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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Mon Jun 19, 2017 10:40 pm
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Retroverbial wrote:
Far too high. You should be seeing a B+ of 412 to 420 VDC.

Pull the cover from the doghouse and check the power-rail resistors.

Arjay


10.93 and 2.23


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Mon Jun 19, 2017 11:27 pm
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Ryan41018 wrote:
Retroverbial wrote:
Pull the cover from the doghouse and check the power-rail resistors.

Arjay


10.93 and 2.23


10.93 and 2.23 ohms? Should be K-ohms, right? You using a GZ34 or 5U4GB rectifier?

http://ampwares.com/schematics/deluxe_reverb_boost.pdf


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 12:37 am
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BMW2002Ti wrote:
10.93 and 2.23 ohms? Should be K-ohms, right?


If those observations are in KΩ, then that's well within tolerance of the schematic's specs of 10K and 2.2K.

The problem lies elsewhere.

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: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 1:19 am
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Ryan41018 wrote:
Retroverbial wrote:
Do the symptoms manifest on both channels?

Arjay


Yes both channels

R


The circuits common to both channels start from the Phase Inverter tube V6
and its circuits, the 6V6's and the output transformer and speaker.

Read resistors connected to V6 , disconnect one side before. 12AT7 pins 2-3-7-8
Read all voltage from V6 to Output transformer
, report.

Did you see this amp working fine before ? Or it is flabby and nasty since you have it ?

Can you post video on You Tube we can hear ?


Last edited by stratele52 on Tue Jun 20, 2017 1:29 am, edited 1 time in total.

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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 1:26 am
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Retroverbial wrote:
Far too high. You should be seeing a B+ of 412 to 420 VDC.

Pull the cover from the doghouse and check the power-rail resistors.

Arjay


Yes but will not do a amp sound nasty and flabby, just shorter tubes's life.
Most of the time it is the Power Transformer give too much power, not resistor.

What is the voltage at Stanby Switch on play position ?

Ryan, what is your rectifier tube ?
And Output Tubes 6V6 or 6V6 GT ?


Last edited by stratele52 on Tue Jun 20, 2017 1:32 am, edited 1 time in total.

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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 1:31 am
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Ryan41018 wrote:


Arjay


10.93 and 2.23[/quote]

These are good


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 7:27 am
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stratele52 wrote:
Ryan41018 wrote:
Retroverbial wrote:
Do the symptoms manifest on both channels?

Arjay


Yes both channels

R


The circuits common to both channels start from the Phase Inverter tube V6
and its circuits, the 6V6's and the output transformer and speaker.

Read resistors connected to V6 , disconnect one side before. 12AT7 pins 2-3-7-8
Read all voltage from V6 to Output transformer
, report.

Did you see this amp working fine before ? Or it is flabby and nasty since you have it ?

Can you post video on You Tube we can hear ?


It was not sounding fine the moment I got it. I can post you tube video later today.

I will post readings off of V6 too.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 7:30 am
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stratele52 wrote:
Retroverbial wrote:
Far too high. You should be seeing a B+ of 412 to 420 VDC.

Pull the cover from the doghouse and check the power-rail resistors.

Arjay


Yes but will not do a amp sound nasty and flabby, just shorter tubes's life.
Most of the time it is the Power Transformer give too much power, not resistor.

What is the voltage at Stanby Switch on play position ?

Ryan, what is your rectifier tube ?
And Output Tubes 6V6 or 6V6 GT ?


Answer: 5u4gb
Answer: JJ 6V6 tubes


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 7:46 am
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5U4 give lower voltage than GZ34 ; good choice.

Good to know amp story ; you never heard amp sound good.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 10:45 am
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Pin readings of V6 Phase Invert

(Pin 2) -0.498
(Pin 3) 0.00
(Pin 7) -0.502

Pin 8 is 0.00

Are pins 3 & 8 Suppose to be ZERO?

Reading pin numbers clockwise looking down into chassis


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 12:23 pm
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Pin 3 and 8 are tied together and you must read +90 VDC ; Something wrong there with your V6 with 0 V
Check all resistors ; 2 X 330K , 22k and 680 ohms
Put new good tube

What about pins 1 and 6 ?

You don't have schematic ?
Voltages are write


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 5:37 pm
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OK, don't panic. That's not too unusual with modern line voltages. Yes, it's high,but it's running normal.
These years have a larger output transformer, hence a lot of flabby subsonic bass.
First, turn the bass almost all the way down. If that helps, you can reduce the bass by change the cathode caps from 25uf to 2.2uf to compensate.
Another approach would be a reissue output transformer.


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 5:56 pm
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Sorry, Tim -- I gotta call horseshit on that.

I have one of these amps. Dead stock and it sounds just great. Very similar in fact to my '68. His amp has a problem. And nebulous mods will not fix it.

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: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Tue Jun 20, 2017 9:45 pm
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stratele52 wrote:
Pin 3 and 8 are tied together and you must read +90 VDC ; Something wrong there with your V6 with 0 V
Check all resistors ; 2 X 330K , 22k and 680 ohms
Put new good tube

What about pins 1 and 6 ?

You don't have schematic ?
Voltages are write


Pulled one leg on all the resistors (330k, 22k, 680ohm) and they all test to exact spec......

However still sounds crappy - you tube video below

https://youtu.be/LU3U4F6wnpg


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Post subject: Re: 1977 Deluxe Reverb - Nasty and Flabby - HELP
Posted: Wed Jun 21, 2017 1:27 am
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Ryan41018 wrote:


What about pins 1 and 6 ?


[/quote]

What about pins 1 and 6 ? ; please finish test on V6 circuit

Power transformer could be the issue.


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