MyRefC build guide

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Actually, thinking about it I will make "statements" from past reading.

I have read that some people can tell a difference if the secondaries are reversed phase. I can't, but I never claimed to have golden ears.

But if the secondaries were wired in opposite phase and put on a single umbilical and run as AC then it would in effect be a balanced power cable and any induced noise would theoretically be cancelled.

Same concept as single ended and balanced signal cables only this would be a constant 50-60Hz wave form.

All this is relevant to THIS thread in the fact that the rectifiers are on the main PCB and if the transformer is housed in a separate enclosure you can experiment with the phase of the secondaries to see which way sounds better to compliment the esoteric components.
 
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Actually, thinking about it I will make "statements" from past reading.

I have read that some people can tell a difference if the secondaries are reversed phase. I can't, but I never claimed to have golden ears.

But if the secondaries were wired in opposite phase and put on a single umbilical and run as AC then it would in effect be a balanced power cable and any induced noise would theoretically be cancelled.

Same concept as single ended and balanced signal cables only this would be a constant 50-60Hz wave form.

All this is relevant to THIS thread in the fact that the rectifiers are on the main PCB and if the transformer is housed in a separate enclosure you can experiment with the phase of the secondaries to see which way sounds better to compliment the esoteric components.
Do you think that it could benefit something if the transformer is placed in the same enclosure than the amp
 
Do you think that it could benefit something if the transformer is placed in the same enclosure than the amp

I think if the transformer is IN the same chassis it is a VERY simple experiment.

I have tried it before and I could not detect a difference, which means absolutely nothing. I encourage others to try simple things like that and learn through their own experiences. Then share those experiences to see if others have had similar results. ;)
 
Problems

I inserted some of the little Wima caps into the wrong places. Two of them are on the underside of one of the boards. On the other board I soldered one of them on the underside and when I realized my mistake I tried to get it out. I ended up twisting the cap off the leads because the solder was down in the via and I couldn't get it out.

What do I do now? Are there any unclaimed boards I can purchase and try over again?
 
If you can't clean out the holes you are welcome to send me the PCB's and I will.

BUT... A solder sucker or solder wick and flux should be able to clean out the holes for you.

That is providing you didn't lift any traces while trying to clean the accident.
My bet goes to solder sucker. One of the most useful tools I have. Since I discovered it, I have never used desoldering braid again. Little risk of lifting a pad if properly used.

Regards,
Regi
 
My bet goes to solder sucker. One of the most useful tools I have. Since I discovered it, I have never used desoldering braid again. Little risk of lifting a pad if properly used.
I don't have de-soldering braid.
I use the solder sucker almost exclusively.
There is a situation where I find that struggling.
Very thick double sided PCB with plated through holes using copper thicker than normal.
It is very difficult to get both sides of the PTH to heat up to and beyond solder melting point and I have had to resort to drilling out the solder (carefully).
 
Agreed. Desoldering through-hole-plated boards can be a bit of a challenge. My technique for this is to add more solder to the joint. Let it cool a bit then, with sucker ready, heat the joint. Hold that heat for a couple of seconds longer after you see the top joint melt. This ensures that both sides of the joint are molten. Be ready with the sucker and, in one movement, remove the iron and place the sucker. Trigger the sucker immediately and in most cases you'll get the majority of the solder out.

If you have a lead still in the hole, and enough to grip with tweezers, I'd heat the joint and tweezer out the remaining leg. You can use the iron to push fron the reverse side of the board in order to get a little more lead to play with. Once you have tweezered out the leg, let the board cool a little. The add more solder to the via. Let it cool a little and reheat as above, with the sucker ready. Using this method, you'll hopefully end up with a clean through-plated-hole.

If you are CAREFUL with the heat, you will not lift a track.

Good luck!

Jon
 
If you're not too far along with the build, you should think about starting fresh with a new board. Not much cost, much better chance of success, and much less frustration.

Why are you mounting caps under the board? Only C21 needs to go under the board, and that's pretty easy to figure out if nearly everything else is in place. Mount it before placing the Blackgate, as that big cap gets in the way of soldering the pads on the top for C21.

One note of caution: the ring of insulation that surrounds the pads for C21 on top of the board is very narrow. If you somehow bridge that ring and get solder on the ground plane, your amp will not work. Be very careful there, and use the minimum amount of solder needed to connect C21 from on top of the board. Not hard to do; just one area where you need to take your time.

Peace,
Tom E
 
Hi Guys,

I'm just about done my case, and will probably try powering things up and checking DC offset before I attempt to drive some speakers this weekend. I already soldered the LED's onto the boards and don't feel like putting one on flying leads to use as a power indicator light, I want to just use another LED and pull power from one of the amp boards. I'll use a dropping resistor to adjust the voltage for the LED. Where would be an easy spot to pull the power from ?

Thanks,

PJN
 
Troubleshooting help needed

I have put two kits (one stereo) together.
I have made nice replaceable resistor dip-pin based sockets.
(I will post pictures later

One channel the relay clicks on. The other does not.

Re-checked all solder joints, nothing seems wrong.

Can someone give me a clue how to start trouble shooting? I don't want to blow the nice parts!!!

Michiel
 
I have put two kits (one stereo) together.
I have made nice replaceable resistor dip-pin based sockets.
(I will post pictures later

One channel the relay clicks on. The other does not.

Re-checked all solder joints, nothing seems wrong.

Can someone give me a clue how to start trouble shooting? I don't want to blow the nice parts!!!

Michiel

You have two boards, one working and one not so you can use the comparison method to troubleshoot. The attached image shows all the parts in the relay circuit. Compare the two boards - are all the part values the same, capacitor and diode polarity the same, anything different about how the parts are placed? If you have the LED connected on the bad board, does it light up? If the trouble is not yet found measure voltages starting at D2 and D3 and work your way through the circuit until you find a large difference in the readings between the two boards. That should localize the problem to a few components.
 

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I have put two kits (one stereo) together.
I have made nice replaceable resistor dip-pin based sockets.
(I will post pictures later

One channel the relay clicks on. The other does not.

Re-checked all solder joints, nothing seems wrong.

Can someone give me a clue how to start trouble shooting? I don't want to blow the nice parts!!!

Michiel
Follow Bill advices, they are straight explained. Compare voltages between these 2 boards in all the components of the relay circuit, and then you should see where is it failing.

Regards,
Regi
 
Uh-oh: I'm getting a bad feeling about the two posters who have built a pair of amps, one working and one dead. In the last group buy, almost everyone had two or more that worked right from the start.

No word of success yet from the "technical people", and nothing much said by anyone about the sound. So far, only one poster has reported complete success, and he complained of excess gain, or at least, more gain than he wanted.

From my own experience, take this for what it's worth. I initially built two amps that worked perfectly from the very start. I ruined one by excessive desoldering of components to test their sound. I built another pair using "premium" components and, of those, one didn't work. I tried all manner of investigation, comparing voltages with the working amp, trying new active devices, and so on. Had a friend, who knows far more about electronics than I do, look at it. Neither of us could ever figure out what was wrong, so I salvaged the expensive components and started fresh with yet another build on a new board. That one worked right away, and after about nine months of frustration, I finally had my stereo pair.

I don't think this amp is very easy for beginners to troubleshoot, and that might be its biggest shortcoming. Unless you find something obvious (bad diode, bad solder, etc.), I wouldn't expect that you'll ever find out why the thing doesn't work. You might consider buying another board, harvesting parts from the bad amp that you know are good, and starting over. I would recommend a fresh LM318 and a fresh LM3886 chip. I think the 318 is sensitive to damage from any kind of fault in the rest of the circuit, and perhaps unusually sensitive to static. A few pages back, someone reported buying a bunch and NONE of them worked.

I'm sorry to learn that you're having a problem, but this is a risk of DIY. Failure is not uncommon. Giving up, though, is not forgiven. Do some testing (maybe someone here can help you interpret the results), but don't be afraid (or ashamed) to just start over. It will be a lot less frustrating overall, and the reward is awesome.

Peace,
Tom E
 
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This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.