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Post subject: 1965 fender deluxe reverb blackface vibrato
Posted: Sun Jan 29, 2017 1:44 pm
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Hi everyone.
My first post and need some guidance. I rebuilt a 1965 deluxe reverb. Amp sounds great and works very good. However I have a problem in the vibrato circuit. Now this is the first amp ever that the vibrato does not work at all that I have worked on. When I short the jack and can see the bulb flash. And the speed control changes the flashing. I can even hear a faint tick tick in the speaker.

But the problem is there is no effect what do ever in the speaker when playing. Looks like everything is working, just no results in the speaker. I will admit I am not a guru when it comes to vibrato or tremolo circuits. I have checked a lot of components in the circuit, re tubed the amp, and reflowed solder connections.
Any guidance would be greatly appreciated.


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Post subject: Re: 1965 fender deluxe reverb blackface vibrato
Posted: Mon Feb 06, 2017 2:44 am
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If the bulb flashes then the oscillator itself is okay. It's possible that either the photo-optical coupler or one half of the tube (V5) is shot. Try replacing the tube first. If the symptom persists then my guess is the trem roach is toast. It's not a real expensive part but removal and replacement will require soldering skills.

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: 1965 fender deluxe reverb blackface vibrato
Posted: Mon Feb 06, 2017 3:25 am
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Hi and thanks for the reply. Although I posted this on the 29th I did however fix the issue later that day.
My first post has been awaiting moderation since the 29th. ( slow forum or not enough moderators to handle the load)

I did rebuild of the amplifier. Recapped, all new tubes, and replaced a lot of failed resistors.
What I did find is the photo resistor was bad. The bulb was flashing but nothing on the other end was working. The resistor in the PR was open. Replaced the PR and all is good. I verified this by lifting the resistor end and connecting a VOM to the leads. Cover the bottom of the amplifier so no light can get in, view reading, remove cover and shine a bright light into the end of the PR. Still no reading. Yep she was open.

My soldering is not too bad. I have been in electronics for 40 plus years. Have over 100 electronic repair videos on YouTube.

Thanks for taking the time to reply to this post.


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Post subject: Re: 1965 fender deluxe reverb blackface vibrato
Posted: Mon Feb 06, 2017 7:35 am
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Leo Fender used four different tremolo circuits and they differ significantly from one another. You might study their various architectures for ease of troubleshooting and maintenance when the next Fender amp crosses your bench.

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: 1965 fender deluxe reverb blackface vibrato
Posted: Tue Feb 07, 2017 2:25 am
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radio tech wrote:
Hi and thanks for the reply. Although I posted this on the 29th I did however fix the issue later that day.

What I did find is the photo resistor was bad. The bulb was flashing but nothing on the other end was working. The resistor in the PR was open. Replaced the PR and all is good. .


Its common problem. I build myself some fender LDR unit for less than $2 as spair.

Image


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Post subject: Re: 1965 fender deluxe reverb blackface vibrato
Posted: Wed Feb 08, 2017 6:56 am
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stratele52 wrote:
Its common problem. I build myself some fender LDR unit for less than $2 as spair.

Image


You can't beat that price.

Good job!

8)

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: 1965 fender deluxe reverb blackface vibrato
Posted: Wed Feb 08, 2017 7:45 am
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stratele52 wrote:
radio tech wrote:
Hi and thanks for the reply. Although I posted this on the 29th I did however fix the issue later that day.

What I did find is the photo resistor was bad. The bulb was flashing but nothing on the other end was working. The resistor in the PR was open. Replaced the PR and all is good. .


Its common problem. I build myself some fender LDR unit for less than $2 as spair.

Image



Wow, that is pretty cheap. Thanks for listing those parts.


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Post subject: Re: 1965 fender deluxe reverb blackface vibrato
Posted: Wed Feb 08, 2017 8:01 am
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I certify that is work as good as original fender LDR.

Not the first time I show that in the forum.

NE-2 is a very common neon bulb.
http://www.jameco.com/z/NE-2-Wire-Termi ... 27351.html

Photoresistor are not critical, many values work well, mine is ;
light ; 2 k ohms
Dark ; 5 meg ohms.
And a piece of heat shrink


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