Crack + Speedball upgrade help

[sleyk]

I am trying to build a speedball upgrade on my crack kit and run into some issues.
When i initially built it, there was smoke coming out of the 270W resistor at terminal 15.  I shut it off and resoldered the loose capacitor to remedy the issue.  I also changed my tube to a tungsol 5998 from the old 6080 stock tube.

I ran a voltage check and all of the voltages are way off

1        1.71
2          4
3          0
4          0
5        2.06
6-13      0
14        .5
15        0

A1    -.6
A2    .3
A3    -.05
A4    0
A5    .03
A6    0
A7    0
A8   

Help would be greatly appreciated

 

[Doc B]

Check your fuse.

 

[sleyk]

I found a loose wire from B2 ---> 2 and resoldered it.

The voltages are still off:

Terminal    Voltage    Expected
1                -1.05
2                .58
3                0
4              .58
5              -1.14
6              0
7              0
8              0
9              0
10            0
11            0
12            0
13            .57
14            .57
18            92
19            94
20              0
21            246

B1          -1.04
B2        0
B3          0
B4          -1.16
B5        .56
B6-8      0

A1-9    0
The 5998 tube lights up but the bottom tube lights up slightly.  None of the LEDs respond.  I checked the fuse and gone over all the wiring to no avail.

 

[sleyk]

Also, I noticed that the 270ohm which was smoking cracked.  I used my multimeter to check the resistance and it reads at 281 ohms.  Could the cracked resistor be the issue?

 

[sleyk]

I found that the 270ohm 1w resistor from 21 to 14 reads -.60 on the multimeter.  Does that  need replacing?

 

[Paul Birkeland]

A cracked resistor means it got so hot that it gave up.  This means that there is a short downstream from that resistor.

I would replace them both (they are 5W), then get back to us.

Another user reported a similar issue, as he had left off the insulating shoulder washers that to between the mounting screw and the TIP50 on the bigger Speedball board.

-PB

 

[sleyk]

Thanks!
I had trouble finding a 5w 270 ohm resistor.  I talked to a guy at the front and he said a 10w 270 ohm works just as fine if not better since it runs cooler.  Is it okay if I use a10w resistor instead?

 

[Paul Birkeland]

Sure, a 10W will work well.

 

[sleyk]

I also can't seem to find any nylon shoulder washers.  What is the name of the washer: Nylon #6 Shoulder wash (x4)?

 

[Paul Birkeland]

I also can't seem to find any nylon shoulder washers.  What is the name of the washer: Nylon #6 Shoulder wash (x4)?

Now I'm really confused.  You have built Crack and are checking voltages, how do the nylon washers come into play?

 

[sleyk]

Sorry for being so brief.  As stated earlier in the thread,  another user had the same issue with voltages and didnt place the shoulder washers in.  I can't seem to find the washers so it may be causing a short

 

[Paul Birkeland]

A shorted power transformer will not cook a component downstream from the power transformer (your 270 Ohm resistor).

 

[sleyk]

I am missing the nylon shoulder washers for the circuit board.  I was hoping I can get the size and name of the type of washers.  I apologize for miscommunicating my concerns.  Thank you!

 

[Paul Birkeland]

I am missing the nylon shoulder washers for the circuit board.  I was hoping I can get the size and name of the type of washers.  I apologize for miscommunicating my concerns.  Thank you!

Are you referring to the nylon standoffs used to mount the boards?  Are you missing all 4 of them? 

 

[sleyk]

A cracked resistor means it got so hot that it gave up.  This means that there is a short downstream from that resistor.

I would replace them both (they are 5W), then get back to us.

Another user reported a similar issue, as he had left off the insulating shoulder washers that to between the mounting screw and the TIP50 on the bigger Speedball board.

-PB

Thank you!  I left off the insulating shoulder (i thought they were made of nylon and 4 of them.  I also replaced my 5w 270ohm resistors with 10w 270 ohm resistors.  I did a voltage check and everything is within 15% of the predicted voltage readings!  I appreciate the advice and the patience you have provided me!

 

[Paul Birkeland]

If you left off the white shoulder washers on the power transformer, then you should take the power transformer off and install these parts.  This can affect the reliability of your amplifier.

 

[Paul Birkeland]

Hello Slyek,

Just checking in to see if you still need assistance.

Sincerely,
Paul