T15 no signal passing...help.

[myopic void]

Hi Tim,

Just finished a T15, double checked the polarity etc..everything looks good, no cold solder joints, bridges to be found. Diodes look correct. This is the simplest pre to build and it would be the one out 6 others I have done already to stump me! LOL!

17v on pin2 +20 tap. No smoke but no sound unless I switch the 48v switch which causes a little low end bump to register on the mixer VU meter.

Thanks for any help.

Best,

Eric

[myopic void]

No Shorts around U4 U5, 48v on pin 2 & 3 works. Checked the diodes multiple times and caps polarity. Could U4 just be dead? I am getting close to 18v on the +20 tap..but not reading on the -20 and PGND.

Any advice is welcomed... How can I check to see if U4 is dead...

Help,

Eric

[myopic void]

anybody???????

[myopic void]

???????

[Mylithra]

Dont know what to tell you.. Sounds like something is installed backward or the wrong resistors in the wrong places. Id double check the values just to be certain though I could be barking up the wrong tree.
Both of my T15s came out right with no troubleshooting so I really havent had this problem.

[myopic void]

Thanks for the email...I am not getting much help on this one? I know the polarity ic correct on most everything as I showed it too a tech friend locally. The op-amps are in the right direction etc. I will start going through the resistors next then. The caps are in the right place diodes etc. Only thing I have no gone over are the resistors after that are one of the op-amps dead or regulators???

Eric

[dkatz42]

Do you have the 0 ohm resistors installed in place of the optional inductors, and the jumpers installed properly?

[myopic void]

Thanks for the email...do you mean R27 and L3, L4 all having the one black band resistor? If so, yes they are installed...there is not a polarity issue there I would not think.

Does Tim Ryan chime on the these questions anymore?

Best,

[myopic void]

I checked each resistor...each color band matches up for the position...Hmmm?

[myopic void]

Ok...I noticed that R30&33 are the smae color stripe as R37...but the values of R37 is different...since I did not measure the resistors when I installed them could one of these being in the wrong place in spite of them having the same color codes? I will have to remove and measure them to see. could these values being in the wrong place cuase no sound to pass?

[greg]

Don't have the answer to your last question. But some of the resistors do have the same color sequence depending on which direction you are reading them. I always meter every resistor before soldering, thus no problems.

[myopic void]

Don't have the answer to your last question. But some of the resistors do have the same color sequence depending on which direction you are reading them. I always meter every resistor before soldering, thus no problems.

Thanks for the email...Good News! It was the r30-r33-r37 mix-up others have noted...There needs to be some notice in the instructions about this. Anyways it fixed. Does Tim no longer service the SCA forum


Thanks SCA memebers for all of the help and suggestions