Help with speedball upgrade (newbie) [solved]

[sparggy]

Hi Guys

After a long break with my crack not working I am taking another go.

I have replaced the heatpad and the led now.

First I will give you my voltage check: (I am on 240V here in Australia)

1: Not sure why but this is showing as -61
2: 182
3: 0
4: 182.2
5: 64.5
6: 0
7: 57
8: 0
9: 100.5
10: 0
11: 0
12: 0
13: 182
14: 0

The LED on board A is replaced but still not lit up (LED 02)
The LED connected to A3 is also not on.

Some other things:

I had the stock crack working perfectly before installing the speedball, although I did some really dumb things when installing the speedball like soldering while it was on (beginners mistake and yes I did learn my lesson but I may have blown something doing this ?)

One thing I have noticed is one of the transistor heatsink gets hotter than the other one, this may just be s symptom but trying to provide as much info as I can.

Sorry if there is poor info here guys this is my first project so still learning the ropes, any help is much appreciated.

[Mordicai]

If it was me, I would remove the Speed ball and return the amp to its original state. If it works, great. The problem is the speedball and it will be easier to work on when it is out. I would think this would give you a place to start from.

[Paul Birkeland]

Remove the 6080 and recheck your voltages.  You are looking to get terminals 1 and 5 to pop down to their correct voltages before moving on.

The dim LED on the 9 pin socket indicates that that half of the tube is not passing current.  This can be an issue related to the stock circuit (probably not since it was working), or the little green PC board feeding terminal 1.  One easy way to check is to simply swap the positions of the small boards to see if the weird voltage follows a particular board.

-PB

[sparggy]

Thanks, I will give it a go this weekend. Thanks for the advice. I think you are right though because when i finished the speedball upgrade i went against all good advice and connected my headphones (luckily they did not get damaged) and one of the channels worked perfectly and the other one did not.

[sparggy]

Hi Guys

I have take the advice I was given by Paul, regarding my voltage check issues.

First I swapped the two small PCB boards and re-tested.

I got the following results:

With boards switched
1: 72V previously showing as -61
2: 187V not much change previously 182
3: 0
4: 187V previously 182
5: 185V previously 64.5
6: 0
7: 105V
8: 0
9: 61V previously 100.5
10: 0
11: 0
12: 0
13: 184V previously 182
14: 0

I then tested the voltages with the 6080 removed as suggested and got the following results

1: 70
2: 229
3: 0
4: 230
5: -0.17
6: 0
7: 1.52
8: 0
9: 1.54
10: 0
11: 0
12: 0
13: 228
14: 0

If anyone has any advice for me that would be great, I have been away from home for awhile so have only recently had the time to work on this again.

[Paul Birkeland]

I'd rehead the solder joints on the small PC board responsible for higher than desired voltages.

-PB

[sparggy]

Hi Paul

Thanks so much for you help this amp has been sitting in my cupboard for ages.

I had a look at the suspect board and found that one of the transistors was in the wrong way around. Fixed it and the amp is now working perfectly.

Thanks for your help :-)