I've just broke my cdp :-(

I've took my cdp apart (Arcam Alpha 1) this morning, took the transport, analogue board and main pcb out to fit a clock and clock psu.

Took away a SM resistor, two SM caps and the original crystal. The new clock was connected to the SAA7220, pin 11,12.

Put it together again, now the thing spins up and doesn't stop.

I've disassembled and checked my connections, for solder splashes etc, but still no go.

Any ideas ???

 

Had exactly the same problem when putting a Trichord clock into my Marantz CD50SE (also uses the SAA7220). The transport spinning for ever is a sign that the SAA7220 isn't receiving a clock signal. In my case it was because I had screwed up the power connections to the new clock board so the clock wasn't working.

What type of clock replacement are you using and where is it getting power from?

Michael.

 

Hello Michael,

Left it for a few hours, going to check it again a little later. Going to get hold of a scope to see what is happening.

Thanks for the tip.

Let you know what happens.

 

Using a Rock Clock & Clock psu from Net Audio.

 

Don't know the NetAudio products so can't give specific help but it sounds like the clock board isn't getting power or the clock isn't correctly connected to the SAA7220.

If it's any help see the link below which has a closeup shot of the connections I made to the 7220. I had one extra connection (to pin 14) for the digital output signal for the Digital Output Board.

http://www.zerogain.com/hifi/images/p10.html

Michael.

 

so far I've determined the psu outputs about 10v dc, but once its connected to the osc, it drops to 2.5v. Something wrong there I think. May be the output or the input to the SAA7220 is shorted?

I am going to disconnect the osc and put a scope to it.

 

+psu is busted. put a 540R as a load, voltage dropped to 2.1v. I'll sort out the psu and try again.

need to get some :SLEEP: now

 

I think it is worthwhile pointing out, that on pcbs, it is VERY dangerous in respect to your units healty to desolder components. Suface mount is nigh impossible unless you are skilled and have the right equipment.
It is not recommended to people who have little soldering iron xp...I speak from xp, doesn't take a lot to knacker a pcb.

 

Hello Lt Commander,
I have plenty of normal soldering practice, in excess of 20 years - Although SM stuff is new to me. If I don't start now, I'll never be able to do it.

firestorm

 

Data, I desoldered the SM caps and resistor (and of course the original clock) off my Marantz CD50SE PCB and it was pretty straightforward

I'm reasonably experienced with soldering but at that time hadn't done any for a long time and certainly hadn't ever worked with SMDs. My (then) soldering iron was a cheap 18W Antex with a tip that was way too big to be messing about with SM components with but even those handicaps didn't present a problem.

With a decent iron that can go a lot hotter for desoldering it should be a piece of cake. Just hold the componet with a pair of tweezers, a quick stab with the iron on each solder "cushion" and you're done

Michael.

 

useing a hotter iron is a big nono, you should only use as much heat as is needed, anymore and it increases the chances of lifting the pad from the PCB

 

If you don't want to put anything back in the place you de-soldered from what's the harm in lifting the pad?

You can see from here that when I removed the caps and the resistor the result wasn't pretty but it worked which was all that matters

Michael.

 

just bad practice

 

got the clock psu back from Net Audio, quick turnaround from Dave.

Fitted it tonight, fired it up, worked first time. Its making sounds again

I'll leave it on repeat overnight and listen to it in the morning, see if things have improved.

Thanks for your suggestions and help.

 

Quick precis :

1) Arcam Alpha (1) with Rockclock + psu. Rockclock is a lower jitter clock, the psu is a simple low impedance psu

2) Started to fit it last weekend. Didn't work. A resistor had popped.

3) Sent back to builder, received it back a couple of days later.

4) Fitted it last night. Left it on repeat for 9 hours.


Results ????

It is still working !

It sounds ?? Marvellous.

Mozart Piano concerto D minor. 2nd movement. Piano a lot more accurate, more texture, more colour, more sublety. Enjoyable at low volumes. Just generally better to listen to. Instruments seem more focussed. Now listening to Profokiev, Kije. It is in the next room and the brass sounds more real.

Will try it with some more modern stuff later ...

Before I say any more, I don't have any business or social links with the guy. Got the Rock clock & psu from a guy called David Pritchard, www.net-audio.co.uk. There are other clocks available, trichord, lcaudio.com, audiocom international and few other very good diy designs available. Check with your favourite browser.

If you have a player that is out of warranty then seriously consider this route. It is worth it, puts a on your face.

More mods to follow. Need to search through the archives. May be :

1) Remove existing opamps in the IV and filter stage and fit turned pin sockets to allow easy opamp swapping. There must be a better alternative to the NE5534 ? Not sure about the OP27.

2) Super reg the analogue supply, must persuade Mr Weekes to order some more SR pcbs !

3) Non oversampling perhaps.

4) More invasive mods, bias output opamps into class A

Happy listening

 

If your cd player is the Alpha 1 then you cant perform a non-oversampling mod as the player is a bitstreamer. If it is an Arcam Alpha (or alpha plus - the older players using TDA1541a) then you can.

Glad you liked what the clock did for your cd player - other things worth trying include the dc coupling caps on the output (If there are any - probably is) - blackgate non-polarised are good there. I personally dont like changing op-amps - i find that usually the change is just that, a change and not always for the better (YMMV). Get some copper sheet and shield the chips (copper must obviously be grounded). Damp the case. Another good one is to simply solder in a new transformer for the analogue stage feeding the analogue stage rectification diodes.

 

Its an Arcam Alpha 0? The first one, based on a Philips chipset and mech. SAA7220 and TDA1541A. Called it 1 as it was the first one to come out, didn't realise there was a an Arcam Alpha One. Did a bit of digging, that has a BB dac.

It already has a seperate psu as standard, seperate from the servo psu, that and a different DAC board is what differentiates the Arcam and a standard Philips player.

Which chips would you shield ?

Thanks

 

Ahh - i did wonder if you meant the original Arcam Alpha. (its just that no number!). Yes has a seperate PSU - but not another transformer no? Another transformer feeding that seperate PSU is worthwhile. As is the non-oversampling mod - but this should only really be done if you change the analogue filtering as well - because without the digital filter the characteristics of the analogue filter will no longer be suitable.

I would shield the dac, the filter (saa7220) and also the large chip probably close to the mechanism - the microcontroller. I made little box patterns on paper and stuck to the copper and then cut out and assembled into boxes with bottom open. Solder wire to top of box and then other end to the gnd plane (scratch off laquer). On the bottom edges i put black insulating tape and thin bits bluetak and then push the whole lot over the chip.

Output caps are well worthwhile.

 

hifikrazy,
do you have any photos of the shielding ? Must look quite good with little copper boxes over the pcb.

There are two transformers as standard. One to feed the analogue circuits, the other feeds the digital side. Mine has a third transformer for the low jitter clock.

Do you have any recommendations for the changes required for the filtering when using non OS ?

thanks

 

Often a ceramic cap after the output resistors is enough.
If not,build a 5 pole Bessel.
The 5534 is ok.