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Post subject: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 8:55 am
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These models don't need the pedal plugged in for the tremolo to work do they? The reverb works without it so I'm guessing no. The tremolo doesn't work and there is no sign of it whatsoever, ticking, etc. V5 is fine/swapped. When I did a recap I did replace the 5/50v cap in this circuit with a 8/150v. Should I check for osc. on the 10m resistor leg of the LDR? Is that the proper way to test the LDR to see if it's good?

I always re-check my solder joints and needed to replace the speed, 3M-RA and re-checked those connections as well.

Just an old beginner - Thanks.


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 9:36 am
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The Twin Reverb requires a footswitch or a shorting plug to engage the tremolo circuit.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 9:46 am
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Thanks Arjay. So both the reverb and tremolo foot switch jacks must be connected in order to complete the ground, being the tremolo end is not grounded by itself.


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 9:53 am
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The tremolo circuit's signal path must be closed for the effect to operate.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 1:31 pm
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All Fender amps need a footswitch to activate tremolo .

Where do you see a 5 mfd cap in tremolo circuit ? Is it a 25 mfd with a digit erase ?


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 1:59 pm
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The 5/50v is on pin 8, V5B on the schematic. This is a 135w Twin. It works fine now after I fixed a bad phono plug on the pedal. After it was back together I noticed a volume loss would start with added distortion after playing it for a while. I swapped out the AT7's and it cleared that up. I think I'll re-tube this amp, the originals from '79 are in there.


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 2:17 pm
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upnorth wrote:
I think I'll re-tube this amp, the originals from '79 are in there.


Definitely time for new bottles.

I recommend Tung-Sol's re-issue 6L6GC-STR's.

*Strongly*.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Tremolo issue '79 UL twin
Posted: Thu Jan 30, 2014 4:01 pm
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upnorth wrote:
The 5/50v is on pin 8, V5B on the schematic. This is a 135w Twin. .




Thank's I see it now .


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