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Eddie Current DIY amplifier "Monolith" - Page 8

post #106 of 172

Power supply problem

I got +12.54 from the + side and -15.56 from the - side.

Is there any test point I could measure to debug the problem?

post #107 of 172

Sounds like something on the + side only, the - voltage seems about right.

 

I had some voltage questions when I was building the power supply, Craigs directions:

Check the voltage drop across the series resistor to the zener to see if the Zener is working. Then measure the voltage at the zener. The output from the transistor emitter should be .6 volts less than the zener voltage.

post #108 of 172

^

 

You probably have a 14V zener installed.

 

1) Also check the voltage at the top of the big cap, just after the rectifier/bridge.  You should measure over 16V, and under 25V.  It should be around 20-22V with a 15VAC transformer.

2) Measure the voltage drop across the 1ohm resistor.  If the drop is disproportionately large, compared to the negative rail, you have something wrong in your amplifier build and it's pulling lots of current.  I would be surprised if something didn't fry if this is the case.

3) If you remove the amp from the PSU, you should have similar voltages on the positive and negative rail.

4) If that's all OK, the zener voltage drop is OK, then the transistor in the PSU is likely borked.  Make sure it's installed correctly.

post #109 of 172
I just checked my copy of "The Art of Electronics"...I can't seem to find "borked" in the glossary....Can you provide a technical definition? :-)
post #110 of 172

see Swedish chef.

post #111 of 172
Quote:
Originally Posted by amcananey View Post

I just checked my copy of "The Art of Electronics"...I can't seem to find "borked" in the glossary....Can you provide a technical definition? :-)

 

It's in the unreleased 10th edition.

 

But, I can provide a visual definition. :D

 

http://youtu.be/br2s0xJyFEM

post #112 of 172

That's nothing like an Icelandic Baker, right? wink_face.gif

 

Quote:
Originally Posted by kevin gilmore View Post

see Swedish chef.

post #113 of 172
Quote:
Originally Posted by shipsupt View Post

That's nothing like an  Viking Baker, right? wink_face.gif

 

Fixed ~ biggrin.gif

post #114 of 172
Quote:
Originally Posted by shipsupt View Post

That's nothing like an Icelandic Baker, right? wink_face.gif

 

not a muppet fan??

post #115 of 172

Actually he was one of my favorites!

 

And Animal on the drums of course.

post #116 of 172

I liked Kermit and Fozzie.  Statler and Waldorf were up there too.  Waka waka!

 

BTW, since you're on the thread.  How do you like the amp?  It looks meh, but perhaps it sounds better than one would think.


Edited by holland - 8/14/13 at 9:32am
post #117 of 172

Well

It looks like my R2 is borked.

I replaced R2.

Then the output on the + side is 32 something.

Ive got following measures

c6 15.36v

d2 15.87v

 

 

c5 32.04v

d1 32.07v

 

Is my d1 borked too?


Edited by mcluxun - 8/14/13 at 3:05pm
post #118 of 172
Quote:
Originally Posted by mcluxun View Post

Well

It looks like my R2 is borked.

I replaced R2.

Then the output on the + side is 32 something.

Ive got following measures

c6 15.36v

d2 15.87v

 

 

c5 32.04v

d1 32.07v

 

Is my d1 borked too?

 

Resistors don't normally fry, but it does look like d1 is borked now.  Double check that the transistor is working too.  There should be a 0.5V-1.0V drop from D1 to the part of R7 that points toward the transistor (or the output of the emitter).

 

Your DC voltage is awfully high.  What's the AC you're feeding it?  What size caps are in those positions?  According to the schematic and BOM, those are 25V caps.  You'll likely be replacing them soon.  25V is marginal there, as an unloaded 15V transformer can reach that limit, but 32V is way high.  Your AC is about 23V.  Is that transformer really 15VAC?

post #119 of 172
Quote:
Originally Posted by holland View Post

 

Resistors don't normally fry, but it does look like d1 is borked now.  Double check that the transistor is working too.  There should be a 0.5V-1.0V drop from D1 to the part of R7 that points toward the transistor (or the output of the emitter).

 

Your DC voltage is awfully high.  What's the AC you're feeding it?  What size caps are in those positions?  According to the schematic and BOM, those are 25V caps.  You'll likely be replacing them soon.  25V is marginal there, as an unloaded 15V transformer can reach that limit, but 32V is way high.  Your AC is about 23V.  Is that transformer really 15VAC?

R2 is fried for sure. It's charred and resistance is way greater than 100.

I used the transformer in the BOM it yields 35vac or 17vac.

post #120 of 172

Weird transformer problem.

I dont know if it's unlucky me or everyone else.

I bought the exact transformer according to BOM, wired as 30vac.

The output is 38Vac! And my home voltage is ~125Vac.

The first time I thought it's a defective product so I get another one free from mouser.

Guess what it's the same thing!! 38Vac.

Anyone else ran into this problem?

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