Just bought a Da Capo
I was made aware by the seller that it needed recapping and sure enough the thing is filled with LXF caps that have leaked. There are some tracks on the PCB that have corroded through so I'll need to fix those. I've read through this thread and seen that caps are rated at 25volts and 35 volts - All mine are at 25volts only. Just out of interest where were the 35v capacitors placed? should I use 35v here or will 25v suffice (I've not powered up and measured any voltages yet, want to get the PCB cleaned and fixed first). I've already bought ZLH capacitors as replacements but if I need to uprate the voltage anywhere I'd rather do that before soldering anything into place (rather than having to pull it and replace it).
I was made aware by the seller that it needed recapping and sure enough the thing is filled with LXF caps that have leaked. There are some tracks on the PCB that have corroded through so I'll need to fix those. I've read through this thread and seen that caps are rated at 25volts and 35 volts - All mine are at 25volts only. Just out of interest where were the 35v capacitors placed? should I use 35v here or will 25v suffice (I've not powered up and measured any voltages yet, want to get the PCB cleaned and fixed first). I've already bought ZLH capacitors as replacements but if I need to uprate the voltage anywhere I'd rather do that before soldering anything into place (rather than having to pull it and replace it).
As you can see from the data, the ZL has higher current at mains ripple, 120Hz, and therefore audio frequencies, which is why I used them.
The ZLH is lower Impedance at 100kHz, but does that frequency matter in this mains reservoir position?
I didn't use any 35V capacitors. So unless yours is different, you should be OK with 25V
2200μF 25V Rubycon ZL 12.5mmx35mm, 5mm, 0.6mm
3400mA rms @ 100k 105°C
x 0.8 for 120Hz = 2720mA
x 0.75 for 60Hz = 2550mA
Impedance = 0.015 mOhm @ 100kHz
Tan loss angle = 0.14 @ 120Hz 20°C
2200μF 25V Rubycon ZLH 12.5mmx30mm, 5mm,
3450mA rms @ 100k 105°C
x 0.7 for 120Hz = 2415mA
Impedance = 0.013 mOhm @ 100kHz
Tan loss angle = 0.14 @ 120Hz 20°C
The ZLH is lower Impedance at 100kHz, but does that frequency matter in this mains reservoir position?
I didn't use any 35V capacitors. So unless yours is different, you should be OK with 25V
2200μF 25V Rubycon ZL 12.5mmx35mm, 5mm, 0.6mm
3400mA rms @ 100k 105°C
x 0.8 for 120Hz = 2720mA
x 0.75 for 60Hz = 2550mA
Impedance = 0.015 mOhm @ 100kHz
Tan loss angle = 0.14 @ 120Hz 20°C
2200μF 25V Rubycon ZLH 12.5mmx30mm, 5mm,
3450mA rms @ 100k 105°C
x 0.7 for 120Hz = 2415mA
Impedance = 0.013 mOhm @ 100kHz
Tan loss angle = 0.14 @ 120Hz 20°C
Da Capo capacitor swapout
Hi Ian,
Thanks for the quick response.
Re ZL vs ZLH - Also consider that for the digital circuits there will be switching at much higher frequencies than 50hz mains and some of this is likely to make it's way back to the power supply as current demand. Having some ripple current capability at that end of the spectrum will do no harm (and might even be beneficial). I'll not lose sleep over it either way
Hi Ian,
Thanks for the quick response.
Re ZL vs ZLH - Also consider that for the digital circuits there will be switching at much higher frequencies than 50hz mains and some of this is likely to make it's way back to the power supply as current demand. Having some ripple current capability at that end of the spectrum will do no harm (and might even be beneficial). I'll not lose sleep over it either way
OK - So I have removed the old caps, cleaned and repaired the corroded tracks on the PCB, fitted the new caps and powered up. I'm getting a hissy 100hz on the audio outputs (but it does now power up which is more than it did before). Without a schematic it's going to be pretty hard to move forwards with this - does anyone have a schematic or can anyone advise the voltages I should be looking out for (I have one rail coming from the transformer at just -1.2v (measured using the can of the filter as ground) - that looks low to me).
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Per channel, you'll be replacing just one op-amp; the 604, but that chip will be removing common mode noise, so best leave it there.
The balanced feeds travel into that via a series of surface mount resistor followed by capacitor to earth. This is the filtering, plus a feedback capacitor around the op-amp.
With the Dacapo, digital signal is sent into those from logic chips in the can. So it's not a DAC chip sending analogue from internal op-amps, etc., to filter and line driver op-amps. It doesn't even have an output resistor after the 604, so if you do change the op-amp you'd probably need to add one.
The balanced feeds travel into that via a series of surface mount resistor followed by capacitor to earth. This is the filtering, plus a feedback capacitor around the op-amp.
With the Dacapo, digital signal is sent into those from logic chips in the can. So it's not a DAC chip sending analogue from internal op-amps, etc., to filter and line driver op-amps. It doesn't even have an output resistor after the 604, so if you do change the op-amp you'd probably need to add one.
Ian. Thanks. So from what you say is there no point where the signal can be taken into a separate outstage ?. The Dacapo I have has one channle out. I have replaced the main caps and found (very) little damage to the board underneath - they were all good when checked) but I can't find a fault from a visual inspection. The Rotel CDP has the discrete output stage on it - see Vibration Isolation Part 3: CD players - which I don't need (it is used as a transport) such that I was thinking I could take a feed into it from a specific point on the Dacapo. Thanks.
Have you put you meter probes on the supply rails to the output op-amps to see if there voltage there? Run a test signal and measured the input pins of them? Then measure at the output of the can. It very easy to see the chain of resistors that go from the op-amps to the can.
Beyond that, the entry to the can. It might be left and right channels coming from the removable digital filter can. I may just have remembered that I found inside that removable can a pair of thin wires and one had detached causing no output on one channel, it was many years ago and I'm not sure now. But that removable can did come apart to reveal the internals.
Is it not best to get the Dacapo working before investing a lot of time trying to modify the output stage?
Beyond that, the entry to the can. It might be left and right channels coming from the removable digital filter can. I may just have remembered that I found inside that removable can a pair of thin wires and one had detached causing no output on one channel, it was many years ago and I'm not sure now. But that removable can did come apart to reveal the internals.
Is it not best to get the Dacapo working before investing a lot of time trying to modify the output stage?
I can only presume that you're Rotel stage basically would just replace the 604 op-amp. But would probably add further filtering that isn't required and which would be engineered for the DAC chipset in the Rotel, not the Dacapo.
If the Rotel stage is a 'discrete op-amp' and nothing else then maybe you could 'chip roll' with it.
Some 'discrete op-amps' can have terrible measurements compared to a decent op-amp and some buffer stages require series capacitors, so you have to choose your best compromise.
As I recall, an it's been many years, F series BG's are the lowest grade and, to my ears at least, tended sound overly harsh and grainy with a bloated and out of control bass. I've used banked polymer caps instead, less bass but more informative and the FK and N BG's sounded more together and easier on the ear than the F.
If the Rotel stage is a 'discrete op-amp' and nothing else then maybe you could 'chip roll' with it.
Some 'discrete op-amps' can have terrible measurements compared to a decent op-amp and some buffer stages require series capacitors, so you have to choose your best compromise.
As I recall, an it's been many years, F series BG's are the lowest grade and, to my ears at least, tended sound overly harsh and grainy with a bloated and out of control bass. I've used banked polymer caps instead, less bass but more informative and the FK and N BG's sounded more together and easier on the ear than the F.
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Yet another desperate cry for schematics...
I recently got an Ordinal on the fleabay - it sung merrily for about half an hour, then one channel died and that was it. It's been sent for repair a month ago, and this is the message I finally got from the technician: "The digital signal passes through the filter but does not reach DAC IC". Without documentation, he's basically stuck there.
Could anyone offer any ideas on how to get any schemes for the Ordinal? Or how to get in touch with John W, as a last resort?
Thanks in advance for any ideas:
Boris
I recently got an Ordinal on the fleabay - it sung merrily for about half an hour, then one channel died and that was it. It's been sent for repair a month ago, and this is the message I finally got from the technician: "The digital signal passes through the filter but does not reach DAC IC". Without documentation, he's basically stuck there.
Could anyone offer any ideas on how to get any schemes for the Ordinal? Or how to get in touch with John W, as a last resort?
Thanks in advance for any ideas:
Boris
Hello!
Became the owner of DaCapo, made repairs. The truth is that something sizzles one channel, it seems like a prong, which is fused .. everything else seems to be in order .. I'll sort it out. I read the branch with great interest. Does someone have an extra filter for sale, better than 18 bits?
Became the owner of DaCapo, made repairs. The truth is that something sizzles one channel, it seems like a prong, which is fused .. everything else seems to be in order .. I'll sort it out. I read the branch with great interest. Does someone have an extra filter for sale, better than 18 bits?
Is John W still very much involved in the FDAC project? Maybe search around for that and the latest posts by John W on any forum. Good luck!
Edit: Also try Linkedin - he's listed on there.
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