Arcam Alpha 5 - no output

[Tyron]

I just bought an Arcam Alpha 5 CD with broken tray load gear. I was hoping to just have to change the gear wheel then have a good working player but life is not always that easy for me!

I loaded a CD manually to test function but have no audio output from rear phono sockets. So I hooked up an old QED Digit external DAC and all is well.

So my question is where should I start looking for the fault please? I'm assuming it cannot be related to the broken tray load issue. I did think there may be a mute switch on the tray but surely that would mute the digital out also?

If anyone could offer me some pointers of where to start I'd be most grateful! Are there any common faults that may cause this? I have taken off the lid and all looks original with no obvious signs of previous tinkering.

Thanks in hope & regards to all!

Tyron

[burbeck]

hi Tyron,

i love these machines sounded nice.
sounds like the mute signal is active, they use transistors to short the output.

there was a stock fault on these units where a capacitor was under rated volts wise and tended to spill the electrolyte on the pcb corroding it along with a few parts including resistor, transistor and a diode.
check this cap it is C416 look for any sign of spillage /corrosion arount it (black substance)
if you have this fault the symptom was mute sometimes intermittantly.

hope this helps

[Tyron]

Hi Bob and many thanks for your quick reply!

I think you may be spot on with C416. Upon close scrutiny I can see some dark patches on its side and also what appear to be scorch marks on the board around R416. I will have to dig out my multimeter and strip out the PCB for further examination. And there I was thinking any fault must be on the plug-in board above!

I wonder does anyone know where I might be able to find a circuit diagram or even better service manual online? Or even if any kind sole may be able to email info to me I'd be most grateful. I'm also hoping to do some tweaks after I've got it working so this woud be most useful!

Thanks again Bob!

Kind regards,

Tyron

[amc184]

I own an Alpha + which I have a service manual for. The plus and the five use the same DAC and transport, so may be quite similar. If you post a photo of the innards of your five, I will tell you if my manual will help.

[burbeck]

hi Tyron,
drop me an email for the manual

[Tyron]

Hi amc184,

I appreciate your kind offer but I think I'd be better off with the correct manual plus I don't have a decent camera to hand at the moment unfortunately.

Regards,

Tyron

[fatmarley]

I'm not sure where i put my manual, but someone will have one over at www.pinkfishmedia.net (diy room)

[Tyron]

Hi Bob,

Thanks for the manual offer. I tried to email you but I am unable to. Although I've been registered on here a couple of years this thread is my 1st post so I am under moderation and therefor unable to send emails as yet

However, I found & changed a setting in my profile that should now mean you could email me if you would be so kind?!

By the way, the new tray drive wheel/gear arrived today (along with new laser for a CD63SE but that's another story!) so a step closer. Still need to get replacement C416 though, or I wonder is it possible to omit this & associated parts if I scrap the mute transistors?

Many thanks again!

Tyron

[burbeck]

hi Tyron
i will email it no problem.
its best to leave mute circuit as is, the problem is that the capacitor was under ratted just put same value but higher voltage type in there, theres plenty of room.

i had one with this fault that had burnt through the pcb as well, and was in an awful mess but was fixed and still runs great

[Tyron]

Many thanks for the manual Bob!

I changed the tray gearwheel so that's working OK now, but I'm a little concerned that when the tray ejects the motor still runs for a little while after the tray has fully extended. I'm thinking this was half the reason for the old gear having its teeth stripped, although I'm aware they were weak.
When I extend the tray manually I can hear a limit switch clicking at full extension. Maybe this is faulty, or perhaps Arcam did not utilise this switch choosing a timer circuit instead?

As for the audio fault I changed C416 for a 63v version, but still no audio . The old one actually looks OK and the black marks seem to be soot from the nearby R415 which I noticed is running very hot so I'm guessing there may be a short to ground somewhere? I will check some voltages later. I'm really hoping it is a power supply fault and not the TDA1541! Incidentally I did remove a link feeding the base resistors of the mute transistors but still no sound

Still, its early days yet!

Regards to all,

Tyron