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Circuit error in Lite DAC-AH: Easy fix - Page 9

post #121 of 209
I get 301 ohm on pins 6 and 8 on all the TDA1543s so that seems fine.

I hope this whole problem wasn't caused by me breaking the damn pot . If it was I'm gonna have all sorts of mods on the way . Pretty much everything but a opamp upgrade actually.

Plus a solder sucker. You ever tried to desolder something without one of those? It ain't easy.

What would a good replacement for c35/c36 be? They appear to be 22uf 40v stock, I may as well get something better for them if I'm going to try to get $25 worth of stuff .

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post #122 of 209
Hey Kim, I noticed you put a heatsink on the ixys BR. Do you even notice it get warm? I actually purchased some from a local electronics store here in my town because those other diodes i was using were just not working out for me. I bought 2 of the 22A 600V IXYS FRED Bridge Rectifier , same ones that partsconnexion carries, and was wondering if i even need heatsinks on them. I would imagine i wouldnt as the dac doesnt draw too much current right ?
post #123 of 209
Thread Starter 
You probably don't need to add a heatsink since the bridge rectifier is able to handle 22 amps. That spec usually assumes that a heatsink is used, but since the DACs are drawing less than an amp, it's almost certainly OK without a heatsink. Besides, there is a sort of built-in heatsink -- the metal plate on one side. I added the heatsink because I had one that fit and I was adding heatsinks to the DACs anyway. I must say though that the heatsink I added to the bridge rectifier does get quite hot -- at least as hot as the DACs, but not as hot as the LM7808 heatsinks. One downside of adding a heatsink to the bridge rectifier is that it does add heat to the DACs nearby. I probably won't add one to my second DAC-AH.
post #124 of 209

Kim, you have PM.

Kim,

I have a technical question that I sent to your PM, would you check your PM please? Thanks.
post #125 of 209
Maybe i do need some type of load on the transformer on the 18v side because i keep blowing a fuse when i try to power it up
post #126 of 209
Thread Starter 
Quote:
Originally Posted by pelayostyle
Maybe i do need some type of load on the transformer on the 18v side because i keep blowing a fuse when i try to power it up
I followed your lead and removed all of the components on the opamp side of my board to make room for larger caps (4.7uF Auricaps). I also left the 18V transformer outputs connected to the board, and I have no problem.

You probably have a short somewhere else, unfortunately.
post #127 of 209
Thread Starter 
Quote:
Originally Posted by pelayostyle
Maybe i do need some type of load on the transformer on the 18v side because i keep blowing a fuse when i try to power it up
I forgot to remind you in case you didn't notice that the IXYS bridge rectifier that you are now using has a different pinout than the stock one. It requires some lead crossing before soldering the new BR. If you didn't do that, then that could be your problem.
post #128 of 209
Quote:
Originally Posted by Kim Hardee
I forgot to remind you in case you didn't notice that the IXYS bridge rectifier that you are now using has a different pinout than the stock one. It requires some lead crossing before soldering the new BR. If you didn't do that, then that could be your problem.
HAHAHA , youre right, pin 1 2 and 4 5 are all gay. Im using the diodes that i had previously gave up on and all is well.

BTW, Im using auricaps now instead of the mundorf. I know i didnt give them a proper breakin but the auricaps sound better off the bat.
post #129 of 209
So...

I sort of fixed the problem. Got the new capacitors today and the static is completely gone, however the volume level, but only on the right channel is VERY low. Like 1/5th the left channel.

The left however, sounds more or less perfect.

Any ideas where to start looking?

Im thinking it might have something to do with the trim pot. With the voltage above 3.9 the left channel sounds fine and is at a normal volume level while the right is very low.

Below 3.85 or so and the volume gets extremely staticy but the volume seems to equalize somewhat.
post #130 of 209
Using the 7806s, I set my voltage at 3.3V and mine sounds fine from both channels. Can you check the voltage on both channels to make sure they are the same? Maybe one of your resistors has a bad solder joint.
post #131 of 209
Thats just the thing, I can't get mine lower than about 3.85v.

Not sure why unless I somehow damaged the pot.

Almost forgot, I somehow managed to rip the LED wires off the board, where the hell were those soldered on? Its not a big deal really, but I would prefer that it work.

EDIT: measuring from signal pin to ground I get about 3.3-3.4mv (measure on the 200m setting) on the left channel and about 3.7 on the right.
post #132 of 209
I just wanted to make sure that you are measuring dc voltage and not ac voltage. I measure dc at the two circles that I use for the bypass, which are shown in some pictures. You should be able to measure any where in the trace that leads to the output section. I get 3.3v not mv
post #133 of 209
OK, im DONE!!! With work and this new girl im going out with i havent had time to work on this thing too much but i finally managed to finish it a couple of days ago.

How does it sound you ask ? AMAZING!! The auricaps have about 48 hours on them and the already sound great, better then the mundorf caps. Im listening to Brand New - Your Favorite Weapon right now and it sounds alot different then it did with the opamps. Im not too good at describing sounds like the rest of you here but i can honestly say that the passive mod is nicer sounding. Music just flows.... guitars stand out more, the singer feels like hes closer to you, drums hit hard, its just more real. I dont know if the other mods i made had anymore impact on the sound then just switching to a passive output alone but it all sounds great together.
On to the PICS !!!

Caddock mk-132 270r on the back cause i had no room on the top. (Rand , you see where the white wires are for the LED)


Ghetto bridge rectifiers , Vishay-Telefunken 1A 1000V Ultra Fast Soft Recovery diodes.


Auricaps for bypass


Vishay vta55 bulk foils in 100r


8200uF Panasonic FC , 680uF FM , LM7808


And another....


Polypropelyne .01 caps from digikey and the micro sinks




Shifted the transformer and flipped power switch


New rca jacks from diyclub. They looked cool and only $6 =)


Here she is action
post #134 of 209
I am going to need someone to mod my Lite Dac-Ah soon.
post #135 of 209

Thanks Kim

For posting this fix. I recently bought one from PV, and soon started to notice the clipping (e.g., Pony Canyon Sampler CD 2002 has many tracks clipping). I knew the output level was too high as I fed the DAC output to a Terratec DMX 6 line in, and could observe the level max out at the moment of clipping. Contacted PV; they offered exchange, but had no clue why my unit was clipping. I wasn't convinced exchanging would fix it. Then I came across this thread which explains everything! I gave the pointer to PV; their response was they couldn't fix it because Li Te didn't admit there was a problem; but they were kind enough to offer an exchange to other models of same price. But I decided to fix it. The board looks too crowded (for my soldering skill) so I attached the 330ohms on the back (accessing the back side is quite easy, see http://www6.head-fi.org/forums/showp...3&postcount=25 ). The clipping is gone!
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