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Topping PA5 fix - D01 Module Replacement for everyone

gamerpaddy

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Mar 6, 2022
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Location
Germany
Ive been working on the PA5 for a while now after mine died suddently,
like many others

Most of the PA5 units develop a crackling, hissing or just go a little silent or completely dead on one or both channels.
This issue is related to the potted D01 module.
Its potting compound expands and contracts when it heats/cools and rips off components in the process.


See my teardown and analysis of it in the PA5 thread here

After some kind ASR member donated a broken PA5 to me for research purposes, i went on an reverse engineered the D01 module.
My intention was to make a replacement module for anyone to build / buy so their PA5 will live again, and hopefully forever.

Its PCB and Schematic files are open source, and anyone who wants their PA5 fixed without dealing with the support or is out of warranty for drilling holes into it... can just order those at their favourite pcb house and even let them assemble it for you.



So ive started by depotting the module, which i did on my previous unit aswell and its now been running fine ever since. longer than before.
DSC02570 (Benutzerdefiniert).JPG

and after stripping & measuring all components, i sanded down the 4 layer PCB
a.jpgb.jpgc.jpgd.jpg

after that, i reversed the schematic from it.
firefox_qlytJs48qo.png

(ignore mute sw L/R, i suspect its mute but could be a floating ground, havent looked into it yet)


And made & ordered some PCB's
IMG_20230421_081948.jpg


After assembling the other side and testing them, they worked flawlessly.
IMG_20230427_205642.jpg
IMG_20230427_205652.jpg
IMG_20230427_205656.jpg

They work, they sound good. Its a worthy replacement for the original Part which will last much longer.

instead of OPA1612 i used OPA1656 since they were in stock and not too expensive, they are very good too, i dont hear any difference.
i cranked the volume to max with nothing playing and didnt hear any hiss / hum.
and i got no way to measure the SINAD of it unfourtainly.


I will not Sell these myself. But i made the design open source so anyone can order pre-assembled PCB's at the usual chinese PCB makers.






The Project can be found here:
Just click on "Editor Open" on the top right.








i havent chosen specific parts for resistors and capacitors in the Bill of materials, when you order them you gotta select your own.
Because sometimes the ones ive chosen are not available 3 months later anymore and you gotta find suiteable parts anyways.

Some component values are weird, just select the ones that are the closest, it doesnt have to be exact. topping used some parts in series to get there like 3x3.3k instead of 10k..



There will be a few versions of this module, mainly focussing on putting every component ontop so Assembly gets way cheaper than both-sided, also DIP8 sockets for those opamp swappers out there. but overall it will stay the same.

just dont pot the module in epoxy or tar.. we've been there. it really doesnt need to be thermally equalized..
Also you dont need a metal shield around it. the D01 metal case is just for looks, it isnt actually connected to Ground for shielding.


edit:
the module i assembled for testing uses slightly different values and opa1656 instead of opa1612 as mentioned, i noticed it having less gain. the original one had its earbleeding volume at about 2/3, this one i can crank to 100% i also noticed a bit tighter bass, at least im seeing the cones move a little more than before.. or im just cranking it further for some reason.
i used 10k instead of 9.9k, 6.8k instead of 6.99k, 1.2k instead of 1.21k, 200 instead of 205ohms and so on.
 
Last edited:

KintsugiUwU

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Apr 26, 2023
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But they will still run hot, even without the compound. I think it was a poor decision by Topping placing the most power hungry components at the front, where there isn't any vents. I still suggest, other than gamerpaddy mod, also to drill some holes at the front of the amp, for maximum cooling and airflow.

Placing a fan that blows air from the back vents also works. Done that last summer, PA5 was cold to the touch
 

GLTRV

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Jan 9, 2022
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Qc
Great work!

If not floating grounds, could the signals you have labeled Mute SW L/R be inputs for offset voltage, VCC/2 perhaps ?
 
OP
gamerpaddy

gamerpaddy

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i will think about it, especially when i made several versions like i mentioned. im working on the cheaper to manufacture single sided version right now.
my modules are socketed, so you can easily swap them for testing.
 

wwenze

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May 22, 2018
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Topping's intention to make the module copy-proof caused heat problem.

So the user had to copy it and open it to public.

Ironic...

Amazing work by the way.
Which means no more necessity for Topping to continue potting the module.

In a sense this work did solve problem for everyone.
 
OP
gamerpaddy

gamerpaddy

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Ive finished the single sided and dip8 version (also single sided, what a mess)

you can chose them on the OSHW website by scrolling down to the PCB Preview and scroll trough until you find the version you want

just a design, not tested, but i doubt it wont work. ive ordered the single sided version for testing.

firefox_p5bn7YAhBB.png
firefox_lRQjTd1yKd.png
 

threni

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Topping's intention to make the module copy-proof caused heat problem.

So the user had to copy it and open it to public.

Ironic...
See also:
copy protection n.
A class of methods for preventing incompetent pirates from stealing software and legitimate customers from using it. Considered silly.
 

BoredErica

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I find audio complicated enough as is. If I were to solder anything I will surely destroy the amp. Theoretically, if somebody could fix it for $150 + shipping and it will work normally and not prematurely fail again, I think that's a good deal. I have no idea how much the parts cost.

I'm typing this while listening to my right channel only BTW. Left one died over a year ago. Yipeeeee.
 

3125b

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I'm typing this while listening to my right channel only BTW. Left one died over a year ago. Yipeeeee.
And you didn't return the defective amp? Or just buy another, cheaper one (maybe used)?

The most expensive part of this fix is having the single PCB manufactured, the components don't break the bank.
Not sure about the legality of offering this part commercially, that might very by jurisdiction.
For the EU Audiphonics has the capacity and may be interested in making these. If legal in France (which I think it would be) they might be able to produce and stock a limited quantity. Although it's probably not really worth it financially.

Because sometimes the ones ive chosen are not available 3 months later anymore
That is a huge problem right now. At work for some of our products I have to change components every production run.
 

audiofun

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Jul 4, 2021
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As far as I see it, the competition among Chinese makers is making normal users' life harder:


Don't understand why Topping and SMSL took that much effort in sanding off the marking of their audio interfacing chip.
A simply Google search "48 pin spdif chip" will reveal the chip smsl uses is the DIX9211 chip, whose TYPICAL CIRCUIT CONNECTION (on page 49) matches exactly well with SMSL's implementation.
Topping's implementation can be also easily identified here.
other forum member also identify their clock circuit here.

The reality here is there is very little point in sanding off the chip marking as for those who really intend to reverse engineering, those are simple quiz.
But for normal customers who need to fix their units (the customer service of topping/smsl sucks), this makes them hard to do so.

Topping makes even stranger move by sealing the PCB inside modules, which causes high failure rate, while doesn't help in protecting their circuit being reverse engineered.
What the heck are they doing?
 
Last edited:

MAB

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Nov 15, 2021
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Portland, OR, USA
Ive been working on the PA5 for a while now after mine died suddently,
like many others

Most of the PA5 units develop a crackling, hissing or just go a little silent or completely dead on one or both channels.
This issue is related to the potted D01 module.
Its potting compound expands and contracts when it heats/cools and rips off components in the process.


See my teardown and analysis of it in the PA5 thread here

After some kind ASR member donated a broken PA5 to me for research purposes, i went on an reverse engineered the D01 module.
My intention was to make a replacement module for anyone to build / buy so their PA5 will live again, and hopefully forever.

Its PCB and Schematic files are open source, and anyone who wants their PA5 fixed without dealing with the support or is out of warranty for drilling holes into it... can just order those at their favourite pcb house and even let them assemble it for you.



So ive started by depotting the module, which i did on my previous unit aswell and its now been running fine ever since. longer than before.
View attachment 281869

and after stripping & measuring all components, i sanded down the 4 layer PCB
View attachment 281862View attachment 281863View attachment 281864View attachment 281865

after that, i reversed the schematic from it.
View attachment 281870
(ignore mute sw L/R, i suspect its mute but could be a floating ground, havent looked into it yet)


And made & ordered some PCB's
View attachment 281872


After assembling the other side and testing them, they worked flawlessly.
View attachment 281866
View attachment 281867
View attachment 281868

They work, they sound good. Its a worthy replacement for the original Part which will last much longer.

instead of OPA1612 i used OPA1656 since they were in stock and not too expensive, they are very good too, i dont hear any difference.
i cranked the volume to max with nothing playing and didnt hear any hiss / hum.
and i got no way to measure the SINAD of it unfourtainly.


I will not Sell these myself. But i made the design open source so anyone can order pre-assembled PCB's at the usual chinese PCB makers.






The Project can be found here:
Just click on "Editor Open" on the top right.








i havent chosen specific parts for resistors and capacitors in the Bill of materials, when you order them you gotta select your own.
Because sometimes the ones ive chosen are not available 3 months later anymore and you gotta find suiteable parts anyways.

Some component values are weird, just select the ones that are the closest, it doesnt have to be exact. topping used some parts in series to get there like 3x3.3k instead of 10k..



There will be a few versions of this module, mainly focussing on putting every component ontop so Assembly gets way cheaper than both-sided, also DIP8 sockets for those opamp swappers out there. but overall it will stay the same.

just dont pot the module in epoxy or tar.. we've been there. it really doesnt need to be thermally equalized..
Also you dont need a metal shield around it. the D01 metal case is just for looks, it isnt actually connected to Ground for shielding.


edit:
the module i assembled for testing uses slightly different values and opa1656 instead of opa1612 as mentioned, i noticed it having less gain. the original one had its earbleeding volume at about 2/3, this one i can crank to 100% i also noticed a bit tighter bass, at least im seeing the cones move a little more than before.. or im just cranking it further for some reason.
i used 10k instead of 9.9k, 6.8k instead of 6.99k, 1.2k instead of 1.21k, 200 instead of 205ohms and so on.
It makes me happy and appreciative to see how far you took this! After all of the anxiety this little amp has caused, you single-handedly brought more support than we got from the after-sales service! And even if everybody isn't getting their kit fixed, the closure is worth something!;)
 
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