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madskaman 5th September 2017 01:51 AM

Wadia x64.4 sledgehammer output stage problem
I have a wadia x64.4 dac that is acting up on me a bit. I have it working well now, but there's an issue with the sledgehammer output stage. Originally, the unit would not play from one channel via RCA outputs. The other channel worked perfectly. I fussed around a little, changed electrolytic capacitors and relays without any change. Then I realized my issue with the positive signal section of the output on one channel. I swapped the positive and negative input signal and the op amps and now it works.

I've been listening to it this way for months, but I'd like to fix it. Comparing side to side, the thing that sticks out is the resistance to ground. On the channel in question, I'm reading open from signal to ground where in the functioning channel I'm reading 220k ohms. It has been this way the entire time. I also swapped out film capacitors from side to side without any change. At this point I'm thinking I have a broken lead somewhere. Any help will be much appreciated.

So, the other part to this is: is this output stage worth fixing or should I put something else in? I'm sure there are better output stages, but not sure which would be a good match for my dac.

madskaman 11th September 2017 01:10 AM

I've got this sledgehammer output stage out again and I cannot find this issue. Im checking the output of the op amp to ground and I'm seeing open on the bad channel. On the good one I'm reading 5.8mohm to ground. I cannot find any other location where the output is ties to ground or anything g else for that matter. Does anyone have a schematic or any ideas?

madskaman 18th September 2017 02:02 AM

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I decided to run 2 stereo discrete jfet buffers in place of the sledgehammer output stage. I built a 15 volt power supply from it and wires it into the same location. I've had it this way for about a week and have been very happy.

RobertS61 10th September 2020 08:28 PM

Strange that nobody reacted.
I have probably the same problem with my Wadia 2000 decoder one channel dead. I have few technical skills so I have no idea how to fix it.
You did well to make your own ouput.

madskaman 10th September 2020 09:06 PM

I was actually able to fix this board after a while. Ended up being the opamp on one channel after all that. Ha5002 I believe.

RobertS61 11th September 2020 07:10 AM

That's great!

The 1000/64.4 and the 2000 are basically the same Decoders I believe. The only thing that differs is the outboard PSU and you need a Digilink 30/40 to connect other sources than the Wadia transports with the 2000.
In that sense the Wadia 1000 is more convenient!

It was an opamp in the Sledgehammer outputchannel that failed I suppose?

RobertS61 11th September 2020 09:47 AM

Wadia 2000, one channel down
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One of my Wadia's ( with the NON-Sledgehammer output) has a problem with the right channel.
XLR output is very soft volume and RCA total silent.
I could swap the right output from my working Wadia 2000 decoder, the Sledgehammer version, with the right channel of the non working Wadia 2000.
Would the different outputs matter anything? Do not want to damage the good working right output of course.
First I could measure all the voltages at the terminals from the DAC boards of both decoders to the Outputboards of course.
I can establish if they're the same and if the rightchannel of the faulty decoder is very different and the fault lays somewhere else.
What would be the most likely culprit?
NON Sledgehammer:
Sledgehammer output:

madskaman 11th September 2020 09:03 PM

I bet you have a similar issue as I had. Probably a blown opamp. You could swap Opamps on the same channel. See if the rca output comes alive? Another location of failure I have seen of these are the internal connections. Make sure the wires are connected to the terminals. It appears as though they are just pressed into place from the factory. I have found that connection loosens or fails over time causing a similar issue. I’d check all of the connectors. Press the wire into the terminal and make sure they’re seated.

RobertS61 13th September 2020 08:20 AM

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Maybe stupid but which are the opamps on the outputboards of the old Wadia 2000?
I only can see transistors but maybe this opamp has another shape?

Would be great if it is a connector that's interrupting the signal or current flow.

analog_sa 13th September 2020 09:22 AM

Are those painted black cans not opamps?

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