TPA3255 Reference Design Class D Amp with PFFB

[Plott]

Thanks X! My plan was to use 10 ga ofc silicon wire, but I don't know if I can mount it properly, because of it's thickness.
Will see First I have to make a connecting/wiring sketch.

 

[xrk971]

You might have a hard time getting that to fit the crimp ferrule of the MiniFit Jr connectors. It will work fine for Faston crimp terminals for speaker outputs though.

 

[turion64]

X: which silicone thermal spacer pads did you use? Any of the type I normally use between transistors & a heatsink all seem to be too thin. I can still see light passing under the heatsink (that attaches to the 3255 chip) and the chassis floor..

Thanks, Pete

 

[xrk971]

Similar to this. 1mm thick works well. You can get from Amazon for more and faster.

https://a.aliexpress.com/_msiSu26

 

[turion64]

Thank you X!

 

[Plott]

Hi,
well, the buffer has also arrived (thanks, X) - so I have everything together now.
I'll start assembling the amp shortly, but the chassis can take a while.

 

[xrk971]

That was surprisingly fast shipment to Austria. Glad it arrived quickly and in good condition.

 

[Plott]

Well... today I wanted to start, but sadly the smps is not complete.
It is not fully assembled, but okay, afterwards Sami sent me the assembling instruction, but even so, the mounting clips for the power devices are missing... waiting for the answer from Sami

 

[xrk971]

That’s strange because he always sent me fully assembled PSU’s before. Can you screw the devices down - are there not threaded holes for the screws or all are spring loaded clips now?

 

[Plott]

No, I can't. The power devices are soldered into the board and have rubber caps, but the holes for the mounting clips are above the devices, so no chance without clips. I also have to solder the thermal switch, but it's not a problem.
I hope he will send me the clips... Or I have to drill new holes and use Keratherm insulation between the devices and the heatsink... but it's not what I paid for...

 

[Plott]

Sami will send me the clips in 48 hours so just a short break.

 

[xrk971]

Sami is pretty responsive. That was a mistake that the clips were not included. Glad it was resolved.

 

[xrk971]

Mikebarney did a fantastic job on this amp. Congrats! He made a nice write up of his build here:

https://sites.google.com/site/mpbarney/xrk-tpa3255-amplifier

 

[Plott]

Today I finished the assembly of the psu - I think I can make the wiring "on the table" soon.

 

[rhing]

Curious what you did with the double-sides blue tape that came with the SMPS. Sami tried to describe where to apply it, but his explanation made no sense to me.

 

[Plott]

There was no tape in my package
However I used my own double sided tape for sticking the white insulation sheet under the board to the heat sink.
Sami wrote I should use hot glue, but the tape will do it too.

 

[Vunce]

Plott,
Did Sami give an explanation why the SMPS wasn’t 100% assembled?

 

[Plott]

Hi X,
could you please check and correct (if needed) the following wiring plan for the psu?

• Main voltage output with the big connectors: to the amp board, it's clear
• 12 vdc output to the buffer
• 3.3 vdc output can be used for an LED on the front with a resistor in series
• AUX (15 vdc) to the amp board - but in your build (and in the picture above) I see a cap on the top of the connector; is it against turn on bump? If so, which value/voltage is needed?
• How/where to wire the further contacts (STDBY, DCER, DELAY?)
• PSU input is J1, whit the left contact live and the right contact neutral? Middle contact not in use?
• J2 has in your build (and in the above too) a jumper - what is it for?
• Where can I set the input voltage to 240vac?
• mains fuse value at 230vac?
• Is the turn on button a locking one or just a push button without locking?

Really not that much
Many thanks in advance

 

[Plott]

Plott,
Did Sami give an explanation why the SMPS wasn’t 100% assembled?

Vunce,
mainly because of the time; they have long delivery time now as stated on the homepage (at the time of my order it was at least 35 days) and I wanted it a little quicker.
And after the psu was on sale, I accepted the assembly, which was really not a big issue.

 

[Vunce]

OK, that makes sense now.
Thanks for the added details, Plott.
Wishing the best for your build👍🏻