bigmouth
Well-known member
anybody have first hand experience on how to change voltages on a coliseum ? looking to change from US to EU.
Coliseum voltage rewiring question
- Thread starter bigmouth
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Boogiebabies
Well-known member
What model ?
bigmouth
Well-known member
MKIIC+ ...
Boogiebabies
Well-known member
So you have an export transformer that is hard wired to 117V.
You need to look at the primary wiring and check where the cloth Black and Brown striped wiring is connected. Also, check where the solid Black cloth wire is going. It may be going to the power switch on the front.
You need to look at the primary wiring and check where the cloth Black and Brown striped wiring is connected. Also, check where the solid Black cloth wire is going. It may be going to the power switch on the front.
merendina
Well-known member
Hi Robert.. how are you? I hope fine..
i will send you some pics of the wiring of mine C+ coliseum 220V
i will send you some pics of the wiring of mine C+ coliseum 220V
bigmouth
Well-known member
hey ed and david ... huge thanx ! so from I see I can only spot one difference.
going from pic 1, between the 2 red flat things at the side rim of the blue board, between the beige (with marks) and the 2 cables (above each other) on the left of it (one greenish, the other black with CABLE on it):
yours has 1 horizontal bar / bridge that seems to connect these together.
mine has 2 bars both pointing inwards (vertical) thus not connecting them.
is that all it takes to change it from 117 to 234 ? that sounds almost too easy ?
also on a different note ... my limit does not seem to work and does not even make a scratching tone or anything. all cables inside seem ok. what can be the cause ? change the tube ? what kind of tubes would fit there ?
going from pic 1, between the 2 red flat things at the side rim of the blue board, between the beige (with marks) and the 2 cables (above each other) on the left of it (one greenish, the other black with CABLE on it):
yours has 1 horizontal bar / bridge that seems to connect these together.
mine has 2 bars both pointing inwards (vertical) thus not connecting them.
is that all it takes to change it from 117 to 234 ? that sounds almost too easy ?
also on a different note ... my limit does not seem to work and does not even make a scratching tone or anything. all cables inside seem ok. what can be the cause ? change the tube ? what kind of tubes would fit there ?
merendina
Well-known member
Your welcome Rob!
This is the tube that works with the limiter 6FQ7/6CG7
Ed Help me with the limiter too, because mine was desconnected..
this is the wiring before the mod
You have to unsolder the red and solder on the second lug.. or vice-versa.
sorry but i can't remeber if is the red or the black one..
Look at this link
http://forum.grailtone.com/viewtopic.php?t=20205&highlight=
good luck Rob
This is the tube that works with the limiter 6FQ7/6CG7
Ed Help me with the limiter too, because mine was desconnected..
this is the wiring before the mod
You have to unsolder the red and solder on the second lug.. or vice-versa.
sorry but i can't remeber if is the red or the black one..
Look at this link
http://forum.grailtone.com/viewtopic.php?t=20205&highlight=
good luck Rob
bigmouth
Well-known member
awesome & thanx again, david ! it seems that the wiring on my limiter is correct. is the limiter really tube-driven ? I could try and change out the tube in that case.
also can somebody confirm if my conclusion on the wiring / rebridging to change from 117 to 234 is correct ? is that all you need to do ? it seems so simple ?
also can somebody confirm if my conclusion on the wiring / rebridging to change from 117 to 234 is correct ? is that all you need to do ? it seems so simple ?
bigmouth
Well-known member
additional question ... anybody have a print or jpg of the circuit of the limit control ?
merendina
Well-known member
nope
bigmouth
Well-known member
you guys are awesome ! just to make sure ...
a) is the limiter tube driven or not ?
b) are my conclusions on changing voltage correct ?
a) is the limiter tube driven or not ?
b) are my conclusions on changing voltage correct ?
merendina
Well-known member
Rob, the elliptic signs show the red wire connected to the resistor that is connected to the 6CG7 pin
I'm not a technician but i think they works together
The 6FQ7 is the phase inverter/driver tube along with the 12AT7 that acts as a buffer
for the other question i can't help you, sorry...
Boogiebabies
Well-known member
It would be best to call Mesa on Monday and ask Mike B. what the voltage is for each taps color. The transformer is much different than the X-101 and I do not think anyone else would have the correct information on an Export Coliseum power transformer.
bigmouth
Well-known member
ok, so first trying to solve the limiter question I got myself a NOS replacement tube, but the limiter still remains "dead". no reaction. according to the seller it functions flawlessly. the wiring appears ok. what else could be the problem ?
