YBA CD3 with Sanyo SF-P1 lens tracking problem : Please help.

[cslaw]

Hi,

The player is unable to read TOC and play cd discs frequently.

The lens is cleaned.

Attached photos of the player showing tuning ports that can be adjusted to make the player track properly again. They are F OFFSET, F GAIN, E/F BAL, T OFFSET, T GAIN, K GAIN, PLL F.



F GAIN, F OFFSET, E/F BAL was tuned ( rotated anti-clockwise ) years back by the authorised agent when the player had the same issue.

If you have knowledge with Sanyo SF-P1 lens / circuitry / tuning, give your advice.

I have ordered a New identical original SF-P1 lens to replace. Should i set all the tuning ports to original factory makings after changing the lens?



Regards.

[Mooly]

You can't hope to do this correctly without an oscilloscope, a service manual and at least some understanding of what the adjustments are...

This is general info only and some of this may or may not be possible with your player.

PLL is adjusted with a frequency counter and reference to the service manual. Usually although it is critical to get right, in another sense it's non critical in that it's an all or nothing thing... the player works or it doesn't. It should never need to be adjusted.

If the pots have all been turned then a full alignment is needed... a good tech could probably do that without reference to a manual.

1. Focus gain can be surprisingly uncritical... you can turn the pot up until you "hear" noise from the pickup itself, then back off slightly.

2. Tracking gain can only really be set with a scope or "know how" using an audio amplifier to listen for a low frequency fundamental appear in the tracking error waveform. That said there is often a lot of latitude to the adjustment. In simple terms if the gain is low the player is sensitive to mechanical shock, if high the pick up is "noisy"

3. Focus offset or bias needs a scope to look at the RF. Again an experienced tech can do this by ear listening for a "null" in the white noise from the pickup itself.

4. E-F balance is very critical and needs a scope to examine the tracking error waveform during "track jumps" to adjust correctly.

Before doing anything all mechanical items have to be in order, spindle motor OK, sled free etc. I assume the laser power has never been altered... and it shouldn't be!

Is that a green LED stuck on the side of the pickup ? Why ?

[stephensank]

The Sanyo SF-P1 is an incredibly reliable & stable laser. It's VERY UNLIKELY that you have anything wrong with the laser or the servo settings(assuming nobody has messed with them since original calibration).
It's a safe bet that either a)grease has dried up on the tracking sled guide rails or other interference with sled motion, b)the platter motor needs attention(often cured just by shooting up with a good silicone spray lub & excersizing), or there are electronic faults such as cold solder joints or failing electrolytic capacitors.

[sidiy]

Originally Posted by Mooly

Is that a green LED stuck on the side of the pickup ? Why ?

It's blue and is there by design (back when blue LEDs where cool, expensive and yet not very stable)
As to why... it's the stochastic noise reduction mumbo-jumbo

Most likely the only 'benefit' (due to its own current thermal variations, power on transients + flex cable resistance) is fooling the constant power circuit into thinking that the voltage on the trimpot has changed.... Which means the servo loop has to re-adjust the laser current in order to keep the optical power constant.

My take on this: remove any variable load supplied through the same flex cable, be it red, green, blue... and the laser will last longer, with fewer errors...etc.

A small TEC supplied by a CCS? well...that will be really cool.

[Mooly]

Originally Posted by sidiy

It's blue and is there by design (back when blue LEDs where cool, expensive and yet not very stable)
As to why... it's the stochastic noise reduction mumbo-jumbo

I seeeee .. just didn't like to ask really

[cslaw]

Originally Posted by Mooly

You can't hope to do this correctly without an oscilloscope, a service manual and at least some understanding of what the adjustments are...

If the pots have all been turned then a full alignment is needed... a good tech could probably do that without reference to a manual.

1. Focus gain can be surprisingly uncritical... you can turn the pot up until you "hear" noise from the pickup itself, then back off slightly.

2. Tracking gain can only really be set with a scope or "know how" using an audio amplifier to listen for a low frequency fundamental appear in the tracking error waveform. That said there is often a lot of latitude to the adjustment. In simple terms if the gain is low the player is sensitive to mechanical shock, if high the pick up is "noisy"

3. Focus offset or bias needs a scope to look at the RF. Again an experienced tech can do this by ear listening for a "null" in the white noise from the pickup itself.

4. E-F balance is very critical and needs a scope to examine the tracking error waveform during "track jumps" to adjust correctly.

Before doing anything all mechanical items have to be in order, spindle motor OK, sled free etc. I assume the laser power has never been altered... and it shouldn't be!

Is the service manual available online?

Tell me more about Tracking Offset.

All mechanical parts are in good clean conditon, spindle motor ( Sanko 71820 ), lens motor ( Sanko 4A 0210 ) has been lubricated with high quality teflon lubricant, are working perfectly. Lens slides smoothly.

I am not sure if the laser power has been altered, & which pot is to adjust laser power?

[Mooly]

Tracking offset usually involves setting the output of the tracking servo to some predetermined DC voltage (often but not always zero).

Laser power is adjusted by a preset on the pickup itself... should never be altered unless you have an optical laser power meter. Normally viewing the RF (eye pattern) on a scope to check the amplitude is confirmation enough.

You'd have to search for manual...

[Michel]

Hello all,

The absolute first thing you have to do when you have reading problems with an Alpha or Delta series YBA CD player is clean the laser. When I say clean I mean using a Q-Tip soaked with glass cleaner. You would not believe how many times a dirty laser lens is what is the cause of the problem. I sometimes get an RF signal that is up to half a Volt higher after cleaning!!
As Mooly pointed out, there is no way to do a proper adjustment without an oscilloscope. You should have between 1.5V to 2V RF at TP16. Sometimes I have to crank that close to 2.5V as many customers want to read CD-R and CD-RW discs and the original setting was a little too low for that. I rarely have to replace laser pick-ups as they are extremely reliable.

As for real defects, the first thing to go bad on the Delta series of YBA CD players is the spindle motor. The second one is the YM7121B or C as the players are extremely sensitive to electrostatic discharges. The third one is the zener diode, D116, regulating the display "high voltage". The fourth one is the tray motor. I am beginning to see tray belts going loose since about a year now.

The easiest way to test the spindle motor is to connect an analog multimeter on the x1 Ohm scale to DM+ and DM- of CN102 and turn the platter very slowly to see if there are shorted spots. The needle should be steady around 15 Ohms.
The same goes for the tray motor on SM+ and SM- of CN102. A good indication that this motor is defective, IC104 gets burning hot.

Another problem I see from time to time is a jerking tray motor while reading the CD. It is more pronounced when using a CD that is not perfectly centered. When I first began to see this problem I thought it was because of off centered disc platters but after awhile I had to dismiss that conclusion as I saw more and more older players having this problem. Since I was not supplied with a schematic by YBA I had to "develop" a fix for that behavior problem. After a lot of experimentation I found that increasing the value of R164 from 2.2k to 15k I was able to eliminate the jerking. This can be done without removing the PCB by soldering the new resistor to the left side of R164 and right side of R166 and not forgetting to cut the right side of R164 AFTER the soldering is done. This new resistor value is not absolute and may differ from one machine to another. The best way is to install a resistor with full length leads in case you need to change that value.

I am at your disposal if you need more information or even parts if you can not find them and would be extremely grateful if someone had the schematic and could send me a copy.

Best regards,

Michel