Marantz CD74 skipping towards end of cd

[matski]

Hi all,

I can't find any info on this fault after searching so I thought I'd post and see if anyone can help! I have a lovely marantz CD74 that sounds wonderful until it gets over halfway through the disc. Then it starts to skip, gradually getting worse as the swing arm gets nearer its limit of travel. Is this a mechanism problem or a laser tracking/focus problem? I have 3 CD104's (yes I know,who needs three!) and none of them do this. One of the 104's is quite beat up so I was thinking of swapping the CDM1's over,but only if necessary.

Thanks

Mat

[brianuk]

hi Mat,

I have an arcam (one of two - not as greedy as you!) and its the same, it will play discs ok but as the tracks go on it gets worse and worse. I think its just getting old, ie knackered!

Are you the guy selling the cd60?

[matski]

Hi Brian,

Crikey, someone has tracked me from Ebay to here! Yes I am the one selling the CD60. I can't keep everything! I have two Cambridge CD2's and a Technics SL-P990 as well. It's an addiction :-) I can't believe what CDM1 mechs are going for.Theres one at over £120 at the moment! Maybe I'll start breaking things down into parts.

Regards

Mat

[brianuk]

Ok i will admit to having 2 104s , a CD100 (yummy) and a bunch of others as well as the 2 Arcams. Some Marantz too

[Sonusthree]

Am I being incredibly stupid (or perhaps optimistic) to suggest that the lubrication perhaps drys out at this point of its travel? Please beat me if I am wrong but I'm interested to know just how many faults on this mech can be rectified without new parts.

[matski]

Hi there,

Is the swing arm lubricated? I thought it worked using electromagnets. Then again whilst I am pretty handy, I could be completely on the wrong track. I'm thinking it may be a "spinning plate" effect where it gets worse towards the outer edge causing focus and tracking problems, but that would be the first I have heard of it on this mech as it is so solid. I'd like to get it sorted so that I can start modifying it. I have the service manual for the 104 but I am not sure how much is applicable to this player,apart from the mech assembly. I don't have a scope so it's a little "hail mary" when I get out the pot trimmer!

[phimor]

Hi Matski,
yes an addiction (I'll stay silent on the number of CDM0/1 players I have except its in double digits..)

With the CDM1, certainly lubrication is not out of the realms of possibilities.

I have used high quality hydraulic oil (LHM-another obsession) but automatic transmission oil is just as good. Very light application - cotton bud - onthe centre pivot might help.

another avenue is to replace the 33uf caps on the CDM board. these are a known source of grief, and they are over twenty years old, so due for replacement anyway.

Please resist adjusting the laser trimpots randomly, as the 'scratch' noise may kill the diode. These lasers are very durable, and the answer is almost elswhere in most cases - as I have encountered so far.

If you have thepatience, try sudstituting the CDM1 from the 104 (should be a straight fit, the only possibility would be the different 'generation' of plugs, but I think it should OK given the contemporary age of the players).

This will tell you straight away if the CDM is at fault...

Good luck

philippe

[Lourens]

Fully agree with Philippe. You can trust those cdm1 addicts -- follow his advice
Almost certainly there is no mechanical or alignment issue. The servo needs attention in the first place, imo. Replacing old caps will probably do the trick. Start with the one on the cdm1 board, but be careful! And of course: check all joints, soldering and connectors!
Moving from track 1 to 9 takes no more than 0.5 to 1 seconds with a healthy servo for cdm1.

good luck
Lourens

[matski]

Hi guys,

I'll try the cdm swap as I think you may be right about the servo caps. The plugs ARE different, so if the fault transfers, I can assume that the problem lies with the old cdm pcbs that I'll have to leave on to fit the marantz. Do you advise replacing the caps like for like or improving them? I know the cdm laser I'll be trying is fine as it works in the 104. I now have 3 working 104s! Funnily enough of the three the A revision is far more consistent and reliable than the two B's I have. I'll get stuck in and see what happens. I'm hoping also that Andy (poynton) has read my reply to his post elsewhere about CD74 spares. I love this player and want to keep it. The only one I have ever thought better built was a CD85 I had a few years ago and stupidly sold when I was more ignorant and needed the cash! I'll let you all know how I get on.

Thanks

Mat

[tubenut]

I have found that skipping toward the end of a disc is often a spindle/rotation problem rather then optical on many Jap machines. The added "momentum" of the faster spinning disc at the beginning of the disc can often "flywheel" past some problems. I am not versed on the CDM1 but know a bit about CDM4. I would check spindle motor and pivot pressure plate as well if it exists on a CDM1.