5e8a build questions

[trane34]

The 100 ohm resistors are to balance the filaments if your pt does not have a center tap for them. Nice looking build. I'd rather use some solder lugs for those center taps rather than soldering them to the chassis. More stable means of construction than using solder as glue.

[Bhabes]

Oo, thank you for that. I will install them!

[Bhabes]

No center tap on this guy, correct?

http://www.mojotone.com/transformers/Fe ... OJO752.pdf

[tsutt]

Yes it does, the green/yellow is ct for the filaments w 3.15 on each side.

[martin manning]

The Mojo layout has 100 ohm resistors coming off the indicator lamp, I suppose to reduce brightness? Anyone have an opinion on that? I didn't install.

Right descision, wrong reasoning... the 100-ohm resistors form an artificial centertap for the filament winding. Since you have a real heater winding CT, you don't need those. Looks realy nice, BTW!

[Bhabes]

Once again proving I know just enough (or don't know plenty) to be dangerous. A ground lug would have been best, but red/yellow and gree/yellow to ground is correct?

[img750]http://kurtsequipment.com/twin5e8a/twin3.jpg[/img]

Edit: oh and thank you for the compliments! I'm sad it's over but REALLY hope there is little troubleshooting!

[martin manning]

Yes Red/Yellow is the HT CT, Green/Yellow is the filament CT, and they are typically grounded together.

[Bhabes]

Longshot, but does anyone have experience with 12" Weber alnico speakers not fitting in a low power mojo tweed twin cab? The speaker measures 6 1/4" in total depth, cab is 10 1/2". Concerned it will hit the preamp tubes. I can call mojo on Monday for advice, perhaps they can tell me if I will have an issue. The weber bell cover would only save maybe 1/4" if removed.

[SoK66]

I know I'm WAY late to the party on this (what's eight years between friends?) but, yes, I have the Weber 12A15-A speakers in my Mojo 5E8-A cap and they do clear the chassis. Close but ok.

This is a very nicely done build. The input jack resistors per the schematic should be 1 Meg. In the build photos looks like the OP used something different, 68k maybe? Can't quite make it out. Input jack wiring on the 5E8-A is an odd duck for Fender of that era, but what it does is result in the high inputs of each channel feeding both triodes of either V1 (Normal) or V2 (Bright). You can;t jumper the channels like a 5F6-A Bassman, but a "Y" cord into the #1 input of each channel gets both V1 & V2 driving the next stage.

(Edit to add, Fender's schematic for their '57 Twin Reissue erroneously has the input jack numbers for both channels reversed.)

Also wanted to mention, Mojo around the time of the OP's posting changed the PT for their 5E8-A kit from the previously specified 753EX (same as the high power Twin 5F8-A) to the lower output 752 (same as tweed Bandmaster, Bassman, Pro & Super). There have been some issues with the 752 having enough power to drive both 5U4s in a 5E8-A. The 753EX was the better PT for this amp, not sure why they switched. The 753EX's dimensions are slightly larger than the 752 and won't fit Mojo's current chassis for the 5E8-A. You would have to clearance the hole and drill new mounting holes.

Very cool amps.