I run all three wires to the source and gnd the -input at that point...works using an ipod for a source.
Hi DUG,
Thanks for your prompt reply. I looked over the schematic a few more times and lifting the pin seemed like the only solution. I might try later with a second set of boards. Not willing to take a chance on ruining this amp just yet.
I have been following gmarsh 's GB thread and will most probably pick up one of his boards. But I like the PTBL option for dual mono or multichannel. It also may have some advantages for me in terms of the output LPF. I would like to try filtering so that the cutoff frequency is upwards of 100 kHz. That is why I wish to increase the switching frequency.
BTW, your board was very easy to build and sounds great.
Thanks again.
Thanks for your prompt reply. I looked over the schematic a few more times and lifting the pin seemed like the only solution. I might try later with a second set of boards. Not willing to take a chance on ruining this amp just yet.
I have been following gmarsh 's GB thread and will most probably pick up one of his boards. But I like the PTBL option for dual mono or multichannel. It also may have some advantages for me in terms of the output LPF. I would like to try filtering so that the cutoff frequency is upwards of 100 kHz. That is why I wish to increase the switching frequency.
BTW, your board was very easy to build and sounds great.
Thanks again.
DUG,
With regard to using the B1, I guess what I wad trying to say was that as the B1 has an output cap, if I understand things correctly, I can forego putting input caps on the amp. The B1 buffer will be in the same case as the amp and its outputs connected directly to it. The TI datasheet led me to believe that the unused input to the amp should be grounded to the chassis through an identical capacitor at the B1 output. Does this make sense?
With regard to using the B1, I guess what I wad trying to say was that as the B1 has an output cap, if I understand things correctly, I can forego putting input caps on the amp. The B1 buffer will be in the same case as the amp and its outputs connected directly to it. The TI datasheet led me to believe that the unused input to the amp should be grounded to the chassis through an identical capacitor at the B1 output. Does this make sense?
Okay I am having a problem and I can't figure it out. I don't think I've royally munged the traces in my rework, but I still can't get there.
I figured out the startup mute wasn't working, so I removed those elements. I removed the slave resistor from the master slave connection to deactivate the function, but left the gain resistor in place. Voltages on the supply caps looks good, as do the connections. I've checked/rechecked my bom and think I have the right components - but I will admit I'm a noob an maybe I should just stick to modding until I have a better idea of what I'm doing. I just really want to hear this card sing.
Maybe I'll just desolder the whole board, clean it up and start over. I have a heat gun station so that's not much trouble.
I still don't really know what to use to clean the board with that is a good fit. Off to youtube I go...
I figured out the startup mute wasn't working, so I removed those elements. I removed the slave resistor from the master slave connection to deactivate the function, but left the gain resistor in place. Voltages on the supply caps looks good, as do the connections. I've checked/rechecked my bom and think I have the right components - but I will admit I'm a noob an maybe I should just stick to modding until I have a better idea of what I'm doing. I just really want to hear this card sing.
Maybe I'll just desolder the whole board, clean it up and start over. I have a heat gun station so that's not much trouble.
I still don't really know what to use to clean the board with that is a good fit. Off to youtube I go...
Good catch - Bootstrap was seated correctly before this pic. Appreciate the reply!!
In this case c14 also came out of place when I removed the inductor (they soak up a lot of air gun heat but it still blows everywhere.
I must have something wrong in my BOM. I know I ordered duplicate resistors (which I corrected in the build) but I am guessing that maybe I have the wrong gain resistor/capacitor combo? I don't need master/slave operation.
Any observations are very welcome.
In this case c14 also came out of place when I removed the inductor (they soak up a lot of air gun heat but it still blows everywhere.
I must have something wrong in my BOM. I know I ordered duplicate resistors (which I corrected in the build) but I am guessing that maybe I have the wrong gain resistor/capacitor combo? I don't need master/slave operation.
Any observations are very welcome.
tpachippins for c13 don't look ok on this photo, so 2 bootstraps look troublesome.
r4 isn't necessary for 20dB master setting, can't see other value for r5, but shouldn't matter if r4 is removed, you can connect a speaker to inductor pads chipside
and two pvcc pins next to c12 bootstrap might not be connected?? photo's always hard to tell
r4 isn't necessary for 20dB master setting, can't see other value for r5, but shouldn't matter if r4 is removed, you can connect a speaker to inductor pads chipside
and two pvcc pins next to c12 bootstrap might not be connected?? photo's always hard to tell
Last edited:
rework update and new pictures
Okay, so I fixed a few errors. My output resistors were completely wrong for the snubbers specified, so I removed. Just working to get it going so I'm not worrying about it for now.
Gain setting resistor confirmed at 39kohms, so that is fine. 100k ohm on R4 confirmed as ok Left R3 in place. Re seated all SMD's. Cleaned and re-tinned the board IC contacts.
Removed the Startup mute components. I know this IC works, I put it in a known good TPA3118d board and listened for over a day.
At a loss now. Giving this 18volts. Confirmed my other SMD's are the right size, including the under side cap.
Massive photos - be warned.
Arg.
Okay, so I fixed a few errors. My output resistors were completely wrong for the snubbers specified, so I removed. Just working to get it going so I'm not worrying about it for now.
Gain setting resistor confirmed at 39kohms, so that is fine. 100k ohm on R4 confirmed as ok Left R3 in place. Re seated all SMD's. Cleaned and re-tinned the board IC contacts.
Removed the Startup mute components. I know this IC works, I put it in a known good TPA3118d board and listened for over a day.
At a loss now. Giving this 18volts. Confirmed my other SMD's are the right size, including the under side cap.
Massive photos - be warned.
Arg.
Attachments
Right - put R3 back in place after the photo was taken 
I've ruled out the IC, confirmed the BOM. I must have a short somewhere. I've brushed the pins with power on (knowing that the chip has a lot of dead-short protection) and I have gotten a couple blips of sound out of it. My only other thought I can come to is to use TI's suggestion and drive the mute pin hi with an inverting transistor from the faultz pin? Any suggestions on cleaning the contacts from the rosin etc would be appreciated. I am only experienced enough to really mess it up and kinda fix it. I attached my BOM earlier.
I've ruled out the IC, confirmed the BOM. I must have a short somewhere. I've brushed the pins with power on (knowing that the chip has a lot of dead-short protection) and I have gotten a couple blips of sound out of it. My only other thought I can come to is to use TI's suggestion and drive the mute pin hi with an inverting transistor from the faultz pin? Any suggestions on cleaning the contacts from the rosin etc would be appreciated. I am only experienced enough to really mess it up and kinda fix it. I attached my BOM earlier.
Alcohol maybe, I use a Kontakt IPA spray, don't really know what is appropiate, IPA works
If you touch J1 pins when power is on and speaker connected, nothing? If you touch c2/c3 chipside nothing? On avcc pin 17 and all pvcc pins you measure PSU voltage? Chippin 10 connected to 11 and to gnd ?
And some more like that. But a short to signal for boostrapinput might not be protected, a too big bootstrapcapacitor can kill chip, so signaloutput too I guess? Not all is protected.
If you touch J1 pins when power is on and speaker connected, nothing? If you touch c2/c3 chipside nothing? On avcc pin 17 and all pvcc pins you measure PSU voltage? Chippin 10 connected to 11 and to gnd ?
And some more like that. But a short to signal for boostrapinput might not be protected, a too big bootstrapcapacitor can kill chip, so signaloutput too I guess? Not all is protected.
I did have a dead bootstrap. Shorting around it causing the TDA to blow - oh well I have a 3118d2 on hand.
Still - c2/c3 gives me nothing. I don't know what my problem is but I'm just frustrated now. I just cleaned the board, removed all smd's on the input side, cleaned again, tinned the contacts, reapplied and still nothing.
voltages look good across the bootstraps at 5v each, bypass caps look good at 17v (PSU) I wish I had something left - I don't think I'll ever know at this rate. Scrap it to crappy soldering skills and too much rework.
I'd be better off starting from scratch if I wanted to go through the pain of ordering the SMD's again.
Still - c2/c3 gives me nothing. I don't know what my problem is but I'm just frustrated now. I just cleaned the board, removed all smd's on the input side, cleaned again, tinned the contacts, reapplied and still nothing.
voltages look good across the bootstraps at 5v each, bypass caps look good at 17v (PSU) I wish I had something left - I don't think I'll ever know at this rate. Scrap it to crappy soldering skills and too much rework.
I'd be better off starting from scratch if I wanted to go through the pain of ordering the SMD's again.
First listen today - making great music!!
BK
BK
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