TDA1541 noise after heat up

[Martynka]

Hello to all diyaudio users,

I bouhgt not working Arcam Alfa 5 CD player. When I got the package, it turned out to be Arcam Alpha 5 plus. ( better CDM and separate clock power suplly ). Inside Arcam I saw TDA1541 S1 with crown. I decide to repair it.

I found and order new CDM9 pro version I repalced it. Now CD player works but... :

- when I use digital out connected to my Musical Fidelity DAC everything sound great.
- when I use analog out on cold player sounds great but after few minutes start hear noise from both chanel ( temp. about 45 C ). First low noise but after higher temp inside ( about 50 C ) louder. Over temp 55 C analog output is dead, zero music, zero noise.
- when cd player is connected to power inside temp is stil about 45 and in analog out still nothing after start.
- when I disconnected Arcam from power suplly and has an ambient temperature everything play after conneted to warm up.

It see like something is wrong with analog line, what I should check first ??

Capacitors around TDA looks not good but it can give noise in analog line ??

Or maybe TDA1541 is broken ?? but why I have still good sound on digital out ??

I have full scheme of this DAC but my knowledge is not that high

 

[rfbrw]

Or maybe TDA1541 is broken ?? but why I have still good sound on digital out ??

The digital out is from the SAA7220P. It is before the TDA1541A. You might want to try freezer spray on the TDA1541A. Cool the chip and see if the noise goes away.

 

[Martynka]

Ok, I though what maybe TDA is bypassed. Yes, I try it and was beter. It means that probably TDA is broken ??

I need put another one TDA and try.

 

[Extreme_Boky]

From memory, the TDA1541 draws a lot of current from -15V DC rail. So, if the freeze spray does not produce any results on DAC chip, spray the -15V DC voltage regulator...

You could replace the tantalum capacitors (the 4 orange-drop-like capacitors) with electrolytes. The tantalums are known to fail.

 

[rfbrw]

Before trying another one check the supply voltages first.

 

[lcsaszar]

You could replace the tantalum capacitors (the 4 orange-drop-like capacitors) with electrolytes. The tantalums are known to fail.

This is the most likely reason. These capacitors are for the two most significant bits filters. I'd replace them with polypropylene or polystyrene if space permits. WIMA MKS-4 in 63V rating might fit there.

 

[Martynka]

Thank's for all answer !

- I have in my home ( bought last week ) almost all caps for this DAC boards ( Arcam use one of the biggest caps with TDA1541 aplication 10 x 220nF and 4x tantalum 470nF ), but I'm in home only in weekend and first I prefer ask "diyaudio" for advice. Last weekand I remove TDA and opamps from board and put DIL sockets to make repair and mods easier.

- I know whitch are tantalum caps but I'm very hapy that diyaudio society can lead an unadvanced user I didn't know that these tantalas are such an important element and that they die so easily.

- I check in datasheet temps for TDA1541 and it should work to 85 C and can be storage to 150 C. Why temp 55 C give noise and after that silent ?? Does TDA1541 often die from overheating ?? I weel check all board with freez spray and check power supply

- I have scheme of this DAC and I see now that digital out is from SAA7220 pin 14 ( and now I know why with NOS mod with bypassed SAA7220 you have only analog output )

Any more suggestions ??

 

[Martynka]

OK, I back home and first sprayed TDA... and in one second Arcam starts play again with clear sound. It means death of 1541 ?? Nevertheless, tomorrow I will replace the caps and check the power supply.

 

[Extreme_Boky]

Replace the tantalum caps first, and check again.

If still a problem, spray the TDA again and if the sound re-appears -> replace the TDA DAC.

 

[Martynka]

I put all new 220 nF WIMA and new 470 nF tantalum caps... still only freezer on TDA helps. I'm start looking for another TDA

 

[sumotan]

1541s are warm to touch but never hot.

 

[978HK]

I put all new 220 nF WIMA and new 470 nF tantalum caps... still only freezer on TDA helps. I'm start looking for another TDA

Could always try a heatsink on 1541A ..

 

[Martynka]

I used copper heatsink without results, still the same, but I saw that maybe some socket pin are not good soldered, I resolder it and try one more time, if nothing change, try with another TDA.

 

[Extreme_Boky]

TDA's damage is isolated to the area around -15V DC pin input, an analog R 2R section... the internals around this isolated IC area, heat up rapidly and there's nothing you can do about it, but to replace the IC.

 

[dowser]

This is a common TDA1541 failure issue - if a heatsink doesn’t fix it, maybe an active fan on it may - get a bit more life out of that S1

 

[rfbrw]

You can also try a Peltier cooler

 

[Martynka]

Yes... let it live

I put on PCB new precision slot for TDA ( first was cheap and not good ) and checked all connections.
After it I checked all power regulators and voltage on TDA1541 pins: all corect -5, +5, -15.
I pushed play and... Arcam played 2 hour without problems with temp about 46 C but few minutes later temp rises to 50 C and I heard distorsion. It was enough to blow gently and everything was back to normal.
I solved problem with bigger heatsink. Little copper goes to voltage regulators ( were hot ) and I used one from old computer.
Now my DAC i powered by ATI

and everything is ok but maybe I add little fun from laptop...

I bought Marantz CD75DX with broken CDM, when I replace TDA to Arcam I will shure that my crown is damaged.

 

[Martynka]

Hi,

It took long time but I bought few parts:

Second TDA1541, Chinese TDA equivalent and new OPA and Schottky diodes.

When I put another TDA1541 or Chinese ( very noisy ) everythink is ok.

It can play all day without change in sound. You had right, my crown is broken inside.

When I solved problem with heat up I started tune my CDP. I changed 11 diode in MB to Schottky VS11DQ10. After that I checked all power line with + and - 25V. I had fluctuation. I checked few parts on DAC boards and:
-Q203 ( FST239 ) was bad - I changed to BC239
-D211 (Zenner diode) was bad - I changed to new 2V7 1,3W (both D211 and D212)
-Q205 (BC547) was bad - changed to new BC547

Now all voltages are stable.

I changed OPA to 604

after that tested all night:

Sounds good !!! Much better with new OPA

Because sometimes my audio system is stay off one or two weeks but Arcam is still powered, I decided to mount switch.

Now I can switch off fully Arcam if no need.


Next step - NOS modification and recap will be soon.


P.S. NOS mod will be the same like in standars Arcam Alfa 5 (without plus ) ??

 

[RS232]

Congrats on the fix but going from an S1 single crown to a plain 1541 is like going from a Ferrari to a Fiat they both do the same but are not the same thing (sound wise)

 

[sumotan]

Well said RS232 but than again Crown S1 or 2 are like vintage Ferrari's which are becoming so rare & valuable.