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Roll Call: Who's building, built, or thinking of building a beta22? - Page 66

post #976 of 2957
6/14/09 at 12:53am
I happened to accidentally get some bi-polar caps, of the same values, for C9,C10,C11,C12. (UEP1H101MPD)

Though I have a suspicion that this is a terrible idea that will serve no purpose other than to demonstrate my total lack of understanding of how different capacitors work, I do wonder - can I use these in my B22?
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post #977 of 2957
6/14/09 at 1:11am
Quote:
Originally Posted by amb View Post
I don't remember what your broken σ22's symptoms are. But the standard thing to do is to check MOSFETs for shorts, check 0.47 ohms resistors for open circuit, and check your BJTs using the DMM's diode check mode (I described this several times elsewhere, search for it). The CRD itself is probably ok, but if you have a spare, replace it anyway.
MOSFETs and resistors look fine so far. It's probably the BJT(s). I might just go ahead and replace them all anyway since I need an excuse to practice using my Hakko 808 desoldering gun anyway. That being said, I could probably use some practice checking them with my DMM as well so I guess I can take a crack at that first.

BTW, three of my four beta boards passed the initial checks fine. The fourth board is getting 0 volts at R9 and is not responding to VR1 adjustment. The LED lights up fine though and the MOSFETs (no shorts) and 0.47 Ohm resistors (no opens) appear to be fine. Suggestions on next steps?

Thanks!
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post #978 of 2957
6/14/09 at 2:20am
El_Doug,
bipolar electrolytics typicallly have higher ESR and do not perform as well as a good polarized cap on these boards.
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post #979 of 2957
6/14/09 at 2:27am
Quote:
Originally Posted by oneplustwo View Post
MBTW, three of my four beta boards passed the initial checks fine. The fourth board is getting 0 volts at R9 and is not responding to VR1 adjustment. The LED lights up fine though and the MOSFETs (no shorts) and 0.47 Ohm resistors (no opens) appear to be fine. Suggestions on next steps?
Search for my post about checking the voltage drop across D11 and D12.
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post #980 of 2957
6/14/09 at 2:30am
Quote:
Originally Posted by amb View Post
El_Doug,
bipolar electrolytics typicallly have higher ESR and do not perform as well as a good polarized cap on these boards.
thank you! 16 new caps ordered
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post #981 of 2957
6/14/09 at 6:16pm
Well, D12 voltage was like 28 so I guess I know what to replace. Hopefully that's the last problem before I finish up the wiring and get a listen!
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post #982 of 2957
6/14/09 at 7:20pm
Quote:
Originally Posted by oneplustwo View Post
Well, D12 voltage was like 28 so I guess I know what to replace. Hopefully that's the last problem before I finish up the wiring and get a listen!
Just to remind you that it's not D12 that you need to replace, it's Q26.
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post #983 of 2957
6/14/09 at 7:39pm
Right. I actually got that believe it or not. Thanks for the reminder though!
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post #984 of 2957
6/14/09 at 8:07pm
hey, I finally got my 2ch b22 cased up well enough to show it. its probably the cheapest case-work in the whole lot but it is stable and functional.

I re-used a 2U PC router chassis, as is apparent:





I also use ABS plastic sheets that my local plastic store cuts to size and those become poor man's LW-panel-express, sans labels

nothing expensive on parts but I did want to pay attention to wiring, routing and layout internally. I believe I have a near silent B22, now.

the case was $15, the plastic was $5. and it will get me by until something better comes along.
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post #985 of 2957
6/14/09 at 8:13pm
Very nice!
Did you source the parts yourself?
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post #986 of 2957
6/14/09 at 8:17pm
what's with the extra caps on the sigma?
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post #987 of 2957
6/14/09 at 8:23pm
Quote:
Originally Posted by oneplustwo View Post
what's with the extra caps on the sigma?
more reserve power for when driving speakers i suppose.
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post #988 of 2957
6/14/09 at 8:34pm
Quote:
Originally Posted by oneplustwo View Post
what's with the extra caps on the sigma?
ha! you saw that?

that was one of the caps that I blew up by installing backwards.

I swore to get revenge on those caps. so I buddied them up so they'd have someone to watch over them. 2 can't be trusted at a time, so I brought in a third.

lol
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post #989 of 2957
6/14/09 at 8:35pm
Quote:
Originally Posted by mattcalf View Post
Very nice!
Did you source the parts yourself?
oh, MORE than once.

(don't ask.)

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post #990 of 2957
6/14/09 at 9:02pm
Very nice. I like the green led's for a change of pace. Neat wiring. You'll have to let us know whatcha think of the SQ now. I've looked high and low for something to route wires that is kinda like those retainers for spark plug wires. I saw them on some machinery when I worked in a hosiery mill once, a long time ago. The machines where Italian.
I like the way you lined up the HS's also. Not a big surprise from you though, you seem to always have neat builds.
Thanks for the pics.
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