TDA 1541 problem (ping Jocko Homo)

[limono]

Hi there
I have Arcam Alpha 5 CD player with overheating TDA1541A chip . I had to add substantial heatsink to the chip to stop crackling distortion out of the player . The question is if the chip with heat sink is operating to its full potential or is it some sort of failure mode?? I'm trying some of the mods (nonos) and passive active I/V with Borbely jfet I/V board (discrete op amp ,buffer filter stage) So far I think I like the active conversion more than passive one (50 Ohm resistor ) with TVC (S&B TX102) pre. I'd like to add a clock upgrade and get rid of SAA 7220 digital filter so what do you think of NET-Audio board ?? ~$100 is a little steep.
I have another 1541 (S1) machine -Mcintosh MCD7007 which is using the same philips chipset so Arcam will be an experiment board. Thank you for any suggestions.

 

[Zen Mod]

Hi there
I have Arcam Alpha 5 CD player with overheating TDA1541A chip . I had to add substantial heatsink to the chip to stop crackling distortion out of the player . The question is if the chip with heat sink is operating to its full potential or is it some sort of failure mode?? I'm trying some of the mods (nonos) and passive active I/V with Borbely jfet I/V board (discrete op amp ,buffer filter stage) So far I think I like the active conversion more than passive one (50 Ohm resistor ) with TVC (S&B TX102) pre. I'd like to add a clock upgrade and get rid of SAA 7220 digital filter so what do you think of NET-Audio board ?? ~$100 is a little steep.
I have another 1541 (S1) machine -Mcintosh MCD7007 which is using the same philips chipset so Arcam will be an experiment board. Thank you for any suggestions.

ping
jocko here:

www.diyhifi.org

 

[Bricolo]

it's been said several times here that the 1541 runs hot, and it will indeed benefit from heatsinking.
but it shouldn't fail without it, and shouldn't also need lots of heatsinks

 

[limono]

Well , I've got this player recently as "non functional" .It played couple tracks then signal was getting increasingly distorted as to the point it did not play anymore (no sound) It's funny because I discovered the reason by sticking a cold finger (damn cold in Detroit these days) to the chip and bringing it back to life. I simply put some heavy
metal part over the dac while experimenting with I/V stages. No I wonder if I should replace 1541A (not easy to find and expensive) or just keep the heatsink. It's been only recently I'm reading on NONOS dacs since I have those two 1541 machines. Thanks L

 

[Bricolo]

having it in a non-os mode will be good in your case, since slower speed means less heat 😉

 

[limono]

Ok screw Arcam :0)
I opened up the hood of Mcintosh MCD7007 circa 1989 with 1541 S1 single crown . I was told it belonged to Aretha Franklin 😀 . I grounded and stuffed blue tack around clock quartz , disconnected elaborated audio board with 40 OPamps and IC volume control and took audio output straight from the buffer stage based on NE5532 (one IC on deemphasis other Bessel filter ) Ummm I like it .I decided I'm not potent enough for elaborate mods . I'll order Net-audio NONOS board substituting SAA7220
connect Borbely discrete I/V opamps on the place of dual opamp ,change SMD caps around 1541 for some poly 0.22 . and maybe maybe knock off some more elaborate regs for Dac chip .Did I forget about anything???

 

[GJF]

Classic TDA1541 failure mode I'm afraid.
Overheating after a short time of operating and steadily increasing levels of distortion!

Try;

www.cricklewoodelectronics.co.uk

TDA1541A £19.00 + VAT and postage

TDA1541R1 £19.00 + VAT and postage

Up until a few years ago they had single crown versions at a lowly £7.00, I bought a pair then for a Sony CDP-227esd that had a chip with the overheating and distortion.

Gary.

 

[aparatusonitus]

I used to have the same problem as you limono, and found TDA1541A faulty. After I change it, everything is O.K.

 

[andrew_whitham]

I'll order Net-audio NONOS board substituting SAA7220

The net audio board is thoroughly professional of course, but its actually real easy to convert to non-os

http://www.diyaudio.com/forums/showthread.php?s=&threadid=86618

Took me an afternoon & cost about 4p. BUT if you are willing to forgo the mute function, (you'll get a click click click as you skip tracks) you shouldn't even need a board.

Take a standard 24 pin chip holder and remove/cut off pins 1, 2, 3, 15, 16 & 18 Then remove the SAA7220 from the CD player - carefully, you'll need it.

Solder in the modified chip holder. Then, using 'as short as you can' wires link the holes 1,2,3 on the player board holes 18, 16, 15. This bypasses the SAA7220. Pop the SAA7220 back in to provide the glue logic.

So long as you didnt toast the '7220 you are now NonOS! if you did the player will sit there and attempt to spin the disc as fast as the motor will allow.

That might be useful to know.

Andy

 

[TimA]

having it in a non-os mode will be good in your case, since slower speed means less heat

I have been wondering about this, specifically how much cooler the chip runs in NOS mode. My NOS TDA1541A reaches 52degC (33 degC avove ambient). Does anyone have any figures for temperarture rise above ambient for this chip when oversampling?

Tim.

 

[limono]

Thanks for responses
i don't care that much for NONOS thing .By ordering Net-Audio board I wanted to get rid of SAA7202 entirely and its influence on the system (if what I read for last 2 days is true🙂 ) and reclock data to 1541 (with Hagclock ) So I guess I will effectively have /2 clock for 1541 and no 7220 pollution for relatively cheap $140. I could probably do much cheaper trying to DIY everything but I always (always ) seem to "break before I make" so I play safe this time (all my CD players are malfunctioning to a degree now🙂 Borbely's board has Jfet filter buffer (3rd Bessel) and my tweeters die at 15K so a little digital pollution (if any ,should be tolerable ) .Any hint for replacing 14 SMD decoupling caps. Maybe just live them in place?

 

[triode_al]

ThaAny hint for replacing 14 SMD decoupling caps. Maybe just live them in place?

Replacing these 14 SMD's give a significant improvement. But the board layout is not very supporting of that, I'm afraid. The attached shows the difference between SMD and new real capaitors on the bottom picturee (kindly copied from the French magazine LÁudiophile).

 

[triode_al]

and the picture

 

[JonHarrison]

Hi,

Is polyproplyene the best choice for the 14 ladder decoupling caps, or what about PPS ?

If you don't want to use axial caps would something like the Wima MKP2 metallized polyproplyene be a good choice?

Is there a benefit to be heard in individually selecting the capacitors to get the closest to 100nF or matching them ?

Cheers,

Jon

 

[triode_al]

I have 100nF caps from Condensator Freiburg, metalfoil, and a dialelectric I don't know what it is, which I selected on a capacitance meter, to within 0,2% (the reading is 4 digits..). The result was very 'light' sound, the square edges were just marvelous 90-degrees edges.
I sometimes see advertisements like: 0,1uF 250V Polystyrene that look very well suited for the job. Polyprop is very good too.

 

[ash_dac]

Hi,

Is polyproplyene the best choice for the 14 ladder decoupling caps, or what about PPS ?

If you don't want to use axial caps would something like the Wima MKP2 metallized polyproplyene be a good choice?

Is there a benefit to be heard in individually selecting the capacitors to get the closest to 100nF or matching them ?

Cheers,

Jon

PP metal film

 

[limono]

I think I could bore 1mm holes into the traces and mount better caps from both sides of PCB .The layout is spacey . I look for the caps on E-pay .Also Welborne labs has wima FKP 5% 0.1/63V should do. One of Polish reviewers called Mac a Christmas Tree. Sure it looks like ,and the drawer opens slow ,smooth ,and sexy .I must be getting old 😀

 

[andrew_whitham]

HOW hot!?

I have been wondering about this, specifically how much cooler the chip runs in NOS mode. My NOS TDA1541A reaches 52degC (33 degC avove ambient). Does anyone have any figures for temperarture rise above ambient for this chip when oversampling?

Tim.

Not THAT hot no figures but I can touch the thing - its hot to the touch, but not finger crispingly so.

because I'm not measuring temp's I dont know how much cooler in Non-OS either. Still hot! -5 deg could make all the difference in the world to the chip though but thats below the detection threshold for my finger...

As an aside, in the olden days, I had a 3dfx voodoo 3 graphics card that shipped without a cooling fan - just a big heatsink. Adding a fan to cool the thing properly gave a 10%+ performance increase on framerate. My conclusion was that chips like to be cool

Andy

 

[Pars]

I think I could bore 1mm holes into the traces and mount better caps from both sides of PCB .The layout is spacey . I look for the caps on E-pay .Also Welborne labs has wima FKP 5% 0.1/63V should do. One of Polish reviewers called Mac a Christmas Tree. Sure it looks like ,and the drawer opens slow ,smooth ,and sexy .I must be getting old 😀

I've heard of some people having problems getting their orders from Welborne recently. Another source for Wima that does sell to the public (small orders) is TAW Electronics. Mouser also carries some, and has no minimum order.

 

[Luke]

http://www.audioworkshop.com.hk/index_en.htm

he is reliable but a bit slow, good prices and the oscillators are excellent value.