No - by 'fix' I meant 'reduce the gain'. Naim run the gain stage at x13, compatible with the old 75mV input standard. Change the 1K resitor in the gain stage feedback network to 2k2 or 2k7 and you get a more 'normal' range of control at the volume knob, and slightly less hiss too. Better than using an offboard attenuator!
my suffering continues...
after some messing around my cd53 still makes trouble.
it has 3 daughterboards: CLK, DOS & servo regs . sometimes it works, sometimes not. the master clk line seems to be very sensitive:
1) some time ago (without dos & servo regs), clk psu was connected as on Ray's site - +10V,gnd jumpers near the 5Vreg. everything was ok
2) next, I put DOS inside, psu before 12V regs - ok
3) decided to put servo regs - Vin after R149/150, U159,158 removed , inserted reg out, u161/162 removed , connected servo reg out, too
I wanted to tap for the clock from the servo reg entry, fried servo opamps + R149/150 as well
4) replaced opamps, connected clock PSU to C803/804 (same as DOS) - cd running ok
5) connected again the clock psu at servo reg entry - no work
voltage sags there to around 10V at motor start -> clock's 7808 says no probably...
6) connected clock psu to unused now +12 after 7812, no voltage sag, but sometimes works, sometimes not - especially when connecting to the amp, spindle motor loses some speed lock....
and finally, it's completely impossible to measure clk while player is running, it's either jumps (scope) or when in stop mode after connecting freq counter, motor starts spinning slowly...
did I fry decoder , servo or dac, too ?
servo opamps seem ok, luckily I ordered 6 of them so maybe it's that again.....
grateful for help in advance....
pawel
after some messing around my cd53 still makes trouble.
it has 3 daughterboards: CLK, DOS & servo regs . sometimes it works, sometimes not. the master clk line seems to be very sensitive:
1) some time ago (without dos & servo regs), clk psu was connected as on Ray's site - +10V,gnd jumpers near the 5Vreg. everything was ok
2) next, I put DOS inside, psu before 12V regs - ok
3) decided to put servo regs - Vin after R149/150, U159,158 removed , inserted reg out, u161/162 removed , connected servo reg out, too
I wanted to tap for the clock from the servo reg entry, fried servo opamps + R149/150 as well
4) replaced opamps, connected clock PSU to C803/804 (same as DOS) - cd running ok
5) connected again the clock psu at servo reg entry - no work
voltage sags there to around 10V at motor start -> clock's 7808 says no probably...6) connected clock psu to unused now +12 after 7812, no voltage sag, but sometimes works, sometimes not - especially when connecting to the amp, spindle motor loses some speed lock....
and finally, it's completely impossible to measure clk while player is running, it's either jumps (scope) or when in stop mode after connecting freq counter, motor starts spinning slowly...
did I fry decoder , servo or dac, too ?
servo opamps seem ok, luckily I ordered 6 of them so maybe it's that again.....
grateful for help in advance....
pawel
ok, got rid of chokes in place of R165 / R164 and set servo regs to +-8.5V
the output stage is disconnected right now and cd works, so apparently nothing fried...
but I wonder about the pcb vs. schematics a bit. I have a cd53 (I think mkI) and it has already some decoder mod from mkII but not in full! it still has U193 as jumper and no c521 -> this came up while I was debugging clk path from dac to the decoder.
which solution is better ? original mkI or rather mkII ? why not feeding the decoder with clk directly ??
greetings,
PAwel
the output stage is disconnected right now and cd works, so apparently nothing fried...
but I wonder about the pcb vs. schematics a bit. I have a cd53 (I think mkI) and it has already some decoder mod from mkII but not in full! it still has U193 as jumper and no c521 -> this came up while I was debugging clk path from dac to the decoder.
which solution is better ? original mkI or rather mkII ? why not feeding the decoder with clk directly ??
greetings,
PAwel
hi Brent,
ok, I was at home for lunch, the pcb has all of the decoder mkII mods.
there is still something dodgy, when I connect the discrete output board, servo becomes somewhat disturbed - one hears more sounds coming out of it.... there must be some ground that disturbs the whole operation.
I am just wondering if one could make the clk line less sensitive... I will also get rid of the other psu resistor/chokes on 2 other servo opamps, let's see...
btw, about connecting the clk, looking at the dac datasheet, maybe it could be better to inject the signal at XTO and not XTI ?
do you connect the clock pcb gnd to the digital gnd , too ? I assume the other XT pin remains floating...
pawel
ok, I was at home for lunch, the pcb has all of the decoder mkII mods.
there is still something dodgy, when I connect the discrete output board, servo becomes somewhat disturbed - one hears more sounds coming out of it.... there must be some ground that disturbs the whole operation.
I am just wondering if one could make the clk line less sensitive... I will also get rid of the other psu resistor/chokes on 2 other servo opamps, let's see...
btw, about connecting the clk, looking at the dac datasheet, maybe it could be better to inject the signal at XTO and not XTI ?
do you connect the clock pcb gnd to the digital gnd , too ? I assume the other XT pin remains floating...
pawel