Some trouble when upgrading with Speedball

[milehead]

I finished my crack about a month ago, and I like it a lot! I decided it was time to upgrade it this weekend with my Speedball kit I bought along with the Crack kit. So I did, and when i plugged it in to do the voltage check almost all of the readings are way off! It seems like the transformer is getting way hotter than it did before the upgrade and the capacitor between T14-T15 is very hot as well. I even saw a bit of smoke yesterday from that area when I was measuring the voltage, and I think that came from the 270 Ohm 5W resistor between T13-T15, but I'm not sure about that. Only half of the LED's on the Speedball PCB's light up as well. What could it be that's wrong? I'm novice in this kind of things as well, so I hope you guys could help me :-\

My voltage readings:
T.....Desired.....Mine
1........75........51,8
2.......170.......56,1
3..........0.........0
4.......170.......55,7
5........75.......52,2
6..........0.........0
7.......100.......40,8
8..........0.........0
9.......100.......41,6
13......170......55,4
15......185......120
21......206......182
A1.......75.......51
A3......1,56....1,48
A6.......75.......50
A8......1,56....1,44
B1.......75......50
B2.......170....54,9
B3.......100....40,3
B4.......75......51,4
B5.......170....54,9
B6.......100....41,4

 

[Grainger49]

First Steps by Dan:

http://www.bottlehead.com/smf/index.php/topic,1667.0.html

It is well written but not often read.

 

[milehead]

I just performed a resistance check and got infinite readings on T7, T9, B3 and B6 where there should be 2,9K Ohms. Could it be that the output caps are broken? I have resoldered all suspicious joints already too.

 

[Paul Joppa]

Those are appropriate, with the Speedball - you removed the 3K resistors when the Speedball was installed. The Speedball manual does not have resistance checks.

The values at terminal 21-15-13 (the power supply) indicate you are drawing way too much current through the 6080; the 6080 voltages are consistent with this.

You said "half the LEDs light up - there are four on the big board, and two each on the small boards. To guess what's wrong, it would of course help to know which ones are lit and which aren't!

That said, it is not uncommon to accidentally reverse the LEDs. If that happened on the big board, it would cause the current source to attempt to draw much more current than it should - resulting in the symptoms you have reported. (Of course there are other ways to produce those symptoms so no guarantees!) When you check for that, also inspect the back side of that board for any possible solder bridges between adjacent pads, or any missed solder connections.

 

[Laudanum]

I dont know if this could be responsible for the problems but I will add it because it is also one of the common mistakes ...  there are different metal "can"  transistors that look the same.  It hasnt been uncommon to switch them and accidentally install the wrong ones on the wrong boards.  Worth double checking.  They do have different markings on the cases.  Then of course the reversed LED's as mentioned and also solder bridges, especially between those little transistor legs.  And I think wrong resistors in wrong location also shows up from time to time.  Seems that those are the main 3 or 4 errors with the Speedball and not hard to make a mistake even when you think you are paying attention. 

 

[milehead]

Now I've triple checked the LED's and it looks like it should. I checked the transistors as well and the right one is in the right place and no solder bridges on them. I have solder bridges on the edge of the large PCB next to the LED's where the R2, the red diagonal cable and the red cable from 2U go to. Could that be the problem?
I controlled if the LED's work and they all do. I marked the lit ones with yellow circles.
http://img820.imageshack.us/img820/2421/img6716re.png

 

[Laudanum]

If you are talking about a solder bridge where I think you are, then no.  I believe those thru-holes are connected together by a trace on the board anyway.  Others will correct me if Im wrong but I think you are fine there. 
If you havent already done so, double or triple check your connection points from the terminal strips to the Speedball boards.  Make sure the wires are coming from the correct terminals and going to where they should be on the speedball boards.  It's not hard to "get lost" tracing the wires after the boards are in place.  You even may want to unscrew the boards and move them out of the way a little to get a good look.  That is, if you left any slack.  It doesnt take much to move them enough to get a good look but you do have to be careful with the solid core wire.

 

[.Sup]

Hello guys I just finished installing speedball. All terminal readings were fine except no19 which should be 0 but I get 75 and no20 which should be 200 but I get zero. I had a hard time reaching these terminals and after several tries to measure it correctly there was a spark. I continued to measure and then there was a short circuit. Amp continued to work, I must have touched something else in the process. I could not reach and measure the tube socket between jack and potentiometer, I can only see two pins but cannot reach any. I plugged the headphones in anyway starting with the cheap PX200. It works, without any hum or any other problem, dead silent as far as I can hear. I am now listening with HE-300 and it also works well without any problems. Any advice, is it hazardous to listen even if everything sounds fine but does not measure correctly?

Peter

 

[Doc B]

There is a sticky right at the top of the Crack forum about Speedball manual corrections:

http://www.bottlehead.com/smf/index.php/topic,1398.0.html

If it's working fine you should be OK.

 

[.Sup]

Ha Doc, you're the best, thanks for that. I was close to getting a heart attack when I saw and heard the spark. I am very happy that this first diy build worked out as it should.
kindest regards, Peter

 

[Doc B]

Oh man, sparks are just part of the game, happens to everyone now and then. Sometimes shorting a terminal might end up blowing something like a transistor or diode. You would know that right away because something in the circuit would stop working. On the early Paramounts there was a condition where if you shorted a couple terminals together one of the LEDs on the C4S board would literally blow up with a loud snap. It was actually pretty cool to watch.

But one of the wonderful things about tubes is that they are pretty hard to kill and usually it's just a matter of swearing, collecting yourself, and checking that everything is still working.

We have developed a little ritual around here that might help others. Whenever a new project is completed the guy who is building it takes a break before firing it up and measuring voltages.

 

[.Sup]

That ritual can only work for the patient ones, for the impatient ones like me it would not. But as much as I am impatient by nature I have to say I controlled myself very well during the process and have double or triple checked after every move I made before I went to to the next task. And the amp is working wonderfully, even before the Speedball there was zero hum or hiss.

kindest regards, Peter