"The Wire AMP" Class A/AB Power Amplifier based on the LME49830 with Lateral Mosfets

[opc]

Originally Posted by miklos

I purchased a kit from a member, but the SMD resistor values doesn't match the shcematic from the first page. Any reason for that?

You need to read the first post right to the bottom...

There's a link posted there to the updated schematic and assembly instructions:

"The Wire AMP" Class A/AB Power Amplifier based on the LME49830 with Lateral Mosfets

The attachments in the first post cannot be modified, which is why there is a big warning in bold letter with the updated post and attachments.

Cheers,
Owen

[npdot]

Originally Posted by miklos

I purchased a kit from a member, but the SMD resistor values doesn't match the shcematic from the first page. Any reason for that?

Look at Post #742.

Enjoy,
Neel

[miklos]

Thanks very much to both of you.

[BuildMeSomething]

Wow, this thread was way back down the list. Took ages to find...

For starters, not a huge up-date from me just more fault finding. Both dps-600's have been up & running after hurting them and one of the amps.

One amp appears to be running fine, however, it's reading 70 to 80 mV on the output with the dps-600. Need to check this with a lower V supply.

The broken & fixed [supposedly] amp was showing some high readings at the output and this [hopefully] has been traced to the P-channel FET. Please, is THIS the correct part?

The DPS-600's now won't start-up with a load =>50mA... Grounding issue perhaps???

|-O-|

Purchased a Raspberry Pi [arrived yesterday] and that got me iching over getting the amps up and running once more. Thoughts are to ditch the dps-600's and go for a lower +/- 20 to 25V supplies...

Regards
Paul

[opc]

Hi Paul,

Send me a PM with your address and I can see if I can mail you a replacement fet. I have a few extras and it will save you buying it.

You problem does indeed sound like grounding issue, as that's the only thing I can think of that would cause a DC offset that high. The only other thing might be grossly mismatched rails on the LME, but even that shouldn't be an issue.

What version are you building? Did you follow the guide closely?

A few pictures might help as well.

Cheers,
Owen

[BuildMeSomething]

Thanks Owen, PM sent...

Amp setup, SE AC coupled build spec as per build guide.

Amp A - Setup A: Bias; minimum, single The Wire psu +/- 23 VDC rails. Measured 1.4mV offset at speaker output. Measured 2.5 to 3 Vdc spike on powering off at speaker output.

Amp A - Setup B: Bias; minimum & 360 mA, dps-600 +/- 55/45 VDC rails. Measured -0.8mV offset at speaker output. Measured 2.5 to 3 Vdc spike on powering off at speaker output.

Amp B - Faulty / blown P-channel fet. Replaced LME, mute components and a few smd caps.


DPS-600 - Initial power up using soft start switch, OK at 360 mA bias.

DPS-600 powering down to power up behaviour [on off on]: bias => 50mA
< 5 sec gap, power up failure.
=> 5 sec gap, power up successful.


Grounding - Uncased, both the remote soft-start switch [dps-600] and small wire on the signal input, cause slight variations on the measured offset as they are moved / touched.

Paul

[hochopeper]

Originally Posted by BuildMeSomething

DPS-600 powering down to power up behaviour [on off on]: bias => 50mA
< 5 sec gap, power up failure.
=> 5 sec gap, power up successful.

This sounds like DPS600 protection taking time to reset ...

[back]

owen if you have spare fets i could use two pairs.

[multisync]

I am in the process of matching fets for the next wire project. +/- 80/90 volt rails, 3 parallel pairs per channel. The fets I received were in 2 seperate plastic tubes, 10 in each tube. The 5th fet in one of the tubes that I thought were all N channel fets was a P channel. I didn't find this out till after hooking the fet up to the test jig that I made. No smoke and it appears to work ok when hooked up properly. All the fets so far are close to each other in parameters. I am matching at 150ma and 1 amp current. They are much closer than bjt's.

The first wire amp has been running pretty much every day. It's still running and sounding fantastic. Many thanks again Owen.

[back]

Originally Posted by multisync

I am in the process of matching fets for the next wire project. +/- 80/90 volt rails, 3 parallel pairs per channel. The fets I received were in 2 seperate plastic tubes, 10 in each tube. The 5th fet in one of the tubes that I thought were all N channel fets was a P channel. I didn't find this out till after hooking the fet up to the test jig that I made. No smoke and it appears to work ok when hooked up properly. All the fets so far are close to each other in parameters. I am matching at 150ma and 1 amp current. They are much closer than bjt's.

The first wire amp has been running pretty much every day. It's still running and sounding fantastic. Many thanks again Owen.

multisync i would like to buy 2 pairs of the spares if you want.i plan on two parallel pairs per channel and +/-70/80 volts rails. it would be nice if you share the test jig too.