Speaker relay question
Mark
contact. The relays & associated parts test OK. The base of the relay
drive xisistor goes directly to the the micro (via a resistor). l have a
feeling that the micro might be at fault & if it is they can be
expensive. l temporarily jumped the speaker relays & got good working
audio out. ls there any reason l can't just jump the relay contacts &
leave them permanently closed? What is the main reason that there are
speaker relays?
Thanks for any help on this.
Mark
Henry McKelvey
Speaker relays exsist in order to protect the power amplifiers from a no
load condition created when the speakers are removed from the unit.
If you remove your speakers from the unit the relays will trip, taking the
amplifier output off of the speaker load and onto a protective resistive or
impedence load. If you jumper the relays your system will work, but you will
lose the protective purpose of the relays.
I hope this helps
"Mark" <markc...@webtv.net> wrote in message
news:24273-3B...@storefull-113.iap.bryant.webtv.net...
Sofie
Do NOT jumper the relay contacts...... if there is a failure in the power
output stage, the full current and voltage of the power supply will be
applied to your speakers and burn out the voice coils. The relay is
energized by a protection circuit that senses any excessive DC off-set on
the power amp output and speaker terminals..... as long as every is OK and
there is no danger to your speakers the relay will energize and connect your
speakers to the amplifier output..... however..... if there is excessive DC
present the relay will NOT energize, thus protecting your speaker from
damage. More than likely there is a failure in the protection circuitry...
OR .... the protection circuitry is working OK and there is excessive DC
present on the output/speaker rail. Troubleshooting and repair is
recommended before further failures occur.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Henry McKelvey
Daniel, Is obsolutley correct. As was said earlier "you will lose the
protective purpose of the relays", if you remove them from the circuit by
jumpering them. To quote Daniel "if there is a failure in the power output
stage, the full current and voltage of the power supply will be applied to
explanation to mean that I approved of jumpering a protective circuit or
device? I have never enguage in nor do I approve of such methods. I
apologize for any misunderstanding my answer may have caused.
Henry McKelvey
"Sofie" <so...@olypen.com> wrote in message
news:Eayu7.92364$hh.82...@bin1.nnrp.aus1.giganews.com...
Mark D. Zacharias
loads. I do this all the time with virtually every brand on the market.
2. The protection circuit exists mainly to protect the speakers. While many
modern receivers do employ current protection as well, they are certainly
imperfect in this regard. Since music is extremely dynamic, any circuit that
would provide perfect protection from a current overload would also protect
the amp from the music as well.
3. The non-closed relay contacts are simply open-circuit, they aren't
connected to any substitute load.
4. Removing speakers from the amp will NEVER trip the relay unless the wires
are touched together in the process. Wires should never be moved or changed
while the amp is on, however, simply because this is a leading cause of amp
failures - touching the wires together.
5. The original posters' problem might be caused by several things, I don't
believe he said whether it was intermittent or not. Jumpering the relay is a
moronic thing to do except possibly under certain "field" conditions where
there is no choice but to do so.
Mark Z.
"Henry McKelvey" <hmcke...@home.com> wrote in message
news:Bdwu7.31428$Xz1.8...@news1.rdc1.md.home.com...
Jerry G.
of the proper impedance range for your amp. Also the contacts in
these relays sometimes go defective. On many of these relays I was
able to open them up, and clean the contacts with a
relay-contact-refurbishing-tool. If not, try replacing the relay.
It is available from Sony parts.
If there is a defect in the output stage of the amp, such as having
some DC out to the speakers, this relay will stay in the open
position, thus cutting the sound output.
If you jumper the relay, you lose the protection to the speakers.
If you have a defect and this relay is not working, the speakers and
many parts of the amplifier can be damaged.
--
Jerry Greenberg GLG Technologies GLG
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"Mark" <markc...@webtv.net> wrote in message
news:24273-3B...@storefull-113.iap.bryant.webtv.net...
mike
There's another thing the relay does. When the amp powers up, there may or may
not
be transient
at the output that can make a loud thump and damage your speakers IF they can't
handle
the full output of the amp.
Disconnect the speakers.
Jumper the relay.
Measure the DC voltage at each pair of output terminals.
If it's near zero, the amp is ok and the protection circuit is probably busted.
If it goes thru the processor, there may be some sense circuit on the input to
the
processor that you can fix.
If the DC voltage is zero and you can't fix the relay, you have a tradeoff
opportunity.
What's it cost to fix the amp vs what your
speakers are worth? Putting a fuse in series with each speaker will go a long
way to protecting
them against amp failure. That's how it was done for many years. If the
"thump" ain't too loud
to bust your speakers, you're in business.
I know what I'd do....but I certainly wouldn't recommend any one else do
anything other
than seek professional help to fix the amp.
mike
Henry McKelvey wrote:
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