Sony BU-1C not reading TOC

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I'm having trouble with my Sony CDP-333ESD which has a Sony BU-1 laser assembly.

I have just replaced the original BU1-E laser with a compatible second-hand used BU-1C.

The good news is that after installing the replacement laser it reads and plays around half of my CD's flawlessly from start to finish. The bad news is that with the rest it will not even read the TOC.

If I load a disc that it 'doesn't like' it will not even spin the disc which suggests to me that it is not detecting a reflective surface from the disc. Is that correct?

So does this mean that the photo detector system is somehow defective? Or could it be that the laser power is just a bit low (because of normal laser aging) and that this only manifests itself as an issue on discs with lower than average reflectivity?

It is very frustrating because it sounds great when playing discs it can read!
 
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Not finding initial focus is the usual reason for the platter not spinning, the causes can include low emission from the laser but there are also other possibilities.

One problem with any 'old' pickup that has been in use (not sealed in the original packaging) is the certainty of the internal optics getting coated to some degree by atmospheric pollution. The scale of that can be from absolutely minimal to horrendous. You just don't know. If a clean cotton bud soaked in iso looks 'dirty' when wiped over the main body of the pickup then that same contamination will have affected the internal mirror and prisms to some extend.

Your best guide is to look at the RF when it does play a disc and gauge the quality and amplitude.

I'm not familiar with this specific player and pickup. Have you followed any set up procedure in the manual ?

Laser power is a preset adjustment and the APC (automatic power circuit) automatically maintains the optical emission of the laser. This is unaffected by any outside factors as the sensor is integrated internally on to the laser diode die. If the 'light' level drops, the current is automatically increased. The laser is deemed to have reached the end of its service life when that current increase is around 10 to 15% higher than the initial value (which is often printed on Sony pickups as the last three digits of the serial number e.g 456287563 would be 56.3 ma)

Put a scope on it, look at the RF :)
 
Hi Mooly, I was hoping you would show up :)

Unfortunately my scope is in bits at the moment waiting for some new PSU electrolytics to be delivered from Farnell. I'll report back with pics when I (hopefully) have the scope up and running again.

I've cleaned the upper focusing lens and also the top surface of the lens underneath.

I installed the laser a couple of weeks ago when my scope was still working and did the PLL, EF balance, focus bias, focus gain and focus tracking adjustments. I freely admit that it's possible I might have one or more of these adjustments less than optimal as I'm only an amateur tinkerer. I find the TG and FG much more difficult than the other adjustments as they are less 'defined' if you know what I mean.

To be honest I stupidly didn't pay much attention to the amplitude and quality of the RF waveform since the machine was quite happily reading the particular disc I had loaded at the time.

Do you think that the fact it plays some discs perfectly and yet won't even recognise that others discs have been loaded is down to variations in disc reflectivity? BTW I'm talking about normal factory CD's here and not CDR's.
 
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A player with a good pickup and no faults normally has quite a wide tolerance to many of the adjustments and should play any commercial disc with ease. Tracking gain and focus gain should have a wide margin. Typically tracking gain is set by turning the gain up such that a low frequency fundamental appears in the tracking error waveform. When this appears just back the gain down a little until it just disappears. To much focus gain makes the pickup noisy (white noise or hiss from the pickup coils). Again turn up to the point noise appears and then back off a little.

Focus bias tends to be critical and directly affects the quality of RF seen on the scope.

If all the adjustments seem to be super critical then that is a sign the pickup is failing (or there is some other odd issue).
 
My oscilloscope is now back up and running again (yay!) so I can give an update to this thread.

The bottom line is that increasing the focus gain quite a bit has helped enormously. There are now very few discs that it will not read the TOC.

I'm happy that I've got the focus bias and EF balance 'spot on' and I'm pretty happy with the T.G. too. I usually find that that adjusting the FG 'by ear' listening to the audible noise coming from the pick-up is the easiest way to gauge the correct FG setting. However, on this player the noise doesn't seem to alter much as you turn the trimmer and I find observing the scope screen hard to interpret.

Here's a photo of the eye pattern, seems healthy enough to me.

20171020_114349 by Michael Pickwell, on Flickr
 
Looks to me like he's only got 125mV P/P there. As his selector is at 50mV per division. Low output looks like it's shot, unless he can boost it? Sony BU-1C are unobtanium.

This looks like a trimpot to boost the output, some times it works, for how long, anybodies guess ?????






Cheers George
 

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The bottom line is that increasing the focus gain quite a bit has helped enormously. There are now very few discs that it will not read the TOC.


An externally hosted image should be here but it was not working when we last tested it.
20171020_114349 by Michael Pickwell, on Flickr

This is what I've been saying to everyone.... for ages.

Disc reflectivity varies enormously (50% !!!). You are lucky to have an oscilloscope. Keep checking the pp amplitude of the eye-pattern signal and then try different CD's... you'll figure it out for yourself. Adjust the trim-pot for the least-reflective CD you have in your collection.

Do not worry about shortening the life of the laser diode... I have adjusted an output on so many lasers pickup and have never heard back from anyone that reported even a single one failed. Few of them came back for re-adjustments after many years - but they just keep going with no issues, as long as an oscilloscope is used to correctly adjust the eye-pattern amplitude.
 
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Looks to me like he's only got 125mV P/P there. As his selector is at 50mV per division. Low output looks like it's shot, unless he can boost it? Sony BU-1C are unobtanium.

This looks like a trimpot to boost the output, some times it works, for how long, anybodies guess ?????
Cheers George

Divider probe ?

I can't make the v/div out in the picture, its cropped off the picture for me. 125mv would be way below what any player would even attempt to work with. Once you get below 800mv or so most players would give up

Thanks for the links... lol, it used to be part of the day job.
 
Hello chaps,

Well to end the speculation here's the answer:

An externally hosted image should be here but it was not working when we last tested it.
20171027_104754 by Michael Pickwell, on Flickr

I've just taken this measurement so it's a different photo to the earlier one.

Probe on x1 and dial on 0.2V/div.

So if the scope calibration is anything like that's just over 500mV pk-pk :(

So what now? Tweak the laser power up as suggested by Extreme_Boky?

Try to clean the internal optical surfaces of the laser?

Or, perhaps it would be prudent to try and measure the laser current as suggested by Mooly earlier before I do anything else?
 
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Lol.

Make 100% certain you are on the correct test point. If the stated output is the usual 1.2v to 1.5v peak/peak then I am really surprised this plays at all tbh.

Ideally you should be using a low capacitance 10:1 divider probe to not load the circuit. Calibration... check using the 'cal' output on the scope and make sure the displayed signal isn't over compensated (rounded edges which would equate to slightly reduced HF response).

If it is easy to get to the points relevant to measure the laser current then yes, it is definitely worth a quick check.
 
Sony CDP-552 esd not reading discs- no rf pattern?

Hi,
I would like to ask for some help diagnosing a fault on my Sony CDP-552esd which unfortunately spins the discs and opens up the drawer. No TOC anymore. I had a look at the SM and followed the troubleshooting section flowchart and i got to the point where I am directed to check for the eye pattern rf signal on my scope.
I connected my scope to the rf test point and just switched on the cd player to monitor the pattern but I do not get any output it seems. I do see a faint-ish red laser beam however only viewed through a dentist type of mirror as it's otherwise hard to detect.
Am I right in thinking that I should be able to see the rf pattern without a disc being played but by just turning on the cd player?

How can I tweak the settings on the rf board to try and adjust the output as it is not indicated on how to do this on the SM. The only adjustments are focus and gain at different test points on the servo board.

Does it sound like the laser unit is busted or is there some hope? On the rf board there are 3 trimpots but i don't want to guess and try my luck without advice.

Many thanks for any help you can give please
 
I shall try again but i did try with the disc spinning and it was not much different if any compared to without the disc. I connected the probe to the rf test point as advised on the SM and the ground cable to the chassis. To see some movement on the scope i had to turn the volts/div to the minimum level but there was nothing similar to what i was expecting.

The disc spins yes and then after few seconds it gets ejected. There is no TOC or anything. Any further clues please?

I was wondering if anyone knew of a website where most CD players are listed by brand and each one shows which laser unit it uses? That would be most helpful as then one could search for a cheap CD player from some charity shop or carboot sale and then take the laser out and fitted to the more expensive machines, just like in my case if my laser has failed.

I have not touched any settings on the laser unit..i just checked the focus and tracking settings on my scope which seem fine as illustrated on the SM.
Thanks
 
IC001, pin8 +5V, pin 4 -5V
IC001, pin5 should go above 1 volt to turn the laser ON
IC303, pin5 4MHz clock signal from the ceramic resonator... these are known to fail.
If the above is okay, move to IC101 and start checking RF signals and conditions.... RV102 -> if this trimpot has oxidised, and the wiper is not touching properly the graphite, the error correction will be skewed.
 
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