[Folsom]

Sooo whenever my minifridge turns on or off I can hear it. When my fan turns different speeds I can hear it.

The freaky thing is when I turn on the amplifier with my fan plugged in, at first I hear a beat, a thump thump thump, of the speakers going in and out...? What the hell?

I just got done replacing the tube sockets today.. ugh. The new ones did not fit so I had to trim the leads. The original one on the left had a problem with it and eventually shorted a giant gap as I found out after awhile. I am wondering if this caused some other problem with it?

It seems like maybe it could be heat related as in it does more things the longer it has been on.

[Folsom]

I tried it this morning and nothing? It must be heat related??? There is one IC on a heatsink inside that maybe needs to be mounted better or something? What the hell is going on...

[Folsom]

I was wrong, it is just a lot quieter when it is not as warm. Failing IC?

[sts9fan]

Ac motors messing with the power?

[Folsom]

Ac motors

Yes they are.

However it should not come across this strongly. Typically I get nothing more than a small tid-bit of fluctuation with any equipment I have ever had.

With the MiniWatt it is LOUD. Also it is more pronounced the longer the unit is on.

The oscillation thing upon turn on is obviously a problem I would think. That should not happen.

My mini-fridge needs a ground and that might help with noise from it. I am going to do that soon. Luckily the flex in the wall is grounded so I can ground to the box itself that the socket is in. I just have to replace the ceramic earlier 1900 socket... Maybe I will add a soft-start circuit to it.

Power distribution in the N3?

Today I will check for any bad solder joints. It seems like an IC is going bad or maybe come capacitors are not soldered correctly and therefor it is taking current more directly and there for every change in the AC line is really loud. It would make some sense as far as bad solder joints because the hotter they get the more resistance would be seen, correct?

According to the Miniwatt website this unit now has an "advanced switching" power supply. What would make an a switching supply so susceptible to changes in current/feedback into AC at low frequencies? High frequencies are eliminated with power conditioning (felix on steroids time 10). It should deliver power on demand but something is bypassing it or demanding more current that should not be? This is a little beyond my current comprehension.



 

[Folsom]

I went through everything in the amplifier that was not an SMD and touched up the solder points. They were not bad but not good either.

I still get it from that damn fan plugged in. I get it when other things in the building turn on and off...

This leaves me thinking I need to isolate my power conditioner in some way. The best I can figure is that the old wiring and mixed up neutrals, random grounds, and really old wiring is transmitting extensive RF noise at low frequencies. If it was above 1600hz it would not be audible in my system.

Unfortunately the oscillation thumping is still there so long as the amplifier is warm and gets turned off and then on again. I am clueless as to what is causing that. I am afraid I am not familiar enough with tubes.

[Folsom]

I put the resistors being used for a log curve back in and now I have a slightly more audible sound since it is easier to drive the amplifier. I traced the leads and discovered the load for driving it was in part via these resistors and the POT, lame but it worked for the stock unit.

The input impedance is probably a bit lower now but that is ok, 50k was more than I needed.

I hate my mini-refrigerator. You would think an earthquake is going on when that thing turns on.

[Folsom]

Well I replaced the socket in the wall that my mini-fridge is on. The old wires fell off the old socket when it was pulled out .

In my MiniWatt I replaced the voltage regulators (LM317's) and that got rid of the sound I get when things in the room turn on or off.

I still have low volume and get the really low thumping sound when I turn it on, play it for a few seconds, turn it off, then turn it on again.

I did find one bad capacitor and replaced it and replaced the one on the other side with the same thing. They went from 150uf to 220uf, which could result in some sort of feedback if I am not allowing the right frequencies through but the thumping has to be super low, way way way below 60hz. I might try some 150uf replacement capacitors but still there is not a good explanation of why both speakers would do it if the problem was the circuit for the one particular voltage regulator and capacitor for the side that had the bad tube socket to start.

MiniNightmare is that it is...

[Folsom]

I guess this might be some human error and I need to put in 150uf not 220uf capacitors. It is all worked out... Good thing opening and closing this unit means continually shortening the wires from the transformers because they break off constantly from being move around even a tiny bit . The challenge is moving around the top piece as they get shorter, oh and soldering them back when they are shorter. You got to do a lot of propping stuff up.