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Yes, the measured output at IC9/12 are the same. The top of a sine wave begins to fold over itself just after .7V p-p. I'll scope it again tonight and give you a picture from pin 4 & 5 of the chips. I double, triple checked both + and - 15.00V inputs of the left and right VA and it's exactly right.
I have gone direct spdif (coax) in and sdpif directly out of the toslink, bypassing the mux, same results.
The volumite is being powered from the B32 board at 3.3V (as perscribed above).
How do I wire it up for PCM? There is Mck, bck, lrck and dout on the mux, but Dck, D1, and D2 on the B32. I'm not sure which clock to use and what to connect to d1 & d2. I haven't found in the Buffalo manual instructions on this.
one more question...what's the best/proper way to include images here?
RossG
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After you have posted a message you will see an "attach" button at the top right. That allows you to attach images etc to your message. Its a little different. So this is odd, since at first it seemed only on the left channel. To connect PCM out of the MUX wire as follows: BCK -> DCK; LRCK -> D1; DOUT -> D2; GND -> GND Let me know how that test works out. Edited by user Friday, May 29, 2009 2:36:10 PM(UTC)
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I connected as PCM, no difference. I began this series of posts saying the left side was distorted. This was based originally on listening tests. I guess the string bass in Spanish Harlem is more towards the left channel than the right. In scope measurements last night I found the sine wave fold over on both channels. My test CD is a 1kHz sine wave which generates a 3V P-P analog signal at the output of my CD player. It didn't produce any distortion with the original Buffalo. Also, the left and right analog channels coming out of the CD player measure the same. So I would expect the output of the Buffalo-32S to be equal, they are not. I dial down the volumite to where the pins 4 & 5 of IC12 produce a .72V p-p undistorted sine wave, but I measure pin 4 & 5 of IC 9 at .60V p-p. So an equal left and right input signal does not produce an equal output between the left and right channels. Below are scope images of the distorted sine wave. I'll only show the right channel because the left looks the same, just a little smaller. Image 1: Pin 5 IC12 krgaunt attached the following image(s):  IMG_2115_sm.jpg (146kb) downloaded 506 time(s).You cannot view/download attachments. Try to login or register.
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Here is Pin 4 of IC12, again, pin 4 of IC9 looks the same just a bit smaller in amplitude. krgaunt attached the following image(s): IMG_2116_sm.jpg (146kb) downloaded 503 time(s).You cannot view/download attachments. Try to login or register.
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Ok, now it gets interesting. Here is pin 1 of IC12 (the output of the Sabre?), again, pin 1 of IC9 looks like this also. This shows the input to IC12 when it's folded over and producing the output image above for pin 4. Edited by user Friday, May 29, 2009 11:07:53 PM(UTC)
| Reason: Not specified krgaunt attached the following image(s): IMG_2119_sm.jpg (135kb) downloaded 478 time(s).You cannot view/download attachments. Try to login or register.
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Hi Ross, Yes it looks like something is amiss, but I am not sure what. Can you send Hi resoultion pictures of the top and bottom of the board?
I need to be able to read part values.
If you can't you will need to send the board in.
A couple possibilities:
1) There is some issue with parts on the board.
2) The DAC itself is borked.
I am still stumped. Have never seen this before.
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krgaunt wrote:Ok, now it gets interesting. Here is pin 1 of IC12 (the output of the Sabre?), again, pin 1 of IC9 looks like this also. This shows the input to IC12 when it's folded over and producing the output image above for pin 4.
Hmmm now that is interesting. Pin 1(and 8) of IC9 and IC12 should be at ~1.65VDC all the time. Edited by user Friday, May 29, 2009 11:11:24 PM(UTC)
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Finally, here is pin 8 of IC12, which is the same as pin 8 of IC9. Same signal conditions as my last post. I can send up to 10Mpix images, but your server limits file size to 200KB. I don't have any sort of web pages where I can post the high res images of the top & bottom of the board. Got any suggestions? PS: what are you doing up so late? Edited by user Friday, May 29, 2009 11:12:26 PM(UTC)
| Reason: Not specified krgaunt attached the following image(s): IMG_2120_sm.jpg (134kb) downloaded 474 time(s).You cannot view/download attachments. Try to login or register.
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krgaunt wrote:
PS: what are you doing up so late?
Truth be told, just got in from a party with some good friends. :)
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Ross, unfortunately I am dreadfully tired and need to get to bed. But I will look at this in the morning. If you can send me some pics. From your scope shots I am wondering if there is some issue with the resistors not matching at the I/V stage. R38/R39 and R24/R25 should all be 360R. Cheers! Russ Edited by user Friday, May 29, 2009 11:23:29 PM(UTC)
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R38,39,24,25 measure 360R. I don't see any solder problems. Did you see anything in the high-res images that I emailed?
Unless you can think of anything else that I can check, I think I've gone as far as I can. Would it be possible to send the board back to you to fix? Any failed components I'll happily pay for. It's possible that I may have caused some part failures in the way I handled the board. No way to really figure out the cause of the problem. I'm only interested in a working board. So any new parts you put on the board, including a new Sabre chip if necessary, I'll write you a check. I'm naturally interested in getting it running, but not in a way that would decrease your slim profit margin.
RossG
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Hi Ross,
I just started a new job, so I have not been able to do much lately. I apologize for the late response.
I will have to get with Brian for a resolution.
Sorry for your frustration. I really don't know what is wrong, its impossible to diagnose from afar.
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Russ,
Thanks for getting back. Thinking back, I believe I initially powered up the Buffalo with a ground connection to only the right VA connector, and no gnd to VD or VA left (maybe the left VA also, can't recall). This was before the info was posted about the jumpers on the underside. I was unaware of the 3 ground planes on the board at the time. Back with my Bufflao 1.0, ESS found noise problems caused by bad ground routing, so with the B32S I made a star ground scheme, with one ground to the board. My guess is that I fried the Sabre chip. In my recent tests, the analog IV sections of the board seem to be doing what they are supposed to do, but the input to IC 9 & 12 is garbage (see post above Friday, May 29, 2009 8:03:23 PM, which is a sine wave output of the saber).
I have no equipment to replace the chip. So once you two are back in business, could we discuss repairing the board and the parts & labor cost to do that?
Ross G
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Are you guys in a position yet to answer the above question regarding sending the board back for repair?
RossG
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Hi Ross.
I am not sure what to do. I don't think we even have any spare chips to pop one in. They basically go to the manufacturer on a just in time basis.
Brian and I have not really had a chance to discuss it. We will soon.
Sorry for the bad luck.
Cheers
Russ
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I understand what you are saying. And I know Brian's working to get this next batch of boards out. But I'd much rather fix this board than purchase another one. So I'm trying to get a handle on my options. Would I be able to purchase a single Sabre chip from a suppler? If so, do you have a way (or could I pay you or our manufacturer) to remove the old chip and install the new one? I feel like I have an expensive boat anchor. Should I look to someone else (like the forum) to get the chip replaced? RossG Edited by user Wednesday, June 10, 2009 9:29:26 PM(UTC)
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Hi Ross, My rework skills are definitely not good enough to attempt it for anyone other than myself. I can't speak for Brian. I am afraid if I tried I might kill the new chip and that would just make things worse. There maybe others who are more confident. Edited by user Thursday, June 11, 2009 5:06:15 AM(UTC)
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Hi Ross,
If you can get the 9018 chip, I'll replace it for you. I have the equipment, and routinely do SMD rework. You can contact me at tailspn(at)yahoo(dot)com
Tom
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Tom,
Thanks for the offer, I think I'll take you up on it. I'll let you know when/if I get a new chip.
RossG
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