CS4397 dac

[Tripmaster]

I have check there is a connection along each track between all of the changed or removed capacitors.

Does anyone know the value of C7?

[gurusan]

as far as I understand it you already soldered the 2 little pads on the bottom of the board next to the chip which effectively bypasses it. Physically removing the chip doesn't do anything extra.

[Tripmaster]

as far as I understand it you already soldered the 2 little pads on the bottom of the board next to the chip which effectively bypasses it. Physically removing the chip doesn't do anything extra.

I had problems soldering these pads at first because there may have been some lacquer/dirt over the contact point. I think the excessive heat trying to get a good contact may have damaged the chip. There was very little left of the solder pads prior to removing the chip.

[alb]

A useful link to identify surface mount caps.

http://library.solarbotics.net/piece...p_code.html#sm

C7 is labelled 104 according to the schematic.

The first two digits are the base numbers ie 10.
The third digit is the multiplier, in this case 4.

So C7 is 100000pf = 100nf = 0.1uf.

[Tripmaster]

A useful link to identify surface mount caps.

http://library.solarbotics.net/piece...p_code.html#sm

C7 is labelled 104 according to the schematic.

The first two digits are the base numbers ie 10.
The third digit is the multiplier, in this case 4.

So C7 is 100000pf = 120nf = 0.1uf.

Thanks for the info, very helpful!

Do you happen to know which chip solder pads need to be connected to enable a bypass?

[iihay]

Thanks for the info, very helpful!

Do you happen to know which chip solder pads need to be connected to enable a bypass?

Answer is lurking here:

http://theartofsound.net/forum/showt...?t=315&page=11

Iain

[Tripmaster]

YES!

I've just soldered the the link in the past five minutes. The sound is back albeit only the right channel, and its not distorted. It is however sadly lacking in the bass department. Progress!

I have checked the connection between pin one of the opamp to the left output pin and its fine. I attached the meter to the right output pin but could not make a connection with any of the other opamp pins. I do have a connection between the blob on the base of the board and the right output.

I have tested the leads to the rca sockets and they appear fine.

Any suggestions?

Richard

[leo]

well done, at least you have some progress!

Don't suppose you have a scope? it would make finding whats causing the missing channel much easier

Regarding the bass, see the bottom pic with the three oscons? try changing the middle oscon to say a standard 10uf electrolytic, let it run for an hour and see if it makes any difference, that cap is for the dacs internal analogue bias, low ESR is good here but I personally didn't like a oscon in that position

also the large pair of caps in the middle of the board seem to be non polar, these are not really suited for supply decoupling, try a couple of polarised caps there instead

I know its hard but also try to keep the legs of the caps as short as you can, your adding inductance with the long legs, the caps should have as short lead length as possible to the chips, it makes them more effective

[leo]

I'll be starting another dac thread soon

[Tripmaster]

well done, at least you have some progress!

Don't suppose you have a scope? it would make finding whats causing the missing channel much easier

Regarding the bass, see the bottom pic with the three oscons? try changing the middle oscon to say a standard 10uf electrolytic, let it run for an hour and see if it makes any difference, that cap is for the dacs internal analogue bias, low ESR is good here but I personally didn't like a oscon in that position

also the large pair of caps in the middle of the board seem to be non polar, these are not really suited for supply decoupling, try a couple of polarised caps there instead

I know its hard but also try to keep the legs of the caps as short as you can, your adding inductance with the long legs, the caps should have as short lead length as possible to the chips, it makes them more effective

Hi Leo

Thanks for your reply

I meant the left channel is working, not right. I intend to cut the legs much shorter when this bloody thing works!

I have put a meter between pin 1 of opamp and L-OUT and its fine. But I don't get a reading between pin 7 on the opamp and R-OUT. If I turn up the volume on the amp and turn the balance control right around I can hear I faint sound (Probably cross-talk)

Completely stumped