.... got any experience of the Ecler "PAM" series of high-power slave amps ?
Specifically why the output relays have had a half inch disc magnet glued to
either side of their cases, at the bottom, and in line with the contact set.
These magnets are detailed as a mechanical fitting drawing in the service
manual, even down to which pole should face in, but nothing that I can see
in the notes as to why they have been fitted. Also, anyone got any
experience of working on these (1400 and 1000 models), and in particular,
the complex logic-controlled protection circuit on the back board where the
output relays are ?

Arfa

"Arfa Daily" wrote in message
...
... got any experience of the Ecler "PAM" series of high-power slave amps
? Specifically why the output relays have had a half inch disc magnet
glued to either side of their cases, at the bottom, and in line with the
contact set. These magnets are detailed as a mechanical fitting drawing in
the service manual, even down to which pole should face in, but nothing
that I can see in the notes as to why they have been fitted. Also, anyone
got any experience of working on these (1400 and 1000 models), and in
particular, the complex logic-controlled protection circuit on the back
board where the output relays are ?

Arfa



Not seen one of those before.

As for the magents, I believe they might be something to do with affecting
the arcing between contacts under various fault conditions?

Phil will know the complete details as I remember him posting on here before
about it.





Cheers,

Gareth.

On 31/01/2014 15:27, Arfa Daily wrote:
.... got any experience of the Ecler "PAM" series of high-power slave
amps ? Specifically why the output relays have had a half inch disc
magnet glued to either side of their cases, at the bottom, and in line
with the contact set. These magnets are detailed as a mechanical fitting
drawing in the service manual, even down to which pole should face in,
but nothing that I can see in the notes as to why they have been fitted.
Also, anyone got any experience of working on these (1400 and 1000
models), and in particular, the complex logic-controlled protection
circuit on the back board where the output relays are ?

Arfa

Some sort of unpowered interlock? Magnets not strong enough to close the
contacts but once current has gone through the coil , the contacts
close. But if for some reason the current stops, then the contacts
remain closed until reverse powered open perhaps at start-up.
Which reminds me I was going to find out,but forgot, how the unpowered,
delay-open, door catches work on washing machines

N_Cook scribbled thus:

Which reminds me I was going to find out,but forgot, how the
unpowered, delay-open, door catches work on washing machines

Thermal device !

--
Best Regards:
Baron.

I had a quick look at the print and I can't say for sure, but I think it's possible that the magnets are there to aid the return springs. Looks like this baby can put out some serious current.

"But if for some reason the current stops, then the contacts
remain closed until reverse powered open perhaps at start-up. ..."

Nope, nothing like that on the print.

wrote in message
...

I had a quick look at the print and I can't say for sure, but I think it's
possible that the magnets are there to aid the return springs. Looks like
this baby can put out some serious current.

"But if for some reason the current stops, then the contacts
remain closed until reverse powered open perhaps at start-up. ..."

Nope, nothing like that on the print.





Perhaps something along this line:

http://www.ia.omron.com/data_pdf/dat...eet_csm570.pdf



Gareth.

"Gareth Magennis"
Arfa

Not seen one of those before.

As for the magents, I believe they might be something to do with affecting
the arcing between contacts under various fault conditions?

Phil will know the complete details as I remember him posting on here
before about it.


** Someone has a good memory.

Similar magnets are attached to the relays in certain BGW amplifiers (
1980s, US made heavy weights) and no doubt for the same reason.

The purpose is to enhance the DC breaking capacity of the contacts - with DC
supplies above about 60V, ordinary relays cannot break arc that forms upon
opening IF the amp " goes DC".

The magnetic force causes arc to form into a U shape, making it longer and
far more likely to break.

IME, an 80V DC supply feeding into a 4ohm load via a large relay will break
this way - but *just* and probably only once !!!!!

It would have NO chance without the magnetic field.


.... Phil

On 31/01/2014 21:48, Baron wrote:
N_Cook scribbled thus:

Which reminds me I was going to find out,but forgot, how the
unpowered, delay-open, door catches work on washing machines

Thermal device !


resourceful stuff that bimetal, from watch escapements , via vehicle
lamp flashers, flourescent tube starters to washing machines, it gets
everywhere

"Phil Allison" wrote in message
...

"Gareth Magennis"
Arfa

Not seen one of those before.

As for the magents, I believe they might be something to do with
affecting the arcing between contacts under various fault conditions?

Phil will know the complete details as I remember him posting on here
before about it.


** Someone has a good memory.

Similar magnets are attached to the relays in certain BGW amplifiers (
1980s, US made heavy weights) and no doubt for the same reason.

The purpose is to enhance the DC breaking capacity of the contacts - with
DC supplies above about 60V, ordinary relays cannot break arc that forms
upon opening IF the amp " goes DC".

The magnetic force causes arc to form into a U shape, making it longer and
far more likely to break.

IME, an 80V DC supply feeding into a 4ohm load via a large relay will
break this way - but *just* and probably only once !!!!!

It would have NO chance without the magnetic field.


... Phil


Thank you Phil. That makes a lot of sense. Have you done much work on these
? I currently have seven of them in, all of which seem to have faults in the
very complex protection circuit, which amongst other things, cuts the supply
to an opamp on the power amp boards, which then causes the amp to actually
produce some DC on its output ...

Arfa

Perhaps something along this line:

http://www.ia.omron.com/data_pdf/dat...eet_csm570.pdf






Or better still, this:
http://www.serelays.com/library/section6/105A_199.pdf



Gareth.

"Gareth Magennis" wrote in message
...

Perhaps something along this line:

http://www.ia.omron.com/data_pdf/dat...eet_csm570.pdf






Or better still, this:
http://www.serelays.com/library/section6/105A_199.pdf



Gareth.



Very interesting ...

Arfa

"Similar magnets are attached to the relays in certain BGW amplifiers (
1980s, US made heavy weights) and no doubt for the same reason. "

You Sir, have redeemed yourself. I thought it impossibble really. Take a bow(ow) LOL.

I **** you not. I'm a pretty fart smeller y'know and I was sure it had something to do with the ridiculous eardrum-melting current but in my morning after you actually opened up a little corner of my mind that had been dormant for some time. I KNEW it had something to do with current, but to extrapolate, it is wholly possible that such an amplifier would be driving a chiefly inductive load. WTF did I think was going to happen with 80 ****ing volts across a (voice) coil ?

(me)DUMKOPF ! It's not a weak spring, it's the fact that plasma can melt even the shiniest of silver plating and weld it quite effectively. One of those moments.

Now I know why we keep you around you autistic, Tourettite scallywag scoundrel !

Back to your regularly scheduled bull****. Be well. And don't forget to eat **** and die !

LOL

(I mean it Phil, I would heve never thought of that in, well, not a MILLION years but maybe a thousand)

"Phil Allison" wrote in message ...


"Gareth Magennis"
Arfa

Not seen one of those before.

As for the magents, I believe they might be something to do with affecting
the arcing between contacts under various fault conditions?

Phil will know the complete details as I remember him posting on here
before about it.


** Someone has a good memory.

Similar magnets are attached to the relays in certain BGW amplifiers (
1980s, US made heavy weights) and no doubt for the same reason.

The purpose is to enhance the DC breaking capacity of the contacts - with DC
supplies above about 60V, ordinary relays cannot break arc that forms upon
opening IF the amp " goes DC".

The magnetic force causes arc to form into a U shape, making it longer and
far more likely to break.

IME, an 80V DC supply feeding into a 4ohm load via a large relay will break
this way - but *just* and probably only once !!!!!

It would have NO chance without the magnetic field.


.... Phil




Phil, you have to also tell us the extremely relevant story of grounding the
speaker relay's normally off terminal, so a "DC fault" amplifier doesn't fry
the speakers via the arc that doesn't die.
(In the absence of a magnet)
I remember you posting about that somewhere too.

This stuff does stay in my head sometimes you know.


Cheers,

Gareth.

N_Cook wrote:

On 31/01/2014 21:48, Baron wrote:
N_Cook scribbled thus:

Which reminds me I was going to find out,but forgot, how the
unpowered, delay-open, door catches work on washing machines

Thermal device !


resourceful stuff that bimetal, from watch escapements , via vehicle
lamp flashers, flourescent tube starters to washing machines, it gets
everywhere


Metal cutting saw blades...

"Gareth Magennis"
"Phil Allison" "Gareth Magennis"
Arfa

Not seen one of those before.

As for the magents, I believe they might be something to do with
affecting
the arcing between contacts under various fault conditions?

Phil will know the complete details as I remember him posting on here
before about it.


** Someone has a good memory.

Similar magnets are attached to the relays in certain BGW amplifiers (
1980s, US made heavy weights) and no doubt for the same reason.

The purpose is to enhance the DC breaking capacity of the contacts - with
DC
supplies above about 60V, ordinary relays cannot break arc that forms upon
opening IF the amp " goes DC".

The magnetic force causes arc to form into a U shape, making it longer and
far more likely to break.

IME, an 80V DC supply feeding into a 4ohm load via a large relay will
break
this way - but *just* and probably only once !!!!!

It would have NO chance without the magnetic field.


Phil, you have to also tell us the extremely relevant story of grounding
the
speaker relay's normally off terminal, so a "DC fault" amplifier doesn't
fry
the speakers via the arc that doesn't die.


** Some power amps use that idea ( ie diverting the arc to ground while
shorting the speakers ) but there has to be fuses in each DC supply rail -
or you will soon have a fire on your hands.




..... Phil

"Phil Allison" wrote in message ...


"Gareth Magennis"
"Phil Allison" "Gareth Magennis"
Arfa

Not seen one of those before.

As for the magents, I believe they might be something to do with
affecting
the arcing between contacts under various fault conditions?

Phil will know the complete details as I remember him posting on here
before about it.


** Someone has a good memory.

Similar magnets are attached to the relays in certain BGW amplifiers (
1980s, US made heavy weights) and no doubt for the same reason.

The purpose is to enhance the DC breaking capacity of the contacts - with
DC
supplies above about 60V, ordinary relays cannot break arc that forms upon
opening IF the amp " goes DC".

The magnetic force causes arc to form into a U shape, making it longer and
far more likely to break.

IME, an 80V DC supply feeding into a 4ohm load via a large relay will
break
this way - but *just* and probably only once !!!!!

It would have NO chance without the magnetic field.


Phil, you have to also tell us the extremely relevant story of grounding
the
speaker relay's normally off terminal, so a "DC fault" amplifier doesn't
fry
the speakers via the arc that doesn't die.


** Some power amps use that idea ( ie diverting the arc to ground while
shorting the speakers ) but there has to be fuses in each DC supply rail -
or you will soon have a fire on your hands.



Yes, I thought the idea was that proper fusing protects both amp and
speakers.

I note that some Peavey amps, for example, do not have any speaker relays at
all, but use a SCR/Triac to short the output in the event of DC, saving the
speakers, but blowing the amps, which dont appear to be fused properly for
such an occurrence.


Gareth.



Gareth.

On 01/02/2014 23:45, Michael A. Terrell wrote:

N_Cook wrote:

On 31/01/2014 21:48, Baron wrote:
N_Cook scribbled thus:

Which reminds me I was going to find out,but forgot, how the
unpowered, delay-open, door catches work on washing machines

Thermal device !


resourceful stuff that bimetal, from watch escapements , via vehicle
lamp flashers, flourescent tube starters to washing machines, it gets
everywhere


Metal cutting saw blades...


bi metal yes, but surely just as a hard surface bonded to softer
resilient backing, rather than for its differential temperature
coefficients of expansion, ie bending on heating property

I like the bi-metal discs that you get in thermal switches, that
suddenly dome in the opposite sense at a precise temperature, and built
in hysterisis as well , before they will flip back the other way on
lowering of temperature.
Perhaps a bi-metal arrangement , even if requiring some diverted current
doing the heating instead of "in-passing" heating , would work as
heavy-duty DC relays, relying on this strong stored mechanical energy ,
rather than magnetism and springs to break contact

N_Cook wrote:
Perhaps a bi-metal arrangement , even if requiring some diverted
current doing the heating instead of "in-passing" heating , would work
as heavy-duty DC relays, relying on this strong stored mechanical
energy , rather than magnetism and springs to break contact

Congratulations, you have invented an automotive turn signal (indicator)
flasher! The non-electronic ones work this way. Some of them rely
on the bimetal heating itself up from the lamp current, and some of them
have a small heating element to do it. Ratings to around 12 A at 12 V
DC nominal are available.

Matt Roberds