Trashdown schematics anyone ?

A

Arfa Daily

Guest
Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ? I have an ABM800H on the bench that has two of them in it. It
suffered a short circuit speaker on the end of it during a gig (it belongs
to quite a famous band and it is a touring rig that works very hard by all
accounts) and it has blown one of the amps to pieces. Just about every
semiconductor is destroyed, and there is more than a little charcoal both
top and bottom of the board, where stuff has literally caught fire. I'm
pretty sure that it is beyond rescue, but it wouldn't hurt to have a squint
at a schematic to see if it looks like a design that would be 'well behaved'
after a major repair. As I'm sure all of us who have been there and have the
T-shirt know, there's nothing more soul destroying than to rebuild a blown
amp, only to find that you've missed an open resistor in the front end, that
causes it to slam over to one side, destroying itself again ... :-\

Arfa
 
"Arfa Daily"

Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ?
Click to expand...
** The schem for the AMB500 is virtually the same, it uses four TO3 MOSFETS
right ?

http://www.schematicsunlimited.com/download.php?manu=ashdown&file=ashdown-abm500-bass-magnifier-schematic.pdf

Hard to imagine the sort of damage you are alleging with lateral TO3 FETs in
the OP stage.

Definitely well worth repairing IMO.


.... Phil
 
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:FXt2t.90025$ZZ.34940@fx06.fr7...
Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ? I have an ABM800H on the bench that has two of them in it. It
suffered a short circuit speaker on the end of it during a gig (it belongs
to quite a famous band and it is a touring rig that works very hard by all
accounts) and it has blown one of the amps to pieces. Just about every
semiconductor is destroyed, and there is more than a little charcoal both
top and bottom of the board, where stuff has literally caught fire. I'm
pretty sure that it is beyond rescue, but it wouldn't hurt to have a
squint
at a schematic to see if it looks like a design that would be 'well
behaved'
after a major repair. As I'm sure all of us who have been there and have
the
T-shirt know, there's nothing more soul destroying than to rebuild a blown
amp, only to find that you've missed an open resistor in the front end,
that
causes it to slam over to one side, destroying itself again ... :-\

Arfa
Click to expand...
m@ashdownmusic.co.uk where m is replaced by nitram reversed was a valid
email address to engineer nitram and surname of plural of where rabbits
live, valid em/person in 2007. If you couch query in suitable techy terms,
more techy than posted in the query here, and include the serial number then
he will reply with schematics
 
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:FXt2t.90025$ZZ.34940@fx06.fr7...
Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ? I have an ABM800H on the bench that has two of them in it. It
suffered a short circuit speaker on the end of it during a gig (it belongs
to quite a famous band and it is a touring rig that works very hard by all
accounts) and it has blown one of the amps to pieces. Just about every
semiconductor is destroyed, and there is more than a little charcoal both
top and bottom of the board, where stuff has literally caught fire. I'm
pretty sure that it is beyond rescue, but it wouldn't hurt to have a
squint
at a schematic to see if it looks like a design that would be 'well
behaved'
after a major repair. As I'm sure all of us who have been there and have
the
T-shirt know, there's nothing more soul destroying than to rebuild a blown
amp, only to find that you've missed an open resistor in the front end,
that
causes it to slam over to one side, destroying itself again ... :-\

Arfa
Click to expand...
"suffered a short circuit speaker " or did the amp dump DC into it?
either way the speaker lead needs checking over plus PAT insulation test
perhaps
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:kiel1l$hv3$1@dont-email.me...
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:FXt2t.90025$ZZ.34940@fx06.fr7...
Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ? I have an ABM800H on the bench that has two of them in it. It
suffered a short circuit speaker on the end of it during a gig (it
belongs
to quite a famous band and it is a touring rig that works very hard by
all
accounts) and it has blown one of the amps to pieces. Just about every
semiconductor is destroyed, and there is more than a little charcoal both
top and bottom of the board, where stuff has literally caught fire. I'm
pretty sure that it is beyond rescue, but it wouldn't hurt to have a
squint
at a schematic to see if it looks like a design that would be 'well
behaved'
after a major repair. As I'm sure all of us who have been there and have
the
T-shirt know, there's nothing more soul destroying than to rebuild a
blown
amp, only to find that you've missed an open resistor in the front end,
that
causes it to slam over to one side, destroying itself again ... :-\

Arfa


"suffered a short circuit speaker " or did the amp dump DC into it?
either way the speaker lead needs checking over plus PAT insulation test
perhaps
Click to expand...
Yes, agreed, it could have been either way round. I was just reiterating
what I had been told by the store that took it in from the owner.

Arfa
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:kiehvi$3d4$1@dont-email.me...
Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:FXt2t.90025$ZZ.34940@fx06.fr7...
Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ? I have an ABM800H on the bench that has two of them in it. It
suffered a short circuit speaker on the end of it during a gig (it
belongs
to quite a famous band and it is a touring rig that works very hard by
all
accounts) and it has blown one of the amps to pieces. Just about every
semiconductor is destroyed, and there is more than a little charcoal both
top and bottom of the board, where stuff has literally caught fire. I'm
pretty sure that it is beyond rescue, but it wouldn't hurt to have a
squint
at a schematic to see if it looks like a design that would be 'well
behaved'
after a major repair. As I'm sure all of us who have been there and have
the
T-shirt know, there's nothing more soul destroying than to rebuild a
blown
amp, only to find that you've missed an open resistor in the front end,
that
causes it to slam over to one side, destroying itself again ... :-\

Arfa


m@ashdownmusic.co.uk where m is replaced by nitram reversed was a valid
email address to engineer nitram and surname of plural of where rabbits
live, valid em/person in 2007. If you couch query in suitable techy terms,
more techy than posted in the query here, and include the serial number
then
he will reply with schematics
Click to expand...
Thanks, Nigel

Arfa
 
"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:aqvavjFt0llU1@mid.individual.net...
"Arfa Daily"

Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ?

** The schem for the AMB500 is virtually the same, it uses four TO3
MOSFETS right ?

http://www.schematicsunlimited.com/download.php?manu=ashdown&file=ashdown-abm500-bass-magnifier-schematic.pdf

Hard to imagine the sort of damage you are alleging with lateral TO3 FETs
in the OP stage.

Definitely well worth repairing IMO.


... Phil
Click to expand...
Thanks for that, Phil. I hear what you're saying about it being hard to
imagine such damage, but trust me, it really is that bad. Most of the TO92s
are just pieces of charcoal, along with areas of the board around them. Legs
are blown off the output devices, and many many resistors are reduced to
charcoal. There are also blackened areas under the board, as well as on top
.... It is quite old, and judging by the amount of flux and soldered joints
under the board, it looks as though it may have had a major repair at some
previous point in its life, although the work has not been done very tidily,
and print may well give way if I tried to remove some of the bits.

I'll take a look at the schems, and make a decision.

Arfa
 
"Arfa Daily"
"Phil Allison"
"Arfa Daily"

Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ?

** The schem for the AMB500 is virtually the same, it uses four TO3
MOSFETS right ?

http://www.schematicsunlimited.com/download.php?manu=ashdown&file=ashdown-abm500-bass-magnifier-schematic.pdf

Hard to imagine the sort of damage you are alleging with lateral TO3 FETs
in the OP stage.

Definitely well worth repairing IMO.


Thanks for that, Phil. I hear what you're saying about it being hard to
imagine such damage, but trust me, it really is that bad. Most of the
TO92s are just pieces of charcoal, along with areas of the board around
them. Legs are blown off the output devices, and many many resistors are
reduced to charcoal.
Click to expand...

** Seeing as there are TWO power channels, both were plugged into the SAME
speaker box.

That is the ONE scenario guaranteed to cause the maximum damage to power
amplifiers.

Lateral FETs are tough as nails but having current driven BACK into them is
another story.

Ashdown amps have no DC rail fuses, which are the only safeguard againt
that.




..... Phil
 
"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:ar085nF4d1jU1@mid.individual.net...
"Arfa Daily"
"Phil Allison"
"Arfa Daily"

Anyone got a schematic for the Ashdown 400 watt 'Bass Magnifier' output
stage ?

** The schem for the AMB500 is virtually the same, it uses four TO3
MOSFETS right ?

http://www.schematicsunlimited.com/download.php?manu=ashdown&file=ashdown-abm500-bass-magnifier-schematic.pdf

Hard to imagine the sort of damage you are alleging with lateral TO3
FETs in the OP stage.

Definitely well worth repairing IMO.


Thanks for that, Phil. I hear what you're saying about it being hard to
imagine such damage, but trust me, it really is that bad. Most of the
TO92s are just pieces of charcoal, along with areas of the board around
them. Legs are blown off the output devices, and many many resistors are
reduced to charcoal.


** Seeing as there are TWO power channels, both were plugged into the SAME
speaker box.

That is the ONE scenario guaranteed to cause the maximum damage to power
amplifiers.

Lateral FETs are tough as nails but having current driven BACK into them
is another story.

Ashdown amps have no DC rail fuses, which are the only safeguard againt
that.




.... Phil
Click to expand...
As I understand it, each (independent) power amp was plugged into its own
cab. The only 'common' point is the drive to the two channels, which are
just paralleled up. Each amp module has its own set of supply windings on
the mains tranny, its own reccies and filter caps, its own fan supply, and
its own pair of speaker jacks.

We have since spoken to Ashdown, and they have a 'modern' drop in
replacement module available, which they say has the same footprint /
mounting and performance figures, but a different power connector, requiring
that it be hard-wired. They say that a replacement module will work
alongside an original without issue. It further turns out that the amp is
shared between two (quite famous) bands, but that this amp is actually owned
by the bass player of the 'other' band, and he doesn't know that it is blown
up ... The guy in charge of looking after the kit, has decided that he wants
to put a new module in. Trouble is, there are none available for around 2
months ...

Arfa
 
Some retarded POMMY Fuckwit


As I understand it,
Click to expand...

** GIANT FUCKING YAWN .............

The " Laws of Physsics " trumps asinine BS any fucking day.




.... Phil
 
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