Sony CDP790 and KSS240 Restoration Project

[Mooly]

Could be a bargain for $10, particularly if it has a good RAFOC (laser assembly) and the CDP997 from what I can see does look very similar to the Sony in this thread...

Enjoy

[maouna]

Can those cheap chinese oscilloscopes be used to show the eye pattern of a cdplayer and to calibrate it succesfully?

Hantek dso5102p usb digital storage oscilloscope 2channels 100mhz 1gsa/s Sale - Banggood.com

Hantek dso2d15 dual-channel + afg digital storage oscilloscope 150mhz 1gsa/s signal generator oscilloscope 2 in 1 Sale - Banggood.com

[Mooly]

No idea tbh as I've never used one. The bandwidth is more than adequate but how a complex eye pattern would look I wouldn't like to say.

I imagine you would see some sampling artefacts and so it would look less clean than viewing on an analogue scope, but that it should be representative in amplitude given the bandwidth.

[maouna]

i was thinking of buying one of these but i cant find a video anywhere showing the eye pattern on such cheap oscilloscopes.I dont know whether they have this chop/alternative mode or not.

[thimios]

Originally Posted by tiefbassuebertr

This laser unit is available between arround € 5,00 - go to
KSS 240A KSS240A KSS 240 Radio CD Player Laser Linse Lasereinheit Optical Pick ups Bloc Optique|Autoradios| - AliExpress
and € 50 - go to
10X(KSS-240A KSS-240 KSS240A Radio Blu-Rays CD Player Objektiv Optische Ton 1Y8) | eBay
Are there experiences, where one get good quality ?

Same thing, in second catalog is 10 pieces.
Good quality, i'm afraid not.

[Mooly]

Originally Posted by maouna

i was thinking of buying one of these but i cant find a video anywhere showing the eye pattern on such cheap oscilloscopes.I dont know whether they have this chop/alternative mode or not.

Chop and Alternate is used when using a scope in dual trace mode. Viewing the eye pattern is done with a single trace so those don't really figure into things.

[maouna]

Chop and Alternate is used when using a scope in dual trace mode. Viewing the eye pattern is done with a single trace so those don't really figure into things.

Looking at this service manual says to set input mode to alternate or chopper thats why i am asking.Havent done such a measurement before and i am a bit confused.

[Mooly]

Well you would normally turn the second channel on the scope off (so it behaves as a single beam) and then the Chop/Alt don't apply. The eye pattern is a single measurement that can be done on a single beam scope.

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The difference if you have both traces running is that Alternate traces out first channel 1 and then channel 2 and so on. Chop displays both together with the traces literally 'chopped' as they scan left to right.

It makes a difference at really low sweep speeds where you want to see both traces together and not have one trace disappear while the other traces out.

Found this:
#31: Analog oscilloscope ALT, CHOP, ADD, INVERT vertical controls - YouTube

That's all it does

[maouna]

Today i received the kss240a i ordered 1 month ago for my denon-dcd625.The original kss240a loooks like the one below on the left but what i received had a 10pin ic instead of a 24pin and another extra ic that the original doesnt have.( picture on the right).When i bought it from the seller ,the photo corresponding to the item was that of the one with 24pins and so i decided to buy it but i received one with 10pin ic.
Is this of inferior quality?

[Mooly]

As far as I know none of the replacements are genuine Sony parts and haven't been for nearly 20 years now.

All you can do is fit it and see how it performs. Its a totally different design electrically but as long as it works to the original spec then it should be OK.

Another difference you will notice is that original parts have the sintered phosphor bronze bearing shells whereas the replacements use moulded plastic.