NAD 2100 protection on!

[jerryo]

Hi,
I have a NAD 2100 amp that only switches on with the "protection" light on.
Inside reveals no burnt components and the fuses are still intact so where should I be looking for a fault. I have the service manual so will start continuity testing and resistor checking when I have time.
I just need a push in the right direction by those who might have an idea where to look.

Many thanks

Jerry

 

[trainman94]

nad 2100

Hi,
I have the same problem with mine. Have not yet resolved the issue.
Check the voltage s at R471 and R 472. If one is at supply voltage that channel may be at fault .
Q 605/606 are the protection circuit. that control the speaker relays. Let me know if you find a solution.

Horace

 

[jerryo]

Hi trainman94,
I don't know about you but I have no-one locally who repairs amps so I am on my own on this one.

Protection light comes on upon switch on and goes out after it warms up.

The symptoms I have are as follows; one channel has centre voltage of 81mv
(0v +/- 100mv) and idle voltage of 16mv (15mv....+/- 2.5mv)
Other channel has centre voltage of 0.6v (!) and idle of 6.4mv which cannot be adjusted; although if you go to turn the idle up the protection kicks in and if you turn it back down it turns off again.
Relays both work with protection. Fuses fine and everthing else looks normal.

If you or anyone else has any ideas where to go next I would really appreciate some help so I can save this amp.

Cheers