On Wed, 12 Aug 2015 14:11:39 -0400, Tim Schwartz wrote:

On 8/11/2015 3:51 PM, Nick wrote:
I've got an Arcam Alpha 8 CD player with a somewhat tired laser, the
player has started to skip on occasion and checking the RF (eye
pattern) shows that the levels are a bit low. Cleaning hasn't improved
matters.

I understand that these laser units haven't been made for a number of
years but there are many 'clones' available. I've now tried two
different replacements and quite honestly they seem to be pretty poor,
in both cases the sled rack doesn't 'mesh' at all well with the drive
pinion which doesn't inspire much confidence!

In terms of electrical performance the first (labelled as NKS210A)
'sort of' worked but checking the RF showed gross distortion and the
player skipped in the presence of the slightest surface damage on the
CD. The second (labelled as KSS210A), gave a much better eye pattern
(levels 'OK' / clean and undistorted) and plays fine except for two CDs
where it has 'issues' (both of these played fine with the original
laser assembly!)

Looking on Ebay there are a multitude of different KSS240A lasers for
sale at differing prices, are there any known good ones to go for?

I also see some sellers have listings like: 'Laserpickup, Original Sony
KSS240A'. Is it possible (likely) that these could be genuine Sony
laser assemblies? Is there an easy way to tell a fake from an original?

Any ideas?

Nick

Nick,

Genuine Sony KSS-240A pick ups have 3 pots on the board, and the
optical chip is 14 or 16 pins (I can't remember), where as most of the
'aftermarket' ones have 8 pin IC's. That said, I've had OK luck with
some of the 'aftermarket' ones (aka fakes)

Also look at the DAC board in the Alpha 8 at R69. It should be
2k2
(2200 ohms) if it is still the original 10k resistor change it, and
maybe Q6 (BC847B) at the same time. This was a factory change because
Q6 would get too hot and fail, killing one of the clocks and causing the
laser sled to go flying to the outside. It could trash the gear rack in
the optical pickup.

Regards,
Tim Schwartz Bristol Electronics

Hi Tim,

Thanks for the heads up on that, something to check when I next have the
covers off!

Regards

Nick