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Db500 the protection circuit operates at low volume

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  • atv1000 Dec 03, 2008

    this is a samson db500a thanks.

  • atv1000 Dec 03, 2008

    when the mic is used at any level on the volume control, the same fault happens ie the protection circuit kicks in and then resets

    regards ken

  • atv1000 Dec 04, 2008

    Thanks Dan I will look into the caps with a scope also the zener diodes on the protection circuit.

    regards ken

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  • Master
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Hi and welcome to FixYa,

Initially, based on your description, an internal electronic failure most likely in the preamp and/or the amplifier stage. this is of course assuming that you have tested and eliminated that the speaker and its wiring maybe at fault. This of course would require a fair familiarity of electronic components/circuitry and safety procedures, use of a DVM and a soldering iron. It would be to your added advantage access to a service manual or at the very least a schematic diagram with voltage readings. Should you be uncomfortable performing a DIY (do-it-yourself), perhaps your best bet would then be to seek the services of a qualified professional.

Just a start, do postback how things turned up or should you need additional information. Good luck and Thank you for using FixYa.

Posted on Dec 04, 2008

  • Louie  Role
    Louie Role Dec 04, 2008

    An alternate possibility is that this unit uses a DC amp design where each stages is directly coupled. The front end would have a Darlington pair and/or a differential transistor pair. Any constant input signal such as AC hum would be interpreted as an audio signal upsetting the balance. One way to check if it is internal to the amp/pre-amp is to measure the voltage across the speaker terminal, with no signal input, it should read 0 volts while rotating the volume control. If there is voltage measured, then the DC bias has to be adjusted or there is a problem at the front end/pre-amp. Another possibility is dirty volume control contacts and spikes and glitches are introduced while adjusting, enough to trigger the protection circuitry.

  • Louie  Role
    Louie Role Dec 12, 2008

    Hi again,



    Any updates or developments so far?



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Hi

The fact it only occurs when you put audio through it at any level from the mic would tend to indicate that the output stage of the amplifier is faulty. There may also be a fault with the speaker system that could also produce the same symptoms. The protection circuits work in up to 7 different ways relating to current draw, DC offset, Thermal conditions present, or inaccuracies between input and output from the power amp stages.

Checking the speaker system/cables with an ohms meter will give you a quick test to see if there is a problem there with a short circuit. Try another speaker connected to the amp may also help you to eliminate that end of it.

Otherwise, most probably when audio from the mic is amplified, there is an electronic fault is producing a DC voltage in the output stage,and firing the protection circuit. This problem is often caused by failing solder or cracked/dry solder joints in and about the output stage. This is where I would start to look for problems. Happy to talk to you further about the problem.

regards
robotek

Posted on Dec 04, 2008

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  • Master
  • 734 Answers

Sound condenser/filter might be faulty due to which it resets at higher volume.....get them repaired

Posted on Dec 04, 2008

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If an amp protection circuit kicks in at volume level changes, the problem is usually in the pre-amp stage. What is happening here is that there is DC voltage being presented to the output stage. That is detected by the protection circuitry and is causing the shutdown. Normally, these amps are designed as cap coupled to filter out any lingering or transistional DC from stage to stage. If the coupling cap has shorted or is leaky, this type of symptom can occur.

Any service shop that works on audio gear should be able to trace this problem with a scope and resolve it quickly and cheaply. Expect a parts cost in the $10-$15 range.

Dan

Posted on Dec 04, 2008

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Sir, did you try to check your settings of your device?

CHARCOIS

Posted on Dec 03, 2008

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If the unit goes in protection mode when you lower the volume down test the boards with controls and remote sensor. Let me have more details on the problem.

Posted on Dec 03, 2008

  • Ginko
    Ginko Dec 03, 2008

    Usually amps fail when you pump up the volume , not when you lower it down.
    When amps fail at a certain point when turnig volume up , that is usually for a shorted speaker wire.

    In your case:

    If this just happened and it is the first time, unplug power cord for ten or twenty minutes, test a different AC socket, in case the one you are using is not well grounded.

    If amp fails at a low volume in general, then it can be any internal problem or faulty component, the board must be taken out and tested.

    If the active speaker fails when you lower down the volume, always at same point, that means that the amp is not stable at that determined ohm level, this because of a faulty component, usually one of the ICs that do the same job of Valves/transistors on the old amps in the amp final.

    If the problem does not goes by leaving the unit unplugged, or using a different socket, the active speaker must be taken apart, and speaker wiring and amp onboard component tested.

  • Ginko
    Ginko Dec 03, 2008

    If the fault only happens when using an external mic, then either the mic is shorted, or there is a fault on the mic wirings, usually the connector wiring.

    Test a different mic first.


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1 Answer

Clip light is on volume is low


It is possible that the amplifier had encountered a fault with a higher current drain which had triggered it to a protection fault condition. The fault can be with your output drivers. Please check for short on the outputs fitted for both the channels. Use a meter after disconnecting to check for short in the drivers. Disconnect the positive and negative voltages to the output and see if the protect changes. Even a fault in the preamp stages that drives in high current into the output can shut the Amplifier. Sometimes this can be a noise which can be a HUM or HISS before the protect works. Faulty capacitors in these circuits also can cause similar issues and needs close observation.You need to confirm and replace the specific stages or outputs. If not there can be issues in the mother board. Maybe the protect circuit by itself is shutting off due to a faulty bias or there is a leak in any voltage/current sensing circuit. Also disconnect the speakers and test, if the amplifier comes out of the protect mode then check for short on the speakers

Nov 30, 2011 | Kenwood VR-307 Receiver

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My stereo sysytem is a mini stereo: serial number 10200055. It currently says "protect", what is this and how do we return our system to normal operations?


Hi there,

When the word PROTECT appears on this display, this means the unit has detected a critical fault which could potentially cause harm to your stereo system.

The most common cause is a short circuit somewhere - something even as simple as loose speaker wiring could cause a short, triggering the Protect message.

You will need to determine if there is a possible short somewhere, so I recommend you start by firstly turning power OFF, disconnecting all speaker wires, then turn unit back ON.

Operate the stereo (without speakers) and turn volume up:
  • If Protect message appears when turning volume up, then stereo unit itself has an internal fault
  • If no Protect message appears, then suspect the speakers may be causing the issue.
  • Reduce volume and turn unit OFF
Re-connect speakers (ensure the connections are secure), turn unit ON:
  • If turning volume up triggers the Protect message again, there is an issue with the speakers or connections

Hope this helps.....

Sep 04, 2011 | Kenwood Audio Players & Recorders

1 Answer

Speakers work at low volume. Around -39 db, receiver shuts off.(protection mode) Tried moving speaker wires, alternating red and black. No go. When powered back up, display says ck sp wires. Once I...


Decibels correspond to the output voltage being sent to the speakers. In your case, the voltage is reached at -40dB is the threshold that causes whatever is happening to operate the receiver's protection circuit. You might have a bad speaker, with a voice coil that shorts at the higher voltage. Below that level it's okay, but at the magic point the insulation breaks down, and that's when the receiver sees trouble.

You might try connecting only one speaker at a time using a short length of wire other than your current ones. If the trouble occurs on one speaker only, you've found the culprit. If the receiver operates normally on each speaker, try reconnecting one speaker at a time to determine if one of the speaker wires may have a short somewhere. There might be a weak spot in the insulation, not causing any trouble until the voltage is high enough.

If the receiver still goes into protection with just one speaker, there's an internal problem. Some part in the amplifier may be breaking down at that voltage. Or a part value has changed, causing the protection circuit to kick in even though there's really nothing wrong. Bad solder connections may have developed. Unfortunately, this kind of problem usually needs the services of a shop with the equipment and circuit information to figure out what's happening. If you can find a Yamaha-authorized warranty servicer, they might already know some typical causes if they've seen units with the same trouble.

Try the speaker test first. Then let a shop tackle the receiver if it looks like that's where the fault is. Good luck and thanks for using Fixya!

Jun 03, 2011 | Yamaha HTR-5830 Receiver

1 Answer

While operating, when increasing volume automatically coming "PROTECT" and switch off the system. If using low volum is working properly. Please advise how to un protect. Regards - Jayaraj


Remove the threat of damage that it senses.

Generally speaking, an amp attempts to protect itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.

Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

Check for loose speaker connections at the speaker as a root cause for intermittent shutdown.

Jun 01, 2011 | Harman Kardon AVR 130 Receiver

1 Answer

Yamaha RX-797 shuts down when playing at low volume while increasing the volume. If you lower the input wolume from the source into the reciver you can increase the volume on the reciver but when you reach...


That would be consistent with reaching an overload threshold on the amplifier's outputs.

This is mostly boilerplate but it may lead you to the problem...

Generally speaking, an amp attempts to protect itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.

Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

Check for loose speaker connections at the speaker as a root cause for intermittent shutdown.

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1 Answer

What if went in safety mode, safety mode is froze in screen. Won't do anything


"Safety" mode - literally? I don't see that anywhere in the manual.

Page 13

Speaker Connection Precautions

(North American and Taiwan models) You can connect speakers with an impedance of between 6 and 16 ohms. If you use speakers with a lower impedance, and use the amplifier at high volume levels for a long period of time, the built-in amp protection circuit may be activated.

Page 66

The STANDBY indicator flashes red


The protection circuit has been activated. Remove the power cord from the wall outlet immediately.

Disconnect all speaker cables and input sources, and leave the AV receiver with its power cord disconnected for 1 hour. After that, reconnect the power cord and set the volume to maximum. If the AV receiver stays on, set the volume to minimum, disconnect the power cord, and reconnect your speakers and input sources. If the AV receiver turns off when you set the volume to maximum, disconnect the power cord, and contact your Onkyo dealer.

Generally speaking, an amp protects itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.


Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.


You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.


If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.


If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

Apr 04, 2011 | Onkyo TX-SR608 Receiver

1 Answer

On my Pioneer vsx-55txi, the protection circuit cuts in whenever I raise the volume to a reasonable level. If I sit 10 feet or more, the volume is too low. I don't like my music or movies loud, but this...


The protection circuit is enabling because the output transistors are 1. drawing too much current causing them to heat-up 2. the transistors are going out 3. the threshold level for the quiesce state is set too high and may need to be adjusted internally. Try to cool down the Unit and see if it occurs again.

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1 Answer

When i turn up volume on receiver it display protected and then i loose sound on my sony str-d865 receiver


That's a protection circuit in the output of the speakers. It indicates a short, or abnormally low resistance of the speaker itself. Disconnect the speaker wires from the unit, and see if the message goes away. If it did, you have a problem with your wiring, or the speaker itself.

Mar 13, 2010 | Sony Audio Players & Recorders

1 Answer

Dra-685 the protection came on ,i found 2 speaker wires together,fixed that,but still stays on,thanks


You may have a speaker that is damaged and causing the protection to operate. Try unhooking all the speaker wiring from the receiver, turn the volume to minimum, and see if the protection still comes on. If the receiver is okay, you can start checking the speakers and wires to determine which one(s) may be responsible.

If the unit continues to go into protection even with no speakers connected, the trouble is inside the receiver. No protection circuit is absolutely perfect, so it's possible something failed before the circuit kicked in. Without the proper test equipment and service information, you won't be able to try fixing this yourself. Take the unit to a shop for an estimate.

Thanks for using Fixya! Hope your receiver's back in service soon.

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2 Answers

Vollume trouble


the system protect is usually displayed when a condition of short or shorting is occurring in the speaker wiring or the voice coil of any of your speakers.... thte circuit of you reciever is trying to protect itself and you from a very costly repair,,,so it you have another set of speakers try to use them and see if the condition still exists and if it does the problem is in the output section of the receiver,,,and if the protect no longer exists you have fixed your problem,,,good luck

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