Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: neskor on December 28, 2020, 08:49:47 am

Title: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: neskor on December 28, 2020, 08:49:47 am

Hi.
I just got old Fender Pro Reverb Silverface from 1976. in unmolested state.
It is 45W version with Master Volume/Boost switch and 5U4GB tube rectifier. No middle tone pot on both channels.
Trying to find schematic or version but without success :(

Title: Re: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: pdf64 on December 28, 2020, 09:12:26 am

https://el34world.com/charts/Schematics/files/Fender/Fender_cbs_45w_mstrvol_pullsw_super_pro_bmstr_rev_2_.pdf

Title: Re: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: vampwizzard on December 28, 2020, 09:38:25 am

alsp here: https://schems.com/bmampscom/fender/cbs_45w_mstrvol_pullsw_super-pro-bmstr_rev.pdf (https://schems.com/bmampscom/fender/cbs_45w_mstrvol_pullsw_super-pro-bmstr_rev.pdf)

Title: Re: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: neskor on December 28, 2020, 09:43:33 am

Awesome :)
Checked amp today and everything is working except vibrato is weak.
Tried to change the tube but no change.
I will try to replace roach.

Title: Re: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: pdf64 on December 28, 2020, 09:45:49 am

Perhaps the cathode bypass cap at V5 pin3 has gone bad? I'd try tacking a known good cap across it to see if that helped, before messing with the roach. Swapping to a suitable LED for the bias or that whole optocoupler might be an upgrade.

Title: Re: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: neskor on December 28, 2020, 10:28:40 am

Thanks,
I will try that first

Title: Re: Fender Pro Reverb Silverface 45W with Master Volume schematic?
Post by: Latole on December 29, 2020, 03:30:54 am

News vibrato caps may fix the issue if not tube. Replace them all
2 X .01
1 X. .022

Or it is the LDR is weak