Hi all,
I bought a Cambridge Audio Azur 640t (version 1) for spares or repair as a friend wants one and is on a tight budget.
Firstly the screen was almost completely faulty, showing hollow squares where the stations are displayed. The DAB wasn't working at all, only FM. Optical output was working but anolog RCA outputs wasn't.
Not sure what the RCA input is though?!
(I have previously had a version 2 that didn't have those)
I've had previous experience with CA caps not being very good so I recapped all electrolytic capacitors except the front panel, so far.
The DAB is now working, the screen is much better only one character is still hollow, see att pics.
I can't find the service manual for the version one so I'm struggling to find abnormal voltages so asking for some help here please.
All diodes, resistors and regulators measure OK, it seems. Solder joints appear fine.
I've read about the regulators being underrated so was thinking of upgrading those but not sure to which, recommendations?, and a new Osram relay for longevity.
TIA!
I bought a Cambridge Audio Azur 640t (version 1) for spares or repair as a friend wants one and is on a tight budget.
Firstly the screen was almost completely faulty, showing hollow squares where the stations are displayed. The DAB wasn't working at all, only FM. Optical output was working but anolog RCA outputs wasn't.
Not sure what the RCA input is though?!
(I have previously had a version 2 that didn't have those)
I've had previous experience with CA caps not being very good so I recapped all electrolytic capacitors except the front panel, so far.
The DAB is now working, the screen is much better only one character is still hollow, see att pics.
I can't find the service manual for the version one so I'm struggling to find abnormal voltages so asking for some help here please.
All diodes, resistors and regulators measure OK, it seems. Solder joints appear fine.
I've read about the regulators being underrated so was thinking of upgrading those but not sure to which, recommendations?, and a new Osram relay for longevity.
TIA!
Attachments
Apologies for the very late reply, I've only just stumbled upon this thread (while looking for something else of course... ).
I have two 640Ts, a MkI & a MkII.
Both display the 'hollow' character on the DAB signal strength (or quality) readout and it indicates the minimum signal strength for acceptable listening. Below that point is 'bubbling mud', above is usually decent music - if decent music is being broadcast.
In other words, the hollow square in that position is quite normal & is supposed to be there.
I have quite a lot of experience of the 'bubbling mud' as I live in an area marginal for DAB signal and unacceptable for FM, unfortunately.
My problem with the 640T MkII is that the display is so dim as to be very difficult to read and doesn't change with the remote control 'brightness' button, so if you have any ideas about that I'd be grateful.
I have two 640Ts, a MkI & a MkII.
Both display the 'hollow' character on the DAB signal strength (or quality) readout and it indicates the minimum signal strength for acceptable listening. Below that point is 'bubbling mud', above is usually decent music - if decent music is being broadcast.
In other words, the hollow square in that position is quite normal & is supposed to be there.
I have quite a lot of experience of the 'bubbling mud' as I live in an area marginal for DAB signal and unacceptable for FM, unfortunately.
My problem with the 640T MkII is that the display is so dim as to be very difficult to read and doesn't change with the remote control 'brightness' button, so if you have any ideas about that I'd be grateful.
Thanks for the reply. That makes a lot of sense with the 'bubbling mud'. Threw me well out that has lol.
As far as I'm aware, the actual display on a lot of CA equipment does go dim. Although I have improved many by replacing its supply capacitors if tested high ESR and/or low capacitance.
On these units it's on the 5v supply (with the large heatsink), probably the 10uF 50v close to the regulator is high ESR due to being small and near high temperature and the 2200uF filter cap possibly low capacitance which I replaced with 3300uF eventually with no issues.
Also, the caps on the front panel board were out of tolerances too. Replacing all those should benefit I guess as CA caps are unreliable FME.
I still have issues with the analog output on this unit which I'll get around to soon. It's either the DAC chip or the Opamp
Edit: It's also worth replacing the four diodes on the 5v rectifier and lifting them 1cm above the board as they get hot, the leads won't be long enough on existing diodes
As far as I'm aware, the actual display on a lot of CA equipment does go dim. Although I have improved many by replacing its supply capacitors if tested high ESR and/or low capacitance.
On these units it's on the 5v supply (with the large heatsink), probably the 10uF 50v close to the regulator is high ESR due to being small and near high temperature and the 2200uF filter cap possibly low capacitance which I replaced with 3300uF eventually with no issues.
Also, the caps on the front panel board were out of tolerances too. Replacing all those should benefit I guess as CA caps are unreliable FME.
I still have issues with the analog output on this unit which I'll get around to soon. It's either the DAC chip or the Opamp
Edit: It's also worth replacing the four diodes on the 5v rectifier and lifting them 1cm above the board as they get hot, the leads won't be long enough on existing diodes
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