reduce power to reduce heat from UPC1342V kit

[nine0nine]

Originally Posted by FauxFrench

If it gets so hot that it smokes, the transistors are probably ruined. Ruined may mean short-circuited. If short-circuited, the power resistors may have much more voltage across them and they burn.
With a modest price and unless you are experienced with amplifier fault finding, you better buy a new module. Else you have to find and order replacement parts, await arrival etc....

Yeah, that's exactly what I'll do, the kit without caps was about $10, so its certainly not worth the time to troubleshoot and replace individual parts.

I'm on vacation from Monday, so amplifier fun has to be put on hold, but thanks to everyone who has helped a noob like me get my system sorted.

[nigelwright7557]

You can reduce bias current (only if too high.)
If that is ok then bigger heat sink or reduce power supply voltage or use higher impedance speaker

[nine0nine]

Small update, after getting stuck in Japan for almost 5 weeks, I am back at my multi-meter finishing off the project.

Built another amp board after binning the old one, and we're currently functional and sounding pretty great!

Currently got the mV set to around 50mV across those 5W resistor and the output volume is a little more than enough for what I need but the heat created is still a little too much for my liking (ie, the wife is gonna complain).

So, 2 options are to fit a fan, which I have allowed for in the case layout and I have a spare 12v source, so thats no big problem, or, reduce the mV trim pot a little more.

Reducing the voltage, with the current status of the case, it would be a big pain in the *** to access the trim pot and then test, so I really only wanna do that if its going to make a significant difference.

[nine0nine]

ran the amp for half a day on and off, and botched a 120mm fan in the top as a test and my conclusion of if I need a fan OR to lower the mV: YES!

Gonna have to do both, I'd wake up in a cold sweat worrying if i remembered to turn off the amp.

Ordered a fan cover, so once that's here I'll set about cutting a hole in the lid and lowering the voltage a little more, then hopefully she'll be ready for her debut in the amp gallery on here.

[chermann]

Hi nine0nine


yes lowering the supply voltage (as nigel wrote) will help for sure. you can use a fan but try to find a fan with low noise like some 17dB or 18db fans like the PC gamer us it. normally these fans are using PWM rpm- so look at some "normal" 12V fans with low noise.
you can also re check if you have enough ventilation through your amp housing
chris

[nine0nine]

Originally Posted by chermann

Hi nine0nine


yes lowering the supply voltage (as nigel wrote) will help for sure. you can use a fan but try to find a fan with low noise like some 17dB or 18db fans like the PC gamer us it. normally these fans are using PWM rpm- so look at some "normal" 12V fans with low noise.
you can also re check if you have enough ventilation through your amp housing
chris

Thanks for the fan info.

I have a few fans here I was using for testing, one was silent, but didn't move much air, the other blew a gale but was pretty loud, gonna see if i can run it at a lower voltage to find a compromise.

Currently waiting on a few bits to be delivered before I tweak it, but running it for a few hours today was bliss after all the problems I've had
pic, if anyone is curious...

[chermann]

Hi
the housing seems to be very compact = less space but you got it! very good.
if i look inside i can guesstimate that the bottom plate has no drilled holes and you get no air convection through the amp. how big are your feets for that amp? its better to drill under the amp boards some holes( as much as better) and let the air flow + have higher feet the start free air convection. thermal past at the chips and heat sink and if you want connect the front plate and the heat sink with thermal paste too.


chris

[kozard]

Originally Posted by nine0nine

Thanks for the fan info.

I have a few fans here I was using for testing, one was silent, but didn't move much air, the other blew a gale but was pretty loud, gonna see if i can run it at a lower voltage to find a compromise.

Currently waiting on a few bits to be delivered before I tweak it, but running it for a few hours today was bliss after all the problems I've had
pic, if anyone is curious...

Is it still running well?


May I ask what supply voltages and speaker impedance you are using?

[zergxia]

A little suggestion: You can carefully adjust the slope of the temperature compensation circuit to achieve stable temperature compensation. Set a most suitable quiescent current with the help of distortion measurement, it does not necessarily need to be large. In the end, you did a great job!

[kozard]

Does anyone have any experience or wise suggestions with regards to lowering the uPC1342V gain and selecting the compensation capacitor?

I currently have 1.8k and 56k for gain (see attached schematic) and 22pF. (Schematic shows 15pF, board came with 22pF.)

I would like to use 5.6k and 56k for gain. However I would like to appropriately adjust the compensation capacitor at the same time.