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Amp Camp Amp

mforys said:
1. I will resolder tonight.
2. I am afraid to hook it up, as Gary said it smoked the first time he plugged it in. Is there a safe way to power it on?
3. I cannot tell. I scrubbed them with my finger and the brown did not come off. Should I just replace these?
4. The board does have the standoffs, but no locking washers. Would the washers prevent shorting?

One more question. Can I safely remove the board from the heatsinks as is? I assume I will just need to add more mica when I put them back?
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Do you know "what" smoked? That's not a good sign. Polarity of C1-C4 look correct, according to this:

http://www.diyaudio.com/forums/diyaudio-com-articles/214808-amp-camp-amp-1-a.html


Are Q3 and Q4 installed in the correct spots? Q3 is ZTX450. Q4 is LSK170 and they should look like these:

http://www.diyaudio.com/forums/blogs/n-brock/attachments/763d1349642522-fs2-11-close.jpg

They look to be the correct parts, based on shape only, but I can't tell without seeing the lettering.


You could bring this up on a variac or dim-bulb tester. To be safe, desolder the wires from the switch (that goes to the board) and the jack, and ONLY test the tabs on the DC jack. Make certain the polarity is correct before desoldering.

At this point, though, I'd take the board off the heatsink and inspect all soldered joints. You may need to reflow things and check that there are no solder bridges.

I believe the board to heatsink is ground, don't think you need locking washers. If any of the MOSFETS or soldered connections are touching the heatsink, you'll have problems.

Last thing to check; make sure the LED is installed correctly:

http://www.westfloridacomponents.com/blog/led-basics-how-to-tell-which-lead-is-positive-or-negative/
 
Last edited:
I was right!

The wiring from the switch to the power supply was wrong. If you look back at the pictures above the blue and black wires needed to be swapped. I did that tonight after inspecting all of the other soldering and it works!

I adjusted voltage and to 10.05 and let it stay on for a few minutes! I will complete the other amp soon and hook them both up for a test.

Thank you everyone for your help.
 
mforys said:
I was right!

The wiring from the switch to the power supply was wrong. If you look back at the pictures above the blue and black wires needed to be swapped. I did that tonight after inspecting all of the other soldering and it works!

I adjusted voltage and to 10.05 and let it stay on for a few minutes! I will complete the other amp soon and hook them both up for a test.

Thank you everyone for your help.
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Glad it was an easy (sort of) fix. Even though it's working now, I'd still be concerned about whatever it was that was smoking when it was first fired up. You should really track down that problem or this may become a bigger issue later.
 
dodog said:
Glad it was an easy (sort of) fix. Even though it's working now, I'd still be concerned about whatever it was that was smoking when it was first fired up. You should really track down that problem or this may become a bigger issue later.
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I agree. I am new to this so any help would be appreciated.

What would be the best way to go about diagnosing what occurred?

Is there a place that I should check knowing that the positive and negative power was inverted?
 
If you didn't lose a transistor (you said the amp is operational), I wouldn't sweat it. Those slightly baked resistors may become the new audiophile "gotta' have".:D If you can hook it up for some listening and hear some hiss, that would be the time to get on replacing components.
 
westend said:
If you didn't lose a transistor (you said the amp is operational), I wouldn't sweat it. Those slightly baked resistors may become the new audiophile "gotta' have".:D If you can hook it up for some listening and hear some hiss, that would be the time to get on replacing components.
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He just sped up "burn in" is all. :thmbsp:

I agree about the transistor although, given how Pass starts designing things with unobtanium transistors, I'd probably by a pair as backups, now, just in case. But that's just me being paranoid.
 
As the guy that first plugged it in, it never really smoked. The light didn't come on so it was off immediately.

It may not look so bad if I would have gotten the saw dust off them before they went to Matt :)
 
ejfud said:
As the guy that first plugged it in, it never really smoked. The light didn't come on so it was off immediately.

It may not look so bad if I would have gotten the saw dust off them before they went to Matt :)
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I think they look fine. Solder could be reflowed but that's about it for looks. If I even attempted to create a speaker cabinet, it wouldn't look 1/1000000 as good as your ACA build looks.
 
Thanks to Matt for the assist. Here's the first amp buttoned up.

D86ABB67-9DCB-48D6-81B3-193A69BD62F0_zpsy9obyv09.jpg


D4939B8E-D814-49B4-966C-A3B34B61A2F0_zpspp3mnusp.jpg
 
Here I go again, coming to the party late as always. Is this amp going to be used as a phono/headphone preamp, or can this be used as an amplifier? My speakers sensitivity is 90dB, so would this work. Could this be bi-wired/bi-amped? Are you planning on making these available to us in any form? Sorry for so many questions.
 
Its a 4 watts/channel SE Power amp,should work with your speakers.Boards and kits are available on Diy audio.

Regards,
Sachin
 
Hi Gary,
Your Enclosure looks too good.It shows your hard work.Let us know how does it sound.


Regards,
Sachin
 
sachu888 said:
Hi Gary,
Your Enclosure looks too good.It shows your hard work.Let us know how does it sound.


Regards,
Sachin
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Your build got me excited about these again and the end is near. I like what I heard from them at Matt's place. I'll share more once the other amp is complete.
 
ejfud said:
Your build got me excited about these again and the end is near. I like what I heard from them at Matt's place. I'll share more once the other amp is complete.
Click to expand...

Thank you Gary.We are waiting for your review:yes:

Regards,
Sachin
 
ejfud said:
Thanks to Matt for the assist. Here's the first amp buttoned up.
Click to expand...

Saw this over on DIY but thought I'd comment here as well. Those cases look great (I can solder but I could never build something that looks that nice). Great job!
 
4Play said:
Here I go again, coming to the party late as always. Is this amp going to be used as a phono/headphone preamp, or can this be used as an amplifier? My speakers sensitivity is 90dB, so would this work. Could this be bi-wired/bi-amped? Are you planning on making these available to us in any form? Sorry for so many questions.
Click to expand...

sachu888 said:
Its a 4 watts/channel SE Power amp,should work with your speakers.Boards and kits are available on Diy audio.

Regards,
Sachin
Click to expand...

It's actually a 5W SE power amp, that can be hot-rodded to 6W with an extra resistor.

Someone just posted (right before Gary!) at DIYaudio, yesterday, about multiple ACA's to drive mids/highs:

http://www.diyaudio.com/forums/pass-labs/215392-amp-camp-amp-aca-150.html#post3725314
 
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