Speedball small board low voltage & LED not lighting [resolved]

[syahn9988]

Hello,

I assembled the crack and had it working fine for a full week before attempting the speedball 1.1 upgrade.

I attempted to attach the small board following instructions but seem to have made an error somewhere:
- none of the four LEDs on the small board light up when turned on
- voltage readings (vs. 12U)
OA: -1.6 V
IA: 0 V
B-A/B: 0 V
IB: 0V
OB: -1.6 V

Additional information:
The two LEDs attached to the 9-pin socket is also not lighting up
Both (stock) tubes lit up when the above voltage readings were recorded
I soldered and resoldered/reheated all the connections in in the small board three times (photos attached)

Can I please have some advice on how to resolve this issue?
Many thanks


 

 

[Paul Birkeland]

I would put the 22.1K resistors back.  You need a far, far better set of end cutters to cut the leads closer to the board.  I recommend the CHP-170.

The IA and IB voltages have nothing to do with the Speedball boards themselves, so seeing 0V there would make me believe that there's an issue with your build aside from the Speedball, so you need to go back to the resistors and debug the original build.

Once you have the 22.1K resistors back in place, let us know what the voltages are at terminals 1-10 as well as terminal 13.

 

[Deke609]

It looks like you might have a solder bridge on that board.  See circled area in attached pic.

cheers, Derek

 

[syahn9988]

Thank you Paul,

Here are the voltage readings (vs. 12U) with the resistors soldered back on (small board taken out) and with tubes in.
1. -0.8 V
2. -0.8 V
3. 0
4. -0.8 V
5. -0.8 V
6. 0
7. 0
8. 0
9. 0
10. 0
13. 177 V

I also measured resistance without the tubes and they agree with the values in the crack manual.

Derek, thanks for pointing this out, I reinspected the small board and there is no solder bridge. It appears like there may be one in the photo due to the angle the photo was taken.

 

[Paul Birkeland]

Terminal 13 is connected with a piece of wire to B5, then B2, then terminal 2, then terminal 4.

You have 177V at 13, then 0V at 2 and 4, so electrically those terminals are not connected and that should be investigated.

Also triple check where the two black wires meet on the headphone jack.  It's very common for one to not be captured by solder, and that can create a bunch of strange problems.

 

[syahn9988]

The problem was resolved by re-soldering the wire connecting 13 to B5.
Enjoying the (surprisingly noticeable) speedball upgrade as I type this.
Many thanks for your quick replies Paul