It is currently Mon Mar 16, 2020 9:04 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 9 posts ] 
Author Message
Post subject: 72 Pro Rev Intensity control affecting volume both channels
Posted: Wed Oct 11, 2017 7:47 am
Offline
Roadie
Roadie

Joined: Thu Feb 21, 2008 12:52 pm
Posts: 292
working on a 72 PR that had the dual channel reveb mod and not sure what else done to it. Going to black face the circuit and convert bias balance to bias adjust.
During the preliminary look over I noticed the Intensity control when on 0 is fine. On 10 is totally attenuates the volume for both channels. Like a reverse master volume. This was before and after I black faced the circuit. Wiring seems ok for this circuit. Dont think it has the mod to defeat the tremolo circuit. Haven't had the chance to replace an caps or resistors in that part of the circuit yet. Any leads would be appreciated. Thank you in advance


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Wed Oct 11, 2017 10:12 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Does the intensity pot have any control over the vibrato? It sounds like the pot wiring is incorrect (wrong line to the wiper).

http://ampwares.com/schematics/pro_reverb_aa1069.pdf


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Wed Oct 11, 2017 12:14 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14045
Location: Province de Québec, Canada
Look Intensity pot wiper go to ground ; Is photoresistor is short ?


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Wed Oct 11, 2017 12:31 pm
Offline
Roadie
Roadie

Joined: Thu Feb 21, 2008 12:52 pm
Posts: 292
BMW and strattele
thanks. Will be looking into that tonight. The pot wiring form the "looks" of it seems to be stock and unmolested.
Will check it all out though....

thanks guys


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Wed Oct 11, 2017 12:44 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14045
Location: Province de Québec, Canada
mxvin wrote:
BMW and strattele
thanks. Will be looking into that tonight. The pot wiring form the "looks" of it seems to be stock and unmolested.
Will check it all out though....

thanks guys


1- Read ohms from wiper to ground
2- Check photo resistor to see if reading is low
3- Not sure; disconnect pot, all 3 wires, or one wire at time

Is tremolo working ?


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Wed Oct 11, 2017 3:12 pm
Offline
Roadie
Roadie

Joined: Thu Feb 21, 2008 12:52 pm
Posts: 292
stratele52 wrote:
mxvin wrote:
BMW and strattele
thanks. Will be looking into that tonight. The pot wiring form the "looks" of it seems to be stock and unmolested.
Will check it all out though....

thanks guys


1- Read ohms from wiper to ground
2- Check photo resistor to see if reading is low
3- Not sure; disconnect pot, all 3 wires, or one wire at time

Is tremolo working ?


Jamming tonight with the boys. Will be back to the amp tomorrow and check those things out..
thank you


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Fri Oct 13, 2017 4:16 am
Offline
Roadie
Roadie

Joined: Thu Feb 21, 2008 12:52 pm
Posts: 292
Thanks for the input guys...
The issue with caused by a dirty intensity pot. Cleaned the pot and all is good. The roach is shot too. Will replace that tonight.
So the amp is all "black faced". Bias circuit converted to bias adjust. Voltages are great and it sounds like it should.
A few more tweaks and all should be good.
Appreciate the help.

BTW......when did Fender go to the 1/4 jack for the vib foot switch? Always thought the older amps had the two RCA jacks for vib/reverb switch


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Fri Oct 13, 2017 4:28 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14045
Location: Province de Québec, Canada
+1 for the fix,

1/4 jack ? 1990 ???


Top
Profile
Post subject: Re: 72 Pro Rev Intensity control affecting volume both chann
Posted: Fri Oct 13, 2017 6:53 am
Offline
Roadie
Roadie

Joined: Thu Feb 21, 2008 12:52 pm
Posts: 292
stratele52 wrote:
+1 for the fix,

1/4 jack ? 1990 ???


Thats what I thought.
Quite odd to have that and the RCA for the rev switch. Have to trace out the leads. Maybe be another reason for that jack in the vib foot switch position.

Old Fender amps....."you neva know what you're gonna get"......:)


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: