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Post subject: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 9:57 am
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Hi! Hope one of you Twinolux owners can check something for me. My Twinolux stopped outputting sound yesterday. The red light lights up and fuse checks out fine. The four preamp tubes are all glowing, the two power tubes are glowing but both rectifier tubes are not lit. Can someone please turn on the power and standby on their Twinolux and tell me if both rectifiers are lit, they are the two tubes at the left as you are looking at the back of the amp. Thanks so much! Really appreciate this.

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 10:12 am
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Yes, the heaters in the rectifier tubes should be lit.

There are three fuses in the amp. You probably only checked the main fuse on the amp control panel. The other two are inside the amp chassis. F1 is the main power fuse. F3 is the heater fuse and since the pilot light is lit, that fuse is good. However, F2 is the high voltage fuse and it may be bad. You should not just replace the fuse without determining the reason that it failed if indeed it did. I suggest you contact Fender Customer Service for the nearest factory authorized service center and take the amp there for inspection and possible repair.

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 11:15 am
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Thanks for getting back so quick!

Your right, I checked the main fuse. Just checking the other two and one has a metal braided filament the other has a white cloth look to it. I used my digital meter on those two fuses and I don't show voltage on either end of both of those fuses wether I probe both ends of the fuses or ground one probe tip and test both sides of each fuse. Any thoughts here or are you still thinking off to the tech? Thanks.

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 11:27 am
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You're not going to read a voltage measuring across the fuse.

The fuse in the 6.3 volt heater line is good because the pilot light is lit (so you said). The other fuse is high voltage and you should read 400+ VDC from the rectifier output to ground.

This is the schematic for the 57 Twin Reissue which should be close to your amp in the power supply. If you do not understand how to read it, take the amp to a tech.

http://support.fender.com/schematics/gu ... ematic.pdf

Tubes can just fail on their own, but it is better to determine if there was an outside cause for the failure.

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 1:26 pm
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Sounds like the transformer is bad. If the 12A fuse were blown (open) then you would read voltage across it. Since you had no voltage on either end of the fuse, that means that there is no voltage from the transformer. This is assuming that your meter works and you know how to use it.

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 3:44 pm
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Removed and tested the 12 amp fuse for continuity as it's ceramic and not clear. Fuse was bad. Put a new one in, played a bunch and looking fine right now. Thanks all! You rock.

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 5:03 pm
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stratrocs wrote:
Removed and tested the 12 amp fuse for continuity as it's ceramic and not clear. Fuse was bad. Put a new one in, played a bunch and looking fine right now. Thanks all! You rock.


Yes, the amp works .... for now. The question that you should be asking is "What caused a 12 amp fuse to blow?" :wink:

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Mon May 27, 2013 5:31 pm
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bluesky636 wrote:
The question that you should be asking is "What caused a 12 amp fuse to blow?" :wink:


Ahh......there's the rub.

Arjay

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Thu May 30, 2013 11:35 am
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bluesky636 wrote:

Yes, the amp works .... for now. The question that you should be asking is "What caused a 12 amp fuse to blow?" :wink:


The suspect and fragile parts are the output tubes wich take their voltage from the 12 amp fuse. Or too hot bias ? Tubes could come defective at high volume

But defective 12 amp fuse might possible too . Today with all China made parts .......

stratoc did you drive the amp a hight volume ?


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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Thu May 30, 2013 11:37 am
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stratele52 wrote:
Today with all China made parts .......


+1000!

:x

Arjay

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Thu Dec 12, 2013 9:01 am
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After 6 months of perfect performance, my Twinolux developed an odor akin to electrical burning and then blew one of the output tubes. I replaced both output tubes and took the amp to my tech, who noticed that the insulation on one of the wires was touching hot metal and suggested this was the cause of the odor. He made the fix, turned the amp on for nearly an hour and all was well...until I brought it home. Since then, the same odor has come back, but intermittently. Sometimes it is strong and sometimes mild. It usually takes 30 - 60 minutes of playing time for the odor to appear. Also, the control panel gets quite hot above the output and rectifier tubes. It's been several weeks now and I'm afraid the replacement tubes will also blow. What's happening? It's going back to the tech next week.


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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Thu Dec 12, 2013 11:21 am
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k8nkris wrote:
I replaced both output tubes and took the amp to my tech, who noticed that the insulation on one of the wires was touching hot metal and suggested this was the cause of the odor. He made the fix, .It usually takes 30 - 60 minutes of playing time for the odor to appear. Also, the control p.......

........anel gets quite hot above the output and rectifier tubes. It's been several weeks now and I'm afraid the replacement tubes will also blow. What's happening? It's going back to the tech next week.



Did your tech check and readjust output tubes bias ?

What fix he do ? ......" wire touching hot metal " ......there is not hot metal in tubes amps. The only things is hot is rectifier and output tubes.

Look you did not see a qualified tech


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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Thu Dec 12, 2013 2:39 pm
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stratele52 wrote:
......there is not hot metal in tubes amps. The only things is hot is rectifier and output tubes.


Actually, the "iron" (both PT and OT) are known to become somewhat toasty with the amp switched on and vigorously played.

Arjay

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Post subject: Re: Twinolux problem, Twinolux owners can you help?
Posted: Thu Dec 12, 2013 3:01 pm
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Retroverbial wrote:
stratele52 wrote:
......there is not hot metal in tubes amps. The only things is hot is rectifier and output tubes.


Actually, the "iron" (both PT and OT) are known to become somewhat toasty with the amp switched on and vigorously played.

Arjay



Not warm enough to burn wire insulation and smell .......in good operathing condition.

If bias too hot or anything wrong it is another story.


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