New Module by Lars Clausen

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#641
classd4sure said:



So then I guess you're ears and speakers are also privy to the high frequency square wave that the polarity of your audio signal is derived by.
Click to expand...

That's the most popular way of measuring frequency response. MLS signals is a series of square waves. Of course you may still be using sine waves. It's perfectly okay. 😀

But I think the NCD is good to allow easy implementation of polarity swtiching (Just to get back on topic).
 
#642
classd4sure said:
Hi Lars,

One module has survived and I've located the problem with the other. Thermal stress caused a solder joint to break, which I repaired, now it has 120hz hum as with a blown output stage, but, but shuts off with .003Vdc on the output two seconds after plugging it in.

Both modules act as before with or without load in terms of powering on and the cycle of flashes, which is that one doesn't enable the output stage without a load attached but the other will. Lars say's this is normal...

Based on the solder joint that failed in question, that of the filter coil because only the very end of the wire was in contact with the joint (imagine that rectifying with a blown output), I'll now direct my focus towards the output stage, drivers and such.

...tomorrow.
Click to expand...

Did not think class D amps could get so hot for thermal stress to be a problem. :xeye: Something else must have happened between the first listening and the blowup.
 
#643
Lars what RoHS compliant solder do you use?? One of the SAC types or some of the more rare low melting types? Reason for asking is that some of the rare types have a hapit of creating uncontrolabele meltingpoins when "contaminated" with the tinning of the component legs. Down to as low as 70 degreed celcius AFAIK worst case though but surely a problem to be avare of. It is especially Indium based solder that have these habits.

Rgds
 
#644
Hello Granholm

I am using a 95.5% tin, 4% Silver and 0.5% Copper type.

About the 'blast problems' Chris have experienced, i think the most probably cause is that some of the THP's have been damaged during the component swapping, that has been going on.
Therefore i have asked Chris to return the amplifier to us, to get the modules replaced from the hand made prototype boards, to real production modules.

These should by the way come in with UPS tomorrow, and so we can start end- testing them, and shipping out the many pre-orders.

Best regards

Lars
 
#645
Hi Lars,

That would be a standard SAC type of solder! No problem with low melting points here! More likely to have problems with themal stress on especially capacitors and of cause micro cracking in bigger parts (BGA's etc) if humidity have not been delt with correctly. But of cause the proto's are hand soldered so it would not be a problem and the production units are produced by a pro..

Having all these issues all over my head these days I am realy looking forward to see how many problems will occur in reality and how much is just speculations. We have done several tests with parts that was not designed for the higher temurature profiles with no major mishaps so fare. But life time of capacitors is a real issue though.. Funny thing is that some suppliers say there components are RoHS Compliant but looking at solder spec they would not be able to solder with a standard SAC profile?!?!? So only complians is about is the content of Lead (and whatever is included) Real PITA.

Have fun
 
#646
Granholm: Thanks for the info. Our supplier of SMD assembly is one of Europe's biggest in EMS, they do aerospace, military, medical etc. on a daily basis. Trust me .. they know what they are doing..... And the parts were all sent directly from the components supplier to manufacturing within about 2 weeks. Without unpacking. So no old parts (with moisture) at all.
So i think it's highly unlikely we will see any problems coming out of the SMD assembly process.

But i'm a bit curious now, which electronics company are you working in?
 
#650
Lars Clausen said:
Hello Granholm

I am using a 95.5% tin, 4% Silver and 0.5% Copper type.

About the 'blast problems' Chris have experienced, i think the most probably cause is that some of the THP's have been damaged during the component swapping, that has been going on.
Therefore i have asked Chris to return the amplifier to us, to get the modules replaced from the hand made prototype boards, to real production modules.

These should by the way come in with UPS tomorrow, and so we can start end- testing them, and shipping out the many pre-orders.

Best regards

Lars
Click to expand...

Good man Lars.
😉
 
#651
tinitus said:
Absolute phase - it does matter, but most people wont notice if it is or not

Problem is that difference is so subtle that you can only tell the difference if you have a remote control, and only if your speaker are really good, and in that case its only very good when in absolute phase:xeye:
Click to expand...

You know, out of curiousity I actually went and swapt the polarity for some recordings that sounded a bit dull and without depth but sounded okay in the store, and you are right. :xeye: Only good when in absolute phase. Now I really need an absolute polarity switch somewhere in the system.😎
 
#655
Lars Clausen said:
Hello Granholm

I am using a 95.5% tin, 4% Silver and 0.5% Copper type.

About the 'blast problems' Chris have experienced, i think the most probably cause is that some of the THP's have been damaged during the component swapping, that has been going on.
Therefore i have asked Chris to return the amplifier to us, to get the modules replaced from the hand made prototype boards, to real production modules.

These should by the way come in with UPS tomorrow, and so we can start end- testing them, and shipping out the many pre-orders.

Best regards

Lars
Click to expand...


Hi Lars.

It was a bad solder joint the wire of the filter coil was pressed against the solder and lightly tacked to it at the end. It makes perfect sense for it to have snapped in the first few seconds of powering up as the coil would have been expanding and pulling away from the joint at that particular moment of initial heating.

Having played it hard all morning prior, with no odd behavior I don't think it would have been an error in THP. After having resoldered the wire and measured across all outputs /transistors, there's nothing that measures differently than the working module. However voltage on the lower rail of the op amp is 0..
So it's going into protection and disabling the output within about a second of powering on. Could be the inductive kick caused by the coil snapping fried the followers to that input rail?

Have your new modules arrived ?

Regards,
Chris
 
#656
Power supply question

On the "NO-NO's" page (got to love the name)
It states:
"Never charge the power supply before inserting the plugs for the amplifier modules. ..."

But the "Quality Policy" page has these tests:
17..Remove + supply.
18..Remount + supply.
19..Remove - supply.
20..Remount - supply.

Is it only doing this with bleed-ed supplies? Power off, bleed, then power on with only one rail?

Not that I'd ever hook up a charged power supply on purpose, but DIY can lack discipline at times 🙂 and I wouldn't normally add bleeders.

Is it that big of a deal with there modules, or just a general recommendation?
 
#657
The quality policy page refers to the tests that are done before shipping in order to ensure a quality product. It's not what you would do to your amp every day, but it ensures that if ACCIDENTALY the situation occurs it's most likely that the modules won't suffer any damage.
 
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