Tube Amp Archive

this just started happening, no changes to the amp, itself so I was putzing along with my amps and looked down to see my 1st build a 5E11 Vibrolux so... I am playing long and turn up the depth control and it starts farting in rythm with the with the oscillations and it doesn't seem to want to go awa...

on a worse note, I was building a marshall 200 watt and fried the 1st power tranny. cause:? shorted capacitor, in the first stage of the bias supply. sprague 8uf 150v dead shorted luckily, and really luckily I found 'that' issue before I fried tranny 2 at 600 bucks a pop, I can't afford to fry too m...

I thought I would post the solution, which was ,as I said, or suspected, a grounding issue. took my eyes a minute or 2 to see it I could see something odd,.....but....... I had the negative bias and ground backwards at the adjustment pot (50k pot) [yeah....go figure that one out...sadly he says....]...

I checked that ground, but I may tend to agree. I will recheck the solder joint on the ring lug on the pt. schematic is actually 5F6A with dual caps, not singles except 5F6A has bias tap from the PT This marshall PT does not, so I tapped the gz34 and even tried the incoming ac (lower voltage) nothin...

please ignore the 6vdc after the 394 vdc
thanks

couldn't find "edit post"



sorry

The bias is correctly connected, but it isn't showing the right information I've done this a LOT and this is my first bias problem, and it is weird. first question....caps facing the right direction Positive to ground.....yes all resistor values check on my Fluke meter 1) won't adjust 50k pot checke...

I was laughing right along with you. My question. was Does anyone have or has anyone seen a marshall plexi 50 output transformer with this wiring color code? see the drawing yes, I know it has taps, and I know this was not the only marshall plexi 50 transformer with this particular color code built,...

edit :

marshall trannies have "different" color codes

The marking are noted on the original post and diagram Those are the ONLY markings on the OT as an added feature, all the wires come out one side ONLY, on the tranny. Usually they come out both sides, primary and secondary Normal wiring, as far as i can tell is primary: red/white/blue or brown secon...

yes, hilarious if you guys think I am funny, then I 'must' be funny. I accept your jabs, graciously.... However................... I was wondering if anyone has actually seen this wiring color code, somewhere, and actually KNOWS, if I am correct or not. marshall trannies have color codes this is fro...

I got this plexi 50 transformer somewhere, and have forgottten the wiring(I know write it down)

here is the diagram

https://ampgarage.com/forum/download/fi ... w&id=59341

Thanks for all of your help and suggestions. Mr. Sluckey's trem-o-lator is perfect and works really....pretty danged well. Almost nah nah, but not quite, perfect. A little reverb and it get close to an echo effect. I have no idea how you figured that out, but it is pretty dern slick I, also, found y...

Mr. Sluckey

this should be somewhere close

I had to order the oscilator, but I ordered it overnight. But everything else is in place.

yes at expense but I have had this in my shop for just at 2 weeks farting with it.

I forgot, yes.
I have built it, it fits the board nicely.

thanks,
I will head to the shop after lunch.