOC, but once it does, it doesn't start on track 1, I order it to go to 2, 3, etc. and it does it without problems, it reads perfectly and if I send it to number 1, it executes perfectly, if I change the disk, the process repeats itself. I thought it might be dirty in the pickup position sensor, but here's the thing, I attached some photos, the sled doesn't activate the switch, there is no physical contact between them and it seems like there never was, it doesn't seem like any part is missing or broken. Is this possible? According to the service manual, the switch signal carries information to the MCU.
Attachments
I'm not familiar with that unit but it does sound strange.
If you manually move the sled away from the centre with no disc in the tray and then open/close the tray does the pickup go back to the spindle motor end of the track?
Has the unit an unknown history? or has it worked in the past and now has this problem?
If you manually move the sled away from the centre with no disc in the tray and then open/close the tray does the pickup go back to the spindle motor end of the track?
Has the unit an unknown history? or has it worked in the past and now has this problem?
Sorry Mooly, I'm a complete idiot, the PCB that contains the switch and the connection of the sled motor and the disk motor, can be placed in 2 positions perfectly, but only one of them is correct.I'm an idiot..I'm an idiot..
Ok, here again, I did the required cleaning, gears, optics, belts, lubrication, but the problem persists, although one observation regarding my original description.I will now tell you with 2 videos what is happening, first I thought that it could not read the TOC, well, it does read it in a timely manner, but it seemed not to because when I insert a CD, it starts playing and that is part of the problem. If after a few seconds when the CD starts to spin I press stop, the time and the number of tracks appear on the display. Now if I try to play from track 1, it almost never succeeds, I took a sample of the RF signal in this situation. If for example I press skip 4 or 5 times to the corresponding tracks and press play, it starts playing from there without any problems, even if I press skip backwards to track 1. There is another video of the RF signal in normal playback, the amplitude is in the order of 1Vpp and it is quite clear, I do not have the correct value specified in the manual. Once the playback starts, the reading is perfect, there are no skips or strange noises. I am quite confused about this.
Both videos seem to show problems with the tracking servo. The first is slow to get a lock and the second one doesn't achieve a lock at all. That could be many things from a problem with the pickup to even something like a badly adjusted tracking gain pot.
I'm going to move all these posts to a new thread 🙂 to keep this one on topic for the Sony player.
I'm going to move all these posts to a new thread 🙂 to keep this one on topic for the Sony player.
Hi xavirom,
I'm just going to throw a couple ideas out. Your E-F balance may be off. This is a critical adjustment. Disc table may be incorrect which could cause the same symptoms.
I haven't read the service manual, or watched the video (watching videos is a PITA for me). If your RF level is correct for that system it may be an adjustment.
I'm just going to throw a couple ideas out. Your E-F balance may be off. This is a critical adjustment. Disc table may be incorrect which could cause the same symptoms.
I haven't read the service manual, or watched the video (watching videos is a PITA for me). If your RF level is correct for that system it may be an adjustment.
Hi @anatech, unfortunately, there are no possible adjustments, following mooly's observation, I was looking at the data sheet of the TA2153 and tried to modify the gain of a stage that I believe is a tracking stage by varying R487 up and down without changes, there are some test sockets, "FEO" and "TEO", I suppose they refer to the focus and the tracking, but I don't know what I should see there, there is no information in the service manual. I attach part of the circuit where the TA2153 is and the only sheet where the CD is referred to in the manual
That sounds like offset test points. Focus Error Output, or Tracking Error Output.
Looks like it is a servo controlled system. If it is, you may have a laser pickup that is out of range for servos to correct (= bad). I would also examine the PCB for bad solder connections. Top offenders are plugs and ICs that get hot. You can look a tthe general condition of soldering at that time. I have had CD players where you basically had to resolder the surface mount ICs and that fixed their issues. Use liquid solder flux and add as little solder as possible.
Looking at the flowchart, looks like you're good up to maybe radial error or PLL lock. We know you are losing PLL lock when the disk spins rapidly. I would monitor the FEO and TEO test points for more information. That should tell you which system, focus or tracking, is your problem.
Looks like it is a servo controlled system. If it is, you may have a laser pickup that is out of range for servos to correct (= bad). I would also examine the PCB for bad solder connections. Top offenders are plugs and ICs that get hot. You can look a tthe general condition of soldering at that time. I have had CD players where you basically had to resolder the surface mount ICs and that fixed their issues. Use liquid solder flux and add as little solder as possible.
Looking at the flowchart, looks like you're good up to maybe radial error or PLL lock. We know you are losing PLL lock when the disk spins rapidly. I would monitor the FEO and TEO test points for more information. That should tell you which system, focus or tracking, is your problem.
I'm still following but it is difficult to suggest anything at a distance. These are not easy faults to find but at some point I think you have to suspect the pickup. If there are no adjustments presets then it uses 'typical' optimised values and you can not compensate for tolerances in the pickup that may have changed over time.