Help Identify this board

[Custom_Amp_30]

Well I have this board that I have been trying to Identify for a while. Who made it and is there a schematic as well as a layout chart so that I can use it. It has two Vactec Vactrol Led Cell, I believe they are model VTL5C3, 5C4.

I first thought that these where old fender boards that had been an experiment using Orange drops, but realized that I had no way of confirming or disputing this from my EBay purchase two years back. I would like to wire this up and see how it sounds.

[LooseChange]

I think it's from an ipsydik funklewagon.

[FYL]

I think it's from an ipsydik funklewagon.

MK II or MK III?


 

[OldHouseScott]

It could be a Rivera era Princeton Reverb II. That schematic shows two vactrols, but I only see 3 bypassed cathodes, not the 4 your board has. Curious indeed.

[Custom_Amp_30]

Thanks, at least I may be looking in the right area. I will check the component list and see how close it may be.

[HotBluePlates]

It could be a Rivera era Princeton Reverb II

I think the vactrol is a red herring.

The board reeks of silverface, from the waxy surface to the board to the particular wire used and the blue caps (these particular ones are typical of silverface amps and are not blue tubular caps like blackface Fenders).

The phase inverter has 47k plate resistors, again pointing to silverface. There doesn't appear to be a reverb circuit (although it could be buried). There look like there could be a tremolo oscillator circuit, but if it is, there's a missing cap and a wrong-value resistor.

The really unusual thing are the 4 preamp cathode resistors and 4 bypass caps. Blackface amp layout show 2 separate bypass caps for a single tube, but in reality they used "3-legged critters"... a bypass cap with 2 sections, 2 positive leads and 1 negative lead. As a result, there is only 1 ground eyelet for a pair of cathode resistors and bypass caps. This board is different: there is an individual ground eyelet for each set of cathode components. You don't see that much in old Fender amps.

I'd look for a silverface amp with tremolo and 4 sets of cathode component eyelets. I think the vactrol was simply swapped in place of the trem roach.

[RicharD]

>The really unusual thing are the 4 preamp cathode resistors and 4 bypass caps.
PA-100 maybe?  Silver face era.  I've never seen one.  Basing my guess on the quad input thang.

[Custom_Amp_30]

Well, I checked that schematic parts listing and believe that It was not from the PA100. I have also went through all of the Fender Layouts that I have from the Tube Amp Book CD as well as most of the other brands.

The Duel Vactrols and the four bypassed cathodes,do not appear on any of these Fender layouts. I will take some time this morning to list the components and values so that It may help ID this board.

I purchased these boards as a set of five, and have been combing Layout diagrams every chance that I get.

[bnwitt]

Looks like a Fender "75" to me.  I've got one on the bench right now.  I'll take a photo of the whole board and we'll compare it.  There is no layout available on the fender 75.  I suspect Fender would have been too embarrassed to draw one up of how one is actually wired.  If you take a picture of a colander full of spaghetti with some capacitors and resistors thrown in that's basically it.  There is a schematic on Schematic Heaven.

From the looks of that one I can imagine a history sort of like this....

"Man this amp sucks!  Maybe if I put some orange drops in place of those blue caps it will sound better?  Nope, still sounds like crap.  Ok, lets' gut this thing and make it a black face.  Bye bye old board."

 

[Dave]

I remember seeing that board on ebay when it was for sale. The listing said that they were unused Fender prototype boards.
Sounds like that may have been the case and that this prototype never went into production.

Dave

[bnwitt]

Well it's not a prototype.  Its a 75 for sure with orange drops on it and Fender wasn't using orange drops back then.  Fender probably wishes that board hadn't gone into production though.  If it didn't come out of an amp it was probably just part of an orphan batch of unwanted children.  I bet it was an amp pull though.  

Here is a picture of the board in the '75' I'm working on this morning.  By the way, the large cement resistor on the left is not part of the board.  It's on a terminal strip next to the board.

[HotBluePlates]

Bingo! Barry is the winner!

Looks like a couple parts got robbed of his board along with the orange drop swap.

[bnwitt]

If I were selling that thing on Ebay and I wasn't the honest me, I'd probably say:

 "Its uh, its uh, a mystery prototype.  Yeah, that's it. A mystery prototype board from Morgan Fairchild's Fender amp division.  Yeah, that's the ticket."  

You'd stand a much better chance of selling it for money that way then saying it's a cast aside board from a less than popular Fender Mesa Boogie knock off amp that someone robbed parts from and replaced the great blue caps with orange drops.  

It just goes to show you can't believe anything you read on Ebay and that many Ebay sellers are doing their part to reduce the garbage going into land fills.  Thank you Meg Whitman.

[Custom_Amp_30]

GIVE THAT MAN A CIGAR. Thanks It also is the last schematic on that Tube Amp Book CD under Fender. Here is the Layout that I was working on. I have to recheck my values. to be sure.



C1   Capacitor, .01uF, 630 volts
C2   Capacitor, .047uF, 630 volts
R1   Resistor, 100K, 1/2 Watt
C3   Capacitor, 250pF, 500 volts
R2   Resistor, 100K, 1/2 Watt
R3   Resistor, 100K, 1/2 Watt
C4   Capacitor, .0047uF, 630 volts
C5   Capacitor, .0022uF, 630 volts
   
C6   Capacitor, 25uF, 25 volts
R4   Resistor, 1.5K, 1/2 watt
   
C7   Capacitor, 25uF, 25 volts
R5   Resistor, 1.5K, 1/2 watt
   
C8   Capacitor, 25uF, 25 volts
R6   Resistor, 1.5K, 1/2 watt
   
C9   Capacitor, 25uF, 25 volts
R7   Resistor, 1.5K, 1/2 watt
R8   Resistor, 68K, 1/2 watt
R9   Resistor, 1M, 1/2 watt
R10   Resistor, 1K, 1 watt
C10   Capacitor, .001uF, 630 volts
R11   Resistor, 1.5M, 1/2 watt
C11   Capacitor, .001uF, 630 volts
   
R12   Resistor, 1.2M, 1/2 watt
R13   Resistor, 68K, 1/2 watt
R14   Resistor, 1.5M, 1/2 watt
R15   Resistor, 220K, 1/2 watt
C12   Capacitor, .0022uF, 630 volts
R16   Resistor, 1M, 1/2 watt
R17   Resistor, 1.5M, 1/2 watt
C13   Capacitor, 220pF, 500 volts
C14   Capacitor, 500pF, 500 volts
LED 1   Optocoupler
R18   Resistor, 270, 1/2 watt
R38   Resistor, 1K, 1 watt

C15   Capacitor, .003uF, 630 volts
R19   Resistor, 100, 1/2 Watt
R20   Resistor, 100K, 1/2 watt
C16   Capacitor, .022uF, 630 volts
R21   Resistor, 47K, 1/2 watt
R22   Resistor, 47K, 1/2 watt
C17   Capacitor, 25uF, 25 volts
R23   Resistor, 1.5K, 1/2 watt
C18   Capacitor, .1uF, 630 volts
R24   Resistor, 1.5K, 1/2 watt
   
R25   Resistor, 100K, 1/2 watt
C19   Capacitor, .0022uF, 630 volts
C20   Capacitor, .1uF, 630 volts
R26   Resistor, 100, 1/2 Watt
C21   Capacitor, .1uF, 630 volts
R27   Resistor, 22k, 1/2 watt
R28   Resistor, 330K, 1/2 watt
R29   Resistor, 470, 1/2 watt
R30   Resistor, 330K, 1/2 watt
C22   Capacitor, .01uF, 630 volts
LED 2   Optocoupler
R31   Resistor, 270, 1/2 watt
   
C23   Capacitor, .01uF, 630 volts
R32   Resistor, 820, 1/2 watt
   
R34   Resistor, 82K, 1/2 watt
C24   Capacitor, .022uF, 630 volts
R35   Resistor, 47K, 1/2 watt
R36   Resistor, 47K, 1/2 watt
C25   Capacitor, .022uF, 630 volts
R37   Resistor, 100K, 1/2 watt
   
R39   Resistor, 470K, 1/2 watt
R40   Resistor, 47K, 1/2 watt
C26   Capacitor, .003uF, 630 volts
R41   Resistor, 220K, 1/2 watt

[bnwitt]

If you need me to verify anything for you before this amp goes back to the owner let me know.

[bnwitt]

Ok, as I often do when working on a messy amp, I did a little drawing to help myself along.  Attached is a PDF of the Fender '75's filter cap board and the layout for the footswitch that you need to run the thang.  By the way, this footswitch also works on the 81 Concert, the Super champ, Twin Reverb II and some other amps according to what I read on the net.  It is model # 017007.  There is a line drawing on the web.  This layout was created from an original footswitch.

[Custom_Amp_30]

Thanks, This has been a good day indeed. Best site that I have found and the assistance was greatly needed   

[bnwitt]

CA30, welcome aboard.  You'll find this site is the best for knowledge (lots of smart tube amp guys not me) and attitude.  I'd say the guys in here have the most helpful and friendly attitude on the net.  After all, they put up with me.

[Dave]

+1 on friendly. Occasionally we have a healthy debate, but it is always respectful and sometimes leads to some pretty good comedy.

Dave