Nomad 100 - Great little amp but reverb has finally died!

[cmac]

So glad I found this forum - so hi all from a Nomad fan in the UK here!

Really hope someone can advise or help me please?

The reverb on my trusty 25 year old Nomad 100 has stopped working (in truth it was never that good) - so I've pulled out the tank and tested it with an ohmmeter and also the leads - all seems OK there. If the tank is not at fault what is the next most likely problem - would it be the 5532 driver IC I wonder?

Also I do have a circuit diagram but cant seem to find a PCB layout diagram for the Nomad 100 anywhere - obviously this would be a real help in troubleshooting!

I'd appreciate any help here please.

Best regards,

Clyde.

 

[luria]

Hi there, mine is also broken. Can´t figure out why.

Here's the schematics I have, hope they help.

 

[DrKev]

I'd first look at replacing the J175 transistor at the end of the reverb circuit. If that's faulty the circuit is permanently muted.

 

[cmac]

I know these amps are 'hand built' but does that really explain why it is so difficult to find a PCB layout diagram?

 

[DrKev]

It's not that hard. Here we'd start from the reverb return jack and look for the J175 next to the 5532 op amp. They're probably all right next to each other.

In other words, you'd be looking for the sticky-upy black thing with three legs next to a lying down flat black rectangle with 8 legs near to the reverb return jack.

If the circuit board is not to jammed full of stuff, it's sometimes possible to desolder that J175 and replace it without dismantling anything. (if not it'll be a good hour or two of taking things apart to get the board out to do a 5 minute job, which may or not solve the problem, which is why so many amp techs don't like Mesa amps).