CS4397 dac

[Makgajwer]

Revised schematics

[iihay]

Not been in here for a while, life gets in the way! Just finishing connecting this DAC to my shigaclone cd player but I'm looking for a good quality connector between the dac and CD. I assume digital coaxial? I have a spare cable but if this is the best route then where do I get a decent socket for the board?

Cheers

Iain

[leo]

I hard wired a 75R BNC socket to the pcb, the single phono socket on this dac board is really poor, it gave me regular drop outs on the spdif

Listening again to this dac a few days ago, its really quite a good little performer on the cheap once modified and a few of the circuit errors corrected

[iihay]

Sounds like a plan, putting an RS order in today but all will be delayed by easter, should have got round to it a while ago! I have a small problem that I need some help with. I have 0.5mv across the right output but 1.4V across the left.

I followed the nulling posts somwhere around post 96ish it has obviously worked on one channel but not the other, poor connection on one of the resistors? I'll read back through again but do you have any pointers as to where to look troubleshooting wise. I'm sure I had this at vitually zero last time I powered up. I could give up and pop some caps on the output but I'm trying to avoid this as I have protection on the amp and I want to keep the mods to a minimum in the signal path.

Cheers

Iain

[leo]

Yes, I'd certainly check the joints, be sure all values are correct etc, somethings way out of balance on that channel giving you the high offset

Caps on the output will only get rid of the DC but you'll probably get a channel inbalance if theres a problem with the resistors

Did you try another op-amp just to eliminate the possible faulty chip?

[iihay]

Yes, I'd certainly check the joints, be sure all values are correct etc, somethings way out of balance on that channel giving you the high offset

Caps on the output will only get rid of the DC but you'll probably get a channel inbalance if theres a problem with the resistors

Did you try another op-amp just to eliminate the possible faulty chip?

That's a great suggestion, I found a spare opamp yesterday when having a garage tidy! I'll give it a try and report back. Joints look ok but tempted to dab them with an iron. It's lead free stuff and I fine it hard to spot bad joints with it.

Iain

[leo]

Ok Iain

Failing that you could post a High res pic and I'll check over it, obviously harder to see things on a pic but may be worth a try just incase

ROHS solder , I hate the stuff!!! only time I use that is at work, my own gear is all lovely leaded

[iihay]

Arse! Just broke the right hand side ( from above, phono and optical to left hand side) pad of C34 away from the board changing the opamp. Can't reconnect it as the pad has come away, is there any other point to connect this to or am I hitting ebay for a new board?

Iain

[leo]

I don't think theres any need to scrap it

So to get this right the pads for C34 are damaged? Its going to be hard to explain how to fix, do you know how to read a schematic?

[iihay]

Yep, rhs pad gone. I'm not the greatest with schematics but try me, I can always ask questions!
By the way I suspect the leg of the cap on C34 was touching the cap next to it. I wonder if this was the cause of the higher voltage. All the resistors seem fine.
Appreciate your help, not really wanting to scrap this, would rather keep the pennies for a buffalo at some point.

Iain