Alternative way to mount the speedball large board? [resolved]

[behnbot]

As my first Audio kit, everything went very well when assembling the crack.  Passed all tests first time around, and the amp actually ran dead silent w/o the speed-ball upgrade. Needless to say I am quite satisfied with the sound, and turnout of the initial project. Yesterday came the time to begin the speedball portion, and this is where I am encountering issues.

I've run into a bit of a roadblock with the large board portion of the speedball upgrade.  I've installed the small board fine, and everything checks out and is running perfectly at this very moment.  My problem at this point, is getting the large board installed, due to a few factors:

I installed my output capacitors very close to the terminal, which is preventing me from being able to bend them down into the center space, or out of the way at all.
I installed the 10W resistors similarly close to the terminal, making it difficult to clip them with the output capacitors in close proximity.
But most importantly-  The screws that are holding the terminals into the top plate are not long enough to install the standoffs! 

My initial thought was that I could simply drill new holes into the plate, and install the large board perpendicular to the original orientation and just make the wires a touch longer.  Essentially I would like to know just how terrible this idea is...

 

[Paul Birkeland]

The screws are long enough for the standoffs, but they need to be in the correct holes.  Check with the stock build manual to be sure that you have the 4-40 3/8" screws in the correct holes. 

You can completely remove the 100uF caps, then clip out the 3K resistors, then just install the 100uF caps on the vent hole side of the rear 5 lug strip.

-PB

 

[behnbot]

I must be missing something, because only see two feasible two holes available in the board, the top hole of the nine-pin and the bottom hole of the octal. 

The screws surrounding the 9 pin are okay, and with some wrestling I can get the standoff in there, as I had no issues mounting the small board's standoffs. It looks as if the thicker mounting around the octal is causing the issue for me.  I can try tightening the screws a bit more and see if that remedies the situation before I simply find some replacement screws.

I will work on re-positioning the 100uf caps, and see what I can do about getting the standoffs in there.  I'm sure I'm just being too delicate with everything since this is my first project with such extensive soldering- and tubes!  Those were a much tighter fit than I expected as well.

I really appreciate the feedback, I built and modded a 3d printer over the last 2 years,  but this is a whole different animal for me. 

 

[behnbot]

After a bit of fuss, I got the large board installed properly (lucky I had enough leads left to remount the 100uf caps in the proper position). 

Every voltage check is flawless except for B+; instead of getting 170-195, I get a steady and constant reading of 49.  I tested out the audio, and it sounds like there is more power and sound coming from the right channel than the left, I even switched my headphones around on my head to verify this.  I can only assume this has to do with the low voltage reading at b+.

Any ideas?

 

[Paul Birkeland]

Every voltage check is flawless except for B+; instead of getting 170-195, I get a steady and constant reading of 49.  I tested out the audio, and it sounds like there is more power and sound coming from the right channel than the left, I even switched my headphones around on my head to verify this.  I can only assume this has to do with the low voltage reading at b+.

If your B+ was 49 volts, then all your other voltages would be very, very low, and your 270 Ohm power supply resistors will start smoking.  Please recheck your voltages and refrain from listening to the amplifier until the voltage checks tell you that it's working.

 

[behnbot]

Performed a full resistance check, and a voltage check on the speed-ball upgrade. Here are my results:

Resistances (with multimeter setting to avoid typos/brain farts when applicable)

1    10.35@20M
2  20+ rising @200K
3  .01
4  Nothing @200M, 1.9@lowest setting
5  1.82@2M  OB and B+ on the speedball are both connected to this Terminal, and both get identical low voltage readings
6  2.48
7  1.2@200M
8  0
9  1.3@200M
10 2.47
12 0
13 steady climb
14 0
15 steady climb
16 0
17 0
18 1.8 falling@2M
19 1.56 slow fall@2M
20 0
21 climbs, then 18 falling@20M
22 0

B3  1.2@200M
B6  1.4, 1.5, 1.6 slowly @200M

RCA Ground    .01 red,    .01 blk
RCA Top          98.4 blk, 101.4 red

SMALL BOARD
OB      1.3@200M
IB      .69@20M
BAB    0,  .01
IA      10 climb @200M
OA      1.09-8-7 @2M

BIG BOARD
B+      1.3 @200M
OA      1.6-1.7@200M
G        .01
OB      1.3@200M (will seem to climb up, then settle down at 1.3

From here I proceeded to perform a voltage check, as the only resistance changes from the stock configuration were the terminals integrated with the speedball upgrade.  I performed the Voltage check at the Speedball only. I placed values slightly outside of the expected range in Blue, big misses in Red.
VOLTAGE CHECK

BIG BOARD

OA  97.8
OB  118.9
G 0
B+  51.5


SMALL BOARD
OA  87.3
IA    189
BAB 0
IB    189
OB  51.5

Terminal 5 has been resoldered, and when I check the resistance from points across the joint, I get a resistance reading of .01. 

I have no idea what to do next. (edited for formatting)

 

[behnbot]

Could this be a bad tube?  Terminal 5 is attached to the A1 post, which has the same low voltage reading.

 

[behnbot]

And apparently I cannot follow directions.  B+ is supposed to be wired to T4, not T5.  How utterly embarrassing.

Time to re-wire.