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    Standby and TSC Problem

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    Scott_A

    Posts : 2
    Join date : 2016-03-07
    Location : Fontana, California United States

    Standby and TSC Problem

    Post by Scott_A on Mon Mar 07, 2016 8:58 pm

    I've had my GM36 for a little over a year, and while playing last night in 5W mode the amp made a loud boom followed by significant volume increase. I immediately switched over to standby to try to figure out what happened, but standby only cut the volume; there was still output. I tried turning my amp off and back on, and then I checked the TSC LEDs. While in standby on 36W only 3 of the LEDs are lit. The third one remains on even when in standby. After further testing, I concluded that valve 3 also is running in 18W, 5W, and 1W modes, whereas TSC should be shutting down both inner tubes in those modes.

    So to summarize: Valve 3 is always outputting, even in Standby Mode.

    Has anyone had or heard of a problem like this? Does anyone have any ideas on what is causing this problem or how to fix it?

    Thanks
    Scott
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    bordonbert

    Posts : 749
    Join date : 2015-01-28
    Age : 97
    Location : Southern England

    Re: Standby and TSC Problem

    Post by bordonbert on Tue Mar 08, 2016 1:01 am

    As long as you are confident that you aren't causing any further damage by testing the amp, try swapping the outer valve pair with the inner pair and see whether the problem moves with the valve or stays where it is with the TSC. Make sure to keep the valves so you know which ones started where. Although we would hope that the fault is with the valve as it's an easy fix, the fact that the TSC shows the LED for valve 3 to be always on doesn't necessarily mean the valve is really outputting, remember that LED is just an indicator and it's sensing and driving circuitry could be faulty instead.

    Also just check in the dark as to whether there are any odd glows inside any of the valves. They may show a faint blue/violet glow inside which possibly won't be obvious in full light and which isn't necessarily a problem, worse could be the whole structure inside glowing a dull cherry red hot, that is a bad fault in the valve. I have seen the red glow on a couple of occasions when I first got my own GM36. Early on one valve overheated like that obviously enough to see it in the daylight. Switching off and on again cleared the fault and I haven't seen it since. The valve continued to work for a good while after that though I have replaced them all since.

    This could be just a valve problem which would be rectified with a valve swap, or it could be something deeper. Can you put your hands on another set of valves you could try just as a test? The fact that the HT fuse has not popped gives me hope but I'm honestly leaning towards saying this is beyond a home repair as it sounds like it could require replacement boards or, worst case, maybe even a new output transformer. Let's hope it's just the valves. Let us know what you find after the swap.
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    Scott_A

    Posts : 2
    Join date : 2016-03-07
    Location : Fontana, California United States

    Re: Standby and TSC Problem

    Post by Scott_A on Tue Mar 08, 2016 3:50 am

    I have tried swapping the inner valves with the outer valves, and the problem doesn't follow the valve. Position 3 continues to output even in Standby. I know this because I can put the amp in Standby and play my guitar and I get a slightly weaker class A type sound being produced. I have a feeling that something on the board went bad and now TSC cannot shut down Valve 3.

    I've had the amp for just over a year and I bought it from Guitar Center in the U.S. Do you think I can still make a warranty claim? How would I go about doing this?

    Thanks for your reply,

    Scott
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    bordonbert

    Posts : 749
    Join date : 2015-01-28
    Age : 97
    Location : Southern England

    Re: Standby and TSC Problem

    Post by bordonbert on Tue Mar 08, 2016 9:43 am

    Good to have the info on that position swap Scott.  Sorry it didn't turn out to be the valve.  I'm afraid I don't know the procedure for making a warranty claim, I'm sure someone else who does know will come in here to help out.  H&K have a 3 year warranty period provided you have registered it in the first month of ownership, and you don't live in North America or Russia. (Huuuhh?)  They don't say what applies in the US or THEM.  If as you say it's just outside 1 year you should still be eligible, as long as you registered and have the warranty card they sent you!  Have a look here:  H&K Warranty

    In the meantime I would contact the Guitar Centre immediately, and I mean immediately, and register with them as having a problem, it might help a little later on to be able to say that you let them know at an earlier date.  I would also get in touch with H&K support direct and let them know the nature of the problem and your circumstances and simply ask their advice, including whether they would support your warranty claim.  You've got nothing to lose now by getting onto it, don't delay, that just makes your case weaker.

    Keep us up to date.

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