Metropoulos Forum

Hi Guys,

I wrapped up my Metro Themed JTM45 Build today and am having a problem. All of my voltages check out but when I plug a guitar in I get absolutely nothing no guitar output. All my voltages check out within reason with the voltage chart included in the MetroAmp JTM45 instructions. I have double and triple checked my wiring, I even lifted the PTP board out to check my under board connections. Through my numerous look through's I have only caught one mistake on my end (0.10uf mustard cap was hooked to pin 1&3 rather than 2&3 now fixed of course).



I made a video to better help illustrate my problem (I just uploaded it to YouTube so it might take a little for them to process it)

The video is somewhat out of sync (Droid X2 is a horrible smartphone btw) but it helps illustrate what I try to explain below

But the main things I wanted to illustrate is:

* When nothing plugged in the amp behaves as you would expect (very quiet but still the normal hiss when volume is rolled up ect)
* When I was taking voltages of the amp it behaved as you would expect slight popping when probing for voltages as well as tapping V1 you can hear the slight normal microphonic)
* When a guitar is plugged in this is when it gets interesting, the amp becomes noisy with absolutely no guitar output. (The guitar as well as cables are in working order tested on my 100w MetroAmp Plexi.) The noise can be controlled using the tone stack knobs touching the bare metal knobs can take away some of the nose. Rotating the knobs can generate a weird space like alien noise making the knobs even more sensitive, even coming close to the knobs will cause the amp to change noise.

* Also could a bad mustard cap be responsible for these sorts of problems? I bought these from a eBay member in Greece, I have no idea how to test them ect.

I'm open to any and all suggestions

Here is my voltage chart


Thanks guys

Pictures are Uploading

Youtube Link
http://www.youtube.com/watch?v=dpKtjEAv ... e=youtu.be" onclick="window.open(this.href);return false;

It is extremely difficult to follow the wires from vol. 1 and 2(they are the same color), also the hum you are getting is from the lamp.

A quick thought is that you may have a poor ground in the preamp (you touching the pot gives it a better ground)

Have a quick check of your grounds (also peek at the Larry grounding thread in the Resto & mods section).

I found it, I wired my input jacks wrong, the switches should have been up.

Oops!

LJay942 wrote:I found it, I wired my input jacks wrong, the switches should have been up.

Oops!

Axeman is right your wire colouring makes it difficult to tell. I try to stick with the Marshall colours like green for the grids, black for the earth, pink is fine for the pot/coupling wires.