Peavey PV14 mixer, 2012

N

N_Cook

Guest
Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.
 
"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.





I had a similar mixer in a while back, and it too had a blown TOP chip, but
not cracked like yours.
To save a bit of troubleshooting time I phoned Peavey UK service dept to see
if there were any knows issues regarding the PSU, and was there something
that might have broken the TOP chip, or was it just the TOP chip that broke.
I was told (a bit sheepishly) that they knew about these TOP chips blowing
up, and if I replaced it the mixer should be fine.

I did, and it was.


Cheers,



Gareth.
 
Are these "chinese versions" of TOP244YN or the real McKoy?
I bought mine from Farnell.

http://uk.farnell.com/power-integrations/top244yn/off-line-switcher-to-220-6-244/dp/9921265



Gareth.
 
On 01/11/2014 15:05, Gareth Magennis wrote:
Are these "chinese versions" of TOP244YN or the real McKoy?
I bought mine from Farnell.

http://uk.farnell.com/power-integrations/top244yn/off-line-switcher-to-220-6-244/dp/9921265




Gareth.
Click to expand...

All I know is the back face is flat unlike the curved one I came across
in a blown Yamaha Stagepas recently, TOP249YN , one of two push-pull ,
pirate or just sloppy manufacture, maybe stress relieving of the metal
after guillotining/machining, developing over time.

Anyway this time.
The drummer knocked the mains lead. I wonder if there is an Achilles
heel with such 110/240V mains voltage auto-sensing SMPS drivers, if
there is a short duration interupt in power and then auto restart after
the 8 cycles noted in the datasheet of these TOP24*YN devices.
Did you get any insight in to what preceeded the failure of your unit?
 
"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.






Oops, I just remembered, my TOP chip wasn't "blown" as such, it was
overheating and shutting down.
I rang Peavey to try and quickly establish if they knew of anything that
might be overloading the chip, or was it just the chip.



Gareth.
 
Reason for the tab insulator. 20mm high heatsink 2 mm from the metal
chassis, so only arctan(2/20) = 6 degree, bending of the pcb would let
340V touch ground.
 
On 01/11/2014 15:21, Gareth Magennis wrote:
"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.






Oops, I just remembered, my TOP chip wasn't "blown" as such, it was
overheating and shutting down.
I rang Peavey to try and quickly establish if they knew of anything that
might be overloading the chip, or was it just the chip.



Gareth.
Click to expand...

Going by the curved over top of the sillypad, this has been subjected to
substantial heat. This is not a mixer-amp, just mixer loads of apamps
and a big DSP chip, so why the heat? Vents are either side of the
chassis with no venting local to the smps which is hemmed in between
chassis base and main pcb
 
Decided to grind 4 holes through the pcb in the heatsink footprint and
give a graduated set to the vanes, to make a staircase, either side,
pointing away from the IEC, plus mica insulator for the replacement.
Perhaps the set to one side plus air from under the pcb may give some
sideways movement. Despite not the slightest local discolour indication
of the pcb overheating or any of that telltale dust accumulation on the
underside of the main pcb directly over the heatsink. But I feel I have
to do something other than just direct TOP replacement
 
"N_Cook" wrote in message news:m350pm$fe6$1@dont-email.me...

Decided to grind 4 holes through the pcb in the heatsink footprint and
give a graduated set to the vanes, to make a staircase, either side,
pointing away from the IEC, plus mica insulator for the replacement.
Perhaps the set to one side plus air from under the pcb may give some
sideways movement. Despite not the slightest local discolour indication
of the pcb overheating or any of that telltale dust accumulation on the
underside of the main pcb directly over the heatsink. But I feel I have
to do something other than just direct TOP replacement




The replacement chip I fitted did not overheat.
Perhaps there is a batch of dodgy chips out there that have a failure mode
that causes overheating.

Unlikely as that sounds, it fits in with my experience, and the fact that
Peavey seem to know that these chips "break".

Why not just fit the new chip and see how hot it gets? You shouldn't need
to add any extra cooling.



Gareth.
 
Putting my deer-stalker hat on. Someone had been inside to replace the
fuse. Left out some of the screws, including one self-tap that holds the
IEC. If that one was previously missing and the IEC just "held" by the
remaining one next to the TOP heatsink,loosened by repeated IEC
insertions AND the sillypad was punctured or close to puncturing. Then
the drummer tripped over the lead, IEC twisted and the IEC holding screw
touched the heatsink, as it is long enough, then blown TOP244, but about
4mm gap to swing across to do so. But as there are no pcb standoffs to
chassis in that area, relying on the IEC screws to chassis, then perhaps
the whole pcb being tilted in a downwards sense, by drummer standing on
the lead, and then only that arctan(2/20) 2mm gap for heatsink to
contact chassis.
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:m37eaf$i00$1@dont-email.me...
Putting my deer-stalker hat on. Someone had been inside to replace the
fuse. Left out some of the screws, including one self-tap that holds the
IEC. If that one was previously missing and the IEC just "held" by the
remaining one next to the TOP heatsink,loosened by repeated IEC insertions
AND the sillypad was punctured or close to puncturing. Then the drummer
tripped over the lead, IEC twisted and the IEC holding screw touched the
heatsink, as it is long enough, then blown TOP244, but about 4mm gap to
swing across to do so. But as there are no pcb standoffs to chassis in
that area, relying on the IEC screws to chassis, then perhaps the whole
pcb being tilted in a downwards sense, by drummer standing on the lead,
and then only that arctan(2/20) 2mm gap for heatsink to contact chassis.
Click to expand...



Seems Peavey these days have turned all Chinese, they always used to be very
conventional and pretty reliable really..

I have a small mixer here now, a PV8 USB. It uses an 8 pin DIL JRC2360
DC/DC converter, I think to generate the 48v phantom from the 15v DC input.

Anyway its busted, and an easy diagnosis because a bench supply input heats
up this chip nicely. (The supplied SMPS wall wart trips out).
In the old days, a fault with the phantomn power part of the PSU was very
unlikely to render the whole mixer dead.

Cuh.




Gareth.
 
On 03/11/2014 15:40, Gareth Magennis wrote:
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:m37eaf$i00$1@dont-email.me...
Putting my deer-stalker hat on. Someone had been inside to replace the
fuse. Left out some of the screws, including one self-tap that holds the
IEC. If that one was previously missing and the IEC just "held" by the
remaining one next to the TOP heatsink,loosened by repeated IEC insertions
AND the sillypad was punctured or close to puncturing. Then the drummer
tripped over the lead, IEC twisted and the IEC holding screw touched the
heatsink, as it is long enough, then blown TOP244, but about 4mm gap to
swing across to do so. But as there are no pcb standoffs to chassis in
that area, relying on the IEC screws to chassis, then perhaps the whole
pcb being tilted in a downwards sense, by drummer standing on the lead,
and then only that arctan(2/20) 2mm gap for heatsink to contact chassis.




Seems Peavey these days have turned all Chinese, they always used to be very
conventional and pretty reliable really..

I have a small mixer here now, a PV8 USB. It uses an 8 pin DIL JRC2360
DC/DC converter, I think to generate the 48v phantom from the 15v DC input.

Anyway its busted, and an easy diagnosis because a bench supply input heats
up this chip nicely. (The supplied SMPS wall wart trips out).
In the old days, a fault with the phantomn power part of the PSU was very
unlikely to render the whole mixer dead.

Cuh.




Gareth.
Click to expand...

Nothing obviously loading the ps (cold) will power up replacement
tomorrow, presumably 48V and raw +/-15V as only one vr on the smps pcb,
component side of the big board not seen.
Looking a bit deeper into TOP24* datasheet. This PV14 has the 4 central
pins connected together, 3 terminal device, which is over-voltage
disabled mode.
So what happens in mains dropout and reconnection scenario, as with
drummer tripping over the mains lead and auto-restart on what it
erroneously determines to be low mains voltage setting. Would
probalistically be the same for those floppy 4-way plastic distribution
sockets, breaking and making, blowing the supply, if this is a potential
failure mode. 240V in the UK.
 
Had some TOP249YN around so tried one in there and went in to .8 sec
clicking protect mode. Thinking it was a mismatch in sense Rs I sent of
for some TOP244YN. Replaced and still went into protect mode even with a
load on the nominal/actual ? +15V line as that line is current monitored
by a dropper to feed the opto-isolator.
Double DVM-D test on the opto in circuit showed no response. Removed the
CNY17 and replaced with a 4N31 which passes the double DVM-D test in
circuit, will mains power up again tomorrow .
So some overvoltage/overcurrent to the C-E of the opto when the ps failed.
 
On 01/11/2014 15:21, Gareth Magennis wrote:
"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.






Oops, I just remembered, my TOP chip wasn't "blown" as such, it was
overheating and shutting down.
I rang Peavey to try and quickly establish if they knew of anything that
might be overloading the chip, or was it just the chip.



Gareth.
Click to expand...

This could be your over-temp drop-out failure mechanism.
Sitting quiescent for 1/2 hour and an IR thermometer to the TOP body 38
deg C. But if you point it to the rear it picks up 78 deg C of the 330R
dropper that is enclosed on all sides by the ps pcb , heatsink,chassis
and main board. Perhaps over hours and lack of through draft that
radiator heats up the heatsink and so TOP , enough to trigger temp protect.
Hopefully the holes I ground through the ps pcb and the staircasing of
the h/s vanes will preclude that.
 
"N_Cook" wrote in message news:m3sp9l$tgj$1@dont-email.me...

On 01/11/2014 15:21, Gareth Magennis wrote:
"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper
edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.






Oops, I just remembered, my TOP chip wasn't "blown" as such, it was
overheating and shutting down.
I rang Peavey to try and quickly establish if they knew of anything that
might be overloading the chip, or was it just the chip.



Gareth.
Click to expand...

This could be your over-temp drop-out failure mechanism.
Sitting quiescent for 1/2 hour and an IR thermometer to the TOP body 38
deg C. But if you point it to the rear it picks up 78 deg C of the 330R
dropper that is enclosed on all sides by the ps pcb , heatsink,chassis
and main board. Perhaps over hours and lack of through draft that
radiator heats up the heatsink and so TOP , enough to trigger temp protect.
Hopefully the holes I ground through the ps pcb and the staircasing of
the h/s vanes will preclude that.





My TOP chip was obviously overheating, you could tell immediately by putting
a finger on it.
It would shut down in 10 to 15 minutes.

The new chip went back in the same place on the same heatsink at the same
angle.
This one did not get finger hot.



Gareth.
 
"Gareth Magennis" wrote in message news:C3s8w.871131$ck2.282052@fx17.am4...



"N_Cook" wrote in message news:m3sp9l$tgj$1@dont-email.me...

On 01/11/2014 15:21, Gareth Magennis wrote:
"N_Cook" wrote in message news:m32qnj$qeb$1@dont-email.me...

Surprisingly strong "electrical" smell around the vent ports.
Blown TOP244YN , 20 ohms across rectified mains cap.
Considering crack to its encapsulation is just observable, on one side
only and then under x30. Distorted top to the sillypad (TM) , what may
be a puncture hole at the non-rounded, but then not sharp, rear upper
edge.
Hang on a bit , although the tab holding bolt has an insulating washer,
the heatsink is isolated, anti-EMI ?. So if it did puncture , why
leading to failure?
Any known problems with these presumably fairly generic SMPS sub-units,
all else checks out (cold) ok. Mica will be going back in there.






Oops, I just remembered, my TOP chip wasn't "blown" as such, it was
overheating and shutting down.
I rang Peavey to try and quickly establish if they knew of anything that
might be overloading the chip, or was it just the chip.



Gareth.
Click to expand...

This could be your over-temp drop-out failure mechanism.
Sitting quiescent for 1/2 hour and an IR thermometer to the TOP body 38
deg C. But if you point it to the rear it picks up 78 deg C of the 330R
dropper that is enclosed on all sides by the ps pcb , heatsink,chassis
and main board. Perhaps over hours and lack of through draft that
radiator heats up the heatsink and so TOP , enough to trigger temp protect.
Hopefully the holes I ground through the ps pcb and the staircasing of
the h/s vanes will preclude that.





My TOP chip was obviously overheating, you could tell immediately by putting
a finger on it.
It would shut down in 10 to 15 minutes.

The new chip went back in the same place on the same heatsink at the same
angle.
This one did not get finger hot.



Gareth.







Just to clarify, these symptoms were observed with the unit dismantled and
the PSU in free air, so I could put my finger on the chip/heatsink.


Gareth.
 
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