[Music]
and today on the bench is a Crown XLS
5000 PA amp it's in pretty bad shape
partly from how it ships in a cardboard
box with the Integrity of a plastic bag
and I'm not gonna lie this one's an
absolute dog it was quite a Bastion bent
it's even got tape holding the front
panel on and there's a lot of screws
missing panels held in with a bit of
masking tape it's not a pretty sight
it's even been a way for repair someone
else where they've carried out no work
hmm at least at the back everything
seems to be there oh apart from the
screws of course these side plates are
all bent from transit although 28
kilograms is going to bend anything I
can definitely say it's had a hard life
and it's that powerful it needs a 20 amp
IEC connector wow well they're not sure
the 5000 watt ratings real because it
only needs 2000 Watts putting into it
they're not powering this up until
they've had the lid off let's see what's
going on a little short sort of screw
that is
it's not quite anything
well luckily
because it's sort of coming out
foreign
is a Phillips head
although it doesn't match the other
screw
and that one's a Torx Drive
off with the lid
on abandon repair when I see one and a
helpful message inside often that's
technicians lower modules are all blown
oh no this is going to be expensive it's
not even fastened down
more useful info here some irf 1407's
gone these would be little to220 devices
so four diodes four fats 12 20247s
12. hmm showing someone's knit two of
them
once it's already disconnected I might
as well unplug these so I can get the
model out of the chassis
oh is that not a plug
oh it's not a plug how annoying the
cable's plugged into here some of this
insulation out the way
oh even these are glued in oh the lining
appears you just to unscrew these
which I think is what I did anyway
can this be lifted away now oh no let's
do the cable
that's cleared a bit of room but it's
still like spaghetti in here
doesn't say on here but I think these
Transformers must be a thousand DH EAS
easily and they're probably 10 kilograms
each big chunk of the way to this a few
other little balls kicking around you've
got three Bridge rectifiers here and
another three on this side and in the
middle here some sort of power
management board not fully sure of its
function it's got two big chunky relays
on there some little Bridge x-rays so
he's probably generating a low voltage
Supply I'm probably handling the inrush
current and that leaves this mysterious
front panel board with the pots and the
LEDs on I'm not sure how it was fixed in
there's no screw holes
I'm sure it wasn't all this masking tape
I think the cooling fan is free to turn
it's probably okay that bit
but there's only two screws holding this
in
won't take long to take out
there we go there's apartments in here
that'll be the English protection that's
obviously blown up
and this Arrangement doesn't exactly
look fetch here originally either yeah
this amps had trouble
I don't think they're the original pots
that explains the mystery of how this is
stuck in I think those would have been
threaded originally
oh what a mess it's like I'm not the
first person in here so take another job
like this you really want a service
manual I had a look online and couldn't
find one of this Crown amp but luckily
I'm understanding very similar to a
phonic XP 5000
that's handy
I'm going to start off by making sure
these things work what's left in this
chassis we can see in the service manual
there's actually three dual rail power
supplies on this three level amp that's
quite fancy so check that all this works
we'll check this one's got a big gash in
the plastic insulation but I think it's
going to be okay just have to take it
back over but we'll check it just
looking at 240 volts to the input of the
Transformer
this is the center tapping on the output
stick the negative Prime in there
just powered up
let's check all these pins so we've got
here minus 118 119 volts
plus one one nine
minus 80.
Plus 80.
minus 40 and plus 40. there we go
let's check some ac voltage
we're looking for 13 volts on either
side of this
and yes
it's there
this skinny wise are undocumented but I
reckon it's just a thermal cutout switch
I'll just check the resistance cross
there
and get the meter probes on it
and they're fine
well that side's okay
to the same this side
Plus 40.
minus 40.
Plus 80.
minus 80 and
plus one's ready well nearly
and there's negative one
perfect suspicious connector out
there you go 13 volts there
and 13 there
on the thermostat
perfect
I might as well check that this fan
actually works but I can't see any of
the writing on it and I can't be
bothered to undo these screws we'll
check what the manual says and not so
hard to find the fan so just 24 volts
but strangely there's a 16 volt
capacitor across it so clearly not
supplying it with 16 volts if that's
traced this through this is off a 14.24
volt rail pretty close to 15. we'll just
set this up in the region of
well that's working fine
so the chassis Hardware is actually okay
good news let's get back to the
amplifier boards now they're stuck
together just about so I'm going to take
a few screws I haven't separate them
two modules are separated now and
they're pretty much identical apart from
a little thermal switch on this side it
says on here that the lower modules
blown and this is at the top so it sort
of implies this one's okay we'll have a
little check over first the main place
to check is this big grower transistor
down here so we've got the negative half
over here and a positive half over there
so on the ends we've got these four
smaller devices these are the mosfets
and diodes for switching the levels and
the best access from underneath I'll
start from Gator source of this one
nothing there from here yeah that looks
a healthy voltage drop then the diode
yeah also good same again here
it's D6 All In Parallel Center need to
measure the one
so we'll go from here to there
that looks healthy into the emitter yes
now those low voltage drop readings
actually caused by these resistors these
are the emitter resistors that join it
all together so we need to check that
there is that low resistance there
otherwise one of these is blown open so
go from the base again
check this one yeah it's good also good
excellent
all the same
okay
the same relations on this side only the
polarity is reverse so we have to use
the leaves of the way around so we've
got the collector
animator they're all good so check the
emitters again
not to dig the leads in a bit
yeah
and good
they're good
same with the level switching Hardware
here
diodes good then we've got the mosfet
that's good
that's perfect diode again
also healthy
finally this mosfet here
okay so the back wall looks good we'll
just check the drivers at the front so
on the negative side we've got an mja
15033 this is a PNP device so just check
there that's good and there excellent
we'll swap the leads over for the other
one
and the positive rail is driven with
this this is an mje 15032 which is npm
and yeah looks great I'll check this
view as well as I'm here
it's fine
so I've Got a Feeling is this channel is
actually good now level 5 Crown this one
but I am expecting trouble which had the
level switch in mosfets
well that one looks okay then the diode
yeah that's good
check this one no shorts
that's good
and this diode so far so good let's take
the power transistors although some of
them are already unsoldered so looks
like trouble and there is
shorts everywhere
well the lower measure short because
they're all wide in parallel shorts on
this side as well
let's check these
that diode looks okay
this mosfets also looks okay
that's good
okay I'm going to tell his PCB off the
rest of this and I've got to take 12
screws out at least oh and these others
the screws all buried down there it's a
bit tight
I know you come
I've got this really wide Soldier 9 tip
on here yeah it's great for getting all
the pins unsoldered in one go
sometimes you need to add a little bit
more solder
just to get it to flow
Works quicker then
another circuit I can measure them more
accurately find out what shorter mod
isn't so this one yeah that's completely
shorted okay this one this one is okay
no shorts here yeah a good one
same here this is also good
and is this one yeah
and finally this one
oh good so we've got one two three four
good ones
and one short and there's the npn side
check these again
yeah this one's also good
and so is this one
as is this one
short we've got a short one there
and finally this one
is good
another short circuit transistors out
there I'm just going to measure these
again just checking on them are blown
open because quite often the exact light
fuses I don't think they're supposed to
and all comments of this track here so
just go from there
that's okay
well that's not one of them
they're all good I managed to get a
whole set of output transistors for it
but I don't know how well they match I'm
gonna check them I checked the originals
of the transistor analyzer and found the
going on the one sides of about 84 so in
this size about 110 these don't have to
match each other but these groups do so
tip these out I hope these aren't fakes
I paid enough for them the markings look
good so we'll see how they measure put
these leads on any order it doesn't
matter
but I'm pleased with that that's pretty
close to the others it's PNP as well I
don't think these are fake Happy Days
just Mark that on the back
and the next one
bit higher 137
to speed things up a bit I've got this
transistor base here so I can just put
the clips on here and hopefully um they
don't short out
nothing to blow up mind you
then I can just push them in
nice and quickly
145
105 bit of a mixture
one two four another good match
109. lovely
oh I didn't mean to take those off
let's put him back again
the 2sc 5359 is a bit of a mixed bag we
can see a few different styles of
marking on here
121 okay sort of matches the other set
but um a bit different for the ones that
were in it already
one month three bit more like it
another one about month three hmm
I'm online
what 10
miles out but then again it is one
that's marked quite differently hmm
definitely a different batch without a
doubt hmm
check this last one
one two six that's a bit more consistent
with the others well there's the entire
collection of good transistors but this
one we saw had a gain of 10 which is way
out of spec should be at least 55
according to the data sheet
I think this is not original
however normally when I say fake ones
they have some very high game like two
or three hundred
so yeah strange one
rest of them however all look pretty
similar some are a bit brighter Mark
than others but the marking scene spot
on and encouragingly the date codes are
different it's another giveaway for The
Fakes obviously it's the same batch code
just flipping them over where them
aren't they going I can now pick six of
the closest matching ones this one's a
bit easier we've sort of got a bit
Middle Ground there so sort of one two
five one two three four five six
okay with those this is a tougher choice
we need this spread enormously as tight
as possible I'm sort of erring towards
hmm one two three four five six
yeah tricky yeah I'm gonna go this way
these transistors aren't made anymore so
I can't really buy a match batch or
anything so the only way to get them
better than that is to keep buying more
and more old spares up and it gets
expensive I think these will do for
another level of quality control I'm
just going to put them on the curve
trays to see what breakdown voltage I've
got this is one of The Originals
supposed to be about 230 volts
50 volts per division across the
horizontal so you've got 100 volts 150
200 250 300 there it is that's breakdown
voltage
okay
put one of the new ones in
so we've got 50 100
150 200 oh
200 volt breakdown it's a little bit low
but I think it's all right in this
amplifier
set this for the PNP
invert the display as well put one of
The Originals in the 2sa 1987
it's about 50 volts 100 150 200 250.
oh it's over 300 volts to break down
and we'll see how the new ones compare
50 100 150 200 250. well they're much
better
nice
it's going to get this heatsink a bit of
a clean up first so if there's any
damage on there
I've come the insulators
[Applause]
yeah to my surprise look at that a
mirror finish I can't see any Distortion
in that really this is pretty flat
that's good to go I'm gonna put some
Heats in Compound on this first because
it's got to be clamped in
I'm just going to run a bead right
across here
another one here
then try and spread it out smoothly
oh
no
I didn't want to do that this is messy
messy stuff
I'll just lay them on
just line the holes up
just put the clamp on top
to pop the screw through there
and just
screw this on
not the easiest way to put these
together I have to say
and gently guys are screw into the
bottom one
screw that in
[Music]
that's including sort of Integrity of
this whole contraption
and the same with these
oh
just Place me in position again
just line these up
I just found a problem with these
transistors
I don't know how well you can make this
side but this one's sitting low it's
actually thinner and this one these are
the new ones these for The Originals
yeah they're a shallower case that's
going on they're supposed to be five mil
thick and this one is this is one of The
Originals
get one of the new ones
and they're all the same
four and a half mil thick and this one
piece clamp isn't going to forgive me
for putting a thinner transistor in so
I'm gonna have to shim it up it's got
this pack of cell pads in the drawer and
they say they are 0.23 mil thick so two
of these should do it
let's check
yeah that should work it hasn't got to
be too accurately sized
just gonna punch a hole in this the
screw can come through it
just pull that on there just to build up
the height
oops same for this one
nothing that's leveled them up nicely
yeah they're not loose so that's a good
thing
that's looking nice and neat now just
gonna put those micro insulators on put
a bit of heatsink compound on there
and just plop each one on
let's give these a little bit of a
wiggle to distribute the heatsink
compound a bit better
but it'll spread under the pressure of
the transistor being screwed let's put
the board back in hopefully it all lines
up properly
I've got a little bit of resistance I
think the legs need to uh be lined up
let's pop a screw in first
[Applause]
just press these into the right place
these diodes need to be connected to the
heatsink this thermal paste here
get a good thermal connection
[Applause]
then we've got this thermistor has to go
on
this Earth tab
quite a lot going on at once
and same with this side
I've neaten these up a bit now now they
don't need to be squashed out of the way
get them off the board really
I'm gonna do a continuity test from the
heatsink to the tabs of these
transistors just to make sure I haven't
got any shorts
and I haven't
and not on that side good news
before I put these modules back in the
amplifier I want to test them on the
bench first problem is the power supply
is quite complicated three different
power supplies for the power section and
then there's a plus minus 15 as well I
haven't got enough power supplies tested
properly hmm well three power supplies
we've got I've got this one for the plus
and minus 15 Volts for the the low
voltage analog then I've got a plus or
minus 40 Volts for the low voltage power
section and then I've got the median
voltage at plus minus 55. supposed to be
plus minus 80 volts and this will go
nearly there but I don't want to put
that on in case some it goes a bit weird
on here because I don't want to blow
this one up it's only supposed to be
doing 60 volts and I've seen weird
things before with oscillations it's a
bit of a rattlesnest to be honest but I
hope it's what's got to be done and put
a bit of a sense check I'm just going to
start off with the module that's not
been blown up
assume it works I've got the lower
medium power supply is already on on
this caps are charged up and so far no
trouble just going to turn it on here
was a bit fuzzy but I reckon that's all
right
let's draw a quarter of an amp office
power supply there that's nice and no
drums on the medium bolt rail
everything's stable
the oscillation is probably caused by
this dodgy grounding I've got going on
the best I could do I think that's okay
let's knock all these off
so I'm looking for identical Behavior
off this channel which you just repaired
fingers crossed start with the chassis
here if that's coming to the plus or
minus 15 volt rail
and this will be the Transformer Center
tapping which is the common of the power
rails not to be confused with chassis
grounds not the same
this is the minus 40 volt rail goes on
there L minus plus 40 alt goes on L Plus
n plus is our plus 55 volt rail
an N minus is a minus 55 volts
minus 15 volts goes on r85
and plus 15 goes on r82
the input signal comes on pin two and
through this connector
this is a floating input so it doesn't
matter which way around
so we'll connect the signal generator
ground to this ground here I need to
link this out this is the connection for
the thermostat in the Transformer if
that's missing it won't work finding the
speaker outputs got this red wire
the positive and the negative
this black one well it's ready to go
start up charging the caps on the low
voltage plus minus 40 volt Supply
and we'll do the same with the medium
voltage rails
we'll go For Broke now
oh that's not good
oh no what's going on here
oh no
I think I broke the power supply
that's another repair
I might do just one supply round for now
so I'll just reset this to 40 volts and
uh we've seen okay it appears that I had
the wrong affiliate connected oops you
wouldn't think it'd be that fussy but
yeah apparently it is
wow similar looking Behavior
it's probably working
we can disconnect all that now I
snapping my power supply put it in
right just shove these two back together
if I recall that only join together this
metal shield
[Music]
now let's turn my attention to these
small boards being molested if we call
the power board I got these inner
suppression thermistors wide like this
this is not original at all a pair of 4
ohm n2cs nothing fitted here if you
refer back to the schematics you'll see
what they should be it says here one ohm
a diameter 30 mil or this part number
here so I picked up a pair of these sl32
so that spec and let's put them in of
course you want to start by taking the
others out
didn't put up much of a struggle
there's still a bit of metal in here
somewhere
[Music]
grab it with a pliers so don't burn my
fingers
it's going to give this board a bit of a
wash first it's a little bit grubby
and I can fit these thermistors in
I've got long legs on these they don't
need trimming
that's a bit closer to original now I
should think
now we've got the front panel board with
the potentiometers which are oh I've got
awful badge I'm not quite sure what they
were thinking there maybe they should be
four pin ones and um yeah I've managed
to get some Originals well I think they
are and these are The Replacements
they're 10K log pots and they've got the
four pins interestingly the fourth pin
actually isn't connected to anything but
um yeah I don't know why they like that
the shafts are a bit too long on this I
think not that we got any knobs with
this but I do think this needs about
five mil cutting off the end of these
[Music]
thank you
magic stock these messy pots I have to
start this one they've clearly torn the
pads off the back
that might be enough to get it off
and they appear to be stuck somehow
um
looks like legs only just reached this
one so um sort of bend them up out of
the way
and one side out
just see some fine wires on there then
so as an attempt to connect it and also
on the back look there's some glue on
top of the solder why have they done
that let's try and clean these holes out
nicely
and now I've noticed the power LED is uh
broken off oh no come off either it's
actually snap one leg off oh
a little unsold of that as well
[Applause]
I understand this would have been a blue
LED very trendy
so
I've got a standard three mil LED it's
not called a flat top but it goes to the
hole I don't think it matters so
I'll try and get the legs in
accordance that got the cathode at the
top which will be the short leg
I was always told short the X was a
negative thing
foreign
which fit beautifully I'm very happy
with that
[Music]
because I've had some places have been
ripped out of these I can't solder the
pots frame on properly so what I'm going
to do I'm going to reinforce it with
these sort of rivets so I'm just plant
one over there
and the other one on here
I'm basically going to fill them for the
solder
fill that right up get the tweezers on
there just to hold it still
there we go wow it seems to got it it's
still the parts but it's a better part
to my book
so check these LEDs work just using the
meter on diode test mode puts a small
voltage across there so yeah yellow's
working in the middle yeah and in the
bottom
yeah perfect let's check this side as
well
okay good we'll put this front panel
back in the chassis
trying to line up the LEDs with the
little holes with the fiddle
there we are
trying to get the nuts to go on straight
it's a very shallow thread
the main switch is supported by these
two screws down here so I can go back in
now
the Power Ball can go back in
it's held on four screws I don't know
where the holes are there there they are
let's get a screw in one corner not too
tight
the other behind this massive thermistor
let me put that there
and it's a good time to put the input
board on as well
come on there you go
jp6 goes to cn6 probably
JP 11 probably goes to cn11
pretty sure this is for the power led
the wire is just Loosely hanging that
direction
there's me for the Dual 13 volt AC rails
there that's off the one Transformer
on the other channel
now JP 71 that'll be the neutral from
the main Supply
right next to it is the same for the
Transformer
this is the neutral for the other
Transformer
it's a bit loose we'll just crimp this
on up a bit
it's too much tighten it up a bit
stop it wobbling around
[Applause]
that's better the Transformer primer
goes on there
same on this one
I'm just in that Gap is where the mains
comes in from the fuses for the channel
one
same for channel two
this is the plug for the cooling fan
came from here
slowly but it still looks like spaghetti
I drop a cable ties through here
see if we can tidy this mess up a bit
and the magic of a few cable ties is
making it look a bit easier to live with
this
just lower the excitement modules in
where they're bang bangs appear plug
those into the input board which we can
still reach it
the Finish is going to be very hard to
put together
same for the other channel
first of all connect this Transformer
Center tap in
because we won't be able to get it this
when I put it in so it's upside down
from the power connector
it's the right way up
and transform a thermostat goes there
[Applause]
is indeed needed some jiggling
I think it's about right now more
connectors to go into the front panel
which is from the lower amp
and the upper ramp
this one's a bit of a nightmare to get
at
I've got enough fingers
same here
let's make a bit of a clearing get this
thermostat Connection in there okay
Transformer Center tapping on j4
power cable on there
anything else oh yeah what's this
thermostat that'll be here
and then we've got the speaker terminals
for this one
there
positive on there
still not fastened down so a bit loose
we'll check there's no cables trapped
underneath before I put any screws in
and that's exactly what I want to avoid
there's a red cable there in the screw
hole I see strands of ribbon cable there
somehow I've got to shove them out of
the way
can just get my hand in that Gap yeah
that's got it
[Music]
I don't know the checks I can do with it
out of the chassis now all I can do is
turn it on and let's hope it works
because it's got this twin shampoo you
see connect to and I haven't actually
got one of these cables in the workshop
and I'm going to give it 20 amps anyway
no way
I'm gonna put some crop tips on here
sassy grounds actually connected to the
oscilloscope and this heatsink now plug
the dummy load into those speaker
connections foreign
well that's great no bangs
beautiful
well there's no smoke now and there's
nothing wrong with the lower module
and that's warmed up a bit half an amp
bit allowed on there
yeah I see no trouble I'll try to me
turning it off
well that was about time now and I've
connected the spacecraft puts each to
these meters and I measure the DC offset
stranger there's half a volt with it
turned off and it is discharging but
interesting
scooter oil
about 2.7 millivolts there four
millivolts there this is great anything
under 10 millivolts is good enough for
me
let's fix electrical problems this amp
but it's still the casing sort out it's
still a bit bashed up and we don't need
this message anymore
oh now you've got the paper insulator
on with the lid
[Music]
oh there's no hole and there's quite a
gap there and he's pulling straight
looks a bit straighter from behind now
just needs two knobs now
looks like I'm gonna have to make some
foreign
[Music]
foreign
from blowing it up again that'll be
appreciated catch you next time