The Amp Garage

I just tried that, no diffenence in the hum

First of all, thanks for all of the responses, i appreciate it. This question was about a ceriatone 20 watt lead and bass build that did recently. It is my first build. I had a thread in the marshall section, but it kind of died out. I have a bad 120 cycle hum and intermittent popping/crackling that...

I just had a couple of questions about bad coupling caps. What are the symptoms? Would a leaky cap cause 120 cycle hum? How high does grid voltage have to be to indicate a bad cap? Thanks![/u]

Plates are at 320 volts, grids at .5 mv, and cathodes are at about 3.5 volts. I replaced the filtee caps, which had no impact on the hum. I also replaced the bright cap because it looked cracked. This helped a bit, but not much.

Well it's been a while since ive posted, but ive found that grounding the turret with the three 220k's and the .0047 removes the hum, but i still cant seem to find the source. Also, Grounding out the pots has no effect.

Well for the 100 ohm resistors, i cant see any visible fratcures on them, but i ordered replacements anyway. I also ordered new caps, so im waiting on those. I report back in a couple days.

I used a crude frequency analyzer application on my phone that also says its 120 hz

And i dont have a frequency tester, but using a tone generator, it seems more like 120 cycle hum

Well im getting about 75 mV accross the speaker outputs.

Also which filter would i replace? Sorry, im new to this; it was my first attempt.

I checked all the grounds and they are reading zero ohms... I reflowed them anyway, and they still read zero ohms, but the hum remains. Something else i noticed was that the hum is effected by the left tone pot, but none of the other pots.

Hi, i recently built a Marshall 2061x with a local electrical engineer that has been building really nice amps for years. It sounds really good, but it hums really, really loud. The weird thing is it occasionally stops, and there is no him whatsoever, and it will stay like that for a few days, and t...

Hi, im building a clone of a marshall 2061x, and i've got a question about soldering wires to the turret board. How exactly should i go about doing it? Can i solder wires directly to the leads coming off the components, or do they have to be soldered to the turrets?