Sabtu, 18 September 2010

TDA1541A , more than I can handle!

Actually I've planned to write about yet another good design bad design thing, this in waiting my mood to finish-tweaking my Spica TC50.
During visit to my audio part supplier friend just before a long Eid el Fitr holiday,  I in all a sudden being blessed by a chance of trying out a bunch of the legendary TDA1541A DAC chips from Philips, not one or three pieces, but 4 tubes with about 8 to 13 chips each!. plus a pair of TDA1541 (non "A")..More than I can I've postponed the Spica tweak and design thing...

My friend is just one out of many victims around the world of TDA1541A frenzy that still on going even today!. It's the Fake or Genuine TDA1541A debacle that started out around 2004. This chip is so high in demand that some people just make  fake ones and sells them. Just read this thread about it in My friend have tested the chip randomly some 6 years earlier, none working he said..

Being a TDA1541 fanatic (see my Sony CDP950 tweak stories starting here ) I took the challenge of testing all 4 tubes, may be, just maybe I can get one or two working chip. As a positive thinking guy I assume there is always some good thing out of even bad guy!. I even told my friend if I can find a good chip I will let him know. So here is the chips, my story & the pics..enjoy!

The tubes, yes in the 90's and early 2000's Philips made the chips in Taiwan, many says even with better production process than in Eindhoven Holland. The highest grade, the TDA1541A/S2 (so called 'double crown') is made in Taiwan.

Testing all the chips here in my salvaged Non Oversampled Sony CDP-M75 with Sennheiser PX100 headphone. This player was totally wrecked and non functional. I've got it from a good friend (thanks mas Yuda!). I planned to take out the DAC only for spare and piggy bagged to DAC in my Lampized Sony CDP950 for higher current output. It turned out that I have the luck to bring it to life :) so here we go..

After testing the chip halfway? Guess what?.. there are 5 chips or so that completely working! But beware!, and I know from the DIYAudio thread later on, there are some chip that can blow your CDP!. Here are the 'test result 'modes' :

  1. the CDP just doesn't want to turn on, no display at all when powered up - the chip felt cold and is busted
  2. as above but the chip felt warm- busted as well
  3. the CDP and the display turns on, the disk spins and worked!....yippee!
  4. the CDP turns on, the display also, the disk spins, chip is very hot and I can hear some music-heavily distorted and interrupted often..then I heard loud DC signal through my daughter's  PX100..frantically  switching off the player.......what... was.... THAT??..
Tried to turn on the player no luck...sigh...yep..sometime you gains..and other time you just loose..within a fraction of a second! This 'mode 4' is by far very dangerous. What I did was repeatedly switching the player on and off during this mode 4, a big No-No, learned later.

After checking the M75 for supply voltages on DAC pins, I found that pin 15 reads should be -14.9 or so... Luckily the other day I got schematic from Mr. Jeffry, thanks Pak! them, testing some components & yes one transistor is surely went busted.

Late in the evening and no electronic shop open for sure, I just browsed my old PCB's junk collection, looking for equivalent replacement, yup, found a better equivalent, 2SB734 in place of the fried 2SA1015. Fit the B734..aah..yes..the player worked again, so I continue testing, until my left hand thumb felt numb putting and removing those 28 legged little monsters...this time I'm very careful, no more switching in on and off again. No display- no disk spin -the chip is simply busted, and yes I recalled another 3 or so chips with 'mode 4'..

At the end of this tense testing session I can smile, BIG TIME :)...the TDA1541 non A worked very well, and hmmm let just say ~20% out of 50 TDA1541A chips are working too. My positive thinking and all the effort paid off well...the harvest? here are they..:)

My conclusions are that these chips were : original and working well (mode 3), the original damaged-rejected ones (mode 4) , original totally damaged rejected ones (mode 2) and the rest is just plain fakes (mode 1)

Me and my friend strokes a win-win deal. I think I'm getting closer to my dream, a dedicated much about these and our audiophiles earthly needs...sigh..., thanks for reading my friend..