Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mcasey1 on June 18, 2014, 10:14:10 pm
-
Hi everyone, I am putting together a PTP Deluxe Reverb build from the chassis and transformers of a DRRI. I have some questions for the wiring of several sections of the amp, and I'm not able to really develop a clear picture of how to wire the various sections from the several layouts and schematics I am using. I have taken a few pictures of sections I have wired or partially wired and drawn diagrams of how I THINK a few sections ought to be wired based on some layouts and schematics. If anyone would be able to confirm these or tell me where I am wrong I would be very grateful!
Thank you.
AC Wiring:
power cable coming in from the top right.
(http://s13.postimg.org/wtcfkecsn/POWER_STANDBY_WIRING.png) (http://postimage.org/)
Reverb Jacks Partial Wiring:
I don't have the reverb output connection wired yet.
(http://s27.postimg.org/oz0fhkm6b/REVERB_JACK_WIRING.jpg) (http://postimage.org/)
Reverb/Tremolo 1/4" Footswitch Wiring:
(see below)
Speaker Jack Wiring:
I don't have the wire to the NFB section in yet.
(http://s1.postimg.org/uvukowoof/SPEAKER_JACK_WIRING.jpg) (http://postimage.org/)
(EDIT: Removed gratuitous links to file uploader sites -- HBP
-
First thing I noticed, the hot wire for the power cord should go to the fuse first, and then the switch.
If anything happens, the AC hot leg is cut off right at the fuse holder
Black is hot, white is neutral in most AC wiring
That's the way I like to run the standby switch
Cut off the high voltage from the rectifier and then go to the first set of filter caps and then the choke
others may like to have their main caps between the rectifier and the standby switch
Not sure what the reverb drawing third lug is that says S.
RCA jacks do not have switches usually, if that is a switch lug in your drawing?
Your picture looks correct for a fender type reverb send and foot switch arrangement except that the two tips are supposed to be connected in parallel
The speaker jacks look fine even if you did flip the color from green to black on your second jack
Don't forget to clean out all the bits like that wire piece sitting on the back of that preamp socket :icon_biggrin:
-
The third drawing is for a quarter inch reverb and tremolo foot switch pedal. I haven't seen any clear drawings or schematics for how to wire both functions to a single switching jack yet. There is a capacitor already wired to the jack from either the tip or switch to ground, I'm not there to look at the moment but I did figure out one end of the cap on that jack goes to ground and a 220k resistor might have been wired on the board to ground. Not sure if it's necessary in the circuit or if it's more needed in the DRRI that this amp is being built from.
You got me on that little bit of wire there by the tube pins!
I will make some modifications based on your recommendations for the power switch/fuse wiring.
On the output jack, I just didn't have any green left!
Thanks so much for the help! Once I get home I will work on it some more and post a few more pictures. I've been working up a bit here and there in short sessions, realizing I can't rectify one layout off the other, one schematic from the other. Pots, preamp and power tubes, input wiring, filter cap working is all pretty straightforward. I want to get it right before I try to power it up!
-
1/4 inch 12B jacks have a tip a ring and sleeve and you would use a 1/4 inch stereo male plug
The reverb and Trem can go to either the tip or the ring as long as the female jack and male plug are wired the same way
The 220k resistor goes from the reverb lug to the ground lug
On the Fender style footswitch cable, the shielded cable is the reverb cable
The non shielded cable is the trem cable
I have Switchcraft 12b jacks on this page
http://hoffmanamps.com/MyStore/catalog/parts8.htm (http://hoffmanamps.com/MyStore/catalog/parts8.htm)
Footswitch cable is on this page
http://hoffmanamps.com/MyStore/catalog/parts18.htm (http://hoffmanamps.com/MyStore/catalog/parts18.htm)
-
It actually is a stereo jack already in the footswitch section so I just wired it up as described and illustrated. If the footswitch works the opposite once I get the amp going I'll just flip the wires on the jack. Thank you!
For the power switch, would it be hot wire from three prong to fuse with the other side of the fuse going to the black transformer wire / neutral wire from three prong going to one side of the power switch with the white wire from the transformer going to the other side?
Thanks again, I really do appreciate the help. It's getting there!!
-
For the power switch, would it be hot wire from three prong to fuse with the other side of the fuse going to the black transformer wire / neutral wire from three prong going to one side of the power switch with the white wire from the transformer going to the other side?
That's the way the 60's schematics and layouts show. But do it this way:
Power Cord Hot -> Fuse center post -> Fuse side post -> Power Switch -> Power Transformer Black Wire
Power Cord Neutral -> Power Transformer White Wire
For a properly-wired outlet, you will be switching off the wire carrying the highest voltage relative to chassis ground/breaker panel buss-bar. If there is a fault which blows the that voltage will not be present anywhere inside the amp other than at the fuse holder center post, regardless of power switch position.
This is slightly better than stock wiring, and pretty close to what you originally drew.
-
It actually is a stereo jack already in the footswitch section so I just wired it up as described and illustrated.
If the footswitch works the opposite once I get the amp going I'll just flip the wires on the jack. Thank you!
You can test the foot switch with a meter and find out which wire is which
-
I've got most everything wired but I have a few more questions:
Will 20 gauge 600V wire work for filter cap wiring?
The choke in the amp only has two black wires, no red third wire. I'm assuming I would just connect the black wires to their respective locations and that would be it, correct?
Thanks for all the help!
-
that wire is fine
300 volt 20 gauge wire is fine
chokes only have two wires and there is no polarity, so either wire, either way is fine
-
Would it be inadvisable to run two of the wires from the filter cap can through the chassis hole currently occupied by the output transformer wires? I cannot fit all of the filter cap wires into the hole going from the can straight up into the chassis so I am running two of them out of the side of the can and in through the OT wire hole.
-
Sounds ok to me
Running signal wires parallel to other wires is usually the only time you can get into big trouble