Advice needed.....grandmeister packed up

Hi. Only had the grandmeister approx 7weeks and at a gig on saturday it just packed up. All lights on but no output so used a spare amp. If i plug guitar straight into fx return the amp works so i have a problem with pre amp. The only one that i cant see is v1 which is the shielded one so i suspect that this is the dodgy one. Now i can send the amp back and get it repaired as its obviously under warranty but i would ideally love to get inside the thing and change the tubes anyway. Has anyone else had this problem and was it the v1. I am a little wary of changing all the tubes only to find i have another problem and then having to send the amp off anyway. Does anyone think i may have a problem other than one or more of the preamp tubes. I thank you in advance for your replies

Although not impossible, preamp tube failures are pretty rare. The amp is easy enough to get into and the tubes are simple to replace. There is an access indicator behind each side panel that H&K use for warranty validation (it tears if you open the amp all the way to let them know someone has been in it), but you can swap the tubes without completely removing the end caps and leave the warranty tape in tact. I can`t speak for H&K, but I don`t suspect an end user swapping the tubes is cause for warranty to be void. If that`s the case then both of mine are out of warranty LOL.

Thanks...its not the pre amp valve so its off for a warranty fix. Will let you know what they find

Hi Fazza.  Welcome to the forum, glad to see you here and sorry to hear about your problem.  This sort of failure is rare particularly in the preamp area I will say.  VJ has already dealt with this in terms of necessary tech advice but I just wanted to chip in and add that I feel in my water that it could be a switching/digital problem rather than a valve going out on you.  Could you describe what was going on at the time that it failed?  Were you actually playing or were you maybe selecting a different setting?  Do the controls, (maybe Volume and Gain), still respond as they should and blink when you reach their current setting, (obviously you can't hear any change)?

Can I also just point out that it really should have been posted in the Grandmeister forum.  This area is just for chat and oddities which are either nothing to do with amps at all or are very general and beyond specific models.  Pleas make sure to come back to us with what H&K find and let us know when you are up and running again.  It's good to have new members contributing ideas.

Good luck with the repair.

* Moved to GM36 Forum

Had a similar problem the first time that I gigged my GM. 2nd song in , the output died. Used a backup for the rest of the 1st set, then tried to troubleshoot the amp. Output was restored for the 2nd and 3rd sets, after doing nothing to the amp. The only thing that I can figure for me was a heat issue. Outdoor summer gig, I was using 5W power out, DI out to the board for mains sound. In the 2nd and 3rd sets, had it set to 16W output, so no excess heat from the reduced power.

I sent mine back to Sweetwater the next day and demanded a new one. I didn't want a warranty repair, since I would always question the reliability of the amp, and I had it less than a week. Sweetwater gave in to my demands, and sent me a new one. So far I have had no problems with the 2nd GM.

Good luck with yours,

I hear what you're saying KY but I promise you, there is no issue with the power soak overheating in the GM36. This one crops up regularly as everyone imagines that power soak can be a problem inside the case but it really really isn't. The maximum it dissipates is 18W when running silent, remember one pair of valves is switched out of circuit for half power when the level is below 36W. That means that on 5W the PwrSk deals with a maximum of 13W. But additionally the quoted figures are continuous RMS and we have a music signal which is much more transient and hence contains less energy that the test RMS levels. 13W is nothing in the scheme of the amp's 200W max consumption unless maybe some of the ventilation gets blocked or the case gets covered and insulated.

I'm 100% with you on getting your original changed, there obviously was some sort of issue there, but it wouldn't be the PwrSk.