Yes I was confused on the model.
That unit is nice.
That unit is nice.
Little Dot MK8SE / MK6 Super Mods (All verified mods are on first page)
- Thread starter Redge78
- Start date
I just finished assembled all the circuit parts, unfortunately the amp won't turn on except only those six tubes light up, also can't take the DC voltage result as unstable reading.
Is that something wrong with transformer? I have repeated checked the connection many many times, no idea what's went wrong?
Check the electrolytic capacitors by the AC input.
If you changed them for higher capacitance OR higger voltage, then it will take longer for cap to charge up to turn on.
Does one meter light up?
The tubes heater will light up regardless if amp work or not because its a direct feed from Transformers,
So don't worry about that.
So don't worry about that.
So far Only tubes light up as normal, the amp and meter are not active at all. I m still figure out what's went wrong. Do You have schematic of mk8se?
Electrolytic caps is brand new Nichicon and all resistor are upgraded to Mills and Dales but capacitance, voltage and resistance still same as usual..
Coupling Caps are Mundolf EVO OIL 0.68uF/450 Volt and WCF are EVO OIL 0.22uF/450 Volt
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So none of the meters light up?
The left should have turned on immediately.
You may have similar Problem as another here who had lost connection of PSU center ground to other side of board under area where the big caps and zener diodes are.
The power was at the first big caps, but missing further down.
I most likely the PSU area your Problem.
The left should have turned on immediately.
You may have similar Problem as another here who had lost connection of PSU center ground to other side of board under area where the big caps and zener diodes are.
The power was at the first big caps, but missing further down.
I most likely the PSU area your Problem.
How to test the PSU? Do I need replace the new one?
If you are not skilled enough to test PSU,
Read back about 10 pages where many here discussed and repaired the PSU.
If you still feel not up to it,
Simply bring to your nearest repair shop to fix.
The rebuilt schematic of this amp (by Coinmaster) is somewhere in this thread.
I will try look for it to post on first page.
Read back about 10 pages where many here discussed and repaired the PSU.
If you still feel not up to it,
Simply bring to your nearest repair shop to fix.
The rebuilt schematic of this amp (by Coinmaster) is somewhere in this thread.
I will try look for it to post on first page.
No, in most cases this is either a board trace open or a single component issue, like the power transistors or the wiring to the board is of, like the transformers.
If you disconnected the transformer, then you may have reversed one of the primary windings, so that they are in parallel instead of series.
I did that by mistake when swapping out a transformer..
So check that the transformer primary are in series, if you disconnected them from board.
Also, be careful to not get shock when testing. check the bridge rectifiers if you replaced them wrong way..
Check for power at the PSU.
Use the PSU schematic in beginning of thread as it shows the estimated proper voltages.
Yeah! I suspect PSU problem, will check later. I also found NPN transistor Collector short with ground, cant find out why?
I remember few months ago, this amp turn on after few minutes, there was suddenly striking light short clearly seen in front of me.
When open bottom case, found one of the resistor explode which cause around that PCB area damage, since then can't proper turn on till now. Do u know what cause amp strike lightning?
Begin I thought wire connection error so I change those garbage thin wire with better one, follow by changed both transistors twice, then upgrade all to similiar amount readinhg new caps, resistors, diode and relay, Can be said 90% of the parts inside this amp are brand new.
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The power transistors have tiny washers on the metal case which prevent the body to touch.
It may have broke if you ddn replace.
Or they may be fine as you can only find out by checking voltages .
Checking for short may not be correct if another conpocomp like the diodes are connected.
Plus caps charging.
So best way is to test unit upside down, for checking voltages with unit on & tubes installed.
Must be careful to not cause a short when testing.
If your components are installed correctly and not higher value electrolytics by the delay circuit , then it would be the board trace.
Only way to check it to use volt meter for proper voltages and see where the power stops.
Read back on the PSU issues.
It may have broke if you ddn replace.
Or they may be fine as you can only find out by checking voltages .
Checking for short may not be correct if another conpocomp like the diodes are connected.
Plus caps charging.
So best way is to test unit upside down, for checking voltages with unit on & tubes installed.
Must be careful to not cause a short when testing.
If your components are installed correctly and not higher value electrolytics by the delay circuit , then it would be the board trace.
Only way to check it to use volt meter for proper voltages and see where the power stops.
Read back on the PSU issues.
Transistors washers has been replaced brand new earlier, both have no problem after diodes reading checked several times.
I just found out the transformer garbage wire ground connection broken, the original wire is very thin and just replaced thicker one.
I also have checked transformer wiring the Voltage and Ohm is normal except green color Ohm reading is 46.8R, too high?
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I never checked the ohm of the transformer so I dunno.
I forgot what the green was for but you can check the schematic that SonicTrance posted.
I forgot what the green was for but you can check the schematic that SonicTrance posted.
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Transformer at last fixed, amp meter light work normal however 0 reading and no sound LOL
Observe if you hear relay click when second meter turns on.
Will need to test volatges of PSU.
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