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Post subject: Issues with 67 Super Reverb
Posted: Thu Jan 09, 2014 10:25 pm
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Hey Guys. Just received a 67 SR I bought from Ebay. It's late at night, so I haven't been able to crank it yet. However, at low volume there already appears to be three issues:
1) Weak reverb
2) background hiss
3) some crackling

The reverb is minimal when dimed. I would have expected at least a tiny cavern, but it is pretty subtle. What could be causing that?

The background hiss may not be an issue. I had an SF Twin back in the 80s, and I seem to recall the same hiss. Is that just a typical vintage Fender characteristic?

The same with the crackling. I tapped lightly on the tubes, but no particular noise resulted. Is some crackling to be expected with an older amp?

I should add that there was quite an assortment of tubes in this thing. Could any of the three problems be related to tubes in need of replacement? Here is what the amp arrived with:

V1- Groove Tube 12AX7C ECC83/7025
V2- Groove Tube 12AX7C ECC83/7025
V3- Groove Tube 12AT7 Sylmar, California (G?)
V4- USA 7025 (That's all that was readable)
V5- RCA Pre (That's all that was readable)
V6- AT7 West Germany ECC(B?) 12AT7
V7- Fender Sovtek 5881 WXT
V8- Fender Sovtek 5881 WXT
V9- Sovtek 5AR4 1112


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Post subject: Re: Issues with 67 Super Reverb
Posted: Thu Jan 09, 2014 10:55 pm
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The weak reverb may be tube-related. V3 and V4 are the operative bottles for this circuit. Swapping them individually with known good substitutes may restore the function. Also, check to ensure that the send and receive cables are securely seated on the rear of the chassis. If either jack(s) or plug(s) appear corroded, clean them thoroughly with De-Oxit contact cleaner.

The poor S/N ratio (the background hiss) may also be a marginal tube but another possibility is a bad cathode bypass cap. A skilled technician's services may be required to isolate and identify it.

The crackling noise (actually closer to the sound of frying bacon) is usually the result of a carbon-comp resistor that has exceeded the duration of its service life. These become brittle and porous with age, often attracting moisture from the ambient air. Often a visual inspection will reveal those ready for replacement but not always.

Your amp is likely overdue for some intermediate-level servicing -- you should find a trustworthy shop that is familiar with blackface chassis architecture and let them restore it to factory specs.

Arjay

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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 2:00 am
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Retroverial +1


Any mod in the amp ? Do you look inside ? Photos please.

Check also;

Background noise ; Need new plate resistors on all 12XX7 tubes.

Cracking noise ; tubes'sockets may need cleaning and retensionning . Check some solder

Weak reverb ; , resistor in reverb circuit , reverb transformer


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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 12:02 pm
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After turning up the amp today, the results were disappointing. Not very good tone at all. I had suspicions based on how lightweight the amp is (55 lbs.). Surely the P10r Alnicos couldn't account for that much weight loss in a Super. Turns out the OT and PT are new. The number on the OT is P-TF22855. The PT is NSC 002798 Rev. B. Are these inferior replacements that could account for poor tone?


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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 12:05 pm
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stratele52 wrote:
Retroverial +1

Background noise ; Need new plate resistors on all 12XX7 tubes.

Cracking noise ; tubes'sockets may need cleaning and retensionning .


Plate resistors have recently been replaced. Tube sockets were cleaned.


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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 12:22 pm
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shelshaf wrote:
Turns out the OT and PT are new. The number on the OT is P-TF22855. The PT is NSC 002798 Rev. B. Are these inferior replacements that could account for poor tone?


I am not familiar with either of those tranny numbers but this chart lists the specific iron used in an AB763 Super Reverb......

http://www.unclespot.com/FenderXFMRchart.html

Arjay

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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 12:47 pm
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TF22855 transformer are made in USA and sell by Antiques Electronics


NSC 002798 ; New Sensor Corp.

newsensor.com/ProductListing.aspx?CatId=57

Can you show some picture inside the amp please, this help us .


Last edited by stratele52 on Fri Jan 10, 2014 12:57 pm, edited 1 time in total.

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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 12:55 pm
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shelshaf wrote:
After turning up the amp today, the results were disappointing. Not very good tone at all. I had suspicions based on how lightweight the amp is (55 lbs.). Surely the P10r Alnicos couldn't account for that much weight loss in a Super. Turns out the OT and PT are new. The number on the OT is P-TF22855. The PT is NSC 002798 Rev. B. Are these inferior replacements that could account for poor tone?


Is there any mod on the amp ?

I fix many Blackface Super Reverb in those years and they had a great tone after the job .

Most critics parts ;
To check ; tubes; are they good ? Bias Ok on output power tubes ?
Filter caps ; good ? B+ voltage = ?
Bypass caps ; replace all.
Phase inverter circuit ; check all resistor .
Speakers ; original or cheap recone or low quality ?


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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 1:36 pm
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stratele52 wrote:

Can you show some picture inside the amp please, this help us .


Yes, will post pics as soon as I can.


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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 2:48 pm
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shelshaf wrote:
stratele52 wrote:

Can you show some picture inside the amp please, this help us .


Yes, will post pics as soon as I can.


+1

Some gut shots of the exposed chassis would help with authenticating this amp.

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: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 5:58 pm
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Yes please show the previous responders some pics, they will be able to tell you quite a bit about your amp.

As a 65 BFSR owner, I can tell you the tone should be FANTASTIC and the reverb should go from a whisper to full on Dick Dale Splashyness! Once this amp is serviced you will have an amp you will never let go of!

T2

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Post subject: Re: Issues with 67 Super Reverb
Posted: Fri Jan 10, 2014 10:44 pm
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T2Stratman wrote:
Once this amp is serviced you will have an amp you will never let go of!


I let go of mine based on the erroneous assumption that "more is better". Traded it in for a Dual Showman that I simply had to have.

Dumb mistake!

(and unfortunately repeated several times until I finally "got it")

:oops:

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: Issues with 67 Super Reverb
Posted: Sat Jan 11, 2014 1:36 am
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T2Stratman wrote:
Once this amp is serviced you will have an amp you will never let go of!

T2



+1 By a qualified tech only


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Post subject: Re: Issues with 67 Super Reverb
Posted: Sat Jan 11, 2014 1:44 am
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stratele52 wrote:
T2Stratman wrote:
Once this amp is serviced you will have an amp you will never let go of!

T2



+1 By a qualified tech only


Absolutely!

Anything less would be like allowing Beavis and Butthead to overhaul a Ferrari Testarossa.

:lol:

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: Issues with 67 Super Reverb
Posted: Sat Jan 11, 2014 2:30 am
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+1 Arjay ,

The problem is that most people do not know how to recognize a competent technician and think it's simple. Like to go in good guitar store , wrong .

In my point of view, they are very rare.
Too many people claim technician while they are simply skilful to repair amps as long as the problem is easy


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