Painkiller said:I bought an unused TDA1541A off e-bay, and have built myself a simple dac. When I power up I get some strange readings, and hope to get some tips from more experienced diyers.
All power supplies work perfectly when not loaded. I use 78xx/79xx series regulators in a pretty regular fashion, but with snubber on outputs. When I connect the chip Vdd2 drops from -15VDC to -5.6VDC. I also get uneven dc offsets on the outputs, 4VDC on the right and 1VDC on the left.
Could there be an external factor in the cirquit causing this, or is it a faulty chip? Board looks clean with no short cirquits or other obvious mistakes.
When I had a VERY similar situation it was lack of triggering to the TDA that caused my weird offset problems. I had the input to my 8414 shorted by putting the wrong capacitors in for C102 and C103. No output from the 8414. No input triggering to the TDA. Once that was corrected my TDA worked perfectly.
Regards,
Dan
An externally hosted image should be here but it was not working when we last tested it.
Well I received a new chip yesterday. This one is definitely different. The printing is much weaker, and it has a white stripe on the left. Still an R1, but now it says HSH88. Seems mote authentic.
Now when I power up, my -15V reg blows. Any chance that the chip draws too much current when powering up? The PSU seems normal during testing with 100mA.
Now when I power up, my -15V reg blows. Any chance that the chip draws too much current when powering up? The PSU seems normal during testing with 100mA.
hi painkiller,
I was so unhappy to see your thread.
Since in China there are too many remark chips us dead or 1541 remark to 1541a.
In my memory. the latest production period of 1541a was not pass 1999.
Probably I was wrong.
I post several photos for U to versify different grade of 1541a.
thx
thomas
I was so unhappy to see your thread.
Since in China there are too many remark chips us dead or 1541 remark to 1541a.
In my memory. the latest production period of 1541a was not pass 1999.
Probably I was wrong.
I post several photos for U to versify different grade of 1541a.
thx
thomas
Attachments
Well, I definitely had a PSU problem. There must have been some bad caps or something. I've made a completely new PSU, and it seems to work without problems.
There is sound now, but it's awfully noisy. I suspect I damaged the chip when the regulator blew. -24V on the -15V pin can't be good. I also get 500mVDC on the outputs. Again not good. The problem is at lest symmetrical though. What other causes can there be for DC on the output?
There is sound now, but it's awfully noisy. I suspect I damaged the chip when the regulator blew. -24V on the -15V pin can't be good. I also get 500mVDC on the outputs. Again not good. The problem is at lest symmetrical though.
What other causes can there be for DC on the output?
Take care when bying 1541...
there are so many fake chips.
even, one diyaudio member find that they marking 1540 chips like 1541...
I had a bad experiance too
the vital importance is to check every character in marking
and compare to original.
there are few wery unique chrs like "A"
or "1", "2" "5"...
almost every one.
if some or one are different that is the fake.
Do not put the new chips in device please there are big chance to damage the PS...
The chip must remain lets say warm only with a test PS and OP amp like IV...
then try to put Riv, with a same Temperature...
The power supply consumption must stay in reasonably values
and no overheating...
The original chips I try, perform on this way.
The fake ones, blow up fuse of 100mA I think at the -15V,
and was very hot...
cheers
there are so many fake chips.
even, one diyaudio member find that they marking 1540 chips like 1541...
I had a bad experiance too
the vital importance is to check every character in marking
and compare to original.
there are few wery unique chrs like "A"
or "1", "2" "5"...
almost every one.
if some or one are different that is the fake.
Do not put the new chips in device please there are big chance to damage the PS...
The chip must remain lets say warm only with a test PS and OP amp like IV...
then try to put Riv, with a same Temperature...
The power supply consumption must stay in reasonably values
and no overheating...
The original chips I try, perform on this way.
The fake ones, blow up fuse of 100mA I think at the -15V,
and was very hot...
cheers
I found a webshop in the UK selling genuine TDA1541A R1's. It's called Little Diode.
So... I have a working chip. Voltages on all pins are right according to the table on Lesha's dac page.
But I do have 500mVDC on the output. And I have 2VDC on the inputs! No wonder the sound is noisy. How can I get so much voltage out from the input pins? Anyone heard of this before?
So... I have a working chip. Voltages on all pins are right according to the table on Lesha's dac page.
But I do have 500mVDC on the output. And I have 2VDC on the inputs! No wonder the sound is noisy. How can I get so much voltage out from the input pins? Anyone heard of this before?
Resurrecting this old thread to report identical experience.
Ebay auction with photo showing a taiwan made TDA1541A but received a fake marked HSH0123 that overloads the -15V regulator.
Hope I get a refund....
Ciao
Andrea
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