The new "My Ref" Rev C thread

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#201
glt said:
Charging up the caps pulls too much current? Typically you put the fuse before the primaries
Click to expand...

Yes, and I have one there. T3,15A

AndrewT said:
fuse the primary to stop the transformer/rectifier/smoothing bank setting fire to the house.
fuse the secondary AFTER the smoothing bank to prevent the rest of the downstream circuit setting fire to the house.

If either of these fuses are too big, then the protection they offer is weakened.

Power Resistors and/or Power Thermistors come to our aid.
Click to expand...

Thanks Andrew for your replay. I do prefer to play it nicely. Fuses to save the amps as good/adequate as possible.
I have read the whole My_ref thread, but don't remember though as if the relay's where applied for the turnon thump also?
Anyway, don't mind prolonging the lifespan of these by cutting inrush current.

udailey said:
Here is how to use that CL60 or THOSE CL60 depending how many 🙂
This is a Nelson Pass power supply and is really more suitable for Class A so dont go trying to use it on your MyRef, but the way the thermistor and 33pf cap is wired can be beneficial and used in your supply.
Uriah
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Thanks Udaily for your replay. I would love to implement Nelson Pass idea's whenever possible. Saw this too when searching, but having a single 230V winding, it don't come that easy and handy. RevC is not a class A driven amp so I suppose it can not be implemented.

Now I have T4 A on each 25V wire and it works ok. Amp has been turned on about 20 times and it keeps playing so well.
I may have misled myself and you forummembers by the incorrect measurements for the toroidcore from the sellers website.
Anyway some inrush reduction will be added.
 
#202
****ed up the 2 Channels 🙁

Hi guys, i burned the 2 amps 🙁 i dont know what happend, i tested in individually, and after mount in the case, and i turn it ON, see some smoke leaving the opamp, so i removed the pcbs and i see that the LM3886 are ****** up too :S

I just see one PCB, right now im without sleep, so i will wake up tomorrow and will check what other **** are broken!!!

I CANT BELIAVE IT!
 
#203
Re: ****ed up the 2 Channels 🙁

samsagaz said:
Hi guys, i burned the 2 amps 🙁 i dont know what happend, i tested in individually, and after mount in the case, and i turn it ON, see some smoke leaving the opamp, so i removed the pcbs and i see that the LM3886 are ****** up too :S

I just see one PCB, right now im without sleep, so i will wake up tomorrow and will check what other **** are broken!!!

I CANT BELIAVE IT!
Click to expand...

Hi, samsagaz. Sorry for the disaster! You did add the insulation between the lm3886 and the heatsink + the plastic for the screw?
Also, always check using a ohmmeter that there is no connection between sink and lm3886.

I can't help you any further though. If they work before and got burnt when mounted in case it is likely a short.
By LM3886TF next, they are insulated.

nenne
 
#204
udailey said:
Here is how to use that CL60 or THOSE CL60 depending how many 🙂
This is a Nelson Pass power supply and is really more suitable for Class A so dont go trying to use it on your MyRef, but the way the thermistor and 33pf cap is wired can be beneficial and used in your supply.
Uriah
Click to expand...


what does the .0033uf line cap do? Is it necessary? Can just one thermistor be used like this? (see attachment [sorry for the ghetto MS Paint schematic:clown:])

btw, .0033uf is 3300pf or 3.3nf (not 33pf) 😉

nenne said:
but having a single 230V winding, it don't come that easy and handy. RevC is not a class A driven amp so I suppose it can not be implemented.
Click to expand...
Can't he just put the thermistor in series with one end of the primary?
 

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#205
Re: Re: ****ed up the 2 Channels 🙁

nenne said:


Hi, samsagaz. Sorry for the disaster! You did add the insulation between the lm3886 and the heatsink + the plastic for the screw?
Also, always check using a ohmmeter that there is no connection between sink and lm3886.

I can't help you any further though. If they work before and got burnt when mounted in case it is likely a short.
By LM3886TF next, they are insulated.

nenne
Click to expand...

well, i didnt used the plastic for the screw (didnt know the purpose of thse little plastic ) 😀

Btw, now i will start checking components to see whats burned. i really dont want to desolder all the pieces, butdont know how to check the complete board if not remove everything...

i inserted the AC again to the boards (using the bulb trick) to see if at least the Relay works and none of the relay starts. Looks like everything are ****** up
 
#209
#212
well, now with other PCB that i finished aseembly and using TF version, when i turn it ON the trafo, the lamp turn it on, and after the relay make contact, the light start turning off slowly, but if i dark the room, i see that an small amount of light come out from the bulb, its not OK, right?
 
#213
samsagaz said:
well, now with other PCB that i finished aseembly and using TF version, when i turn it ON the trafo, the lamp turn it on, and after the relay make contact, the light start turning off slowly, but if i dark the room, i see that an small amount of light come out from the bulb, its not OK, right?
Click to expand...

Could be ok. When I started my kits with bulb in series it only started to glow if I turned the volume up to 50%. Fuses on the secondary was T2,5 A, they did not survive without the bulb in series. Never tested in dark though. Measure on speaker out that there low values of ac and dc , not more than 10mV dc. Then that side is ok. Dig up some junk speakers, connect some source to input and test . The relay's are for speaker protection and for turnon thump, I have looked that up.

Good Luck nenne🙂
 
#214
well, looks like im ****** up, the other pcb that i mounted have problems too!!!, when i turn it ON, the relay dont make contact, the led dont bright, and the lamp are 100 bright.

When i turn it OFF, the relay make contact for just 1 second and the led bright too for the same time :S


Strange Syntom, right?
 
#215
nenne said:


Could be ok. When I started my kits with bulb in series it only started to glow if I turned the volume up to 50%. Fuses on the secondary was T2,5 A, they did not survive without the bulb in series. Never tested in dark though. Measure on speaker out that there low values of ac and dc , not more than 10mV dc. Then that side is ok. Dig up some junk speakers, connect some source to input and test . The relay's are for speaker protection and for turnon thump, I have looked that up.

Good Luck nenne🙂
Click to expand...

Just to be correct here, the bulb shall light up and slowly dim down, when the power is turned on. If something is wrong light stay on.
Then you can measure and test like the above description.

nenne
 
#216
nenne said:


Could be ok. When I started my kits with bulb in series it only started to glow if I turned the volume up to 50%. Fuses on the secondary was T2,5 A, they did not survive without the bulb in series. Never tested in dark though. Measure on speaker out that there low values of ac and dc , not more than 10mV dc. Then that side is ok. Dig up some junk speakers, connect some source to input and test . The relay's are for speaker protection and for turnon thump, I have looked that up.

Good Luck nenne🙂
Click to expand...


Well After 15 seconds of the Amp ON, the R11 Blow :S How is possible that i cant build an amplifier!! DAMN!
 
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