Aleph 5 progress report

[Llafriel]

Hello!

I'm happy to report that our aleph 5 project is making very good progress indeed. We are three guys building six monoblocks in total.
We finished soldering two days ago and tested them without fets first. Another post here in the forum told us that connecting the common point of C6, C8 and R7 to earth would allow us to measure as if the fets were there. All six pcb's measured fine.Yesterday we connected fets to one pcb and gradually applied voltage. A tense moment But everything worked fine, including all the measurements. Now we had the courage to try some music, and music there was! Sweet undistorted music, although the labspeaker certainly has seen better days. After this success we hooked up our psu. Voltage on the rails was 41,2V. This is unconnected. Another tense moment as we connected everything and applied power... A slight hum from the toroid, and then silence. The toroid hum fades away and the speaker is dead silent. Nice!
Measuring R14 and Q5 gave us 5,12V. A bit higher than what the service manual suggests but is a result of the higher rail voltage? Z5 read 9,0V. Dc on the output was 12mV and ripple from the psu 40mV. IRF9610 are matched but IRFP240 aren't. This being a test run after all.
Hopefully the measurements will stay the same after averything is assembled.

A thanks to Mr. Pass for his designs and support to diy'ers. And also to this forum of course.

Eystein.

[Llafriel]

A picture of the test setup. Is this the best heatsinked Aleph? The reason for this is that we haven't recieved our silpads yet. Instead of wating used one sink per fet.

[Llafriel]

Another picture. Psu connected and amp is playing.
Toroid is 500VA/30V from reichelt.de. Two bridge rectifiers and 4x22000uF Panasonic THA caps.

[Llafriel]

A picture of two pcbs. Bought from Kristian Kljucaric, excellent service and quality. One transistor missing. C5 will not be used. Some of the Panasonic FC caps are connected the wrong way in the picture. This was corrected before testing of course!

[chipco3434]

Are you really that well organized, or did you clean up your bench before the photos?

My area (...being recently exiled to a subterranean location) isn't quite that organized.

Looks great!

[Llafriel]

Thanks, and no. Hehe, camera zoom is sometimes very convenient. But this is a school lab so I have to clean up after each session wich of course does help.

[steenoe]

Llafriel, nice pics

Is this the best heatsinked Aleph?

Thats a clever idea to bring down thermal resistance
You can just skip the insulators then Very cool
If you are building Aleph 5's, which have 2x3 fets in parallel, you really do need to match them 3 fets in parralel

Steen

[Phill]

hello

your radiators are MF30-2F-151.5 Conrad ? are they ?
you put one by channel of them?
if the answer is yes, be carefull, dissipation is not sufficient !
if the answer is no, it's all good...

for 36v and bias 1.9A, radiators 300x225x50 + 150x225x40 are not sufficient, for one channel Delta T = 40°C
I use fan...120mm,12V / 7V



Phill

[Llafriel]

Thanks for the replies guys.
The fets weren't matched because it was a test run. We've already matched fets but didn't want to fry the good ones. We'll use them for the final assembly. The heatsinks are indeed from conrad. We'll use two for each channel so we should be on the safe side.

[steenoe]

We've already matched fets but didn't want to fry the good ones.

Pheew You seem to be on top of things, then Happy listening, cause thats what it will be Very nice project, as it seems.

Steen