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Hi Iain,
Hold on a mo, it is the pads nearest where its mark U1 on the PCB that has lifted? for the left channel?
If so you can run small wire from the SMD pins on that chip which will do the same job, give me ten minutes and I'll edit the pic to show you which pins to link on that chip for the left channel.
What you then need to do is set your multi meter to continuity and measure from the output socket Left to the linked C6 to be sure it measures continuity.
Does that make sense?
Got a pic coming, hold on;) should make it easier for you.Quote:
Originally Posted by iihay
Just as long as its the left channel
This is incase the pads for the left channel are lifted
http://i273.photobucket.com/albums/j...untitled-2.jpg
Splendid that's easy, I'll give that a go. On inspection it looks like my blob on the R channel has linked to a pin as well which I'll have to sort out, bit of a large blob!
Appreciate the help.
Iain
No probs, of course you can easily just cut this chip out and link the appropriate pads, its not needed anyway once the linkings been done
Also if your blob of solder for the right channel touches pin3 or 4 then don't worry about it, the pads go to those pins anyway
Left it as it is then :) Not having a good day soldering wise, I just lifted the a pad from C6 as well. Fortunately it was still connected so I have linked it out and hope all is ok. The soldering iron is turned off now as I obviously have lost the knack today!Quote:
Originally Posted by leo
Ordered up some others bits from RS so hopefully will have the DC mod completely by tomorrow.
Thanks for the help
Iain
BTW, are those cap values for the DC mod crtitical, the ones around the chip, or can they be a little higher? I know I have nothing quite that low but I may have a few spare caps in that sort of range.
Iain
150pf is the values that gives best measurements for that particular filter with the 30k's etc, I guess you can try 100pf, I'm not sure how it would sound, may not make a huge difference.
main thing is getting those 4 resistors the same where as in the standard circuit they are way out and don't make sense, I've no idea why they even fitted such values:lol:
Oh 180pf should be ok too
Hi leo , thanks for all the explanations :) sorry for not being able to receive messages, i hope i will soon.
Hi, it looks like i can't post or even pm you now, no idea why i could not receive pm from you leo... the receive message from other box is checked in my option..
Hi gabdx,
All has been explained in an email :)
Please, as per our policy and request to you, pop into the welcome room and briefly intoriduce yourself and your system to our members.
What is your first name?
Thanks in advance.
Marco.
Hi Gabriel,
Thank you for complying with our request. Welcome, and please continue to enjoy the forum :)
Marco.
Must admit Marco I do much prefer to call people by their proper name, it seems a bit odd saying hi to some of the strange usernames;)
Yep, that's the whole point of why we ask people to sign posts with their real names. Therefore your username can be 'toxiccockhead405' as long as you sign it as 'Frank', or whatever. You can even make up a Christian name if you like as long as it sounds 'real'! :eyebrows:
Marco.
Right now my dac doesnt work at all :( voltages seems extremely low, i am going to recheck the power supply and evrything ,
Leo ! now i can post :) thanks Marco , now for the serious part , i have the bottlehead
preamp with a 33 K resistor in the input ,
I also have another integrated amp with a 100 K volume pot...
Both are unbalanced in, so can i plug (with capacitors of course) the unbalanced cirrus chip into one of these ???
EDIT : the cirrus output used to be 2.5 v DC , now its 0.7 DC and some 0.4 AC... weird , i checked the power supply and its all good 4.7 V and 13 V close enough. The RCA voltages are just around milivolts of DC
On ac the RCA are varying with music around 0.2 Volts AC if i only touch the + or - with one leg of the voltmeter /
If getting a ground point and touching the + or - on the RCA i get around 0.5 Volts
Bottom line i hear no sound !
Yes, I sometimes use my middle name on forums if a member has the same name as my first, as you say though its got to be more convincing than saying Hi toxiccochead:lol:Quote:
Originally Posted by Marco
Toxiccockhead405 is actually my real first name, I just use Iain for forums :lolsign:Quote:
Originally Posted by Marco
Hi GabrielQuote:
Originally Posted by gabdx
Bloomin heck, how did you manage that l:doh:
If your 5v supplies are a lot lower than normal you probably have something dragging it down, could be anything from a short to bad instability somewhere .
You could try posting a close up pic of your dac and we can look for possible faults.
I presume you mean can you plug the output of the dac chip directly into the pre-amp through coupling caps?
If so, yes you can but I wouldn't recommend doing this with a solid state pre amp if it only has single line in rather than balanced.
You won't get the benefit of the noise canceling without a differential to line out using this type of dac, you'll also have no output filtering, it may sound pretty nasty, you can of course try it, using something like the lampizator valve stage makes things a little more forgiving when using the dacs direct negative left and right out.
You can also try it with your bottlehead pre, I've no idea what it will sound like but just be careful if you give it a go;)
You edited before I posted:ner:
I presume this 0.7v DC is what you are measuring at the dacs differential outputs to ground and not on the line out after the op-amp?
Yes i can post a picture very soon,
regarding the voltages on the supply , i think i have partially fried the little regulators feeding it with incorrect wiring on my china kit transfo, these guy in china didnt gave me any instruction how to connect it ! Since i have replaced it with a wall pack 9 V that really is giving me over 11 volts. Ill try it with direct coupling on the preamp we will see.
Can I call you cockhead for short then ? :eyebrows:Quote:
Originally Posted by iihay
Exactly , and it used to be 2.5 VQuote:
Originally Posted by leo
http://gabdx.webs.com/DACG/Picture%20009.jpg
http://gabdx.webs.com/DACG/Picture%20011.jpg
http://gabdx.webs.com/DACG/Picture%20013.jpg
http://gabdx.webs.com/DACG/Picture%20014.jpg
Yes, problem with a lot of this stuff is that its usually cheap for a reason, I won't comment on here my experience with certain products made in China:steam:Quote:
Originally Posted by gabdx
did you try removing all the links across C27,28,30 and 31 and measure again? this just eliminates any problems on the boards analogue sectionQuote:
Originally Posted by gabdx
Also check the voltage on the dacs onboard U4 SMD regulator, it should be 3.3v
Check for any shorts or track breaks around capacitor C25, this is for the dacs internal bias
Also check the CS4397 analogue supply pin (pin22) it should have 5v going to this pin
i did mesure again without the links and it give low reading, mostly around 0.4 volts ac or dc.
the 22 pin indicate - 1 V and 21 +1 V, the U4 has 3 pins, 1 to 3 = -2 V
2- 3 = around 1 V.
Imo it looks bad
Quote:
Originally Posted by gabdx
Hmm, thats not good mate:scratch:
The onboard 3.3v seems a little low but its that 1v for the dacs analogue which is the main problem.
Set your multimeter to continuity/bleep, turn the dacs power off and measure pin22 to ground, does it measure short circuit or low ohms?
If so you either have a short somewhere on the supply lines or if your very unlucky the dac chip may have gone
I'll wash and then you can drop the toxic ;)Quote:
Originally Posted by leo
Iain
--
Another totally off-topic post from the keyboard of Toxiccockhead405
Another thing to check, the small connectors inside the big white plastic plug, those things are really shite in all honesty, I've known the plastic sleeving for the cables can sometimes not be stripped back enough so the metal crimp does not make a good contact with the cable core.
Because my dac uses a different regulated supply to the standard one I removed the plastic socket and fitted something else
Thats a little bit too much info there mate:lol:Quote:
Originally Posted by iihay
Hahaha... :lolsign:
Slightly off-topic but it reminds me of a wee joke...
A chav Scottish couple called Bobby and Betty are trying to mix it with the posh set are at a dinner party. The champagne's flowing and everything's going well. The hostess spotting that they're without nibbles passes them a tray of canapés and asks Betty in a snooty voice: "Cheesy dip?" to which Betty replies: "Naw, hen, he washed his cock this morning..."
:eyebrows:
Right, back to DACs...
Marco.
Thats put me off Dairylea dunkers forever!
Nowt wrong with these odd off topic posts, it adds a bit of flavour to the discussion even if it does involve a bit of cheese :lol:
Ground is ok, no shorts , only short to the 5 V , 20 M ohm to the Ground = evrything ok
I RESOLDERED every power connections :)
Good news the cirrus dac show a healthy** weird**1.7 V AC+DC , with some weird 0.4 V DCat output.... i think i am going to try it directly on my buffer ( bottle head foreplay ) then to the integrated tube amp...
...hope nothing blow up
It mesured around 0.1 V DC without any music playing at the output of the buffer same with music playing... ok...i hope... should be ok ... if you have a bottle head pre, never turn it down first it gives 20 V DC... you hear my speaker cry when i did that sometimes... they need mostly only 5 V to play at peak level!
result : just noise, ground problem, sound like a rca socket with defective ground, leo i anticipate your next post, change the kit sockets, lol ill try to tight them very hard and it should work :mental: , but i think even then it's not going to work . Anyone has a good dac to recommend me ?
Not a great thought! Back on DACS I am interested on your thoughts as regard the PSU. How good/bad is the supply supply versus a decent diy job?Quote:
Originally Posted by leo
Iain
My dac looks worst and worst , before i rip evrything apart ill try to revert all the modifications...
I never had the standard psu so can't comment on its quality, it certainly helps to use the best you can though, something with low impedance low noise is what I use for both analogue and digital regulationQuote:
Originally Posted by iihay
Theres plenty of cheap diy designs about, its easy to go mad but obviously seems to defeat the object of this cheap diy project.
Could use something like a cap multiplier supplying a shunt set for 5v for the dac.
Adding a current regulator diode from the op-amps output to the supply pin with worst PSRR can add a nice improvement on the cheap, if you can't find a suitable CRD its easy to make one using a Jfet with a resistor through it to set the current, also add a resistor before the CRD to help with the capacitance
I think its just been a bit of bad luck you've had, it makes sense removing the mods to see if the fault can be isolatedQuote:
Originally Posted by gabdx
I think it's completely out of usage , the cs itself seems dead, maybe i did a short some capacitor and it burned something inside... I tried evrything i could and nothing works.
If the CS8416 receiver or the CS4397 dac chip has gone theres the option of replacing the chip if your confident
http://uk.farnell.com/1023396/semico...questid=484498
http://uk.farnell.com/1023451/semico...gic-cs8416-csz
Got to be cheaper in real terms to buy another board.
Thanks guys, especially leo :) and hi iihay i got me too a ska under construction :)))
Well i might buy a Rakk, or some modified lite 60 , i still don't know and my confidence with china products is going down and down ... though i think the dac is my fault it's a warning about it for moders !, had no problem modifying my dared amp tough ! no chips :)
I had 2 other bad experiences with chinese products : buying on ebay this guy a opamp like 85 $ and its a non working one, lost my money,
Now i bought some preamp transformer and the instructions are far from clear.. chinese is so tempting because it looks half price of usa gear but there is always a catch somewhere in the design or on reliability.
You'll love the SKA, quality bit of kit :)Quote:
Originally Posted by gabdx
Quote:
Now i bought some preamp transformer and the instructions are far from clear.. chinese is so tempting because it looks half price of usa gear but there is always a catch somewhere in the design or on reliability.
I bought a Lite remote controlled Pre-Amp from DiyClub.biz. Cost aout £20 with shipping. 4 unbalanced and one balanced input, relay switching for inputs, Alps motorised pot.
Kit came with no instructions at all as to which pins to attach which sets of wires, and more inportantly how to wire up the senser and adjuster. I emailed and got some info back. Pidgin English! Good start.
Turns out the wire patch cables are insufficient. Some pin sets are 6 pins and the cables have only five wires and 5-hole connectors. If I didn't have copius amounts of "rubbish" that I have taken off over the years. I would not have been able to get it working.
The thing is actually very good for the money and the volume control works quickly. However if you were a newbee you would not have got it working.
Some more fiddling, poor things had more alterations :lol:
http://pic20.picturetrail.com/VOL129.../331627487.jpg
Hi guys !
I also have this DAC and i have done those simple bypassing mods and i putted 2 oscons in C20 and C17.However ,i have not tested if it's working.
Offsets with original opa are 75mV for L and 180mV for R .
Are those values ok?
Will it be ok if i solder 75R coaxial cable direct on board instead of RCA socket?
I 2 have one of those JVC transports so i would solder coax on it 2...
Theres a flaw in the original output stage, no matter what chip you use there will always be a DC offset, if you want to lower this you have to properly mirror the differential output, by changing a couple of caps and resistors it lowers the DC offset to +/- 1mV , it also improves the frequency response , the original circuit doesn't make a lot of sense TBHQuote:
Originally Posted by chakija
for now the DC offset is too high so use a decent quality pair of coupling caps on the output to be safe, even though your amp may have an input cap its not recommended to have DC across the pot tracks for the pre, in a lot of cases you get the coupling cap after a pot so any DC tends to give a scratchy sound when adjusting volume, it can damage the tracks
Well ,i think i menage to kill my dac 2 .
With stock opa bypassed ,i connected to 2.2uF and 47R on 100K pot ,and then to my aleph J iteration amp (babbelfish J).I got some loads on speakers even with pot turned down.I didn't have courage to even touch the pot !
I instantly turned it off after 1 minute.
When i turned it on again and measure offsets ,i had some huge values like 1700mV ,and after few secs i didn't have any value at all.Finally ,i cut bypasses and measure exit's from dac and it seems dead.:wah:
Source is from my jvc transport connected directly on board with 75R coaxial.
I disconnected spidf and i tried to measure again.
I have now 0.25 V on R+ R- and L+ L- from dac.Does this means it is maybe still alive ??
I've been following this thread for a while and have finally decided to contribute something, albeit a request...!
Leo, do you have a link to a schematic of this amp? I'm just wondering how you know so much about how to effectively modify it, or have you just worked it all out? I'm more interested in the output stage, as I'm considering using it to feed my main amp.
thanks
Lots of experience in fiddling with things:lol: I find it hard to resist not to meddle with any piece of kit I buy.
Everything is made to a given price, the tweeker does not have these limitations so if theres anything we don't like in a particular circuit we simply faff about until its improved.
Theres also a few design errors on this dac which is probably why they are being sold for cheap
There is a schematic for the dac somewhere (I'll see if I can find it) although a lot of the part numbers on the drawing is different to whats on the pcb so it just requires working out