65 Reissue Twin Reverb PT

[plexi50]

I have a 65 reissue twin reverb with a bad PT. Thermistor is good. No continuity through PT line load leads. I dont see a thermal fuse on the schematic for the PT. Does anyone know if this PT has a internal thermal fuse?  Pretty beefy looking PT.

[stratele52]

Bad news ,

I never see a internal fuse inside amp power transformer.

You are sure of your test ? Voltmeter ?
Be sure amp is good , no short , before putting a new one

[plexi50]

No voltage on line lead out of transformer to board. No filament or HV rectification. Thermistor is good

[stratele52]

No voltage on line lead out of transformer to board. No filament or HV rectification. Thermistor is good

So your transforme have a thermistor ? And it test good . !!! Why transformer don't work ? Primary AND secondary CAN'T BE   both opened !!!

Because , no voltage reading , no ohm reading ( no continuity through PT line load lead ) = meter not working ?

Be sure .

[plexi50]

I finally got around to pulling both the PT & OT bell ends to look inside. Both transformers are char broiled. I didnt get the power tubes with the amp as it was given to me. But i would have loved to see them. I suspect someone could have replaced or moved around the power tubes with broke off guide pins and just stuck them back in the tube sockets. Cant really think of another reason how both transformers thoroughly fried other than maybe a high voltage surge. The amp was used at a well known amusement park here in Florida.
Maybe it went on the water log ride?

[DummyLoad]

recycle bin~!

it is possible that doug's Part number 022756 or hammond 290FX may fit...

--pete

[sluckey]

it is possible that doug's Part number 022756 or hammond 290FX may fit...

They may fit, but would require a lot of modifications to work. The TRRI uses a non center tapped HT winding connected to a FWB recto with STBY switch wired to ground. And it has a totally separate bias winding. If I was gonna use either of those transformers, I'd think strongly about ripping out the PCB and dropping in a turret board.

[DummyLoad]

The TRRI uses a non center tapped HT winding connected

ugh! nasty. should have looked at the schematic first. looks like fender is your go-to for this repair mr. plexi50.

I'd think strongly about ripping out the PCB and dropping in a turret board.

agreed, i wouldn't give it a second thought if it were my amp too, however, plexi50 does state that it is a repair, and therefore probably not worth the work.

Primary AND secondary CAN'T BE both opened !!!

actually, they can... i've seen this, more than once - catastrophic failure of ckts. attached to a secondary causes a slow-melt-fire that burns through insulation and takes out the primary winding. it can also be flash-arc fire.

--pete
 

[plexi50]

It was a repair until the cost exceeded and the realization set in that it was not worth buying the same transformers and possably having them go again down the road. I dont have much faith in the reissue transformers. The customer was going to chuck it so he gave it to me

And yes i am doing something with it that will make me happy. A Deluxe reverb 25-30 watt out to do nicely. GZ34 rectifier and two 6V6GT. There is no way i ever want to own a 100 watt amp again. Totally useless to me and my ears.
 

[HotBluePlates]

... There is no way i ever want to own a 100 watt amp again. Totally useless to me and my ears.

Your name isn't "Plexi100"...  

[eleventeen]

I have often wondered whether reformed Twin Reverb amp owners would go for a mod that would knock down the B+, bias, and drive voltages some such that amp would use 4 qty 6V6. Bring back the 70's (when every 2-6L6 amp HAD TO BE hotrodded to 4 x 6L6) but run them in reverse, LOL. It'd be a pretty simple set of mods, really, and 6V6's have quite a different tone than 6L6. Of course, the amp wouldn't get any lighter or smaller to move around. Maybe it wouldn't be much different than yanking out 2 of the 6L6's.

[plexi50]

Well with a 100 watt OT it wouldnt have the tone of a more controllable low wattage amp even with 2 6L6 tubes pulled. But the idea of 4 6V6 tubes sounds cool. I just have to have the rectifier tube though and i have already removed one of the 8 pin octals

[eleventeen]

So is your intent to go with dual 6V6 or dual 6L6 (or something else)?

I have an old Princeton Reverb which I modded up to dual 6L6 power. The transformers are from a Dynaco 35 watt amp which fell into my hands (this was done 30+ years ago) GREAT amp, with an Altec 417-8H speaker. It's pretty much a clean machine...not something a tweeder would like, I guess. But it can get quite loud, not that I need that. At lower power it has a beautiful warm sound. When I first built it, it had an extra gain stage made out of the tremolo (which I never use) ckt, and it was screaming out of control loud! But that's ripped out now and it's pretty much a stock Super Reverb, AB763 circuit. Just thinking about it, I've never experimented with a 12AY7 or 5751 in first position and I probably should do that...but there's almost nothing I am unhappy with on this little dude. For me, these old Princetons Reverbs and/or Deluxe Reverbs are just the cat's pajamas, amp-wise.

[plexi50]

Deluxe Reverbs are just the cat's pajamas

You can say that again* Im going to stick with a pair of 6V6 tubes. But will try 6L6 as well. I am out of power transformers at the moment with a 5 volt recto tap. 12AY7 tubes are pretty sweet. There gain factor is 44%. I will try one of them as well when i get this up and running.

[eleventeen]

Incidentally, an amplifier which has caught my eye of late is the Peavey (yeah, I know) ValveKing 112. Dual 6L6, 12", switchable, reverb. Check it out when you get a minute. I am wondering if you have an opinion. 3 x 12AX7, 2 x 6L6. Nice size, interesting features. I am told the original 12" speaker is a dog. PC-built, of course, including the 6L6's on PC-mounted sockets, ugh. That said, these can be found used for $250 which to me is below the parts cost. I found one in the local craigslist for $130 but it was gone in a heartbeat. I daresay one could not build the amp for $250. even with free labor...and of course some folks detest PC board construction....I prefer hand wired, but I have no such "deal killer" level prejudice.

[plexi50]

I have not had a ValveKing 112 in here yet. I know they have problems with the connectors and high voltage feed to the OT and power tubes from what i have read. And as far as the layout goes i cant say. There was a Peavey amp here in a head form that really impressed me as far as the layout went and it sounded pretty D good. Bad news is that was a year or more ago and dont remember what it was. Even before responding to your post i have been thinking about that amp since. I quess i have to go through a hardrive to see if i took pics of it and see what it was.

Peavey amps have been around a long time and they were generally built like tanks. Cant say that about many of them built today though

Still Peavey makes some great sounding amps. My 1993 Classic 50 is never going any where. Unless the revolution begins at which point were all screwed. Got to have electricity. Start saving lightning bugs in jars  

[plexi50]

... There is no way i ever want to own a 100 watt amp again. Totally useless to me and my ears.

Your name is "Plexi100"... 

Im shrinking. Plexi20

[plexi50]

Well i had time to finish the 65 Twin reverb over the last 3 days. I made rectification changes to the board,bias r and standby switch B+ location. Threw in a Deluxe reverb PT with a 5U4GB / 385VDC plates. Also used a SS rectifier plug which is more in line with a GZ34 400VDC plates @ -37 bias grid. Dont have a GZ34 at the moment. Sounds great. Nice breakup. Running a pair of 6V6S power tubes and 12AU7 for the reverb driver. The reverb is way to much for me but i can figure that out later when time allows. Low wattage has really changed my whole attitude about what is usable over the last few years.

Just thought of something that could possably be a problem. I grounded the PT / CT to the same lug as the artificial 100r heater filament CT. Could that induce hum? Should they be on seperate areas of the chassis?

[tubeswell]

Where's the main gutshot? 

[plexi50]

Where's the main gutshot?  

Ya know that is weird that they ran the mains wiring accross  the filament wiring half way down the middle of the chassis. Plus the ground switch is just sitting there. It was never wired up. For looks or what?

[sluckey]

Plus the ground switch is just sitting there. It was never wired up. For looks or what?

Mine doesn't have a ground switch.

[plexi50]

Plus the ground switch is just sitting there. It was never wired up. For looks or what?

Mine doesn't have a ground switch.

Do you mean the ground switch is missing all together?

[sluckey]

Do you mean the ground switch is missing all together?

Yes. Chassis isn't even punched for one. The pic in my owner's manual doesn't show one. My original schematic does show one.

[plexi50]

Hum!!!!! I mean hmmmmmmmm! My board has a date of 1991. Do you know your board year off hand? Strange little differences in everything these days.

[sluckey]

Don't know the board date but I bought the amp new in 2003. My guess is the $4 switch was included in early reissue models just to make it "look" authentic, but was later dropped by the penny crunchers.

[plexi50]

In the year 2510, if amps are still around by then,you wont be able to play the blues,cause the amps will be missing there tubes ,who0o0o0o0  

[Davidg]

To Address OP's concerns and add one of my own I didn't think you could fix an internal fuse on a PT and it was there for fire protection more than anything? Can they be replaced and antbody know how?