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Little Dot MK VI / Little Dot MK VIII SE Owners Unite - Page 83

post #1231 of 1400

Woo amps are much easier to visualize and work on and they do not have a DC servo circuit added to it. Sorry for your loss. 

post #1232 of 1400

Woo stuff is all aesthetics, nothing special about the sound for the price.

post #1233 of 1400
Quote:
Originally Posted by DefQon View Post
 

There is nobody else to blame but yourself due to the mods you performed yourself. Electronics don't die randomly, there is a sole reason for it.

 

Sorry for your loss. 

 

But if you post pictures of the PCB myself and the rest of the community here can help identify, mitigate and fix the problem your amp has experienced.

 

Or go the expensive route and get it checked by a qualified tech.

I agree that this major failure can only be blamed on me, asI am not qualified to work on this amp. BUT, the modifications done before were done at the factory, with factory approved parts, and the resistor that burnt started to burn at 2 months old, before the amp was even burnt in. So the amp that cost me almost $1500.00 had a defect from the factory, has been running not properly balanced,since almost new, and to return it to the factory to be repaired would cost me over $500.00 in courier costs if I want it insured. So my point is that the factory warranty is worthless, the amp is built with cheap nasty ten cent resistors, and I can't find any shop that is willing to work on it.

 

As for pictures of the PCB, there is nothing showing as obviously burnt. I have looked and looked with a magnifying glass and bright light. Although the upper-side of the circuit board is covered with a silver grey film/coating, looks almost burnt, but covers the entire circuit board. 

 

So the bottom line is after replacing the resistors (the first ever modification done to this amp) it worked very well for a couple of hours, then failed totally. In that 2 hours I heard the amp was like it was when new. That sound (when new) only lasted for a few weeks before it started to degrade and the smell of slight burning started every time I used the amp. So this amp was defective from the factory, and a warranty that requires me to spend over $500.00 to make a claim is not really a real warranty. That is why I will buy my next amp from a trusted manufacturer that has real after sales service........not just a pretend warranty.

post #1234 of 1400
Quote:
Originally Posted by ozaudios View Post

Email sent to David at Little Dot......NO REPLY.

I contacted a local repair shop that works on tube amplifiers, they NEED a circuit diagram to work on the amp.

Looks like it is time to buy a WOO AUDIO WA22, at least their warranty is actually worth something. 
Instead of Woo, I would pursue your previous comment about making an amp yourself. There are lots of DIY designs out there and you seem to be interested in modding and such. I say go that route.
post #1235 of 1400
Quote:
Originally Posted by Maxvla View Post


Instead of Woo, I would pursue your previous comment about making an amp yourself. There are lots of DIY designs out there and you seem to be interested in modding and such. I say go that route.

Thanks, can you or anyone else point me to some designs? I do not know where to look, who to trust, or which designs are good or bad. I would really like to build my own amp, but where do I start, where do I get a design/circuit diagram from?

post #1236 of 1400
Your complaints about shipping costs are unfounded. Their warranty is just as any other warranty is. You send your unit in to be repaired/replaced, they send you the repaired or replaced unit. You agreed to the shipping costs of their warranty when you bought the amp in the first place. I regret that the amp has been problematic and now died, but high shipping costs is not their fault, so stop blaming their 'pretend warranty'.

It's an expensive lesson learned about dealing with China-direct products. Cheap and usually works well, but if something goes wrong it's very expensive to get service. That's the risk-reward of China-direct products. An equivalent product in your neck of the woods would likely cost £1500 due to parts and especially labor costs. You pay more for having local access so that you don't have to pay those high shipping costs. In the end you still pay. The only way to avoid this is DIY. You become your own warranty.
post #1237 of 1400
Quote:
Originally Posted by ozaudios View Post

Thanks, can you or anyone else point me to some designs? I do not know where to look, who to trust, or which designs are good or bad. I would really like to build my own amp, but where do I start, where do I get a design/circuit diagram from?
Start here: http://www.head-fi.org/f/6/diy-do-it-yourself-discussions

and here: www.diyaudio.com
post #1238 of 1400
Check for shorts. Failure doesn't necessarily mean physically burned out component. You need a DMM to measure components and do diode test on the diodes if they are borked. Have you checked the fuse?
post #1239 of 1400

OK, thanks for the advice. I have looked at the fuses, they look OK but I need to test them (I have seen fuses that look good but test as dead). 

 

There was a very strong electrical burning smell! Sudden and very strong. So I expect to see a burnt component. My nose tells me that one of the resistors I replaced (at the edge of the board) or a small capacitor beside it is the source of the burning smell. I need a multi-meter. 

post #1240 of 1400
Quote:
Originally Posted by ozaudios View Post
 

OK, thanks for the advice. I have looked at the fuses, they look OK but I need to test them (I have seen fuses that look good but test as dead).

 

There was a very strong electrical burning smell! Sudden and very strong. So I expect to see a burnt component. My nose tells me that one of the resistors I replaced (at the edge of the board) or a small capacitor beside it is the source of the burning smell. I need a multi-meter.

lol you don't have a DMM and you're modding? You got cojones man.

 

Sounds like a short, check that resistor. Worse comes to worse you may need to measure each resistor or just the resistors you replaced with a DMM if no physical damage is sighted.

 

You should turn the amp on again and quickly verify where the smoke or smell is coming from.

 

If you replaced caps, you might've reversed polarity. Cap's do go boom but they will emit smoke and smell.

 

Diodes could be blown if the short has tripped that far into the amp.

post #1241 of 1400
Quote:
Originally Posted by DefQon View Post
 

Woo stuff is all aesthetics, nothing special about the sound for the price.

 

supposedly using a tube rectifier lowers the switching noise from the SS PSU.

 

Not sure if i buy that since the difference probably isn't noticeable by human ears.

 

But it sure does look pretty.

post #1242 of 1400
Quote:
Originally Posted by mab1376 View Post
 

 

supposedly using a tube rectifier lowers the switching noise from the SS PSU.

 

Not sure if i buy that since the difference probably isn't noticeable by human ears.

 

But it sure does look pretty.

 tube rectifiers usually will have more of a voltage drop than SS rectifiers and draw more current. Different compatible rectifier tubes can change the sound a bit depending on the voltage drop of the tube.

post #1243 of 1400

Hello guys, 
anyone has the wiring diagram of the little dot mk vi +? 
thanks

post #1244 of 1400

I wish I had a wiring diagram...... I might have to make my own.

 

So I got a DMM, tested the resistors that I installed and they all read 330 or 329 Ohms. I tested them from the opposite side of the board and got the same reading. I could see nothing wrong, so I put it all back together and tried it. 

 

At first everything seemed good, the left gauge light up and all seemed normal. Then the Right gauge got power, the light went on and the needle went off the scale and the burning smell started.

 

Can anyone suggest what I should test with the multi meter? Should I try other tubes? How do I test the transformers.... when no power is supplied to them I hope, what do I have to do? Can I take readings from the tube sockets? What can I test with the multi meter? I know I could test every component in the board and look for a problem, I just want to know if there is anything to look for first, or is it just the long and difficult job of testing every component on it's own?

post #1245 of 1400

Do a diode test on the diodes or bridge rectifiers. Have you tried different sets of tubes to eliminate possiblity of a shorted tube? 

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