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Equipment Repairs => DVD/VIDEO/Home Cinemas/Hi-Fi/Mp3/Camcorder => Topic started by: Turnip on June 11, 2010,11:38:52

Title: NAD C300 (audio)
Post by: Turnip on June 11, 2010,11:38:52

Hi folks,

Have a couple of these, one where unidentified output FETs are shot, the other, where voltages seem fairly normal, but the speaker protection relay doesn't click in.

Wondered if there is a 'NAD' nerd about as schematic is rather complex. Note that folks don't bin these like 'Goodmans' and such - tend to be passed on, father to son, daughters go for more fashionable gear.

Must be a reason - Chris.

Title: Re: NAD C300 (audio)
Post by: Keith on June 12, 2010,07:51:10

Hi Chris,

The FETS are STP55NE06L BUK556-60 should do.
The one where the relay does not operate could be a mute problem not protection. Do you have any o/p signal at the relay?
There are a few 1N4148's and caps in the protection circuit that could cause problems.
Are there any signs of liquid spillage? EG corrosion on component legs. Amps do tend to get the odd drop of beer into them, don't we all?!

I tried to upload the manual but it wasnt having it, will try later if you need it.

Keith

Title: Re: NAD C300 (audio)
Post by: Keith on June 12, 2010,08:07:40

Manual

Title: Re: NAD C300 (audio)
Post by: Turnip on June 15, 2010,12:06:30

Hi, and thanks Keith,

Surprisingly, neither amp has had a Beer upgrade, so will get those FETs for the first, and check audio on relay primary - incidentally, there is no headphone output on that second one.

Thanks for the manual - will peruse, and hopefully make a pound, first of the week  - Chris.