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700RB problems

M

Montgoda19

Jun 6, 2011
9
0
Pittsburgh
#1
Well i turned on my head for practice the other day and It started to smell really weird like electrical. Then white smoke started to come out of the lid! I did some research and found that the culprit is the resistors. Now heres a picture but i can tell the color bands on them nor can I find any schematics on the head but as you can see its is slow r73 and r74. does anyone know the right resistors i should replace them with, i work at radioshack so i can pick them up right away! but here is a picture! http://i.imgur.com/sB5Xf.jpg
 
#3
Montgoda19 said:
does anyone know the right resistors i should replace them with
Click to expand...
Don't bother. I suspect those resistors aren't the problem, they're just involved in the circuit where the problem lies, and the real problem is a shorted output stage due to one or more failed output transistors. But that's just a guess.

Also, you'll need to repair any burned board traces that were smoked by the heat.
 
#5
craig.p said:
Don't bother. I suspect those resistors aren't the problem, they're just involved in the circuit where the problem lies, and the real problem is a shorted output stage due to one or more failed output transistors. But that's just a guess.

Also, you'll need to repair any burned board traces that were smoked by the heat.
Click to expand...

+100

The resistors did not cause the problem, they took the hit.

Lots of bass? High gain? Poor cooling?
 
#6
I recently picked up a 700rbii that was pulled from a combo. The fan on the heatsink doesn't start running when you turn it on, is this normal? Not sure if it has an always on fan or if it responds to heat load?
 
#12
The old 700rb (not the II) is many, many years old and did have some problems. It was replaced a long time ago by the 700rb-II, which cured those issues as well as upped the power. Same story with the old 1000rb and the 1001 being made now.

I've seen guys beat the crap out of older 700rb's with no issues and others with repeat failures. Don't know if it varies by production run or year or what.
 
#14
I would think older models still in use today may not be the problem amps, but, for peace of mind, if i was shopping used now, I'd probably stick to the "II" models. They have the sort of rock-solid reliability you expect from GK.
 

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