Gm stopped working

I haven’t had my GM40 very long, maybe 2 weeks and when I turned it on today and switched it from standby to play I saw where on the TSC lights only the ones in the middle were on. And the power soak was suck on silent, when I would attempt to turn up the volume but nothing would get louder. Switching it from standby to play doesnt change the power soak at all

Hi Eric.  Most people would jump in and suggest "sya valves m8 swap em out for new set of my Xpensiv favrits". That may well be the problem but, ultra simple things first.

Do you have both the Master Volume AND the Volume control turned up?  The Volume is a digipot so its position may not be the same as the setting it is carrying.  Turn it fully down then back up again until it flashes.

The two middle LEDs are on to show you that the corresponding valves have been taken out of circuit because the power soak is set to a level below the 40W maximum.  That is the first step in switching from 40W to 20W and below, the inner pair of valves is taken completely out of circuit.  If the other two LEDs remain switched off then the outer pair of valves are still active which is what you would want for 1W, 5W and 20W.  If the power soak were set to silent it should turn on all of the LEDs to show the amp has no power valves currently working.

I assume you are already aware that the power soak is controlled by the 4 clear buttons on the back.  For every situation except running at full power one of these should be lit.  The silent playing setting has its own button, (the one with the speaker and a cross over it).  Do any of those switches have a blue light in them?

Have you tried all of the switches back there to select any level other than silent?  If you have selected a different setting manually and the amp still does not come to life then it suggests you could have a fault in your speaker setup but that would be odd given the LEDs.  The amp automatically switches itself to silent mode when it detects a fault on its output.  If the speaker is disconnected it will kick out and also if there is a short on the output.  That should have lit up all four LEDs though and you are not seeing that.

If none of the simple things above work then rule out your speaker cable if possible by swapping it out for a different one to test.  Also check the state of the actual speaker by feeding it a signal from a different source.  Even a small battery will make it pop and crackle lightly and let you know it is working.  Once they are ruled out we can think of a possible fault in the amp though this must be very unlikely.

the volume control on the right is above half but the master doesnt even effect the overall sound at all, ive gotten it turned up all the way and its still quiet and i cant even interact with the power soak it stays on silent with an orange glow, but when i turn the master volume all the way up it makes a tea kettle like noise

Ah!  Now that does sound like you have a problem that isn't just incorrect selections or settings.  The tea kettle sound does suggest that you could have a valve problem.  It could be other things but the valves are always the most likely suspects to be eliminated so best address them first.

The factory fitted valves in the H&K amps are generic Chinese ones.  People moan a lot about that but H&K say, with a lot of sense, the idea is that they know most guitarists will swap out the valves for something esoteric they are in love with that week as soon as they receive the amp.  Putting in a better set of valves from new does not make sense as it would push the price up for something which is going to be binned immediately.  As the manufacturer they stick to a cheaper set which we know does occasionally have problems early on.  It is rare but it does happen.  If valves are going to have a "go/nogo" type of problem it is almost always in the first few hours of use.  And of course it happens with any valve make.  I have had this with a JJ and others with other makes too.  Incidentally, there is nothing wrong with those Chinese valves as long as they give you the sound you are happy with.  Don't feel you have to part with sums of money to buy something made by blind monks in a Buddhist monastery on the slopes of a mountain in Tibet by the light of the new moon.  Changes in sound due to valve swaps are very highly massively incredibly overstated!!!  Even the difference in the most esoteric valves against these Chinese ones are "subtle at best" and can rarely be identified in honest properly conducted double blind listening tests.

One really simple test you should try here is to put your guitar lead into the Loop Return socket and touch the tip.  If the amp makes a buzzing sound then the power amp stages are working.  If it still only makes that bubbling sound then the power amp is where the fault is located and that would most likely mean the PI (phase inverter) valve.  That is the smaller 12AX7 fitted nearest to the 4 EL84 power valves.  It would also be a good test to see if the Loop Send will play into another amp's Loop Return but that needs a second amp of course which you may not have. You could swap over two of your 12AX7s to test that but it makes more sense to address this under warranty.

If you bought the amp brand new this early valve failure should be covered.  Are you able to take it back to the store where you bought it?

so i put the cable in the loop return and touched the tip and it made the normal buzzing noise, and i noticed with it on ultra and the gain all the way up with the guitar plugged in is when it does the tea kettle noise, i turn i on and i can see the 4 valves in the back are glowing but not the two in the front. also when the guitar is plugged i can hear it but very quietly

Right, some of that info changes things a bit.

You have proved that the power amp section is working as it should.  You would not have heard the buzzing when you touched the plug tip if it were faulty.  The problem would seem to be in the preamp section.  I think you may just be missing the glow in the preamp valves, it is not as pronounced as it is in the EL84 power valves.  With the 12AX7s used in our amps it is not always easy to see if you don't look very carefully or are experienced with them.  Are you sure they are not glowing at all?  It would be unusual to have a problem with more than one valve at a time.  Just for the record, there is also a third valve under the aluminium screening can clipped onto the chassis.

Now for the different line you have suggested.  You say the kettle noise happens on the Ultra channel with the Volume up full.  That would be very normal for all amps with a high gain channel.  All valves produce noise, (like the kettle sound but also as a high pitched hiss or a deeper roar), and that noise signal is only unnoticeable when the gain of the overall circuit is low enough to keep it below a particular level.  When the Ultra channel is selected, settings in the amp are changed to increase the gain, (some of us would say to an insane level but hey...).  This means that any noise from the earlier parts of the circuit will now be amplified a lot more and they then become noticeable on the output.  Of course, a faulty valve can produce a lot more noise than a healthy one but perception of noise levesl is a personal thing.  Without hearing it first hand it is difficult to say whether it is normal or not.  Let's trust your instinct on this one.  If your noise level is very high then it may mean you have a preamp valve gone down.

It does suggest that now you may have to swap out at least one, (and probably only one), of those original valves.  I would say again that this should be done under warranty even though most people would just stump up and replace themselves.  It is easy and cheap to buy new valves but you must be careful.  The warranty does say that the amp must remain in original form and registered for warranty within 30 days of purchase.  Is that the case with your own?  It also says that the fitting of non factory replacements can void the warranty and this includes the valves!  I quote:

H&K Warranty wrote:II) What voids the warranty:
The warranty is void if
• the authorized dealer, distributor, or warrantor determines that the product has been damaged
by improper or faulty handling, installation, transport, or service, failure to comply with the
operating manual instructions, application errors, misuse, extraneous cause, or as the result of
a repair or modification not carried out by the authorized dealer, distributor, or warrantor, or
natural wear and tear (e.g. tubes),
• the serial number of the device has been removed, defaced, or in any other way rendered
illegible,
• non-original parts and/or vacuum tubes have been installed in the device.
• the product was not purchased as a factory-new good from an authorized Hughes & Kettner dealer.

Note the bit about "natural wear and tear".  Your fault is not that!  Also note that second to last line, "and/or vacuum tubes"!  Now it is unreasonable to expect that you should stick to the Chines types they fitted.  We think here that it implies the stupid practice of substituting "equivalent" types (they plain aren't!) for the 12AX7 such as 12AT7 or 12AU7.  That is a definite electronic no-no and I for one would be behind H&K in denying warranty claims if that has been done.  Is your own amp all original?  If so I would seriously consider taking it back for a valve replacement by them.  If it is still unregistered then do it quickly.  The window is only open for 30days after purchase.  You can do it online here: H&K Warranty Registration

its all original, i did the tube bias and all 4 lights flashed for awhile then only the far left one flashed twice. what makes no sense it i can hear the amp working but its like its being limited by something and wont allow me to increase the volume.

Yes, this is odd. Your bias is fine. The lights flash to show the level of each corresponding valve's current bias setting. If you coujnt the number of flashes it will show you how the bias is set. If three of those lights flash exactly the same number of times they are all set exactly the same. The fourth one flashing twice more means that one is slightly different but it is still easily within the recommended level which, for the record, is a maximum of four flashes in difference between either valve in one of the outer or inner pairs. The two pairs do not have to match each other, only the individual valves in each pair need to match.

Can you describe to me what happens when you press the selector switches for the Power Soak on the back? Assuming you already have one switch selected with its LED lit and its switch button inwards, press another one. The new switch button should lock in and the previous one should pop out. You should see the button you press light up and the other one which was lit should go out. Make a number of selections in turn to check that all of the switches actually do that even if you get no change in sound.

The only situation I can think you might be in which you describe in your earlier post is with the Silent switch permanently engaged. If that is the case and you cannot select anything other than Silent even when you push the other buttons then it does point to you having a problem in your output area, either the Power Soak itself, the speaker plug, cable or cabinet. However the test with your cable in the Loop Return socket should rule that out. Was the buzz you heard when you touched the tip of the cable a loud one, (which it should have been)?

Do you have access to another 12AX7 which you know is a good one to borrow temporarily for a test, maybe from another amp of your own or a loan from a friend's amp? If so I would swap out each of your valves in turn with that, (I can talk you through the procedure to keep things as they should be and it is perfectly safe electrically). Other than taking it back to the sales place and getting them to do it there is no other way to check them. That would confirm or rule out the preamp valves as a source of the problem.

well i had it sent back to be looked at and they claimed it was functioning fine, it came back today and when i plugged it in still has the silent mode issue even with getting new power cords and guitar cables

That's interesting to hear their report.  It should indicate that, assuming the repair centre has done a bit of work and investigated as they say, there is nothing wrong when it is used in a known good system.  The amp is not being damaged by this problem - yet!  It does point to something in your own system which is at fault.  A new power cord and guitar cable will not help with this problem if I have what you mean by those descriptions correct.  It is the amp in protection mode caused by something which is connected to its output.  Either you have a problem with your speaker cable or the speaker itself is at fault so we need to check those out.

Have you tried replacing the speaker cable?  I realise that might be what you mean by the "power cable" but I just want to make sure.  I know this is a newbie point but, you do realise that you must use a specific speaker cable and not a standard guitar signal cable.  There are a number of amps flowing from the output of the GM to the speaker and a guitar cable is nowhere near man enough for that job, even temporarily.  It will fry!  If you have used a signal cable thinking they are the same then that will be where your problem lies.

A bit of advice here.  Even if they are thick enough to handle the high current the speaker cable is the area where 99% of these problems are caused.  They get twisted in use, kicked and trodden on, and bashed backwards against walls.  They get yanked and one of the soldered connections inside can break off and they come together.  They really need to be made with specific speaker jack plugs which are a larger size to accommodate the thicker wire you must have for high current transfer.  Do a search for "Neutrik NYS225" online to see what they should really look like.  After a number of "bad experiences" I now will not use anything other than those shaped plugs for my speaker cables which I solder on myself and I always sleeve all of the internal terminals with heatshrink.  For the same reason my speakers' sockets are now all Speakon types which accept both Speakon and jack plugs.  If you use ordinary slim cheaper signal jacks with ineffective cable restraints the internal terminals are very easily bent together if the cable is pulled when they can short out.  This is not a disaster for a guitar signal, it just goes silent, but in the case of a speaker cable it can easily blow the amp with very expensive consequences.  The GM series has protection against that.  The Power Soak kicks into Silent mode automatically.  Which sounds fairly familiar.

Then there is the possibility that the problem is actually inside the speaker itself.  Have you another amp which you can test the speaker and your cable with?  Once again the wiring inside the cabinet socket can easily get wound around and short together.  Even the speaker itself may be faulty unless you can test it with another working source.

So...  What speaker are you playing the amp through?  What is the state of your speaker cable and the speaker itself?  Do you KNOW they are both good by using them with other gear?




EDIT:

I will also add that I'm not sure of the effect of using too low a speaker impedance on the protection circuitry.  The GM series is meant to be used only with speakers of 8-16ohms impedance.  If, for example, you have two 8ohm drivers and you have put them in parallel then you are trying to drive 4ohms and that is outside the design parameters.  It will try to pull too much current out of the amp and that may be sensed internally.  I would hope the protection circuitry would be kicked in by that but, I'll be honest, I'm not sure if the amp continues to try to work with just the sound suffering.   So if you are using more than one speaker or a design with multiple drivers you have wired up yourself you may have dropped to too low an impedance.