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another weird s/pdif unstability problem in BIII dac with sidecar and s/pdif pcb
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hello
somebody mentioned transistor error on sidecar
I have BC 639 on at least on of them
is it supposed to be BC550?
can this cause the trouble?
best
Leif
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Rank: Member
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removed transformers and installed jumpers on s/pdif pcb
still weird:
both s/pdif 1 and 2 play rock solid when other input is unconnected from rack isolated rca connector to pcb input
once wire from unused rca minus is connected to unused imput minus, active s/pdif looses lock
not same with positive lead to positiv input
neither input will play with muinus signal connected to gnd instead of minus input header. i.e shorted
if I hook up both inputs and put a jumper between the minus signals on the rca connectors, and move source cable from Denon dvd to input 1 to 2 the lock is stable on either input whether selector is on 1 or 2
not so wth wav sd card player player
any way I can measure if a source is consumer lvl or ttl lvl?
any checkpoints I can Ohm to look for differences on input 1 and 2?
best
Leif
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Try tying - to GND on the input headers (directly).
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still without transformers: tying minus to gnd on input headers on s/pdif board mutes the signal when playing with good lock and disconnected minus lead on other input, mutes anyway actually are the R5-16 correct values at 4K7? when I measure across R13/14/15 and 16 I get 4K7, the rest 2K9 just touching the minus header on the unused input with a screwdriver creates immedeate dropouts and instability on the other input in use what puzzles me is that both dac´s are the same, even slightly differently configured this grounding scheme has always been good enough with BII or any other application at least I2S is rock solid now best Leif Edited by user Tuesday, April 17, 2012 2:51:52 PM(UTC)
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Hi Leif,
I think Henri has got the solution in his hand. I try to get me some drawings so we can use it too!
Jordo
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hello
will try tonight, but first I have to fix my mailbox that was seriously spammed yesterday, despite I never open anything!
now Microsoft closed it, so I have to re-initiate it through some sort of MS initiated process
best
Leif
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Ok, sorry to hear! We builders can use all the time available.. I made a little drawing which I made from the pictures Henri showed me. I hope it's correct like this. Maybe Russ or Brian can approve this. I will ask them. Success! Jordo Jordo attached the following image(s):  spanningsdeler.png (12kb) downloaded 170 time(s).You cannot view/download attachments. Try to login or register.
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Ok forget the last picture, this is how it should be done: Jordo attached the following image(s): spanningsdeler 2.jpg (18kb) downloaded 169 time(s).You cannot view/download attachments. Try to login or register.
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I replaced the 10K on input 3&4 with 75R and there´s no change
still unstability with open unused input or connected unpowered
best
Leif
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Jordo wrote:Ok forget the last picture, this is how it should be done:
As long as by + and - you mean the TTL output of the TORX board. :)
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Like this or reversed? (I just worked out the picture before I read your post) Jordo attached the following image(s): spanningsdeler 3.jpg (27kb) downloaded 145 time(s).You cannot view/download attachments. Try to login or register.
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Jordo wrote:Like this or reversed?
(I just worked out the picture before I read your post) Reversed.
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Hahaha! I was already busy correcting it. Henri fooled me. He is drawing from right to left  Edited by user Thursday, April 19, 2012 4:30:04 PM(UTC)
| Reason: Not specified Jordo attached the following image(s): spanningsdeler 5.jpg (27kb) downloaded 130 time(s).You cannot view/download attachments. Try to login or register.
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Rank: Member
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can´t even make it work properly with:
75R on all inputs
w/o x-formers on s/pdif 1&2
both pluss and minus tied to gnd on unused/and unwired 3&4
??????????????????????????????????????????????????????????
separate switch for vdc to sidecar "b" taken from BIII I2C header
best
Leif
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could you guys possible send me 2 FW chips to test
I´ll pay of course
can´t think of anything else.....
pleazee?
best
Leif
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Jordo wrote:Hahaha! I was already busy correcting it. Henri fooled me. He is drawing from right to left That is still not right , the 75 would come at the opposite end of the 270R.
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Russ White wrote:Jordo wrote:Hahaha! I was already busy correcting it. Henri fooled me. He is drawing from right to left That is still not right , the 75 would come at the opposite end of the 270R. Damn, I will adapt it this evening. But some other solution maybe; Someone on the Dutch DIY Audio Forum came up with the idea to connect the Toslink module directly to the DAC bord so the S/Pdif module and Sidecar will be bypassed. This will prevent some TTL conversions. And the COAX cables can be connected to the S/Pdif board the conventional way.. The only downside will be that the Toslink to DAC signalcables will be a bit longer.. I will try it this evening. Sounds like a good idea? Jordo
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Hi Jordo, I'm thinking of redesigning the backplate of the dac in a way that all the inputs lye directly behind the 4*SPDIF board. I'll try to design a double layer print that houses 2 SPDIF modules and 2 coax inputs and place for the Voltage dividers. The board should be mounted on the connector of the 4*SPDIF board and he inputs will be shielded with Tin compartments connected to GND. In that way you will not have a need of coax or whatever kind of wire to connect to the 4*SPDIF board and influence on one eachother will be minimised. I want to do this because I think the SPDIF inputs are very sensitive for all kind of factors: Long wires, interferences, etc. Btw.: I appologise for the confusing information I gave about the Voltage divider. I attach a few pictures of how it should be . I think I switched the values of the resistors in one of the pictures i've sent. Kind regards, Henri henri47 attached the following image(s): fig05.gif (4kb) downloaded 69 time(s). spanningsdeler.png (9kb) downloaded 71 time(s).You cannot view/download attachments. Try to login or register.
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Rank: Administration
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Yes that is correct. It is very easy to neatly accomplish this without any board. Just take the two resistors and solder one end of each together along with the hot wire of the pair or coax. Then put the free end of the 270 in the OUT terminal, and the free end of the 75R in the GND terminal along with the cold wire or the pair or coax(soldering them together is a good idea). Run this to the SPDIF4 or Sidecar if you are using it. Very simple. To be clear the SPDIF4 module is a comparator circuit. It is designed to turn a small signal into a large one. The TORX board is already a large signal and it can easily swamp the comparator input as well as distort smaller signals via EMI. It also likely causes some nasty reflections. It is *MUCH* better to convert a TTL signal to consumer level prior to the SPDIF4. In my experience, and long as you keep the ribbons short and the pairs from the consumer inputs twisted or shielded you need not fret very much. Still it is definitely best to keep the routing as neat and short as practical. Cheers! Russ Edited by user Saturday, April 21, 2012 6:07:41 AM(UTC)
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another weird s/pdif unstability problem in BIII dac with sidecar and s/pdif pcb
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