[baronbeehive]

Last advice is that you must be careful with the board trace when pulling out the diodes.
If I recall correctly, there is a bottom trace in that area that goes from one side to the other, so very important not to pull the pads of the board there.
You could do a search in thread for that.

Definately check runs on BOTH sides of the board, but then he probably knows this.. he reads the thread lol!

 

[Maxx134]

Yes those wires are probably THE most fragile of all the other very fragile wires!

Yep, there was one owner who was simply rolling alot power tubes, and then a pop & Smoke!
He got scared & turn off immediately, then opened up to find that one of those transistor wires had poped off.
He was lucky because when he soldered it back and it worked.

 

[baronbeehive]

Yep, there was one owner who was simply rolling alot power tubes, and then a pop & Smoke!
He got scared & turn off immediately, then opened up to find that one of those transistor wires had poped off.
He was lucky because when he soldered it back and it worked.

I have to own up and level with you.. I haven't replaced those wires.. BUT I'm somewhat OCD about checking them before putting the board back in. Maybe next time I open it up... .

 

[CopperFox]

So I replaced those transistors, resistors and diodes. Now both the UV meters and their lights work, but there isn't sound output of any kind.

I'm thinking in the process I might have broken the relay behind the volume pot by touching it with my soldering iron - would that have this kind of effect? Will replace that next. (What else could/would cause this? Don't really see any signs of something else being wrong on the board)

If relays are mechanical, does it matter what orientation it will be installed in (I'd assume not)? Would want to mount it sideways so I wouldn't have to take the PCB out again.

 

[baronbeehive]

So I replaced those transistors, resistors and diodes. Now both the UV meters and their lights work, but there isn't sound output of any kind.

Good work! If you've uprated those components to higher wattage then that more or less eliminates the PSU area as the problem for now and in future!

What do the meters read?

I'm thinking in the process I might have broken the relay behind the volume pot by touching it with my soldering iron - would that have this kind of effect? Will replace that next. (What else could/would cause this? Don't really see any signs of something else being wrong on the board)

You mean you've touched the black plastic cover? That shouldn't have an effect if that's all. Do you have a picture?

I think you are going to have to get that multimeter and start checking the resistances of some components because you won't be able to tell by just looking. I will post a pic for you to take some measurements.

Also have you done the usual checks after work on the amp such as checking for solder splatts, touching wires, broken wires, loose connections. You can tell that a connection is bad often only by checking continuity with neighbouring connections on the trace with a multimeter.

A broken wire can be difficult to see if it's covered by heatshrink for example, or if it's on the reverse of the board that you've just put back.

 

[baronbeehive]

The resistor in the centre that feeds the meters with current might have gone open.

Also by checking the resistances of the resistors in the bottom row you can check if there are any that look out. There are 12 resistors on each side and their values repeat so you can see by checking if any are out. If one of them is out it might also point to an opamp failure connected to that resistor.

There are other ways to check the output is ok but you need to be experienced with the multimeter.

 

[CopperFox]

Good work! If you've uprated those components to higher wattage then that more or less eliminates the PSU area as the problem for now and in future!

What do the meters read?

You mean you've touched the black plastic cover? That shouldn't have an effect if that's all. Do you have a picture?

I think you are going to have to get that multimeter and start checking the resistances of some components because you won't be able to tell by just looking. I will post a pic for you to take some measurements.

Also have you done the usual checks after work on the amp such as checking for solder splatts, touching wires, broken wires, loose connections. You can tell that a connection is bad often only by checking continuity with neighbouring connections on the trace with a multimeter.

A broken wire can be difficult to see if it's covered by heatshrink for example, or if it's on the reverse of the board that you've just put back.

The UV meter on the right says about 38-45 ma and on the left it's between 25-40 ma (with the M1060C phones). That's the way it had been before so it looks normal to me.
With higher impedance headphones the readings had been going higher to about 60, but I only tested with the M1060Cs after replacing the transistors.

Here's a picture of the relay:



AFAIK, these relays' function is based on mechanical movement so I'm thinking any change in its physical form could be interfering with its function.



EDIT: Update: now I have sound working in the left channel but nothing on the right. So maybe it wasn't the relay after all. Not sure if I did anything to fix the left channel.

 

[baronbeehive]

I don't know about the relays, I don't think they are mechanical and I don't think a burn on the outside would hurt.

You have sound on one side now, if that came back all by itself it suggests to me that there is an intermittent fault with a connection, that can happen, as it did with me when I re-arranged components inside. When you have a lot of new components jostling for space a movement of one can interfere with the circuit if there is a fault with a solder joint, the only way you can tell is to wiggle it from side to side and see if it causes the problem. Of course you cannot do this while the amp is on or you might not be around long enough to appreciate the wonderful SQ of the Little Dot! This is another reason you will have to get that multimeter. If you had one you could test the continuity while wiggling the connection - with the amp off - and you would be able to tell straight away if there was a fault. Without that it's a bit like a fiddling around in the dark and hoping you find something.

The ammeters should read about 60mA with 6AS7 power tubes, and about half that with 5998 tubes. Both meters should read the same to indicate that both channels are functioning normally. They will only vary under extreme volume intermittently. If they don't read at those values or both read differently then something's wrong with either, or both channels.

From what you say I can't tell what the trouble is specifically, but as you have done the right thing and renewed the PSU components then at least that shouldn't go wrong again. So we are left with trying to zero in on the fault(s). You will also need to check that everything is ok visually like I said before because that could cause problems as well.

I suggest you get a multimeter and then you can test each component, that way you should be able to tell fairly quickly where there is a fault. We can help when you are ready.

That shouldn't put you off because it's easy getting the hang of using the multimeter, and you will have to use it to check both channels are functioning properly, that is the only way to know.

 

[CopperFox]

I don't know about the relays, I don't think they are mechanical and I don't think a burn on the outside would hurt.

You have sound on one side now, if that came back all by itself it suggests to me that there is an intermittent fault with a connection, that can happen, as it did with me when I re-arranged components inside. When you have a lot of new components jostling for space a movement of one can interfere with the circuit if there is a fault with a solder joint, the only way you can tell is to wiggle it from side to side and see if it causes the problem. Of course you cannot do this while the amp is on or you might not be around long enough to appreciate the wonderful SQ of the Little Dot! This is another reason you will have to get that multimeter. If you had one you could test the continuity while wiggling the connection - with the amp off - and you would be able to tell straight away if there was a fault. Without that it's a bit like a fiddling around in the dark and hoping you find something.

Now I got sound in both channels. The fault was that the right side cathode resistor was somehow loose without looking or feeling like it was.
Replaced one of the coupling capacitors on the left side as well due to one leg snapping so that will now need some burn-in.

Next I'll be trying those +2000uf Nichicon caps for the cathode bypass position.

 

[baronbeehive]

Now I got sound in both channels. The fault was that the right side cathode resistor was somehow loose without looking or feeling like it was.
Replaced one of the coupling capacitors on the left side as well due to one leg snapping so that will now need some burn-in.

Next I'll be trying those +2000uf Nichicon caps for the cathode bypass position.

Excellent .

You see what I mean about checking, saves a lot of hassle later. When you bend the capacitor leg bend it away from the body of the cap otherwise it's liable to snap, I've done it too.. we've all done that!

Keep us posted on progress!

 

[baronbeehive]

Guys, I had almost forgotten what an emotionally challenging experience for the nerves it was sitting waiting for that other meter to light up after working on the amp ! As it was I made a schoolboy mistake with 2 or the connections the wrong way round , and that was despite checking everything in triplicate.

I've finally got around to fitting some OCC silver output wires from the output XLR's right through to the headphone socket in an effort to boost the top end slightly, I'm talking of high hats, cymbals mainly, everything else sounds so good on this amp, and so does that but I feel it could be slightly more emphasised to make everything stand out on the sound stage that bit more. I don't mean sybillant sounds though.

Those silver wires are expensive though, so I compromised and fitted 24AWG to supplement the silver plated copper that were already there, rather than going for say 20AWG from scratch. The copper should complement the silver and as they are silver plated I don't think adding silver wires will smear the sound or anything like that.

That should be my last foray into the guts of the amp hopefully, I never want to see them again lol.

I will report back on my impressions when I compare it to my APPJ which is already slightly more emphasised in the treble frequencies.

 

[baronbeehive]

SMLD MODS: (continued.. er.. finished)

Silver output wires -

The finished amp.. at last!

I don't envision doing anything else, changes to PSU would entail building it in another chassis, not necessary.

The SQ is truly endgame, airy expansive soundstage, highly resolved, transparent yet euphonic too, I can't think of ever getting rid of it.

I've yet to trial it with the silver wiring.

You can follow my mods pages: 50, 53, 55, 57, 62, 65, 66, 68, 69, 70, 71, 72, 147, 179, 230, 231, 234 which include pics. Also Mogos mods are here; 33-38, and SonicTrance here: 23, 43, including some great pics.

Edit: Anyone want a soldering iron.. surplus to requirements .

Edit: There's still some room in the upper end of the amp for something.. any ideas anyone lol!

 

[AngryTank]

Anyone got any recommendations for tubes for my Mk8 SE?

 

[baronbeehive]

Wow! I really didn't expect this.. but the silver wires have made a major difference.. in the direction I was hoping! First impressions are very favourable. I didn't expect to hear much difference, maybe a slight sharpening, but the difference is fantastic. I don't think I am being influenced by my expectations here.. but I was certainly hoping..!

Comparing with the APPJ as a baseline which I was able to switch between it and the LD side by side, the LD now is level in terms of treble texture which is there at high levels to add to the realism especially the soundstage, the APPJ is good but the LD's soundstage is second to none and gives the impression of greater resolution which may or may not be the case in reality. Guitars ring through with incredible clarity for example. Not only that the whole frequency band seems to be tighter, bass as well which is very welcome. Transparency is at the highest level, probably slightly higher than the APPJ although I put that down to room reverberations through speakers.

Anyone who wants clarity and texture to their music should really go for these OCC silver wires, the image is still very full bodied but compared to the OCC copper wires I had in originally the copper wires are much warmer and smoother, a little too much for me perhaps. One reason I didn't expect much difference, the 24 AWG wires were very thin and I thought that the lack of girth in the cross sectional area might have adversely affected the fullness of the sound. Also adding wires to those already in place might have affected SQ. but none of these concerns actually came about.

Both amps are pretty much how I like the sound to be and both perform at the highest level. I still can't really get over the shock of how good the modded APPJ is considering the mods were very simple to do, whereas the LD needed much more in the way of mods to bring out the best end game level.

So all in all a very worthwhile addition and the final touch to my LD, true to say silver wires and silvery sound!

.

 

[CopperFox]

I would have thought that a sledge would be more useful in the Arctic lol!

Well... it was announced by the FIA some days ago that this will be on the WRC calendar this year... so there is at least some use for cars. Trying to figure out how to apply to be a marshal there.

Then there is reindeer dodging as well!

Fun fact: the WRC is currently sponsored by Asahi Kasei corporation, which is best known on these forums for their subsidiary Asahi Kaisei Microdevices (AKM).