Help - Crate BX-100 - sound in earphones but not in speaker
Griffin
ext. speaker jack). Speaker seems good - makes sound when tested with
battery - no voice coil rubbing sound. Could this be the output
transistors? They never get warm. Is there a simple test (I have
access to a multimeter)? I have basic skills - can solder and
replace components - but not so good on troubleshooting. Of course I
tried all the controls.
I know this is not a great amp but it's free and I can't afford a good
one or the price of a repair shop. I could afford a few parts, though
if I knew which ones.
board...@techie.com
Does it have a loop labeled either effect send/return or preamp out/
pwr amp in? If so, plug a cable into those jacks....one end to the
send, the other into the return. Got sound from the speaker now? Then
the jacks either need to be cleaned or replaced.
If there's no loop, its hard telling what it might be. Could be
anything from a bad op amp in the front end (or missing voltage rails
to the front end) to a failed output section. Although when the output
section goes it usually shorts and will take out the fuse to let you
know.
board...@techie.com
I just re-read the post.....there's a headphone jack. The speaker gnd
passes through shorting contacts on that jack and if you've used that
jack even a few times they can get sprung and the shorting contacts
won't reliably short. Check that jack.....pull the chassis out, hook s
spkr up to it and put a signal into it. Push on the contact closest to
the front panel (the first one the plug sees when you plug in a
cable). Got output now? Replace that jack. Or if you want you can put
in a mini toggle on the rear panel to manually close/open that set of
contacts. Those cheap-o plastic jacks aren't really rated to pull
speaker current through the shorting contacts....its kind of a corner
cutting way to go about it. They could've muted the signal to the
output section with a few more parts....but that costs money.
Rusty Patina
much. Your post was SO much more helpful than Lord Valve on the other
newsgroup.
On Mon, 27 Apr 2009 10:59:16 -0700 (PDT), board...@techie.com
wrote:
board...@techie.com
> BINGO! That was it and I like the auxiliary switch idea. Thanks very
> much. Your post was SO much more helpful than Lord Valve on the other
> newsgroup.
>
>
the .amplifiers group doesn't see much action. An even better place is
here:
http://music-electronics-forum.com/forumdisplay.php?f=22
A lotta sharp cats hang out there.
fitn...@gmail.com
solution
Lord Valve
Paris is on fire, and you're jacking off on a thread that's
SIX YEARS OLD about your goddamn headphone jack. Pull your
head out of your ass and go buy some weapons.
Fuck you.
Universe
the amp is powering up? Do the output transistors remain cold, as in
the original post above?
The output stage and supply are the first places to check. That
circuit uses opamps in the preamp, and you don't normally expect them
to go bad.
If you have access to an oscilloscope, you could see if any signal is
getting to the output stage.
richardni...@gmail.com
Universe
wrote:
>
>>Hey Thanks ! Same thing happened to me. Got it for free on CL and very same
>>solution
>
>You've probably checked for blown fuses, right? Any indication that
>the amp is powering up? Do the output transistors remain cold, as in
>the original post above?
>
>The output stage and supply are the first places to check. That
>circuit uses opamps in the preamp, and you don't normally expect them
>to go bad.
>
>If you have access to an oscilloscope, you could see if any signal is
>getting to the output stage.
extension speaker jacks that break the ground connection to the
speaker. Just for fun, turn the amp off, disconnect the speaker, then
measure resistances from both of those disconnected wires to ground.
What readings do you get?
Lord Valve
Universe
<ghost....@gmail.com> wrote:
>Look, asswipe - the world is going to hell in a handbasket,
>Paris is on fire, and you're jacking off on a thread that's
>SIX YEARS OLD about your goddamn headphone jack. Pull your
>head out of your ass and go buy some weapons.
salvation is to somehow get three deranged bag-ladies to post their
apocalyptic visions and Tourettes "fuckyous" to a deserted amp group
with 5 people reading!
But where can we find three deranged bag ladies? Who will step up to
face ISIS here on aga, the only remaining arena in the free world?
Silly old douchebags.
