Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: norneslo on June 21, 2014, 08:10:00 AM
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I'm doing this installation for a friend, so I verified the amp was working with music and headphones before starting, but did not check the voltages on the stock kit. After installing the speedball at voltage check I see these readings that are wrong (all others are ok):
terminal voltage
1 0
5 0
7 57
9 59
of note, the D1 LED on both A and B boards do not light, and it appears to me that the leds on the 9 pin tube socket are also not lighting. Both tubes glow. The large speedball board lights up fine.
Maybe resolder terminal 1? I checked voltage up the line at B1, as that feeds down to terminal 1 and I see 0 there as well.
Thanks in advance,
Ron
Updating this post on Sunday at 3 PM EST:
I'm also building a Quckie, and in stuffing the PJCCS board for that, I got to the step to insert MJE350 Transistor in the Q2 outline, and my transistors don't have a metal side. Same with the speedball kit I'm working on in this post. Possibly did I insert the resistors backwards in the A and B board for the speedball? Looking at my Crack, the speedball I installed last time did have the metal side on the resistor, so I got the orientation right. I'll post about the Quicke in its forum.
Ron
Picture of Resistor orientation in A and B:
http://1drv.ms/1yBESS2
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Ack!! just saw the post above http://www.bottlehead.com/smf/index.php/topic,845.0.html proper orientation of the TRANSISTORS! They are backwards! Answers my PJCCS question also. I'll see if I can get them out of the boards and flip'em.
EDITED - I had resistor in the sentence above, in fact I was referencing the MUE350 transistors and link.
Ron
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Orientation of resistors does not matter. What matters is you have the proper resistor in the proper place. You could damage the board removing them to flip them.
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0V on T1/T5 generally means that the center leg of the MJE350 isn't soldered properly.
Please triple check that the 2N2907's and 2N2222A's are in their correct positions.
The LED's on the sockets will light when the two small boards are working properly.
-PB
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PB, should I bother flipping the MJE 350 in the B board? I already flipped the MJE350 in the A board, so it's been re-soldered now. 2N2907's and 2N2222A's are lined up with the notch on the part lined up with the notch on the PCB. They look the same as my other working speedball.
Thanks,
Ron
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PB, should I bother flipping the MJE 350 in the B board? I already flipped the MJE350 in the A board, so it's been re-soldered now. 2N2907's and 2N2222A's are lined up with the notch on the part lined up with the notch on the PCB. They look the same as my other working speedball.
Flipping?
If you put one in backwards and turning on the amp will usually destroy both transistors on that board.
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By flip, I meant to reverse the orientation of the MJE350. My older speedball had the metal face on these resistors, so I put them in correctly during that build. On this one, I missed that detail, and did not catch that I had placed them backwards, with the new all black MJE350. I have already desoldered the MJE350 on the A board and reversed it, and was starting on the B board, but it sounds like these and possibly the 2N2907s may be blown from your last comment. If that's correct, I'll remove the MJE350's from both and also remove the 2N2907's and get replacement parts. Does this sound correct? Thanks,
Ron
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If the MJE350's were installed backwards, then yes, you will need new MJE-350's and 2N2907's. (Basically, a new pair of small boards).
The text on the MJE350's faces the closest edge of the PC board (away from where the metal tab would be on some variants).
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Just updating, after getting replacement transistors from Eileen, I removed and replaced the transistors, and I get good voltages at all readings, and it sounds fine.
Ron