Do you have a Pioneer mini-hifi (X-HM71-S, X-HM71-K or X-HM81-S, X-HM81-K) or amplifier (X-HM20, X-HM10) that suddenly stopped working? Maybe all it does when plugged in is flash a little red / blue light on the front panel and refuses to switch on?

Fault reset now working again

Fault reset now working again

Well I’ve now had three Pioneer X-HM71-S (Silver) and X-HM71-K (Black) systems that have failed in this way and finding out why has prompted me to tell others what happened and Pioneer’s response.

Let’s start with the good news – your Pioneer will most likely be easy to fix and does not need replacing – see end of post. (Note X-HM20, X-HM-10 may just need unplugging for 5 minutes to reset see the comments below).

The bad news is that you won’t find any clue in the instruction manual that came with your system. There’s not one mention of a flashing light or what to do if you are unlucky to have this occur. I guess most owners will simply give up and look for a new model thinking they’ve broken it. Or take it for service. Lucky for Pioneer if you choose to buy another Pioneer – I won’t and here’s why.

The Problem

The red timer light just blinks and the Pioneer won’t switch on.

The problem in my case was due to the overload protection software triggering that puts the unit into a permanent ‘fault’ condition which can’t be reset by simply powering down and up again. I tried Google for helpful suggestions of holding down multiple buttons such as stop and power when plugging in but this did not work.

Before finding out about the secret buttons I took the units to an approved Pioneer service workshop where they reset the fault code. The reason for this Pioneer inform me is that an engineer needs to check for damage before reset to ensure the device is not permanently damaged. The service workshop will likely insist the problem was caused by you having been clumsy enough to wire up the speakers incorrectly or short out the speaker wires or have a fine wire that touched the chassis. The overload protection circuit does not lie they will say and it must have happened. Will consumers buckle under the insinuation and pay the service fee ‘fine’?

Given in my case I had three units fail in two separate installations that I’d personally wired up without any trace of faulty wiring I wanted to understand why I was being wrongly accused. So I wrote to Pioneer UK.

Their reply was to condemn my speakers as being not suitable for the X-HM71. Suggestion was to use the Pioneer speakers supplied instead of my JPW or Gale Gold Monitors, not a choice I wanted given the Pioneer’s inferior quality.

Having said that I should say Pioneer now produce some far better sounding speakers than you may expect although the pair bundled with the X-HM71 were not in that category (you get a clue by their light weigh feel. Pioneer wanted to see the impedance curve of my 20 year old speakers to point the finger but of course could not find any from the manufacturer. It took me 20 minutes or so to measure the impedance of each of my speakers and send Pioneer the curves.

JPW-Impedance-Curve

JPW Gold Monitor Impedance Curve

Gale-Impedance-Curve

Gale Gold Monitor Impedance Curve

 

 

Pioneer’s reply was to agree the speakers were not to blame after all. It cost £30 a pop for DK AVS to reset each X-HM71 which developed the mysterious flashing red timer light after the 12 month warranty had expired. The third one failed after just a couple of months so was returned for a full refund.

So why did the protection trip? I still don’t know why and Pioneer don’t seem to know either. Here’s what they said:

The protection circuit can activate by several methods. The timer light will flash in a particular timing sequence to indicate to an engineer what area the fault is in. Some are recoverable by the end user just by pressing the power button again. Other more serious errors, that can cause permanent damage, are not recoverable by the end user. This has been done to stop the user from trying to turn the unit back on and causing more substantial
damage. The method to de-activate this protection is only available to engineers who can check the relevant circuit area for damage, and if all is ok, they can release the protection without fear of further damage.

Is that clear? No, I don’t think so.

In the old days an anti-surge fuse was fitted in the power supply that could be seen to have blown and easily replaced by ‘end users’. Trouble is that now days the electrickery has become more complex – the audio amplifiers in the Pioneer are ‘Class D’ (not quite bottom of the class) rather than the more traditional top of the Class A or A/B analogue amplifiers. Class D amplifiers essentially switch on and off at supersonic frequencies that even bats would have trouble hearing. The on / off switch duration changes – a bit like morse code dots and dashes – in time with the desired audio frequency signal. After some high frequency filtering the audio signal is fed to the speakers as in the higher class amplifiers.

So why should you care?

Well Class D amps are cheaper to manufacture and can produce more audio power efficiently so long as they keep switching. If they stop switching the output devices can fail rapidly especially if the speaker connection is short circuit or shorted to chassis. So manufactures like Pioneer have to design and fit elaborate protection to monitor the amplifiers and switch it off as soon as it thinks there’s a problem to avoid permanent damage. A simple anti-surge fuse would likely be too slow to respond to prevent damage.

But hold on a minute, why can’t the protection circuit and software be designed to trigger and reset on power cycle or recover if the fault condition goes away? A permanent fault such as a shorted speaker would immediately trigger the protection and switch off the amplifier each time. A glitch or power spike that triggers the protection once would reset next power cycle if the problem has gone away. Sounds too simple and probably is but the question remains why not at least let the end user know that a flashing light means a fault has been detected?

And the explanation for not mentioning the indicator light’s meaning:

Remember that the flashing light on these products can mean various different things, some recoverable and some not depending on the timing’s. Also most of our products will have a form of indication when a problem occurs, and these lights will mean totally different things. There is no generic indication.

And no indication to the end user (that’s you and me) what action to take. So there you are, left with a bill for repairing a product that has no fault except for the protection circuit that has decided there’s been a fault.  Inherent poor design, could do better, definitely class D.

Update: Thanks to Prassel and Martin (see comments below) here’s the way to reset the fault. Suggest you double check the speaker wires are not shorting out on either left or right channels before attempting reset the lock.

X-HM71 or X-HM81 Reset Lock

X-HM71 or X-HM81 Reset Lock

Or if this does not work try pressing the “STANDBY/ON” and “STOP” buttons simultaneously on the front panel.

On the X-HM10 / X-HM20 simply unplug the unit wait 5 minutes and try again, the fault condition should clear.