Did I just fry my capacitors?

[JimmyN]

Hi, I installed a Speedball on my Crack today, but made a stupid mistake.

In the second to last instruction of the manual I connected the black cable from 3U to O instead of G on the PC board. When I powered it on to measure the voltage I noticed a weird smell after 30 seconds or so (could have been smoke, but I didn't notice any) and quickly pulled the plug.

Now when I measure the resistance on terminals 7 and 9 I get something in the Mega ohms instead of 2.9K ohms.

Also when I retry plugging it in, after fixing the wiring, the small tube doesn't seem to be lighting up like it used to. Just two small bright dots at the top of it. Could I have fried that one? Also the cover plate isn't getting hot at all.

All the diodes light up though, so I guess I did something right there.

[Paul Birkeland]

This is the appropriate time to do voltage checks.  We can't really say what may or may not be right or wrong with your amplifier based on how it smells or how warm it feels to the touch.


The burning smell was probably from the MJE350 or 2N2907 on the small green PC board where you had your wiring error.

[JimmyN]

All right, here are my voltages (the values from the manual in parenthesis)

1  88.4V (75-90)
2  160V (170)
3  -2.5mV (0)
4  159.5V (170)
5  83.8V (75-90)
6  ~0mV jumping around (0)
7  105.8 (100)
8  0.7mV (0)
9  103.9 (100)
10 ~0mV jumping around (0)
11 0.7mV (0)
12 0.0mV (0)
13 159.8V (170)
14 -0.2mV (0)
15 178.7V (185)
20 -0.3mV (0)
21 200.5 (206)

They all seem to be ok.

A1 to A9 and B1 to B8 also seem to measure within the correct voltages.

Does this mean it should be safe to plug in some headphones and test it?

//Edit: I took a chance with an old pair and it seems to be working beautifully. Guess I was needlessly worried.

[Paul Birkeland]

Yeah, it looks like you shut the amp off in time. 

Enjoy the tunes!
-PB