$175 Class D amp--120 wpc

Paul B · « **Reply #1680 on:** 24 Jul 2010, 12:36 am »

Hi all, could I get some assistance please?

Just finished assembling my SDS258 but getting no sound.

The amp appears to be working ok - I have 2 blue lights on the amp board (and 2 on power supply) and am happy with all wiring.

My question - are there tests I can perform with a multi meter on the input and output terminals on the amp board to determine if it's working ok?

That way I will know if it's a problem with the amp or if I need to take another look at my connections to rca and binding posts.

Excellent thread by the way, thanks to the contributors.

Paul

jtwrace · « **Reply #1681 on:** 24 Jul 2010, 12:39 am »

It's easier to post some nice clear detailed photos.

Make sure the little switch on the amp board is on. Also, if you're using XLR o RCA make sure the jumpers are correct.

Paul B · « **Reply #1682 on:** 24 Jul 2010, 01:18 am »

pics of amp and power board added. I haven't touched the jumpers so hopefully they are correct.

jtwrace · « **Reply #1683 on:** 24 Jul 2010, 01:22 am »

Jumpers are on 2&3 which is for RCA input. Is that what you're using?

The amp is on right?

Are the gain pots soldered properly? Turn up midway?

Paul B · « **Reply #1684 on:** 24 Jul 2010, 01:33 am »

Yes I'm using RCA. Amp is on - 2 blue lights on power board, 2 yellows briefly on amp board then they turn off and 2 blue lights remain on.

I have turned the gain pots up all the way. Here they are pictured - I hope i have soldered the red & yellow the right way.

jtwrace · « **Reply #1685 on:** 24 Jul 2010, 01:42 am »

If your amp is setup for single ended input. The important thing to remember is… do not use the – on the input for single ended. Connect the + to + and the negative to G (ground). If you connect to -, it will damage the amp. For balanced input, just remove J1 and J2 jumpers completely. J1 and J2 have jumpers on pins 2 and 3… this is for single ended input. If you change the jumpers to pins 1 and 2, it will reverse the polarity… most situations this will probably not sound as good, so no need to mess with that.

For the potentiometers included, the black wire goes to the center pin on the pot, and if holding the pot with pins facing up, the yellow wire goes on the left, and the red wire on the right.

Paul B · « **Reply #1686 on:** 24 Jul 2010, 01:49 am »

I am using + and ground on inputs per instructions.

on the gain pots - the yellow should go on the left if holding the pot with pins facing down, but is that with the gain knob pointing towards you or away?

jtwrace · « **Reply #1687 on:** 24 Jul 2010, 01:49 am »

My gain pot is seen here..

jtwrace · « **Reply #1688 on:** 24 Jul 2010, 01:54 am »

Quote from: Paul B on 24 Jul 2010, 01:49 am

on the gain pots - the yellow should go on the left if holding the pot with pins facing down, but is that with the gain knob pointing towards you or away?

Pins up with the knob to your chest. See photo above. If I had my amp here, I'd take a better picture. If you wait until tomorrow, I can do just that. I'm trying to help you now so you can sleep tonight.

Paul B · « **Reply #1689 on:** 24 Jul 2010, 01:57 am »

ok thanks for that

My red & yellow wires need to be switched

Barry_NJ · « **Reply #1690 on:** 24 Jul 2010, 02:00 am »

Quote from: Paul B on 24 Jul 2010, 01:57 am

ok thanks for that

My red & yellow wires need to be switched

Couldn't you just turn the knob the other way?

jtwrace · « **Reply #1691 on:** 24 Jul 2010, 02:06 am »

Quote from: Barry_NJ on 24 Jul 2010, 02:00 am

Couldn't you just turn the knob the other way?

I follow directions...

Paul B · « **Reply #1692 on:** 24 Jul 2010, 02:18 am »

may as well correct the pot wiring

but still no sound

I might look into how I can test the speaker terminals on the amp for a signal

wushuliu · « **Reply #1693 on:** 24 Jul 2010, 02:38 am »

Quote from: Paul B on 24 Jul 2010, 02:18 am

may as well correct the pot wiring

but still no sound

I might look into how I can test the speaker terminals on the amp for a signal

Hate to ask the obvious but are you sure your source is sending an audio signal to the amp?

Paul B · « **Reply #1694 on:** 24 Jul 2010, 02:50 am »

Yep the source works ok with another amp

It must be either the amp or my connections to RCA/binding posts

The soldering look fine to me, so I was wondering if there was a way to test the amp

tobebu02 · « **Reply #1695 on:** 24 Jul 2010, 11:30 am »

Quote from: Paul B on 24 Jul 2010, 01:18 am

pics of amp and power board added. I haven't touched the jumpers so hopefully they are correct.

It looks like your connection from transformer to PS board is wrong. 2 Blues together and connect to Gnd. 2 Greens either connect to AC1 or AC2. Experts please confirm.
Thanks

Paul B · « **Reply #1696 on:** 24 Jul 2010, 11:38 am »

That's the correct 230v wiring per latest diagram from Tom.

I have been getting assistance from various sources and working through things slowly. Will get there eventually!

tobebu02 · « **Reply #1697 on:** 24 Jul 2010, 11:51 am »

Ok,
Hope things work out for you.
Thanks,

walkern · « **Reply #1698 on:** 24 Jul 2010, 12:38 pm »

What I discovered on my 254S was that the input level controls (the pots) worked the opposite of what I expected. When I turned them (what I thought was) all the way up, they were in fact turned all the way down. Turning them counter clockwise (in my experience) usually means you are turning things down, but I found these pots worked the opposite way. Turning things clockwise turned these down, and counter clockwise turned them up. So try setting the pot 'volume' in the middle instead of all the way in one direction or another and see if you get sound that way. Your connections from the transformer must be correct or you would not get blue LEDs lit up when you turn the amp on.

Best of luck,

Neil

Nick77 · « **Reply #1699 on:** 24 Jul 2010, 01:53 pm »

You might try turning the amp board switch off and a brisk turn back on??