JMP2203 MV serial#04587M

[agreenwo]

Hello, I recently picked up a Marshall JMP2203 MV amp with serial #04587M. I don't know much about repairing these amps and am looking for advice. It seems to me I am not getting full volume out of the amp. I was told the tubes have been replaced but I am not sure. The components inside all appear original but again I am not sure. I noticed the standby switch looks to be wired incorrectly, please look at pics. There appears to be an oily film on all tube bases and throughout other components in the amp, it does not appear to be coming from caps. I do want to duplicate this amp with new components for a project, is there clear instructions available for this particular amp, I seen the great instructions on this website but I don't think there a match to this amp. thanks in advance.

[RagnarMarGunn]

Metroamp MV kit was a copy of 2203 MV. You can view these instructions here:
http://forum.metroamp.com/viewtopic.php?f=47&t=26255

[neikeel]

We would need to see some more photographs of the amp, i.e. inside overall and outside.

There are a number of reasons why an amp might not be giving its best, most commonly poor valves or settings or use (if you are not familiar).

If the amp were faulty I would expect other issues (extra noises, smells etc)

Cannot see oily in the pics and the switch pics are so zoomed cannot tell where the wires go.

[agreenwo]

Thank you for the reply, It seems I can only post 3 pictures at a time, I have many more. I am actually trying to make a second amp by copying what I see in this amp. The standby switch is a DPDT throw switch however 2 screws are missing from and it appears someone wired both the red and white wire through one of the switches. Thanks again for the help

[neikeel]

As it is a Canadian amp I am unsure of the extra fusing arrangements.

The HT switch on UK models of that era has the feed from the HT fuse going to the switch and then to the board where there is a corner turret to which the OT centre tap and choke hooks up, thereafter the HT goes down the B+ line .

On your amp there is the white wire from the fuse board (output from rectifier - there will be another wire to the HT filter caps) going to one half of the switch and the other side is the white wire from the OT primary centre tap and the other a wire from the choke input side. The reason two screws removed is it is being used as a single pole switch. On the other hand the mains is being used as a DPST switch and will have all terminals used.

This aspect of the amp is not good to copy. Much better using the Metro 2203 or SDMs 2203 layout, IMO of course.

[agreenwo]

thank you again for the reply and the advice, as I work towards starting this project I am sure I will have a lot more questions. Is the instructions I downloaded complete, If followed exactly can I be successful with this project?