volume wackiness in my SF Princeton Reverb

helliger · December 16th, 2004, 02:03 PM

So I just bought this SF Princeton Reverb, put a Weber in it and it sounds great. However, it has developed this weird volume problem. I just went to use it and the volume wasn't working at all. The amp seemed to be putting out full volume but I couldn't lower it at all. After a while it started working again.

I'd wiggle the volume back and forth but it wasn't doing anything. The amp was really loud though and sounded normal. It sounded like it was stuck on ten though.

I'm thinking either there's a bad connection on the volume pot or the volume pot is going out altogether. It's not scratchy or anything although it was until an amp tech put a little contact cleaner with lube in the pot.

I'd rather not have to bring it in again if it's something small that I can fix.

I opened it up and looked at it. I think maybe the volume pot has been replaced because it says Taiwan on it. Did they use volume pots from Taiwan in 1973?

thanks

Marky D. · December 16th, 2004, 06:49 PM

Maybe it's still gunked up. I'd shoot it w/ some more contact cleaner, then work that sucker back & forth. I have similar pot weirdness w/ my DR.

Also, look for cracks in the solder joints on the volume pot. Make sure to discharge the caps before poking around too much in there.

What kind of Weber did you put in?

Good luck..

helliger · December 16th, 2004, 07:59 PM

Quote:

Originally Posted by Marky D.

Maybe it's still gunked up. I'd shoot it w/ some more contact cleaner, then work that sucker back & forth. I have similar pot weirdness w/ my DR.

Also, look for cracks in the solder joints on the volume pot. Make sure to discharge the caps before poking around too much in there.

What kind of Weber did you put in?

Good luck..

I'll try that.

How do you discharge the caps? It looks like it's not the best solder job and the volume pot must have been replaced at some point because it says Taiwan on it.

I ended up putting a Weber 10f150T 25 watt with light dope in it since many people seemed to recommend it. So far it sounds really nice but it's not worked in yet so it's kind of stiff sounding. It's sounds a hundred times better than the 70's oxford speaker that was in there.

I had tested a Celestian Vintage 10 in it and that sounded great too. I yanked it out of a Trace Elliot Velocette I sold to my friend so I put it back in for him. The Celestian had a tighter bottom end but maybe that's because this one is not totally worked in yet?

I'll wait for this one to work in but right now I'd say the Vintage 10 sounded a hair better.

thanks

jjmantele · December 16th, 2004, 09:04 PM

Sound like the pot was changed. All the pots should look pretty similar. I think CTS brand was common then.

Sound like the connection to ground for the pot it not good. The ground would be one of the outer lugs. If you look at the pot from the back of the chassis the left lug is probably the ground. Originally it was probably an un-insulated type wire (no plastic/cloth covering on the wire.)

Is one of the outer lugs soldered directly to the back of the pot itself?

helliger · December 17th, 2004, 02:07 AM

Quote:

Originally Posted by jjmantele

Sound like the pot was changed. All the pots should look pretty similar. I think CTS brand was common then.

Sound like the connection to ground for the pot it not good. The ground would be one of the outer lugs. If you look at the pot from the back of the chassis the left lug is probably the ground. Originally it was probably an un-insulated type wire (no plastic/cloth covering on the wire.)

Is one of the outer lugs soldered directly to the back of the pot itself?

There's one wire and it looks like it's split to attach to both the left lug and the middle lug.

The left lug has a seperate piece of unisulated wire which if I remember correctly is soldered straight from the left lug to the chasis.

That whole area looks a little sloppy.

jjmantele · December 18th, 2004, 11:53 AM

A volume pot should have 3 exclusive connections:

input (s/b from middle lug of treble pot here)

output (to grid of a pre-amp stage)

ground (always an outer lug)

Sometimes there's a "bright cap" connected to the input and output too.

Other pots (tone, vib, etc) sometimes have only 2 wires or have one outer also connected to the middle lug. Those are wired as "variable resistors" as apposed to the "voltage divider" type of wiring on a volume pot.

If either outer lug is connected directly to the middle lug the volume pot is not wired correctly.

December 16th, 2004, 02:03 PM	#1 (permalink)
helliger TDPRI Member Join Date: Oct 2003 Posts: 15	volume wackiness in my SF Princeton Reverb So I just bought this SF Princeton Reverb, put a Weber in it and it sounds great. However, it has developed this weird volume problem. I just went to use it and the volume wasn't working at all. The amp seemed to be putting out full volume but I couldn't lower it at all. After a while it started working again. I'd wiggle the volume back and forth but it wasn't doing anything. The amp was really loud though and sounded normal. It sounded like it was stuck on ten though. I'm thinking either there's a bad connection on the volume pot or the volume pot is going out altogether. It's not scratchy or anything although it was until an amp tech put a little contact cleaner with lube in the pot. I'd rather not have to bring it in again if it's something small that I can fix. I opened it up and looked at it. I think maybe the volume pot has been replaced because it says Taiwan on it. Did they use volume pots from Taiwan in 1973? thanks

December 16th, 2004, 06:49 PM	#2 (permalink)
Marky D. Tele-Meister Join Date: Mar 2003 Location: Minneapolis, MN Age: 48 Posts: 314	Dirty Pot? Maybe it's still gunked up. I'd shoot it w/ some more contact cleaner, then work that sucker back & forth. I have similar pot weirdness w/ my DR. Also, look for cracks in the solder joints on the volume pot. Make sure to discharge the caps before poking around too much in there. What kind of Weber did you put in? Good luck..

December 16th, 2004, 09:04 PM	#4 (permalink)
jjmantele Tele-Holic Join Date: Aug 2003 Location: New Jersey Posts: 851	Bad ground on pot? Sound like the pot was changed. All the pots should look pretty similar. I think CTS brand was common then. Sound like the connection to ground for the pot it not good. The ground would be one of the outer lugs. If you look at the pot from the back of the chassis the left lug is probably the ground. Originally it was probably an un-insulated type wire (no plastic/cloth covering on the wire.) Is one of the outer lugs soldered directly to the back of the pot itself? __________________ JJman If it says "Vintage" on it -it isn't.

December 18th, 2004, 11:53 AM	#6 (permalink)
jjmantele Tele-Holic Join Date: Aug 2003 Location: New Jersey Posts: 851	Volume Pot A volume pot should have 3 exclusive connections: input (s/b from middle lug of treble pot here) output (to grid of a pre-amp stage) ground (always an outer lug) Sometimes there's a "bright cap" connected to the input and output too. Other pots (tone, vib, etc) sometimes have only 2 wires or have one outer also connected to the middle lug. Those are wired as "variable resistors" as apposed to the "voltage divider" type of wiring on a volume pot. If either outer lug is connected directly to the middle lug the volume pot is not wired correctly. __________________ JJman If it says "Vintage" on it -it isn't.