"Andy" wrote in message
ups.com...
On Aug 23, 2:51 am, "Dave Plowman (News)"
wrote:
In article . com,
Andy wrote:

No the batt is new and this model has a reputation on cutting out. The
main problem is it really comes underpowered, it comes with a non
standard size 2.5AH batt. I have spares and can easily replace it when
it cuts out but I am a performer and if it cuts out mid song, my show
really goes to ****. Can anyone tell me if its possible to by-pass
this cut off feature and how to do it? I have ask the company for a
technician repair manual but they refused. Any help please.

Well I use radio mics for a living and I always replace the batteries
before they fail. You get to know how long they last. It sounds like this
battery is running a power amp so the life will vary with load. So
replace
it for the worse condition. I'd say it's likely they have a very good
reason for this auto cutoff at this battery voltage. You can't just magic
that reason away. If the life isn't long enough use a larger external
battery.

--
*If you don't pay your exorcist you get repossessed.*

Dave Plowman London SW
To e-mail, change noise into sound.


Can anyone answer my question though. I fully understand the situation
(I shouldnt do it, its under powered, its there for a reason). Let me
just start again as people are getting hung up on the background. here
another scenario: "A person made an amp with an auto batt cut off and
I purchased it and wanted to remove it".



OK then. How does it cut off ? Is the power to the main board controlled via
a relay, that opens when it detects the low battery condition ? Or does it
just cut off silently ? If the former, then it is easy enough to just short
the relay conatcts. If the latter, then you need to locate the switching
transistor that controls the feed. This should not be too difficult. I would
expect it to be either one of the larger D-line package transistors at a
minimum, or some type of flatpak package like a TO220. It should be easy
enough to follow the battery "+" around the board until you arrive at such a
transistor. Once found, it should only be necessary to short its collector
and emitter pins, to effect a bypass. If you want to get a bit cleverer,
locate the sensing circuit, which is likely based on either an opamp wired
as a comparator, or an actual comparator IC, and alter the threshold set
point resistor(s)

Arfa