Modding NAD C542 running into problems...


2007-12-19 8:16 am
Hi, I'm new to this forum, and I'm hoping to get some help from you guys.

I came upon a thread in this forum where some people were very enthusiastic about modifying the Nad c542 cd-player. As I have some experience with DIY having built my own speakers and a gainclone, I thought I would give it a shot!
Initially everything worked well and I got significant improvements removing the muting transistors and replacing the DC-blockers in the output section with MKP-type capacitors. I went on to replacing some of the transistors in the output section and some filtering caps in the power supply with Black gates. This also worked very well.
But when I moved on to replacing some caps around the DAC-chip and reinstalling, in the power supply, some of the Nichicon fine golds that had been pulled out from the output section, I ran into problems...
When I turned the CD-player on it played for a minute or so and then one channel just died. Since just one channel were affected I thought the problem must be in the analog section. Probably due to a capacitor somehow malfunctioning when it got warm. Would this reasoning be correct?
I should mention that some of the capacitors i put in were lover voltage rating then the ones pulled out. This was because when I ordered the capacitors I was looking at the service manual, and here some caps vere 16v, that turned out to be 50v in the actual player... So I pulled these out again and put the original caps back in. The problem remained just the same.
Since then I have been trying a lot of things, gradually turning the player back to what it was before it started malfunctioning, but instead of getting better, the player has been getting worse! Now there is noise in one channel and both channels are going on and off it seems. I dont want to mess any more with it before asking you guys what you think. Does this sound like bad capacitors to you, or might I have inflicted more serious damage to the chips or something like that? Of course I have tried putting most of the original capacitors back, but I can not trust them completely since they might have been damaged while being desoldered.

I would be so grateful if anyone could help me out here...