No problems with Crack build, but stumped by Speedball

[LepakVT]

Hi there,

First time builder here. I completed the Crack build the other night and it worked flawlessly after the first go-around. I tried my hand at the Speedball upgrade, but I've run into a dead end for the moment.

My initial sound test resulted in no sound in the right channel, but the left channel sounded great. So I went back to review my work.

Symptoms:

• LEDs on the right side of the main board did not light up (yellow oval in the picture linked below)
• LED connected to A8 did not light up
• Smoke from the area of 11~16!! Couldn't tell the exact source before I shut it down (source in the red oval in the picture linked below

LED orientation on the main board was OK.
I did not mix up the 2222/2907 transistors.

My voltage check was cut short after the smoke appeared.
1: (75-90) 1.7
2: (170) 50
Game over

I'm disappointed in myself that the Crack build went off without a hitch, but the Speedball has owned me this afternoon.

Apologies for the out of focus cell phone picture (unit is not on)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F4B5iLN5.jpg&hash=2001c7bdc467c11bde5e9069a214a17e23ec3979)

Thanks for the help!!!
-Andrew

[Doc B.]

Sounds like a short. Check for miswires to the big board.

[LepakVT]

Discovered broken connections from 2U to B+ and 3U to Ground. Caused by cutting the thin wire when stripping insulation. I probably have more of these going on.

Still no change to the LEDs. No smoke this time, but there is still considerable heat coming from that side of the kit - probably would've started smoking had I left it powered on longer. Not noticeably hot on the opposite side.

I'm going to sleep on it and take another look in the morning.

Cheers.

[LepakVT]

I completely removed the 3 Speedball boards this morning and did a complete re-wire of these 3 boards without any changes. A8 LED and the 2 right LEDs on the big board did not light up.

Edit: I just turned the unit on with the lights off and I think I saw the A8 LED light up for about 4 or 5 seconds before going out after powering up.

[Natural Sound]

Did you install the transistor insulators on the heat sinks correctly? You can check with an ohm meter. Compare the good side with the one that isn't working.

[Paul Birkeland]

You can try running the Crack with just the 12AU7 to see if the voltages at 1 and 5 will settle to their correct values.

Since the LED's are not installed with the striped side up, it's very difficult to tell if you might have put one of them in backwards.

Can you recheck your voltages at 1 and 5 again with just the 12AU7 in?

[LepakVT]

I attempted to remove the LEDs on the right side of the main board to double check orientation and I ended up completely breaking one apart. And it was on correctly before breaking it.

Edit: I checked transistor resistances on the Speedball components and was unable to get any reading on the the 2N2907 on the small right-side board. Sent an e-mail in to get replacement LED(s) and transistor.