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Post subject: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 1:43 am
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Hi Guys & Grils,

My first post here. I bought 2 weeks ago a 2009'er TRRI with a small defect. While fixing it I saw a couple of leads going to a not so very vintage PCB full of SMD components. It is wired to the low voltage power supply board and the position where the LDR should be. So probably it has something to do with the vibrato.

Does anybody know the exact function & if I can replce it with a LDR? All other components are present as in the schematic, so it might work.

Attached a few pictures to show what I mean.

Cheers!

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 1:49 am
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That's your tremolo oscillator/modulator circuit. It replaced the traditional opto-isolator assembly a few years back in a valiant-but-vain attempt to cure the infamous "trem tick". New DRRI's are similarly afflicted with this "improvement".

:lol:

Arjay

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 4:17 am
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Does anybody have any experience with replacing the PCB with the original LDR? Do I need to modify anything else?

Also a schematic including the trem PCB would be highly appreciated.


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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 5:06 am
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IMO you can't replace this circuit by the original LDR . Your amp have nothing to to with original Twin Reverb.


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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 10:14 am
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Hi Mantas,

I believe that this was used in the DRRI, but might be the same one in the TRRI. It's worth a look anyway. Look at the last post on the second page for the PDF attachment.

http://www.christianguitar.org/forums/t194751-2/

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 5:17 pm
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As long as the other components in the tremolo circuit are unchanged or can easily be replaced, I see no reason why that PCB couldn't be replaced with an LDR. Just because the Reissue is based on a PCB vs the hand wired eyelet board of the original is no reason that it couldn't be done.

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

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 5:42 pm
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Yeah, just looking at the wires, two in, two out, and the other three are for the supplies to the board. Looks doable to me, although I don't know why you would want to have the ticking back. No one will know that there is a surface mount component board in your amp anyway. :wink:

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Wed Feb 27, 2013 5:49 pm
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shimmilou wrote:
Yeah, just looking at the wires, two in, two out, and the other three are for the supplies to the board. Looks doable to me, although I don't know why you would want to have the ticking back. No one will know that there is a surface mount component board in your amp anyway. :wink:


Its not like the amp is "vintage". :lol:

What's with the creepy free image hosting site? :roll:

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Fri Mar 01, 2013 1:51 pm
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One of the reasons to replace it would be that I don't trust the pcb with the high temperatures in the amp when it is tilted backwards. The front even gets untouchably hot!

Further it is just an experiment to see what it does for the sound, the ldr is just a couple of euro's and it is not much of a trouble...

Thank you for the schematics, I will post a reply if I was able to get the ticking back :D


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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Fri Mar 01, 2013 3:56 pm
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Mantas wrote:
One of the reasons to replace it would be that I don't trust the pcb with the high temperatures in the amp when it is tilted backwards. The front even gets untouchably hot!


Such fears are groundless.

I once played my TRRI continuously for six hours -- outdoors, driven hard, with the ambient air temperature approaching 108 degrees.

The amp never even burped.

Arjay

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Thu Mar 07, 2013 10:19 am
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The sad thing is for probably less than what you paid for the reissue, you could have had a 70's SF. Mine never ticked at all and was rock solid reliable and sounded great.

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Post subject: Re: What is this SMD PCB doining in my TRRI
Posted: Thu Mar 07, 2013 1:28 pm
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63supro wrote:
The sad thing is for probably less than what you paid for the reissue, you could have had a 70's SF. Mine never ticked at all and was rock solid reliable and sounded great.


+1

I've seen the prices for SFTR's drop dramatically on the secondary market -- often as low as $650.

Arjay

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