[mcgo]

You do like the TDA1543 I've been through a few dacs during this journey and I am now 100% sold on the NOS sound! Hopefully the train-wreck of delta-sigma will fade away as more audionerds demand multibit solutions, and with the availability of the oldskool TDA1543, everyone can make the switch for minimal outlay! It is the difference between lifeless and lifelike. The DS crowd can keep their crazy THD numbers and smeared time-domain timbre and I'll enjoy the one that sounds great!

 

[Bubel]

Hi guys, my first post here. Got my Muse last day - badly packed. It`s sound pretty good for...one minute, after that - terrible loud static noise on booth speakers and sound becoming muffled. When digital (I`m used optic) cable unplugged - no noise after few minutes of use but random cracks and hisses for very short period of time only in left speaker. I checked the PCB and find out that C15 cap is inverted. The others 3 have 104 mark in opposed direction. Could this be a problem? Thank you!

 

[jwr3]

Isn't c16 a non-polarized ceramic cap? WHAT is the value of your wallwart? Voltage and amperage?

 

[Bubel]

Isn't c16 a non-polarized ceramic cap? WHAT is the value of your wallwart? Voltage and amperage?

I tried 12V 6A, 12V 2A, 12V 1A, 9V 850mA - same result.
And I switched cap "polarity" - nothing changed

 

[jwr3]

I tried 12V 6A, 12V 2A, 12V 1A, 9V 850mA - same result.
And I switched cap "polarity" - nothing changed

The 12 volt 6 amp and 12 volt 2 amp could have burned out the input diode and the LM 417. It did mine. I replaced them and got back music. And it still works fine. The 9 volt 850ma may be safe to use. We're you using the 12 volt when it stopped working?

 

[jwr3]

The 12 volt 6 amp and 12 volt 2 amp could have burned out the input diode and the LM 417. It did mine. I replaced them and got back music. And it still works fine. The 9 volt 850ma may be safe to use. We're you using the 12 volt when it stopped working?

OOPS! LM 317 NOT 417

 

[Bubel]

The 12 volt 6 amp and 12 volt 2 amp could have burned out the input diode and the LM 417. It did mine. I replaced them and got back music. And it still works fine. The 9 volt 850ma may be safe to use. We're you using the 12 volt when it stopped working?

Yes, I was used 12V first time. Seller`s page stated 12-15V for this board. Is there a easy way to check if LM 317 and diode burned? I only have multymeter

 

[jwr3]

Yes, I was used 12V first time. Seller`s page stated 12-15V for this board. Is there a easy way to check if LM 317 and diode burned? I only have multymeter

OK. I measured the voltages on my Muse TDA1543 X 4 DAC . The is the one I repaired 2 or 3 years ago. Using a 9 volt 500ma wall wart I measure 9.79 volts at v-in of THE LM 317 . And 7.58 volts at v-out and 6.34 volts at the pin labeled adj (adjust) if you're not familiar with an LM 317 pin out, Google LM317 PIN OUT. You should also get about 7.58 volts at pin 5 of the four TDA1543 chips. I don't remember the voltages when it was broken. The voltages may fluctuate some as the voltage at your wall outlit does . Or as the DAC warms up. Also, the input diode may NOT be bad. It is probably a 1N4004. I replaced it with a 1N4007 for fun. Hope this helps. The holes are small. I used toothpicks to keep the each of 3 holes on the board open after heating for inserting the new LM 317 (and 1N4004) if those are the broken parts. Your 9 volt 850ma wall wart should be safe to use. The high amperage 12 volt wall warts will cause the LM 317 voltage regulator to become very, very hot. And possibly fail to work very quickly. Remember the balance between voltage and amps. High amps will make an unregulated 12 volt wall wart read 18 volts or more with no load. Jim

 

[Bubel]

Using a 9 volt 500ma wall wart I measure 9.79 volts at v-in of THE LM 317 . And 7.58 volts at v-out and 6.34 volts at the pin labeled adj (adjust) if you're not familiar with an LM 317 pin out, Google LM317 PIN OUT. You should also get about 7.58 volts at pin 5 of the four TDA1543 chips.

If I`m using 9V - I only have 3V and 1.5V on LM317 legs and very loud nouse but with 12V LM317 voltages are 5V and 4V (roughly) sound less noisy but it`s there. I think LM317 are busted. Thank you very much for pointing this out - I`ll try to fix it!

 

[Sapientiam]

LM317 has three legs so what are the voltages on all three legs? So far you've only mentioned two.

 

[jwr3]

LM317 has three legs so what are the voltages on all three legs? So far you've only mentioned two.

The 3rd lead is a fixed value through a resistor or pot. If you get 9 to 11 volts in (on an x4 DAC) and 7.5x volts out, I don't think tampering with the fixed adjust value is needed. I've not done so on the 6 DACs I've rebuilt.

 

[Bubel]

Last day voltages LM317 voltages with 12V adapter was 5V and 4V but today it`s only 4.5V and 1.25V and sound lack of noise - pretty clear but with some little noticeable cracks.

Center leg gives 0.01-0.02V

 

[Sapientiam]

With the centre leg effectively at 0V, it cannot be an LM317, rather it must be some form of fixed voltage reg. Like an LM78xx for example.

 

[Bubel]

Replaced the LM317 and it`s fixed the loud constant noise. Thank you very much for pin-pointing the problem Jim!
Unfortunately the crackling sounds in left channel wasn`t relevant to LM317 problem - it`s still there. It`s sounds just like constant old vinyl record cracks. What this could be?

 

[jwr3]

Replaced the LM317 and it`s fixed the loud constant noise. Thank you very much for pin-pointing the problem Jim!
Unfortunately the crackling sounds in left channel wasn`t relevant to LM317 problem - it`s still there. It`s sounds just like constant old vinyl record cracks. What this could be?

You did not say you got sound or music. Did you? Did you get music in both channels? What were the voltage in and out of the new LM317? Is the voltage out around 7.5 volts with the 9 volt wall wart? Do you get a similar voltage on pin five of all four TDA1543 chips? Or just one channel? I don't know what is causing noise in one channel. The digital noise MAY be coming from one bad TDA1543 chip. But check the manufacturer's solder first. I'm just guessing here. Does toslink and coax both work?