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
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
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
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
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
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
I'm not sure where i put my manual, but someone will have one over at www.pinkfishmedia.net (diy room)
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
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
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
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
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
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
I did as you suggested Bob, took out Q2, no sound.
So studied circuit diagram & set to with multimeter:
Analogue volts (+/-25v) to audio board OK
30v on all 4 op-amps (pins 2 & 3)
-15v, -5v & +5v all present on TDA1541 DAC
Signal injected at DAC analogue out pins 6 & 25 produce audible output to my amp/speakers.
Does this mean my DAC is dead?
Or is there anything else I should try before seeking a replacement?
As mentioned previously the digital out is fine.
Thanks for all the help so far!
Tyron
So studied circuit diagram & set to with multimeter:
Analogue volts (+/-25v) to audio board OK
30v on all 4 op-amps (pins 2 & 3)
-15v, -5v & +5v all present on TDA1541 DAC
Signal injected at DAC analogue out pins 6 & 25 produce audible output to my amp/speakers.
Does this mean my DAC is dead?
Or is there anything else I should try before seeking a replacement?As mentioned previously the digital out is fine.
Thanks for all the help so far!
Tyron
Hi chaps,
Been busy with other things lately but got a chance this evening to look some more at the Alpha.
Bob - I checked the electros around the TDA, 3 x 100 microF's - took them out and all read 94 ish + on a cap meter. Also checked C223 680pF that's across TDA pins 16 & 17 (in situ) with meter - also OK.
Roar - after reading your comment about SAA7220 problems I decided to try a quick bypass to zero oversampling to remove it from circuit. I lifted resistors (R213/4/5) between TDA pins 1, 2 & 3 and the SAA, then connected TDA pins 1, 2 & 3 to SAA pins 1, 2 & 3 respectively. Still no sound though.
Was my thinking right that if the SAA 7220 was causing the fault then bypassing it as I did above should restore audio? I'm now not convinced - after some thought I suspect the SAA still being connected at its pins 1, 2 & 3 could still affect the digital inputs? But then the players digital out would not work (which it does) surely??
I hope all of the above makes sense?!
Anything else I can do to prove the TDA is or is not faulty? Or should I just try to get another to try? I've read about S1 & S2 'crown' versions - are they worth seeking out and paying extra for? What are the best sources and fair prices for different versions?
Many thanks again to all for such good advice! I'm gaining loads of knowledge from this forum - it's fantastic!
Regards,
Tyron
Been busy with other things lately but got a chance this evening to look some more at the Alpha.
Bob - I checked the electros around the TDA, 3 x 100 microF's - took them out and all read 94 ish + on a cap meter. Also checked C223 680pF that's across TDA pins 16 & 17 (in situ) with meter - also OK.
Roar - after reading your comment about SAA7220 problems I decided to try a quick bypass to zero oversampling to remove it from circuit. I lifted resistors (R213/4/5) between TDA pins 1, 2 & 3 and the SAA, then connected TDA pins 1, 2 & 3 to SAA pins 1, 2 & 3 respectively. Still no sound though.
Was my thinking right that if the SAA 7220 was causing the fault then bypassing it as I did above should restore audio? I'm now not convinced - after some thought I suspect the SAA still being connected at its pins 1, 2 & 3 could still affect the digital inputs? But then the players digital out would not work (which it does) surely??
I hope all of the above makes sense?!
Anything else I can do to prove the TDA is or is not faulty? Or should I just try to get another to try? I've read about S1 & S2 'crown' versions - are they worth seeking out and paying extra for? What are the best sources and fair prices for different versions?
Many thanks again to all for such good advice! I'm gaining loads of knowledge from this forum - it's fantastic!
Regards,
Tyron
Hi Tyron,
You said here:
Did you mean that an external audio signal injected here produces sound on the amplifiers output (implying that the analog output stage is functional), or that you detected a signal from the DAC that produced sound?
If the first case is true (I think that is what you meant), then I wouldn't worry about muting transistor etc, as they are part of the analog output stage.
The next move I would make if I were you is to get out your solder wick and remove the TDA1541A. Install a socket in it's place, and chuck a known good DAC chip in there. I would gladly lend you one of my collection (all tested good in my Alpha +), but you might want to try some geographically closer DIYers first.
If this fails, then you might have to look further upstream, but the removal and bypassing of the SAA7220 seems to clear that chip.
Good luck,
Anton
You said here:
Did you mean that an external audio signal injected here produces sound on the amplifiers output (implying that the analog output stage is functional), or that you detected a signal from the DAC that produced sound?
If the first case is true (I think that is what you meant), then I wouldn't worry about muting transistor etc, as they are part of the analog output stage.
The next move I would make if I were you is to get out your solder wick and remove the TDA1541A. Install a socket in it's place, and chuck a known good DAC chip in there. I would gladly lend you one of my collection (all tested good in my Alpha +), but you might want to try some geographically closer DIYers first.
If this fails, then you might have to look further upstream, but the removal and bypassing of the SAA7220 seems to clear that chip.
Good luck,
Anton
hi
sounds like next move is sub the dac chip then,
i do not recommend that you socket this chip. soldering directly onto the board is better, the chip runs quit warm and the solder joint can dissipate better than contacts on ic socket.
in fact i usually bond the chip to a small alu heatsink this gives the chip better life span
sounds like next move is sub the dac chip then,
i do not recommend that you socket this chip. soldering directly onto the board is better, the chip runs quit warm and the solder joint can dissipate better than contacts on ic socket.
in fact i usually bond the chip to a small alu heatsink this gives the chip better life span
It is not something that has ever worried me, but I guess it depends on the implementation. My Arcam + has its TDA1541A socketed, main because I use it as a testbed for the chips.
If you were concerned about it, you could remove the socket after you had finished troubleshooting the DAC.
If you were concerned about it, you could remove the socket after you had finished troubleshooting the DAC.
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