[sft]

some suggestions

1] test the psu with two 10K resistors as loads to see if the psu is OK.
2] erase the heat transfer compound under silicone wafers.(amp unit)

 

[Kenny12]

i thought heat transfer compounds were good for insureing that optimal transfer occurs between the silicon and the heatsink. at least whats what i think it is for my cpu anyway. And silicion wafers by themselves arn't very good at that right?

 

[sft]

1]the silicon wafer + compond is not a good idea.
2]It looks like something wrong with the amp unit. try to resolder two 500R, clear pcb carefully then solder again.

 

[Edwood]

Quote:

Originally Posted by sft 1]the silicon wafer + compond is not a good idea.

Why, other than the mess? Wouldn't heatsink grease compound help to fill the tiny gaps?

-Ed

 

[sft]

grease compond help to fill the gaps formed by two rigid interfaces.(ex mica and HS). I don't think it's helpful in this application. Basically grease compond is not a good thermal conductor.
off topic...

 

[Edwood]

Quote:

Originally Posted by sft grease compond help to fill the gaps formed by two rigid interfaces.(ex mica and HS). I don't think it's helpful in this application. Basically grease compond is not a good thermal conductor. off topic...

If a thin spread of grease is used, surely thermal grease is a better conductor than air?

-Ed

 

[MisterX]

http://www.onsemi.com/pub/Collateral/HB206-D.PDF

Page 45.

 

[Garbz]

Is the ground connected?

 

[Kenny12]

HUH? ground connected? atm the two +30 and -30 rails arn't even working when connected to psu.. i'm not even testing sound yet

 

[Pars]

Quote:

Originally Posted by Kenny12 just testing out the psu board now. found a very weird problem, when i connect the -30v and the +30v together either the -30V works or the +30V works, i can't seem to get both to work at once.... heres a extra large picture http://img.photobucket.com/albums/v3...2/44d583f5.jpg anyone have a clue? the leds don't light up on the amp board either

If you are using the transformer from Alltronics that Skyscraper recommended in the other thread, it would appear from the picture that the secondaries are out of phase with each other. Looking at it from the perspective of your picture, I would hook it up orange-white-black-red, or from the board edge with the AC1 AC2 labels readable (right side up), the opposite (red-black for AC1 and white-orange for AC2). This would hook Sec1 to AC1, and Sec2 to AC2, in phase (was never sure if this made a difference or not as I had never tried it differently). Any comments from anyone else?

Chris

 

[dgardner]

Quote:

Originally Posted by Pars This would hook Sec1 to AC1, and Sec2 to AC2, in phase (was never sure if this made a difference or not as I had never tried it differently). Any comments from anyone else?

Since it's full wave rectification, I don't think it really matters.

 

[dip16amp]

Are there jumpers to bypass the missing OPA541 and 0.2 ohm resistors? Not sure how you are getting the outputs of the LM317 regulators to the output wire blocks.

 

[Kenny12]

theres jumpers from underneath the board bypassing all the opamp stages

 

[dip16amp]

Quote:

Originally Posted by Kenny12 theres jumpers from underneath the board bypassing all the opamp stages

Do you have a picture of that?

 

[dip16amp]

Quote:

Originally Posted by Kenny12 i heard of people using 10k and it not being enough, what other value should i get just in case?

The main problem with using 10K ohm pots is that they are wired on the board in parallel to the 500 ohm resistors which sets the bias currents throughout the amp. That reduces the actual resistance to 476 ohms which will drive the output transistors alot hotter than normal.

A 50K ohm pot will reduce the actual resistance to 495 ohms which is no quite as bad but can only be used to lower the resistance so you would have to try it to find out which side it needs to be on.

A 10K ohm pot can be used if the 500 ohm resistor is replaced with a larger resistor like 1K ohm which will allow the actual resistance of the two to be adjustable above and below 500 ohms.