Fender Dual Showman....made in 1966

[SoulFetish]

Just so happens i just haf a drip edge silverface princeton on my bench on Friday which looks to be in factory condition. It was build in the exact way we are discussing in this thread so I snapped some pics to clear up some confusion. (Im doing this on my phone so lets see how it turns out)
The first couple of pics show the original wiring and then rewiring the line chord with proper earth connection (via soldering in this case, but i prefer crimped terminals). The neutral and live wires have been rewired so the live is in series with the fuse and switch.











FYI- i used a washer magnet to hold the wire flush and still for soldering and secured the wire with its own designated strain relief to protect it.

[bsco]

OK. Back at this again....powered it up and the voltages check ok....will install the output tubes later next week and give it a good check out...however, I do have a problem.......I think.........I seemed to have misplaced the back panel....I have searched down in the basement and even upstairs here in the house but can't find it so far......anybody here on this site have a Fender back panel which would fit the dual showman cabinet?? Doesn't matter if it is from another Fender head as long as it will physically fit......I would be very willing to buy it no problem.....I am hoping that over the weekend I will find it but it does have me worried just in case I do not.....
Cheers

[The Dude]

Was it there to start with? I often get amps in without those back panels.

[bsco]

Was it there to start with? I often get amps in without those back panels.

I just talked to the owner.......He has the back panel.....Boy and I ever happy about that.......when he had originally dropped it off I didn't make note that the back cover was not there......what a relief......I can sleep stress free tonight...from now on I am going to make a note of anything that is missing when something is dropped off to me.....and...while I had him on the phone, I asked him about the pots.....as some of them had been replaced......

There is a mixture of white splined plastic shafts, regular metal shafts and a couple of brass shafts...I don't think that it came from the factory like that and the owner said he had bought that brand new and it was never repaired....he did however inform me that he had it on consignment at a local music store for sale but after a year, he decided to take it back.....so I figure the pots were replaced there....

The head was bought back without the tubes installed...the tech said he didn't want to transport the head with the tubes installed because he was afraid they might fall out......the owner picked up the tubes a few days later(which was strange) and when he got home he opened the package up to find what he thinks was a different set of tubes....but he couldn't say for sure.....so I better stick them on a tube tester to at least check to see if they have good emission and no shorts or leakage before I install them.....and use a variac......only goes to show that there are a few shady people out there that make it bad for us honest folks...I'll fire the amp up later this week and let you know how it works out.......
Cheers

[g1]

If they are solid smooth metal & brass shaft pots (not split knurled) I think they may be factory. I don't think they could get all the values needed with just one type of shaft so I think you end up with a mix, at least in some era/models.

[bsco]

If they are solid smooth metal & brass shaft pots (not split knurled) I think they may be factory. I don't think they could get all the values needed with just one type of shaft so I think you end up with a mix, at least in some era/models.

when I install the output tubes after the weekend, I was going to have a look at the numbers on the pots to see if I could make some sense out of the numbers printed on them....the plastic shafts are solid spline type.....thanks for that tid-bit of info....

[52 Bill]

....I was going to have a look at the numbers on the pots to see if I could make some sense out of the numbers printed on them....the plastic shafts are solid spline type.....

1966 was probably a transition year after the sale to CBS. I've seen mixed metal and plastic pots shafts in a lot of those amps from that time period, but I never bothered to check the pot codes to see what the difference was. You may find that the metal shafts are older and the plastic ones might have the new CBS part numbers stamped on them.

Later amps had all plastic shafts and push on knobs. The older metal shafts could get banged without breaking. You might have to replace a cracked knob, but not a broken pot. The plastic ones were always breaking off, and replacing a pot on some of those amps took a complete disassembly of the front panel to get to it.

[bsco]

Just back at this amp again.....tested the output tubes for shorts/leakage....checked ok......so I installed them.....powered it up and checked the bias to the output tubes....measures -49V.......checked the idle current.....the two inside tubes measure in the mid 30's mA and the outer two measure low 50's mA.....so I switched them around and the measurements followed the tubes......so there is one high and low on one side and the same on the other......Took some pics of those pots...hope they are clear enough.....I think I have one there that is wrong.......

[Leo_Gnardo]

Just back at this amp again.....tested the output tubes for shorts/leakage....checked ok......so I installed them.....powered it up and checked the bias to the output tubes....measures -49V.......checked the idle current.....the two inside tubes measure in the mid 30's mA and the outer two measure low 50's mA.....so I switched them around and the measurements followed the tubes......so there is one high and low on one side and the same on the other

As Enzo has noted many times, Fender factory just plugged in sets of tubes without caring a fig about matching. So you have the choice of leaving the amp as is, or if you & your customer are striving for perfection and he's willing to spend then get a matched set.

[Helmholtz]

Just back at this amp again.....tested the output tubes for shorts/leakage....checked ok......so I installed them.....powered it up and checked the bias to the output tubes....measures -49V.......checked the idle current.....the two inside tubes measure in the mid 30's mA and the outer two measure low 50's mA.....so I switched them around and the measurements followed the tubes......so there is one high and low on one side and the same on the other......Took some pics of those pots...hope they are clear enough.....I think I have one there that is wrong.......
[ATTACH=CONFIG]52818[/ATTACH][ATTACH=CONFIG]52820[/ATTACH]

What is pic No.3?

[bsco]

Pic #3 was something that was not supposed to be uploaded....I tried to delete it but couldn't get rid of it......
Cheers

[bsco]

As Enzo has noted many times, Fender factory just plugged in sets of tubes without caring a fig about matching. So you have the choice of leaving the amp as is, or if you & your customer are striving for perfection and he's willing to spend then get a matched set.

The amp sounds good actually and I guess overall both sides are matched pretty close to each other......I'll check with the owner and see what he wants to do......
Cheers

[bsco]

Just checked with the owner and he is leaning towards a new matched set....he did ask me something...is 6L6GC a better fit than the 6L6WGB which are in there now?? I thought they were compatable but I could be wrong......so I figured I would ask here.....
Cheers

[bsco]

Looks like the owner is leaning towards a matched set of new tubes....he did ask me something that I am not sure about...he asked me which was better....the WGB's or the GC's.....and to be quite honest, I am not sure....suggestions??
Cheers

[Leo_Gnardo]

Looks like the owner is leaning towards a matched set of new tubes....he did ask me something that I am not sure about...he asked me which was better....the WGB's or the GC's.....and to be quite honest, I am not sure....suggestions??
Cheers

I favor the GC generally. By WGB, is he referring to Philips/ECG 6L6WGB? Those - to me anyway - compare to real (not Russian or any other modern) 5881. Good tough tubes all right but may fall short of the mark if his style tends towards playing very loud. And the Philips these days sell for gold dust money while you can get perfectly competent 6L6GC at reasonable price from JJ or Shuguang. Some of us have had good success with Ruby tested & matched sets of Shuggies.