Amp 6 help

[JWFokker]

So I've got an Amp 6 that I've built, but when I hooked up my power supply to it (no voltage regulator or rectifier used - it's jumpered as shown in the directions) the big power cap C99 cooked itself. I double checked the cap orientation and I double checked the voltage, it was putting out a steady 13VDC, which is what I use to power my modified Sonic T-Amp.

I opened a support thread at 41hz.com but it's been over a week and Jan hasn't replied so I've given up hope there. Anyone know what might be going wrong?

[GJF]

Sounds like reverse voltage or over-voltage.
Are you sure your power supply only delivers 13V and that you connected it the correct polarity?

[JWFokker]

I'm certain of the voltage because I did check it immediately afterward, and it's what I've been running my SI T-Amp on. Having the voltage reversed is more troublesome because the documentation provided by 41hz.com simply sucks. Things are mislabled or inconsistent. One one diagram, hole 1 is marked as negative in, and hole 3 is positive in. In the appendix, hole 2 is referred to as AC 1 and hole 3 AC 2, which would make hole 1 ground, as it is actually printed on the PCB board. The board however, has no indication of positive or negative for the other two holes. Hopefully someone who has a working Amp 6 see this and know for certain.

[Pano]

AMP6 basic or normal?

[JWFokker]

The normal Amp 6.

[DocLorren]

That amp needs AC not DC since it has a rectifier onboard. Might have gone wrong there I guess

[Pano]

The regular AMP6 does run off AC, as there is a rectifier onboard. But DC will also work, and it doesn't matter which way you connect it, the rectifier bridge takes care of that.

Did you come in the normal power inputs or go directly to C99? If you "jumpered in" maybe you bypassed the bridge and hit the C99 with reverse polarity?

Anyway, check your connections. This amp is made to run off about 15V AC which is converted to DC on board. Once it is rectified you should see about 20V on C99. Then the regulator will drop the voltage down to 14 or 14.5, depending on the resistor you installed.

DC will not hurt the amp or the cap if you were to bring it in the normal power points at the edge of the board. But 13VDC is not what you want to use, at least not in the long run. You need that 15VAC rectified to about 20VDC (no load) to give the regulator some room to work.

Let us know what you find.

[JWFokker]

It does indicate in the manual that you can use a DC power supply without a rectifier and regulator. Re-reading it now indicates I may have killed the Tripath chip however.

Amp6 with 12V DC / without rectifier / without voltage regulator

If you use AMP6 with a 12V DC source like a 12V battery, or an external 12V DC supply, you can remove the rectifier and voltage regulator, as they cause a voltage drop of about 2V and thereby limit the maximum input power. Note that keeping the rectifier, gives input polarity protection. Without the rectifier, you must ensure the amp is connected with proper polarity, or the Tripath chip will be damaged.
• Optionally remove the rectifier
• Remove the voltage regulator Q3
• The following components will not be active and can be removed
o R100, R101, R102, C100, C102, D20
• C99 can still be used, if the power supply works with a capacitive load
• Jumper the rectifier if it has been removed and Q3 as shown below.
• Connect the external power as shown below. Polarity MUST be correct, or the Tripath chip will
be damaged!

Jumpers are black bold horizontal lines (Q3, pin 1-2 and rectifier, pin 3-4).

Here's hoping frying the capacitor blocked the power from reaching and killing the Tripath chip.

It also occurs to me now, that perhaps the power connection is different when using a DC power supply rather than AC. In the normal configuration, the power inputs are ground/AC1/AC2, where as in this diagram, it would be DC -/nothing or ground?/DC +. Is that possible?

[Pano]

If you had the regulator in place the Tripath chip probably survived. If not, you may have killed the chip.

You are better off running this board with AC and letting the rectifier and regulator do their thing. Having the regulator so close to the chip helps the power regulation a lot.

If you want to run one on your own supply, like a battery, the AMP6 Basic would be a better choice. Just watch that polarity and voltage!

[soundphreak]

Are you positive you have the cap orientation correct? On my board the + sign was missing the vertical bar because of some error in printing on the board, this was mentioned on the 41hz site in one of the amp6 threads. The negative side of the cap ( with the white stripe ) should face the toroids. The + side has the square pad on the board. I only mention this because I found it a bit confusing myself.