840C
the right channel works at power up but is faint , then after about 30 seconds the right channel makes a whooshing sound then pops back to full volume .
maybe a dry cap ?
if left on in standby it works fine thats what makes me think a dry cap but the service manual says there are no cap s in signal path ?
the right channel works at power up but is faint , then after about 30 seconds the right channel makes a whooshing sound then pops back to full volume .
maybe a dry cap ?
if left on in standby it works fine thats what makes me think a dry cap but the service manual says there are no cap s in signal path ?
I've looked at the manual and it appears to use relay muting in a shunt to ground arrangement so I doubt its that tbh.
It needs a scope and a check on the analogue stages. 5 minutes work should show where the problem lies by looking at the output of the opamp signal chain. It's a complex circuit and the manual is spread over many pages so its one of those "where you need it in front of you" in order to make sense of it all and the layout.
It needs a scope and a check on the analogue stages. 5 minutes work should show where the problem lies by looking at the output of the opamp signal chain. It's a complex circuit and the manual is spread over many pages so its one of those "where you need it in front of you" in order to make sense of it all and the layout.
I had the same problem 1-2 years after I got the player. (But in the left channel)
I started leaving the player on at all time to bypass the problem, but now the noise is there all the time.
I googled the problem and found one guy having the same problem. He sent the player to service, and they changed four capacitators in the power supply. They told him it was a issue with this player, and they changed these capacitators every time they got one of these players in.
I have now dismantled my player and downloaded a service manual. I will try to locate the faulty caps, but I am not shure if my electronics skills will be good enough...
If you get your player repaired, or anyone know which capacitators this is, please tell!
I started leaving the player on at all time to bypass the problem, but now the noise is there all the time.
I googled the problem and found one guy having the same problem. He sent the player to service, and they changed four capacitators in the power supply. They told him it was a issue with this player, and they changed these capacitators every time they got one of these players in.
I have now dismantled my player and downloaded a service manual. I will try to locate the faulty caps, but I am not shure if my electronics skills will be good enough...
If you get your player repaired, or anyone know which capacitators this is, please tell!
Interesting...
The power supply in this player is very "complex", well complex in that it uses many regulated supplies, not complex circuitry.
If it is a PSU issue then I would look at the supplies to the analogue stages and the DAC (for the relevant channel) and perhaps do a quick measure of those supplies when the problem occurs.
The power supply in this player is very "complex", well complex in that it uses many regulated supplies, not complex circuitry.
If it is a PSU issue then I would look at the supplies to the analogue stages and the DAC (for the relevant channel) and perhaps do a quick measure of those supplies when the problem occurs.
CAMBRIDGE AZUR 840C: Dodgy Chinese capacitors.
Hi Folks,
I'm new to this forum, but would like to seek your advice.
I have a Cambridge AZUR 840CD Player. Nice one , IF it works .
It already had an intermittent problem with the CD (Sanyo) drive, (a couple of years ago), which I repaired by exchanging it for a new one (they are quite cheap ; about 40$.
Now, the player has developed another problem, which seems to be common for this type..
Once switched ON from cold, initially both channels pop & crackle.
One (L) quickly recovers though, and is fine after some 5 minutes.
The other (R) channel stops with popping and crackling, and does not recover but has much reduced output (50% less), some distortion/white noise.
Some 2 months ago, also this channel would recover, but it has deteriorated over time.
The rest of the player is AllRight. Currently I feed the digital output signal into an external DAC (part of TASCAM HS2) and still can enjoy the music.
I heard from the Importer's Service Rep (nice chap) that there are bad capacitors in the DA system / power supplies.
Looking at the schematic, I would like to replace C152, C156, C159, C98 (10 uF NP), left channel and C54, C154, C55, C99 (10uF, NP) Right channel, all around the DA chips.
I read somewhere that the service dpt . of Cambridge replaces some cap's as a matter of course (each time an 840C is brought in).
Are these indeed the offending C's ??
Furthermore, I intend to replace C64/C65 (10u, 35V) DAC1_VA_+5V
C112/C250 (10u, 35V) DAC2_Va_+5V
C46/C137 (100u 35V) +/_ 15V LCH
C104/C105 ditto RCH
C115 10u 35V +5V DAC
C247 10u 35V -5V
C246 ditto -5V(2)
C141 ditto +5V
These are all major C's in the DA converter + OpAmps I can think off.
I do not want to MOD the player ; just fix it
Any more suggestions??
Which Caps should I use?? I intend to at least double the Working Voltage of the CAPS (to 63V) and use Panasonic caps (freely available from CONRAD)..
Will this do the trick in your opinion??
NB I have included the schematic.
http://akdatabase.org/AKview/albums/userpics/10006/Cambridge Audio Azur 840C SM.pdf
Any help is welcome!
Thanks for your support!!
kind regards,
Martin , Holland
Hi Folks,
I'm new to this forum, but would like to seek your advice.
I have a Cambridge AZUR 840CD Player. Nice one , IF it works .
It already had an intermittent problem with the CD (Sanyo) drive, (a couple of years ago), which I repaired by exchanging it for a new one (they are quite cheap ; about 40$.
Now, the player has developed another problem, which seems to be common for this type..
Once switched ON from cold, initially both channels pop & crackle.
One (L) quickly recovers though, and is fine after some 5 minutes.
The other (R) channel stops with popping and crackling, and does not recover but has much reduced output (50% less), some distortion/white noise.
Some 2 months ago, also this channel would recover, but it has deteriorated over time.
The rest of the player is AllRight. Currently I feed the digital output signal into an external DAC (part of TASCAM HS2) and still can enjoy the music.
I heard from the Importer's Service Rep (nice chap) that there are bad capacitors in the DA system / power supplies.
Looking at the schematic, I would like to replace C152, C156, C159, C98 (10 uF NP), left channel and C54, C154, C55, C99 (10uF, NP) Right channel, all around the DA chips.
I read somewhere that the service dpt . of Cambridge replaces some cap's as a matter of course (each time an 840C is brought in).
Are these indeed the offending C's ??
Furthermore, I intend to replace C64/C65 (10u, 35V) DAC1_VA_+5V
C112/C250 (10u, 35V) DAC2_Va_+5V
C46/C137 (100u 35V) +/_ 15V LCH
C104/C105 ditto RCH
C115 10u 35V +5V DAC
C247 10u 35V -5V
C246 ditto -5V(2)
C141 ditto +5V
These are all major C's in the DA converter + OpAmps I can think off.
I do not want to MOD the player ; just fix it
Any more suggestions??
Which Caps should I use?? I intend to at least double the Working Voltage of the CAPS (to 63V) and use Panasonic caps (freely available from CONRAD)..
Will this do the trick in your opinion??
NB I have included the schematic.
http://akdatabase.org/AKview/albums/userpics/10006/Cambridge Audio Azur 840C SM.pdf
Any help is welcome!
Thanks for your support!!
kind regards,
Martin , Holland
found the dodgy cap
the cap in attached pic was causing the problem
the cap in attached pic was causing the problem
An externally hosted image should be here but it was not working when we last tested it.
Last edited by a moderator:
Hi
Thanks for the support.
All 10uF, 50V elco's were changed (by Rubicon) and player is fine again.
Was this due to inherently bad Capacitors (or because the C's are too close to the hot heatsink and get roasted?).
In the latter case , the lay out of the PCB is inherently wrong
NB Also C270 470uF 16V (feeding relais) was replaced.
Regards,
Martin
Thanks for the support.
All 10uF, 50V elco's were changed (by Rubicon) and player is fine again.
Was this due to inherently bad Capacitors (or because the C's are too close to the hot heatsink and get roasted?).
In the latter case , the lay out of the PCB is inherently wrong
NB Also C270 470uF 16V (feeding relais) was replaced.
Regards,
Martin
Power Switch Solution
I had a problem that sounds exactly like what you are describing, "a low volume in the right channel and then a whooshing sound before it pops back to full volume." I would even get a shift of volume between channels sometimes, as if some poltergeist was twisting a phantom balance control. Like you, I left my 840C on at all times to avoid this problem but the frequency of occurrence just got worse. Occasionally we might get a power outage and it was nearly impossible to get the channel to come back on. At first I thought it was a Dry Cap as others have postulated, so I took the 840C apart to run tests on the caps with an ESR meter. I found no issues and put the unit back together. The problem was no better. I tried cold shocks on the caps but all to no avail. I consistently had a low volume on the right channel. I could barely hear it. Sometimes it was slightly distorted as well.
I put the cover back on and was about to give up when I began to consider the manual switch on the back of the unit that I never use and wondered if it could cause a relay issue in the circuit board that it controls. While power was applied, I cycled the switch several times, in conjunction with the front power button and my problems suddenly went away and have not come back. The unit has been playing for days now without a hitch.
It's impossible to know the root cause without a dissection of the Power PCB, Relays and Switch assembly. Here is my guess. Apparently, when this unit is left on for extended periods, the rear switch contacts build up some kind of resistance from oxidation or arcing that deprives the relays of power (RL-1 & RL-2). This in turn will likely reduce contact pressure and deprive circuits downstream of power.
If anyone has a loss of channel volume, funny sounds in a channel or shifting balance between channels, I suggest you try cycling the main power switch at the back right corner. Worked for me and I did nothing else to repair mine. Wonder how much money Cambridge repair facilities make off this little design quirk?
the right channel works at power up but is faint , then after about 30 seconds the right channel makes a whooshing sound then pops back to full volume. maybe a dry cap ? If left on in standby it works fine that's what makes me think a dry cap but the service manual says there are no caps in signal path ?
I had a problem that sounds exactly like what you are describing, "a low volume in the right channel and then a whooshing sound before it pops back to full volume." I would even get a shift of volume between channels sometimes, as if some poltergeist was twisting a phantom balance control. Like you, I left my 840C on at all times to avoid this problem but the frequency of occurrence just got worse. Occasionally we might get a power outage and it was nearly impossible to get the channel to come back on. At first I thought it was a Dry Cap as others have postulated, so I took the 840C apart to run tests on the caps with an ESR meter. I found no issues and put the unit back together. The problem was no better. I tried cold shocks on the caps but all to no avail. I consistently had a low volume on the right channel. I could barely hear it. Sometimes it was slightly distorted as well.
I put the cover back on and was about to give up when I began to consider the manual switch on the back of the unit that I never use and wondered if it could cause a relay issue in the circuit board that it controls. While power was applied, I cycled the switch several times, in conjunction with the front power button and my problems suddenly went away and have not come back. The unit has been playing for days now without a hitch.
It's impossible to know the root cause without a dissection of the Power PCB, Relays and Switch assembly. Here is my guess. Apparently, when this unit is left on for extended periods, the rear switch contacts build up some kind of resistance from oxidation or arcing that deprives the relays of power (RL-1 & RL-2). This in turn will likely reduce contact pressure and deprive circuits downstream of power.
If anyone has a loss of channel volume, funny sounds in a channel or shifting balance between channels, I suggest you try cycling the main power switch at the back right corner. Worked for me and I did nothing else to repair mine. Wonder how much money Cambridge repair facilities make off this little design quirk?
Relays RL1 and RL2 are switching the inductive load of the transformer secondary. I imagine the contacts get in pretty rough shape over time and probably form a high resistance. Hence the reason cycling the system on and off can improve the situation as the contacts wipe and probably knock off some of the carbon. Measurements across the contacts should provide some indication.
The manual power switch on the back handles the transformer primary and two inductors L1 & L2. Switching this combination of inductive loads will arc and char the contacts as well.
CAP Identifications
OK, I contacted the Cambridge Importer and they told me the likely candidates for making the noise were C217, C224, C271, and C272. When these have not been changed for 10uf 63vdc, they have been known to produce these symptoms. Whenever they have an 840C in for service, they make sure to change them all as a precaution.
Mine were 50Volt, so I changed them, but the problem persisted. I finally had to use a scope and trace down the noise. I found that it was C224 failing in the circuit but it appeared to be labeled C225. The stenciling is terrible on the left channel and I replaced the wrong cap the first time around and this is why the problem persisted. See photos of the stenciling.
The problems are gone and I am very grateful to the Cambridge Importer for their help but wish Cambridge did a better job of circuit board parts identification.
OK, I contacted the Cambridge Importer and they told me the likely candidates for making the noise were C217, C224, C271, and C272. When these have not been changed for 10uf 63vdc, they have been known to produce these symptoms. Whenever they have an 840C in for service, they make sure to change them all as a precaution.
Mine were 50Volt, so I changed them, but the problem persisted. I finally had to use a scope and trace down the noise. I found that it was C224 failing in the circuit but it appeared to be labeled C225. The stenciling is terrible on the left channel and I replaced the wrong cap the first time around and this is why the problem persisted. See photos of the stenciling.
The problems are gone and I am very grateful to the Cambridge Importer for their help but wish Cambridge did a better job of circuit board parts identification.
Attachments
Ca 840c
I'm about to embark on this fix, as I have a hissing in my left channel after turning on the CD player. It goes away if I power the CD player down and back up once or twice.
I just ordered the 10uf 63V caps for the job.
Are these polarized?
Is a 15v soldering iron enough?
And I have just rosin core solder. Is that ok to use?
Thanks guys!
Mike
I'm about to embark on this fix, as I have a hissing in my left channel after turning on the CD player. It goes away if I power the CD player down and back up once or twice.
I just ordered the 10uf 63V caps for the job.
Are these polarized?
Is a 15v soldering iron enough?
And I have just rosin core solder. Is that ok to use?
Thanks guys!
Mike
They all look to be polarized in the pictures.
15 volt or 15 watt ? Voltage doesn't matter, its the wattage that determines the heating ability.
15 watts is very low and may not be able to remove and resolder parts neatly if there is anything in the way of much copper print to take the heat away. You risk doing damage with to small an iron.
The solder sounds OK. Never use plumbers solder (acid flux).
15 volt or 15 watt ? Voltage doesn't matter, its the wattage that determines the heating ability.
15 watts is very low and may not be able to remove and resolder parts neatly if there is anything in the way of much copper print to take the heat away. You risk doing damage with to small an iron.
The solder sounds OK. Never use plumbers solder (acid flux).
My experience (which is much and varied as a service tech) says that 40w or higher is better.
I used to have an Antex 18 watt iron and it was OK for small stuff where there is little to take the heat from the bit. Try soldering anything where the heat could be conducted from the tip and it was no good.
I used to have an Antex 18 watt iron and it was OK for small stuff where there is little to take the heat from the bit. Try soldering anything where the heat could be conducted from the tip and it was no good.
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