Bellringer!! PMX2000

[MARSHALL BUSTER]

Hi i thought i would start a new thread for this as iv noticed it said in others that it can help get a responce, plus its a new problem anyhow so here goes..... o by the way iv copied this from the old thread!!!!!!!!!!!!!!!!!!!! but to recap the amp was blowing the main fuse.

Hi again
Just an update on the PMX.

I replaced one pair of 2SC5200 (NPN) & 2SA1943 (PNP) as these were the only components i could find faulty!!.

After building it back up, i switched her on and she sprang back into life again and all was working fine, for 3 hours i fed her some Guns n roses and she loved it!. Then after testing i turned off the i pod and switched off the PMX, 'thats when it got interesting....

There was a very low hum starting to come from the speakers '''with power off''' and then it stoped. I tried to turn it back on again but the fuse had blowen, the PMX uses a 6.25A but i was only using a 1A fuse for testing so i poped a 2A in and it works again, happy dayz, but the hum still comes when i turn the power off so i have to remove the kettle lead incase it burns something out.

Im just wondering is this hum normal for the PMX2000??? i also have a Peavey XR684F but that has no hum at power down, it just switches off and thats that!!.

I have no idea whats causing the hum like i said its fine untill you switch it off and you get the hum. I dont know how long it lasts for iv pulled the lead out so as not to further damage the unit every time it hapend. ( Them parts are hard to get to on this amp so i dont wish to hurt them.)

Thanks for taking the time to respond to my thread, Take care.

[mozwell]

sch

[Jazz P Bass]

That schematic has been floating around for a while.
The problem is, there is no power supply drawing

[Enzo]

See other thread.

[mozwell]

PMX1000 with power supply. It should be "similar" enough to hopefully help out with your problem

[Enzo]

That is handy to add to the files, but the PMH1000 has an SMPS and digital amplifiers. The PMH2000 has a basic linear powr supply, and discrete bipolar power amp. They are not similar at all. In fact the schematic for the PMH2000 powr amp is almost identical to the Peavey XR684 power amp. The part numbers won't match, but you can generally use that schematic to work on the Behr. At least as a guideline.