IcePower module

[Phil Allison]

Jeff Urban wrote:

-----------------

** The one in question showed 2V rms at 500kHz across the bridge >mode outputs.

Completely harmless, far as I can te

Not if you got piezo tweeter, and some electrostatics.

** Mere supposition, not one tiny bit fact.

The impedance of speakers at 500kHz is not a published spec, nor one tested by reviewers.

So Jeff must be getting his info from where ?

His arse maybe ?

Some folk have a lot of data stored in there.


..... Phil

 

[Jeff Urban]

>** Mere supposition, not one tiny bit fact.

No, here's a fact, THEY ARE CAPACITIVE.

I have already had problems due to tape bias on those. Wasn't filtered out well enough. Couldn't hear the bias but you could definitely hear the hum.

Fact is any HF leakage out that class D amp will see a near dead short on the load if it is piezo. The idea was efficiency. Don't got it like that.

Sorry to intrude on your vision of perfection.

 

[Clifford Heath]

On 24/9/19 3:00 pm, Jeff Urban wrote:

** Mere supposition, not one tiny bit fact.
No, here's a fact, THEY ARE CAPACITIVE.

Piezo devices have all kinds of wacky high-Q resonances that push the
impedance all around the place. Overall capacitive, but you should stick
it on a VNA to learn the truth.

Or just chuck them in the bin and replace them with something more
recent than the 1980s. Piezo's make my ears hurt.

Clifford Heath.

 

[Phil Allison]

Jeff Urban is being Silly wrote:

** Mere supposition, not one tiny bit fact.

No, here's a fact, THEY ARE CAPACITIVE.

** So is nearly everything...


> I have already had problems due to tape bias on those.

** Tape bias is not 500kHz, more like 50kHz.

You were not using an IcePower module.

Fact is any HF leakage out that class D amp will see a near dead
short on the load if it is piezo.

** Horse manure.

Firstly, the impedance of a twin lead speaker cable at 500kHz is 20 ohms or more - in series with the load.

Secondly, nearly all piezo tweeters have an inbuilt 30ohm series resistor or a small lamp to protect them.

Thirdly, a class D amp already has a large value cap DIRECTLY across the output to act as a filter.


> Sorry to intrude on your vision of perfection.

** Sorry to burst your bubble pal.

I see you make no more mention of electrostats?

I used to own Quad ELS and know lots about them plus most others.

Wanna continue displaying you ignorance?


..... Phil

 

[Phil Allison]

Clifford Heath wrote:
---------------------

Piezo devices have all kinds of wacky high-Q resonances that push the
impedance all around the place. Overall capacitive, but you should stick
it on a VNA to learn the truth.

** Some early versions were pretty much a 100 or 220nF cap.

Speaker lead inductance, plus the usual series inductors built into linear amps, rendered them harmless.

In any case, Class D amps are perfectly OK with capacitive loads.

Despite what some NG Henny Penny is claiming ....


..... Phil

 

On Tuesday, 24 September 2019 06:00:48 UTC+1, Jeff Urban wrote:

** Mere supposition, not one tiny bit fact.

No, here's a fact, THEY ARE CAPACITIVE.

I have already had problems due to tape bias on those. Wasn't filtered out well enough. Couldn't hear the bias but you could definitely hear the hum..

Fact is any HF leakage out that class D amp will see a near dead short on the load if it is piezo. The idea was efficiency. Don't got it like that.

Sorry to intrude on your vision of perfection.

Piezo drivers are capacitive (albeit with a lot of resonance peaks/troughs), but piezo tweeters generlly include a transformer to raise the voltage, and are usually in series with an external resistance, since some amps don't like C loads. I've never measured one at half a megahertz, but expect it to look largely like a transformer at that f.


NT

 

[John-Del]

On Monday, September 23, 2019 at 8:37:14 PM UTC-4, Phil Allison wrote:

** The modules are a mass of SMD - so essentially non repairable by audio techs with regular bench equipment only.

.... Phil

I can promise you that if you saw several of these a month, you would have by now acquired both the equipment (cheap enough) and the skill to do this in your sleep.

Although SMD requires a learning curve, it is not difficult if the tech has decent hands and magnification.

 

[Michael Terrell]

On Tuesday, September 24, 2019 at 9:51:23 AM UTC-4, John-Del wrote:

On Monday, September 23, 2019 at 8:37:14 PM UTC-4, Phil Allison wrote:


** The modules are a mass of SMD - so essentially non repairable by audio techs with regular bench equipment only.

.... Phil

I can promise you that if you saw several of these a month, you would have by now acquired both the equipment (cheap enough) and the skill to do this in your sleep.

Although SMD requires a learning curve, it is not difficult if the tech has decent hands and magnification.

It only took me abut 15 minutes to learn on 1206 & 0805 components, over 22 years ago. It wasn't long before I was working with 0402 and the occasional 0201 sizes which required a stereo microscope, due to my life long vision problems.

 

[Ralph Mowery]

In article <0c05ba1d-a671-484b-af34-dee126ba3f47@googlegroups.com>,
terrell.michael.a@gmail.com says...

** The modules are a mass of SMD - so essentially non repairable by audio techs with regular bench equipment only.

.... Phil

I can promise you that if you saw several of these a month, you would have by now acquired both the equipment (cheap enough) and the skill to do this in your sleep.

Although SMD requires a learning curve, it is not difficult if the tech has decent hands and magnification.


It only took me abut 15 minutes to learn on 1206 & 0805 components, over 22 years ago. It wasn't long before I was working with 0402 and the occasional 0201 sizes which required a stereo microscope, due to my life long vision problems.

I don't know about those modules, but for about $ 500 or less you can
get set up for SMD repair. I bought the Stereo microscope for $ 200,
and a cheep hot air and soldering iron setup for about $ 70. This is a
hobby, I would spend about 3 to 4 hundred for a good hot air station if
repairing them all the time. Then a few more dollars for fine solder
and tweezers.

I watched youtube and practiced on some old computer boards. I was 65
at the time. There may be some components that have multi leads under
the device that may require lots of practice.

 

[John-Del]

On Tuesday, September 24, 2019 at 2:57:04 PM UTC-4, Ralph Mowery wrote:

In article <0c05ba1d-a671-484b-af34-dee126ba3f47@googlegroups.com>,
terrell.michael.a@gmail.com says...

** The modules are a mass of SMD - so essentially non repairable by audio techs with regular bench equipment only.

.... Phil

I can promise you that if you saw several of these a month, you would have by now acquired both the equipment (cheap enough) and the skill to do this in your sleep.

Although SMD requires a learning curve, it is not difficult if the tech has decent hands and magnification.


It only took me abut 15 minutes to learn on 1206 & 0805 components, over 22 years ago. It wasn't long before I was working with 0402 and the occasional 0201 sizes which required a stereo microscope, due to my life long vision problems.



I don't know about those modules, but for about $ 500 or less you can
get set up for SMD repair. I bought the Stereo microscope for $ 200,
and a cheep hot air and soldering iron setup for about $ 70. This is a
hobby, I would spend about 3 to 4 hundred for a good hot air station if
repairing them all the time. Then a few more dollars for fine solder
and tweezers.

And FLUX! Flux is a magic elixer when it comes to SMD work.

I watched youtube and practiced on some old computer boards. I was 65
at the time. There may be some components that have multi leads under
the device that may require lots of practice.

Many modern SMD ics use a heat sink belly pan even if the IC has conventional leads. These must be heated by air to release the bottom pan. I've even seen 8 pin buck ICs that look totally conventional, but have a belly pan.

Before removing, check the datasheet to see if it has one. If it doesn't have a belly pan, blob both sides of the IC and lift off with tweezers.

One trick I taught my students was to take a Dremel and *carefully* mill down the top of the defective IC until the die of the IC was exposed. In this way, the IC would heat much more quickly from the top and release in far less time in order to reduce collateral damage to the PC or surrounding devices.

 

[Ralph Mowery]

In article <ec79a806-7232-427a-b119-82a2d991b8d6@googlegroups.com>,
ohger1s@gmail.com says...

And FLUX! Flux is a magic elixer when it comes to SMD work.

Yes, some good flux. Usually the real thick kind in the things that have
plungers and look like a big shot.

As that woman on you tube (Jessica Jones or James or something) said
'they like copper, heat and flux'.

 

[Phil Allison]

John-Del wrote:
--------------
Phil Allison wrote:

** The modules are a mass of SMD - so essentially non repairable by audio techs with regular bench equipment only.


I can promise you that if you saw several of these a month,
you would have by now acquired both the equipment (cheap enough)
and the skill to do this in your sleep.

** The bigger issue with SMD boards is that makers do not expect them to be repaired so discourage service techs from even attempting.

To this end, they make NO service info available, provide NO schematics and sell NO spare parts that go on such boards.

Invariably, the PCBs are double sided with vias, making visual circuit tracing a nightmare and hence fault diagnosis too.

By sheer dint of effort I have fixed a number of items that used SMD, sometimes using regular parts to relace SMD versions.

One ( famous Italian make ) powered speaker PCB was possessed with heat sensitive intermittents that another good tech could not fix. I found a faulty via and fixed that - then found about 20 others after applying heat to them individually using a soldering iron tip. Some of the vias were solder filled, so not so easy to run a wire through.

BTW:

My eyesight is Ok and I have a magnifying glass - I still fix broken, hair fine wires on Accutronics reverb unit coils ( ones with plugs and sockets) rather then replace the whole tank.

Investing in SMS gear and a stock of parts would NOT be sensible or economic.


...... Phil