Help. Lights on, no-one home

twa · 03-05-2008, 09:50 PM

Hey guys. I have a jcm2000 tsl 60. It's died on me, absolutley no sound coming from the speaker, there is a slight hum from the amp (normal?). The light on the power switch is glowing, the tubes are all glowing, although very faintly, the fuses are both good, the speaker worked through a different amp. I gigged with the amp 4 days ago and all was good. Any suggestions/thoughts would be greatly appreciated.
Would a faulty tube stop all sound?
Also if you remove a power tube do you need re-bias if you put the same tube back in?
Cheers TIM

timstoel · 03-07-2008, 08:45 PM

It could be dirty tube sockets, or a loose wire/solder joint somewhere. Do you get more noise with the volume controls on the amp turned up? That could narrow it down to one section of the amp.

Tim

twa · 03-08-2008, 04:15 PM

Hi Tim
I get no sound at all out of the speakers, just the real faint hum from the amp. I've think I've eliminated all the obvious things fuses, cables etc. Just seems kinda weird that it goes good one day and nothing the next. (or maybe not that weird

)

timstoel · 03-10-2008, 06:54 PM

It could be a bad output jack, loose solder joint on the output transformer, or a bad speaker cable. If for instance, the input jack or one of the preamp tubes were bad, you would hear hiss when you turn the volume controls up. The problem is probably somewhere between the output tubes and your speaker. Try another speaker cable, or if you have it, another speaker.

Tim

twa · 03-11-2008, 02:11 AM

I tried another cable, still nothing. The speaker worked fine through different amp

Adwex · 03-11-2008, 10:15 AM

Yes, a faulty tube could stop all sound.
No, removing and replacing a power tube does not require biasing.

I would get one preamp tube and use it to replace the first preamp tube in the amp. If that doesn't work, put the old one back, replace the 2nd one, etc....they're cheap and don't need to be biased.

twa · 03-11-2008, 11:22 PM

Thanks alot for the replys and advise. I'll post outcomes

twa · 03-26-2008, 06:49 PM

Just got the amp back from tech. It was a failed output resistor, $90 job for a $1 part. Oh I wish I had the Know how. Thanks all for your replys

03-05-2008, 09:50 PM	#1 (permalink)
twa Junior Member Join Date: Feb 2008 Location: New Zealand Posts: 5	Help. Lights on, no-one home Hey guys. I have a jcm2000 tsl 60. It's died on me, absolutley no sound coming from the speaker, there is a slight hum from the amp (normal?). The light on the power switch is glowing, the tubes are all glowing, although very faintly, the fuses are both good, the speaker worked through a different amp. I gigged with the amp 4 days ago and all was good. Any suggestions/thoughts would be greatly appreciated. Would a faulty tube stop all sound? Also if you remove a power tube do you need re-bias if you put the same tube back in? Cheers TIM

03-07-2008, 08:45 PM	#2 (permalink)
timstoel Member Join Date: Jan 2008 Posts: 62	Re: Help. Lights on, no-one home It could be dirty tube sockets, or a loose wire/solder joint somewhere. Do you get more noise with the volume controls on the amp turned up? That could narrow it down to one section of the amp. Tim __________________ http://www.newoldsounds.com - rare NOS capacitors, tubes, speakers and more

03-08-2008, 04:15 PM	#3 (permalink)
twa Junior Member Join Date: Feb 2008 Location: New Zealand Posts: 5	Re: Help. Lights on, no-one home Hi Tim I get no sound at all out of the speakers, just the real faint hum from the amp. I've think I've eliminated all the obvious things fuses, cables etc. Just seems kinda weird that it goes good one day and nothing the next. (or maybe not that weird)

03-10-2008, 06:54 PM	#4 (permalink)
timstoel Member Join Date: Jan 2008 Posts: 62	Re: Help. Lights on, no-one home It could be a bad output jack, loose solder joint on the output transformer, or a bad speaker cable. If for instance, the input jack or one of the preamp tubes were bad, you would hear hiss when you turn the volume controls up. The problem is probably somewhere between the output tubes and your speaker. Try another speaker cable, or if you have it, another speaker. Tim __________________ http://www.newoldsounds.com - rare NOS capacitors, tubes, speakers and more

03-11-2008, 02:11 AM	#5 (permalink)
twa Junior Member Join Date: Feb 2008 Location: New Zealand Posts: 5	Re: Help. Lights on, no-one home I tried another cable, still nothing. The speaker worked fine through different amp

03-11-2008, 10:15 AM	#6 (permalink)
Adwex Senior Member Join Date: Sep 2006 Location: Long Island, NY Posts: 717	Re: Help. Lights on, no-one home Yes, a faulty tube could stop all sound. No, removing and replacing a power tube does not require biasing. I would get one preamp tube and use it to replace the first preamp tube in the amp. If that doesn't work, put the old one back, replace the 2nd one, etc....they're cheap and don't need to be biased. __________________ www.myspace.com/rockerlivemusic

03-11-2008, 11:22 PM	#7 (permalink)
twa Junior Member Join Date: Feb 2008 Location: New Zealand Posts: 5	Re: Help. Lights on, no-one home Thanks alot for the replys and advise. I'll post outcomes

03-26-2008, 06:49 PM	#8 (permalink)
twa Junior Member Join Date: Feb 2008 Location: New Zealand Posts: 5	Re: Help. Lights on, no-one home Just got the amp back from tech. It was a failed output resistor, $90 job for a $1 part. Oh I wish I had the Know how. Thanks all for your replys

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