New TK2050 board

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I have a 500va 25v transformer i would like to use, what value for R36?

I am sorry, but that information is not valid anymore. After one board couldn't take 34VDC yesterday, we have adjusted the new max volage to 31VDC or 22VAC.

That resistorchange was only to make the 24V relays handle more voltage.
Hope you have some other way to power them up.
 
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Rfbc?

What value for RFBC/RFBB is used on this board? Is the input gain set to unity, RI=RF? Was the schematic posted earlier in the thread? Is good quality heatsink paste used or rubber adhesive used? It seems that the TP2050 output chips are barely able to get enough heat transferred through the die to the heatsink as the early Sure amps with passive heatsink and rubber adhesive were prone to burn up at voltages higher than 24v.
 
I wish I had read previous posts as my amp also decided to smell. It was on 33V with 8 Ohm test resistors. I kept it on voltage for a while to be sure it works OK.

I'm sorry to hear that. I had emailed everybody, but just realized you was not on my list because you were the first one buying.


What value for RFBC/RFBB is used on this board? Is the input gain set to unity, RI=RF? Was the schematic posted earlier in the thread? Is good quality heatsink paste used or rubber adhesive used? It seems that the TP2050 output chips are barely able to get enough heat transferred through the die to the heatsink as the early Sure amps with passive heatsink and rubber adhesive were prone to burn up at voltages higher than 24v.

here is the schematic http://steinar.eu/tk2050/AMT2050%20TK2050.pdf

My understanding is that the chip should power off if it gets to warm.
 
Protection

here is the schematic http://steinar.eu/tk2050/AMT2050%20TK2050.pdf

My understanding is that the chip should power off if it gets to warm.

The spec sheet for the TK2050 mentions an over temp protection circuit built in but it doesn't work at all in practice for some reason as hundreds of 4X100 users can attest to. Those amps are prone to burn up two of the chips due to a slight warpage of the circuit board which results in a poor fit between two of the chips and the heatsink. Sure was eventually forced to disable two of the outputs and sell the boards as two channel amps because of this. So it appears that the heatsink to chip interface and quality of paste is critical. Even so, it seems to me that the circuit temp can actually momentarily spike much higher than the heatsink temp causing failures on an otherwise 65C heatsink. You may want to do some measured thermal stress testing by fixing a temp probe to the heatsink, then gradually covering the heatsink with a towel to find the failure behavior at different supply voltages and choose the highest voltage that still won't fail with the heatsink completely covered. 31v may still be a bit too high of a risk for that heat sink once people start putting the modules into a case.
 
Thats an idea for later. It's not possible on this board. And I'm not sure how big demand it would be for this feature.

Is it just a matter of the relays? the sureelectronics board are advertised to work from 10V up. I suppose I can bypass the relays if I choose to use only 12V. Thanks for all your work and info.
 
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