Crack Speedball upgrade help.

[kt3z]

I finished building my crack speedball amp, checked the steps three times, and when i check the voltages, they are all lower than what they should be. Im not sure what that means or which one section specifically is the problem. The voltages are

1- 45
2- 55
4- 55
5- 45
7- 40
9- 40
13- 55
15- 114
21- 184

Any help on how i would go about fixing this would be greatly appreciated!

 

[adydula]

Wow they are low compared to what the manual states....I just did mine and they are what they should be...

I would check the installation over again....check that you have the correct transistors in the right position and that they are in the right holes / orientation. Check the wiring all again.

Its good that you have no "smoke"!!

If your crack was working before, then its definetly an install issue, wiring, components in the incorrect location etc...also check for shorts on the boards.

AND

If you moved wires around to install the plastic standoffs make sure you didnt push any tube socket pins together and short etc..easy to do around the smaller 12AU7 socket..

Good Luck!
Alex

 

[kt3z]

why do you say its good that I have no smoke? is this usually a sign of a something that blew out?

Also how would i check for shorts along the board?

the crack was working before i installed the upgrade, but never with speedball, but i dont understand how the voltages are at about 1/2 to 2/3 less than it should be.

Ive checked the steps time and time again, but I am also colorblind, and some of these resistors are colored, so im starting to think that might be the problem, ill have to bring in someone else to see if I got that right. And i think thats the problem actually ill see if it is. It would have been nice if they were labeled with words on the tape for us colorblind folk 

 

[Doc B]

Use your multimeter to check the value of the resistors. Those tiny stripes are difficult for everyone to make out.

 

[Paul Birkeland]

Pull the 6080 and then recheck with just the 12AU7 running in the amp.  Voltages at terminals 1-5 are all you need to measure for this test.

-PB

 

[kt3z]

1- 185

2- 195

3- really hard to get to with the chip in the way but its reading 190

4- 195

5- 193

 

[kt3z]

ive checked now for the fourth time, and ive completed all of the things in the instructions. Is it possible that a piece is broken?

 

[Paul Birkeland]

1- 185

2- 195

3- really hard to get to with the chip in the way but its reading 190

4- 195

5- 193

Terminal 3 is grounded, it should read 0V.  If you have 190V on terminal 3, you have 190V on the chassis, and you have a serious wiring error that you need to correct.  This is not a wiring error with the Speedball, but an issue with the original kit construction.

This most often manifests itself as a bad connection of the black wires running around the volume pot and headphone jack, particularly the two black wires that connect together at the headphone jack.

Once that is corrected, recheck the voltages and let me know what you get. 

 

[kt3z]

Okay It's definitely a soldering issue, I just realized that not all of the LEDs were on, does anyone know which joints specifically from the picture? It's going to be interesting re soldering this

 

[Paul Birkeland]

Are those LED's on the big board glowing with no 6080 plugged in? 

In all honesty, I would resolder every joint in the amplifier before going much further.  Keep at it until your T3 is back at 0V.

-PB

 

[kt3z]

T3 is at 0, i really couldn't get an accurate reading on it, but i finally moved some stuff for soldering again. Then i plugged it in with the main tube to check voltages. While waiting the 30 seconds before doing anything, i noticed that some of the LEDs were off. If you can't tell by the build I'm a first time builder so i expected some problems. Is the only fix to this resoldering everything? I only had to resolver 2 joints on the original crack build.

 

[Paul Birkeland]

OK, with just the 12AU7 in, what voltages do you get at 1-5?  Also, with just the 12AU7 in, if any LED's glow on the big PC board, there is a rather large construction mistake causing this.  Common issues would be:

Mixing up 2N2222 and 2N2907 transistors
Mixing up 31.6 and 237 Ohm resistors.
Mixing up jumper wires connecting to the PC board.
Backwards LED's.

 

[kt3z]

with just the 12 AU7, i got the same voltages again but with 3 being 0, so:

1: 185

2: 195

3: 0

4- 194

5-194

 

[Strikkflypilot]

And the LEDs?

 

[Paul Birkeland]

with just the 12 AU7, i got the same voltages again but with 3 being 0, so:

1: 185

2: 195

3: 0

4- 194

5-194

Are the LED's on the socket glowing?  If so, I would be suspicious that you've switched the R1 resistors between the two boards.

-PB

 

[kt3z]

That picture is has the 6080 tube inserted, when i take the 6080 off no LEDs on the big PC board turn on, I was just trying to show you the 3 LEDs that aren't on.

With just the 12AU7 i have the three LEDS on the 2 smaller PC boards, but one of them is off. If you look at the picture, in the bottom left, only one of the two LEDs are on on the small PC board.

I know i placed all the LEDs in the right direction, so its either soldering or mixing up the resistors.

Also what do you mean by the LEDs on the socket

 

[Paul Birkeland]

Also what do you mean by the LEDs on the socket

There are two LED's on the 9 pin socket.  They will help indicate what might be going on.  Is one glowing much more brightly than the other?

 

[kt3z]

they seem to be about the same brightness on the 9 pin socket

 

[kt3z]

Are the LED's on the socket glowing?  If so, I would be suspicious that you've switched the R1 resistors between the two boards.

-PB

I did not switch the resistors; I've checked the ohms and they match up to what the directions say they should be. I even checked them all individually to see if maybe i just switched two of them, but it all checks out fine

I did not switch the transistors as I've checked the writing on it

Not all of my LEDs are on, and i assume they are supposed to be? On the Main PC board, one of the LEDs is extremely bright, the one above it off, and the two other on the other side are significantly less bright than the first one stated.

also i don't know if this helps, but most of my voltages are now reading around 70 with both the 12AU7 and 6080 plugged in it reads:

1- 75

2- 70 (incorrect, should be 170)

4- 73 (incorrect, should be 170)

5- 74

7- 60 (incorrect, should be 100)

9- 63 (incorrect, should be 100)

13- 76 (incorrect should be 170)

15- 129 (incorrect should be 185)

21- 195

 

[Paul Birkeland]

they seem to be about the same brightness on the 9 pin socket

With just the 12AU7 in the socket, having ~180V on terminals 1 and 5 combined with glowing LED's on the 9 pin socket is almost always switched R1 values (sending 30mA through a 12AU7 at 1.5V of bias gives you about 180V of plate voltage).

If that is not the case, then check the actual wiring of the boards to the terminal strips.

DO NOT plug the 6080 back in yet, this is just camouflaging the first problem that we need to resolve.