Will a protection relay fail cause DBT Glow ?

CavScout

Super Member
I have an amp that is stuck in protection and now the dim bulb tester has a faint glow.
Can this failed relay (for whatever reason) cause this ?
 
A faint glow is good. You're looking for the bulb to light up brightly when you power on the amp and quickly go dim.

If the DBT lights up bright and stays bright, you have a short somewhere in the amp.
 
It also depends upon the unit being tested and the dbt bulb wattage.
For example you can put a big Marantz 2385 (known to be okay) on a 25 watt dbt and it will stay bright no matter what.
Put the same 2385 on a 100 watt dbt and it will be bright and then dim down.

Bob
 
For example you can put a big Marantz 2385 (known to be okay) on a 25 watt dbt and it will stay bright no matter what.
Put the same 2385 on a 100 watt dbt and it will be bright and then dim down.

Good point. DBTs won't bite you, but they can give you a good nip every now and then.
 
I find it best to run an amp up on a DBT before working on it just to see how it will react. I will also take baseline measurements with a scope of power output, noise, wave shape and whatever else before going at it with the iron.
Not always possible of course but it's good to know. Some amps don't react well to reduced voltage/current and it's nice to know that before pulling your hair out after you've had it scattered all over your bench.
 
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