Hi guys,
Has anyone experienced a crackling/distortion problem with their CD63? Only on one channel? (Comes and goes with the music.)
It's happened to mine four times recently, but the odd thing is, the 1st and 4th time it was the left channel, the 2nd and 3rd times it was the right channel!
The signal is leaving the DAC in this state - it's not the analogue filter stage or anything,
I wonder if it's a power supply sequencing issue - maybe the clock isn't coming up quick enough.
If I 'reset' the machine (shorting the capacitor CF03 next to the reset transistor - the legs are long enough I can do this from above) it reboots and is then fine.
Obviously this does not take down any of the power rails.
But equally if I switch off and on again it is fine.... but that's not a cold start anymore.
It's only been doing this recently - and (I think) coincides with two recent mods:
a) installing Tent X02 and XO Supply (transplanted from my now decommissioned CD67SE).
b) replacing RC filtering with LC filtering on all three power pins of the decoder chip (1mH/14R + ferrite beads & 220uF/16V + 47nF). One of the decoder VDD pins was originally being fed from the raw 5v, so I corrected this PCB error, but the two digital supplies have their own filters and are not connected together directly (as in the data sheet). I don't know if that could be it.
If it's that the clock or a rail is not coming up in time, then increasing CF03 will make the machine start up later after powering it on. E.g., changing it from 4.7uF to 10uF will double the time from 1s to 2s. I will try that first.
Any other ideas? Anyone had this issue?
I'm slightly worried that the DAC chip is failing.
I could take the DAC off my old CD67 board but I don't fancy doing that very much!
Cheers,
Glenn
Has anyone experienced a crackling/distortion problem with their CD63? Only on one channel? (Comes and goes with the music.)
It's happened to mine four times recently, but the odd thing is, the 1st and 4th time it was the left channel, the 2nd and 3rd times it was the right channel!
The signal is leaving the DAC in this state - it's not the analogue filter stage or anything,
I wonder if it's a power supply sequencing issue - maybe the clock isn't coming up quick enough.
If I 'reset' the machine (shorting the capacitor CF03 next to the reset transistor - the legs are long enough I can do this from above) it reboots and is then fine.
Obviously this does not take down any of the power rails.
But equally if I switch off and on again it is fine.... but that's not a cold start anymore.
It's only been doing this recently - and (I think) coincides with two recent mods:
a) installing Tent X02 and XO Supply (transplanted from my now decommissioned CD67SE).
b) replacing RC filtering with LC filtering on all three power pins of the decoder chip (1mH/14R + ferrite beads & 220uF/16V + 47nF). One of the decoder VDD pins was originally being fed from the raw 5v, so I corrected this PCB error, but the two digital supplies have their own filters and are not connected together directly (as in the data sheet). I don't know if that could be it.
If it's that the clock or a rail is not coming up in time, then increasing CF03 will make the machine start up later after powering it on. E.g., changing it from 4.7uF to 10uF will double the time from 1s to 2s. I will try that first.
Any other ideas? Anyone had this issue?
I'm slightly worried that the DAC chip is failing.
I could take the DAC off my old CD67 board but I don't fancy doing that very much!
Cheers,
Glenn
I thought that after I posted!
This is a 63.
So far I have seperated 5 different feeds for the dac
U192 removed to feed pins 3&7 (no onward supply)
U352 removed to feed pins 22&26
U352 removed to feed pins 17&21
RD01 lifted on supply end to feed pin 27
RD04 lifted on supply end to feed pin 16
All caps changed inductor instead of resistor yada yada yada.....
I was going to build both of the PSU's to supply all the above with both S-Regs and additional 340's (or should I build one of the PSU's for the servo and other 5v stuff?
or
should I build 1 PSU for the DAC, and 1 PSU for the clocks and leave the rest powered by the main 5v reg on the board?
I'm sure I just added more into the mix instead of just answering the question!!!
This is a 63.
So far I have seperated 5 different feeds for the dac
U192 removed to feed pins 3&7 (no onward supply)
U352 removed to feed pins 22&26
U352 removed to feed pins 17&21
RD01 lifted on supply end to feed pin 27
RD04 lifted on supply end to feed pin 16
All caps changed inductor instead of resistor yada yada yada.....
I was going to build both of the PSU's to supply all the above with both S-Regs and additional 340's (or should I build one of the PSU's for the servo and other 5v stuff?
or
should I build 1 PSU for the DAC, and 1 PSU for the clocks and leave the rest powered by the main 5v reg on the board?
I'm sure I just added more into the mix instead of just answering the question!!!
Glenn, i had something like that with my CD67. Only happened with a discrete output though, not opamps. Changed the dac and it was fine afterwards.
Ian, if it were me, I'd do the last one on your list. Using one hole from U200 to feed dac analog and one hole of rd04 for digital.
Cheers, Lee.
Ian, if it were me, I'd do the last one on your list. Using one hole from U200 to feed dac analog and one hole of rd04 for digital.
Cheers, Lee.
and it's still down a decoder... 
There is a trick to removing these chips!
I managed to remove some RAM in my old XBMC xbox this way.
strip 2 or 3 strands of copper wire from some cable about 4 times the length of the chip you want to unsolder.
twist them together so they are slightly more rigid.
Pass the strands between the legs, board and chip all the way along 1 side of the chip. Anchor the strands to something else on the board at the far end of the chip (solder to another component its just so you dont need someone else to hold it).
Starting from the free end,run the iron along the top of the legs and pull the wire out so it passes between the legs and pads.
The iron will only be in contact with the chip for a fraction of a second.
When you have the wire out, all the legs will be unsolderd!
Repeat for the other side.
It works, I've done it!
I managed to remove some RAM in my old XBMC xbox this way.
strip 2 or 3 strands of copper wire from some cable about 4 times the length of the chip you want to unsolder.
twist them together so they are slightly more rigid.
Pass the strands between the legs, board and chip all the way along 1 side of the chip. Anchor the strands to something else on the board at the far end of the chip (solder to another component its just so you dont need someone else to hold it).
Starting from the free end,run the iron along the top of the legs and pull the wire out so it passes between the legs and pads.
The iron will only be in contact with the chip for a fraction of a second.
When you have the wire out, all the legs will be unsolderd!
Repeat for the other side.
It works, I've done it!
Muting relay
Now I've removed a whole load of naff stuff around headphones and muting circuits, I need to address muting so I don't firghten the wife and kids every time I turn the CDP off before the amp!
I've looked at Farnell and they do loads. I specifically looked for silver contacts but they don't seem to have any in the UK.
Can anyone suggest an alternative. It seems silly to go to all this trouble and then put cr@ppy relays in the signal path!
Cheers
Ian
Now I've removed a whole load of naff stuff around headphones and muting circuits, I need to address muting so I don't firghten the wife and kids every time I turn the CDP off before the amp!
I've looked at Farnell and they do loads. I specifically looked for silver contacts but they don't seem to have any in the UK.
Can anyone suggest an alternative. It seems silly to go to all this trouble and then put cr@ppy relays in the signal path!
Cheers
Ian
RCruz said:
I used to find it impossible to remove even a 3-pin regulator (TO220 etc.) but now it's very easy, just heat all the pins at the same time using lots of solder and slide it out. Then use a desoldering pump to remove the solder.
If the chip has more pins and you need to remove all the solder before the part, it certainly helps to flow fresh solder in there first. Another thing that helps here, a lot, is to have a flexible silicone-tipped (oor er!) desoldering pump. This allows you to press the tip right up against the joint with heat applied and generally enhances the success of the solder removal. Silicone doesn't melt at soldering iron temperatures, which is handy.
Simon
I just use a normal iron Ricardo. Years of practice. I can do the decoder removal from 2 pcbs and resolder the good one back to the correct pcb with in 15 - 20 mins
The safest way is to use a small and thin tip, turn up the temp and flick up one leg of the ic at a time. If it's a 4 sided chip then lift the pins on 3 sides then flow solder along the remaining side, quickly get it all hot and slide the chip away. A 2 sided chip like the 63 dac can be swapped in under 3 mins.
Brent
The safest way is to use a small and thin tip, turn up the temp and flick up one leg of the ic at a time. If it's a 4 sided chip then lift the pins on 3 sides then flow solder along the remaining side, quickly get it all hot and slide the chip away. A 2 sided chip like the 63 dac can be swapped in under 3 mins.
Brent