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Messages - Fixr1984

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Tubes and Hybrids / Re: Rectify 110v?
« on: April 07, 2012, 04:35:40 PM »
So I would basically run the second one backwards and the I would rectify the 120VAC when I am done

Tubes and Hybrids / Rectify 110v?
« on: April 07, 2012, 01:24:54 PM »
I found a tube preamp that I was thinking of building and it calls for 150v for B+.  Can I rectify my 110v from the wall outlet to DC and use that?  Do I need to actually build a power supply using a transformer?

Amplifier Discussion / Re: Transformer issues.
« on: April 06, 2012, 11:40:40 PM »
Yea I probably should have posted that. It is -33.5VDC. 

Amplifier Discussion / Re: Transformer issues.
« on: April 06, 2012, 10:35:00 PM »
I have decided not to use the power led setup from the power supply board so that is no longer an issue for me.
I measure 33.5VDC from +V to ground.  Everything seems to be working fine, I've done some testing into a speaker and it sounds pretty good.  Just need to get my preamp done.  Had a buddy bend me up a chassis so things are finally coming together.

Amplifier Discussion / Re: Transformer issues.
« on: April 01, 2012, 10:24:18 PM »
Its too hard to see what is going on with the mask on the circuit board, it looks like there is a diode coming off of AC1 and from there it goes to a resistor and then to the led. (crappy description i know).  As far as power I have.  51.7VAC from the transformer, out of the RS604 I have 47.0 VDC, and from the output pads of the power supply board +V and -V I have 67.2VDC

Amplifier Discussion / Re: Transformer issues.
« on: April 01, 2012, 04:19:45 PM »
I had an RS604 lying around so I gave that a try.  I get dc voltage where I am supposed to now and with a speaker hooked up and my mp3 player to the input i get an amplified sound.  I cant get the LED to light up tho.  I only get 1.2vdc on the led pads.  Is this because of the board layout and using a different transformer?  I dont really care if the LED will light up as long as the board is working properly.

Amplifier Discussion / Re: Transformer issues.
« on: March 21, 2012, 04:32:41 PM »
Thanks, I will give it a try.

Amplifier Discussion / Re: Transformer issues.
« on: March 20, 2012, 09:56:01 PM »
Its hard to see the traces on the top of the board.  Hope this helps

Amplifier Discussion / Re: Transformer issues.
« on: March 10, 2012, 09:43:40 PM »
Here's the schematic.
What I did that seemed to work for the power supply board was to run one red to AC1 and the other to AC2 and then I took the black wire to the other AC1 and AC2 spots.  Not sure if that was right or not but I was able to get a good DC reading from +v and +PGND.
I do pop a fuse when I try to connect the amplifier board. It only happens when I hook up all 4 wires.  If I have either just the + wires connected  or just the - wires it wont blow the fuse.  Is this an issue with the way I have the AC wires connected or an issue with the amplifier board.

Amplifier Discussion / Re: Transformer issues.
« on: March 09, 2012, 12:57:18 PM »
Sorry to keep asking the same thing over and over but I'm really scratching my head.  Looking at the pictures it makes sense but I have spaces for 4 wires to hook up to the board and thats where I'm getting lost.  I should add that I have the kit from
Here is a picture I found showing you what I mean.  There are 2 wires going to each side and I'm lost......So I run a red wire to each side then what is the other wire?  This is like my kit but not the stereo version.
Thanks for putting up with me. ;)

Amplifier Discussion / Re: Transformer issues.
« on: March 09, 2012, 07:38:59 AM »
Thanks.  The next part that confuses me is where to hook up the wires to the power supply board.  Do I run a red on each side and "y" the black to go to both sides?..AC always confuses me:)

Amplifier Discussion / Re: Transformer issues.
« on: March 08, 2012, 10:12:31 PM »
Unsure of the original wattage, its an old Sherwood reciever, no wattage markings.
The wires in the picture are left to right; Blue 1, Blue 2, Red 1, Black, Red 2.
Red-Red: 51.6vac
Red1-Black: 25.8vac
Red2-Black: 25.8vac
Blue-Blue:  7.4vac
Blue1-Black:  16.8vac
Blue2-Black:  11.0vac
Red1-Blue1:  5.3vac
Red1-Blue2:  .5vac
Red2-Blue1:  39.2vac
Red2-Blue2:  34.4vac

Amplifier Discussion / Transformer issues.
« on: March 07, 2012, 11:02:23 PM »
I am finally getting around to finishing up my Lm3886 kit.  I have a transformer from a home stereo i want to use.
First off can I do that, secondly how do I know what wires go to my power supply board.  I have the 2 ac input wires and there
are 5 wires from the secondary side.  There are 2 reds and 2 blues and one black wire.  The AC voltage varries depending on where I'm measuring from.  Where should I be testing and what should I be looking for?  Thanks for any help.

Amplifier Discussion / Re: RobertT.....
« on: November 29, 2006, 11:59:26 PM »
me too.
I deleated it already

Amplifier Discussion / Amp LED's
« on: September 24, 2006, 10:34:21 PM »
One of my Marshall's is an AVT50. I bought it new and less than a year into having it I fried a resistor and had to have it repaired. The repar guy said the fan quit and the output transformer got too hot and cooked the resistor. Recently (its been about 9 months since the repair) I smelled a burning smell again but havent noticed any huge performance issues. Last time the sound crackeled a little bit and slowly got worse. Now on to the LED part of my question. I have noticed that If i take a fuzz pedal (fuzzrite) and turn both knobs all the way up two of the LED's inside the amp on the board light up. I am assuming they are just being used as clipping diodes and that I'm driving the preamp pretty hard and its sending enough volts to light them. I can turn the volume and gain all the way up on the amp and they wont light. To me the amp is starting to sound a little weak and was woundering if what i described my have damaged something. I still have warranty on it but I dont want to take it in again and be without it again for a month unless there is something obviously wrong with it. Ok I'm out of breath. Any ideas?

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