Hi
have 2 older sony's here, both have similar symptom, probably been answered many times so here goes
both read disc's, shop soiled, both play throughout discs, the 970 may skip at some point and both skip(backwards) on playback when i tap (gently) top of facia, the 790 is the more sensitive of the two, is it down to not being used in a long time or something a bit more sinister like being 30 years old or so the lasers are past their sell by dates.
have 2 older sony's here, both have similar symptom, probably been answered many times so here goes
both read disc's, shop soiled, both play throughout discs, the 970 may skip at some point and both skip(backwards) on playback when i tap (gently) top of facia, the 790 is the more sensitive of the two, is it down to not being used in a long time or something a bit more sinister like being 30 years old or so the lasers are past their sell by dates.
Hi
i will tackle the 970 first, i have backed off focus gain a bit, it improved a little, quite easy on this player as its on the main board, i downloaded service manual to see where it is first, i did experiment with it a bit further back to no improvement,
the player reads the disc pretty quickly and is pretty quick to play when thats pressed, it seemed to skip on different places on facia when tapped depending where the adjustment was at which ever time or maybe i am imagining that, its also less likely to skip in the middle area of disc on playback. a bit worse at beginning track one than last track.
the player has a kss 150 laser, i have already cleaned that.
i will tackle the 970 first, i have backed off focus gain a bit, it improved a little, quite easy on this player as its on the main board, i downloaded service manual to see where it is first, i did experiment with it a bit further back to no improvement,
the player reads the disc pretty quickly and is pretty quick to play when thats pressed, it seemed to skip on different places on facia when tapped depending where the adjustment was at which ever time or maybe i am imagining that, its also less likely to skip in the middle area of disc on playback. a bit worse at beginning track one than last track.
the player has a kss 150 laser, i have already cleaned that.
You might find this thread of interest as it dealt with a CDP790:
Sony CDP790 and KSS240 Restoration Project
Sony CDP790 and KSS240 Restoration Project
hi
will have a look through that, being that i am more mechanical than electrical, would this shock fault point to any dampening in the drive unit and would probably help with parts that are now unobtainable.
will have a look through that, being that i am more mechanical than electrical, would this shock fault point to any dampening in the drive unit and would probably help with parts that are now unobtainable.
There could be many reasons for skipping although susceptibility to mechanical shock isn't a prime requirement for a non portable player.
As always you need to look with a scope at the quality of the RF signal as a starting point. If that is poor or marginal then adjustments become ever more critical with the player still performing badly. When the mechanics and optics are good the adjustments tend to have a very wide range before usability issues arise.
There are/were special discs available for checking how well a player copes with precisely defined errors on a disc.
CD Error Correction. Is it Audible ?
As always you need to look with a scope at the quality of the RF signal as a starting point. If that is poor or marginal then adjustments become ever more critical with the player still performing badly. When the mechanics and optics are good the adjustments tend to have a very wide range before usability issues arise.
There are/were special discs available for checking how well a player copes with precisely defined errors on a disc.
CD Error Correction. Is it Audible ?
ahh yes a scope, i do have one, belonged to my dad, its a tektronix 2225, might be time to get accquainted with it.
if as you say mechanical shock isent a prime requirement, i take it the aim will be to get these players to skip as little as possible.
i havent looked further at the 790 player as yet i will go with one at a time.
when i see the insides of the 970 player and the fact it has an aliminium drive unit, they dont make them like that any more.
if as you say mechanical shock isent a prime requirement, i take it the aim will be to get these players to skip as little as possible.
i havent looked further at the 790 player as yet i will go with one at a time.
when i see the insides of the 970 player and the fact it has an aliminium drive unit, they dont make them like that any more.
No stand alone player should skip at all when playing CD's in good condition. Tapping the case when playing isn't really a valid operational condition although it shouldn't skip in practice with any normal user movement around the player. It's all very subjective though as to what is to much of a jolt or not.
Hi i have checked the rf signal, i take it thats the one with the criss cross pattern that comes under focus bias in the service manual, and that is present, its a little blurred on this scope, you can adjust until it peaks and then goes off, with that i found that it was pretty close to the pic in the manual, so put adjustment just before it peaks which is near enough to where it was to start with.
i had difficulty with the probes as they cannot connect directly to the wire links on the board, i could think of only two ways to deal with that, one was to solder wires to them and the other which is what i did which has risks of its own, is put needles down thru holes so far which worked for this test, do not have a test cd so used a shop soiled cd for the test, not ideal but its all i have. there is another check that needs both probes will have to do the solder method a 4 needles is far too risky.
i had difficulty with the probes as they cannot connect directly to the wire links on the board, i could think of only two ways to deal with that, one was to solder wires to them and the other which is what i did which has risks of its own, is put needles down thru holes so far which worked for this test, do not have a test cd so used a shop soiled cd for the test, not ideal but its all i have. there is another check that needs both probes will have to do the solder method a 4 needles is far too risky.
Yes, that's the one. Quality and amplitude are all important. This is from my actual player from that earlier thread and it should look every bit as good as this. The diamond shape should be clear with very little fuzz and jitter to it. The amplitude should be at least 1 v peak to peak and preferably a little more.
Make sure your scope is calibrated correctly and preferably use a divider probe (a X10 probe as they are called) to minimise loading on the circuit.
If using a divider probe then it's vital to check the calibration using the scopes front panel 'CAL' output and to tweak the trimmer cap on the probe to give the best squarewave response with no under or overshoot.
Any good quality commercial disc is fine for all adjustments, the 'eye' pattern is the same for all. Just try at least a couple to make sure you haven't got a disc of low reflectivity which does occasionally happen.
Read the first post of that thread all through as it details setting up.
Make sure your scope is calibrated correctly and preferably use a divider probe (a X10 probe as they are called) to minimise loading on the circuit.
If using a divider probe then it's vital to check the calibration using the scopes front panel 'CAL' output and to tweak the trimmer cap on the probe to give the best squarewave response with no under or overshoot.
Any good quality commercial disc is fine for all adjustments, the 'eye' pattern is the same for all. Just try at least a couple to make sure you haven't got a disc of low reflectivity which does occasionally happen.
Read the first post of that thread all through as it details setting up.
Attachments
ok have done that, the settings on scope were 1v per div, .5 sec per div and set on 10x, dont have a camera so i can say the trace is not as nice as yours, i see the criss cross partterns and things are more brurrey/distorted than in your pic, also a slight pulsating that would be with the slight wobble on platter, no improvement with adjustment rv104, only makes things worse even to a point when the disc spins and no sound produced, have set rv104 (focus bias)at best position.
i work shifts so this is usually the time i would reply through the week.
i did play around with the scope settings, above settings were the best.
i take it that the 30 year old laser is coming to the end of its life.
i work shifts so this is usually the time i would reply through the week.
i did play around with the scope settings, above settings were the best.
i take it that the 30 year old laser is coming to the end of its life.
It's quite possible the pickup is flaky. I seem to recall problems with the mechanical lens suspension changing in characteristics (so nothing you can fix there). Twenty five years ago we were ordering these by the dozen.
The internal optics are also bound to have become coated with atmospheric pollution by now.
If you are only experimenting then you could try tweaking the laser power although normally that is a big no no. If you are just seeing 1 volt peak to peak (so that's the scope set on 0.1V/Div with a X10 probe) you could try increasing that to 1.2 volts peak to peak and see if it improves things.
Even CPC don't seem to stock these anymore 🙁
The internal optics are also bound to have become coated with atmospheric pollution by now.
If you are only experimenting then you could try tweaking the laser power although normally that is a big no no. If you are just seeing 1 volt peak to peak (so that's the scope set on 0.1V/Div with a X10 probe) you could try increasing that to 1.2 volts peak to peak and see if it improves things.
Even CPC don't seem to stock these anymore 🙁
from what i have read its just the chinese 210a thats available for this model, not much to loose at 8 quid a pop.
have put a laser in a marantz cd63se before, that came with spindle motor etc, it appears these dont.
quite strange as it reads and plays, i know they dont last forever though
its just above and below the first segment lines on scope screen whatever that means
have put a laser in a marantz cd63se before, that came with spindle motor etc, it appears these dont.
quite strange as it reads and plays, i know they dont last forever though
its just above and below the first segment lines on scope screen whatever that means
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The 790 I have uses the KSS240 which is totally different to the 210.
The scope reads amplitude on the vertical scale so it all depends what settings you use. 50mv/div (with a X10 probe) would be what I would use. So my image above is showing 1 volt peak to peak.
The scope reads amplitude on the vertical scale so it all depends what settings you use. 50mv/div (with a X10 probe) would be what I would use. So my image above is showing 1 volt peak to peak.
yes, nobody has anything proper these days, a mate of mine used to fix cb radios, back years ago when the final transistor blew for whatever reason, replacement of the (mostly) c1969 was commonplace and they were easily obtained, now you get inferior copies or if originals turn up they cost a fortune, looks like cd player lasers are in a similar world, have ordered a laser, just incase, so will be weekend when i get round to installing it and see what happens.
i actually think that when player is tapped, the laser possibly because of age cant keep up, whenever i did that when it was connected to the scope i could see the distortion it made.
whatever happens we are all stuck with modern copies now, shame really.
i actually think that when player is tapped, the laser possibly because of age cant keep up, whenever i did that when it was connected to the scope i could see the distortion it made.
whatever happens we are all stuck with modern copies now, shame really.
have fitted new 210a laser, did find a broken part in the drive unit which was a part that stops the sled drive cog dropping out, a L shaped thing, only option was to super glue it back into place, it just slots back into the hole where it came from, but wont stay there unless i glue it, dont know if was a cause of the issue in the first place, anyway its all looking good..... so far, no skipping and playing a cd as i write this, have not readjusted anything as yet.
how do you connect the scope to the test points on the 790 player when its on the bd board through the hatch below.
its like you have to make any adjustments with the player upside down
its like you have to make any adjustments with the player upside down
I would guess I probably tagged some leads to the tests points or possibly I had the whole mech free and could somehow juggle it around... something you do get adept at doing... but I can't remember for sure now.
Thats the puzzler, the test points are solder pads and rather small ones at that, its kinda like for example to adjust rv102 which is also on bd board, solder wires onto test poiints, put cd in, flip player upside down, connect scope to wires, press play and adjust if required when its all upside down, sony saying we've made this hard for you to fix so the idea is throw it in the bin and buy a new one from us, if you see what i mean.