Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Bo-Lennart on June 09, 2021, 04:13:21 am
-
Hi all...
I'm new at these forum.
I help a friend of mine with his FENDER SUPER REVERB amplifier. I looked at the net for a schematic, but no one is similar to this amp. The closes I come up with is AA1069. But the difference is:
- The grid-resistor in the phase inverter (12AT7) is 330k (not 1M)
- The cathode resistor in the reverb-driver is 470ohm alone, no capacitor.
(in most schematic it's a 2,2k in parallel with 25microF).
- The resistor in the high voltage path (after the choke), is 2,2k and 10k. In most schematic they are, 1k and 4,7K.
Can anyone of You out there, come up with the right schematic number?
The amp seems to be from the mid -60. Sold in SWEDEN. Modified to fit the SWEDISH electric laws, like a DPST power-switch.
With the best regards from SWEDEN
Bo-Lennart
-
Welcome to the forum.
Look amp is a 100 watts Super Six Reverb with Master Volume . ;
Updated at 10:23
-
OK, Thanks. You are absolutely right about the resistors I mentioned. But it's still a SUPER REVERB, with only two 6L6GC and it have a tube-rectifier (5U4GB). And it doesn't have a mid-pot in the NORMAL channel. Only in the VIBRATO-channel. And it don't have the MASTER VOLUME with PUSH-PULL SWITCH. But You are absolutely right about the resistors I mentioned.
Thanks for Your reply.
// Bo-Lennart
SWEDEN
-
IMO "standard" a Super Reverb may work fine with your resistors value.
Is there any issue with the amp ?
I read few times, Fender may do some mod an assembly line, or it ia special product for export ?
-
Thanks Lalole for Your reply.
It wasn't any big issue on this amp, just scratchy pots and my friend want me to make a re-cap. And that what I did. It works fine after cleaning the pots and the re-cap.
You might have right there, about that FENDER made some modification for export. That make sense. But it's funny that they didn't make a documentation in form of a schematic-version.
OK, maybe I let the resistors be. Anyway the amp is working alright.
Thanks again for Your comments. I appreciate them.
// Bo-Lennart
-
Can anyone of You out there, come up with the right schematic number?
This matches your criteria...
https://el34world.com/charts/Schematics/files/Fender/Fender_cbs_45w_mstrvol_pullsw_super_pro_bmstr_rev.pdf
-
The description seems close to the 70W late 70s version
https://el34world.com/charts/Schematics/files/Fender/Fender_cbs_70w_mstrvol_pullsw_super_pro_bmstr_rev.pdf
What’s the text on the back panel by the speaker jacks?
...But it's funny that they didn't make a documentation in form of a schematic-version.
...
We can’t be sure that they didn’t. It seems feasible that not every such document is currently in the public domain, hosted on the internet and helpfully tagged.
-
Can anyone of You out there, come up with the right schematic number?
This matches your criteria...
https://el34world.com/charts/Schematics/files/Fender/Fender_cbs_45w_mstrvol_pullsw_super_pro_bmstr_rev.pdf
100% right
-
The description seems close to the 70W late 70s version
Not really. The reverb drive cathode resistor is different. And the B+ droppers are different.
-
Back in the day, I’ve heard that Hagström (?) imported US amps to Sweden. They then changed the power transformer and made some other minor changes for Swedish electrocal safety regulations.
I’m thinking that if the replacement transformers didn’t have the exact same secondary voltage, they may have changed some of the dropping resistors to compensate?
-
It's also 45 years later. Somebody may have changed parts for better förortsreggae tone.
-
It's also 45 years later. Somebody may have changed parts for better förortsreggae tone.
:w2:
Look original as schematic.
https://el34world.com/charts/Schematics/files/Fender/Fender_cbs_45w_mstrvol_pullsw_super_pro_bmstr_rev.pdf