Hello all,
Am new to the forums and have a limited knowledge of electronics so have a question that someone may be able to help with...
I have a circa 1990 Adcom GFA-555 power amp that was purchased in the USA, so runs on 120 volts. I live in Australia which has 240 volts. I am running this amp from an external step down transformer, but am interested in seeing if I can convert it to run on 240 volts and do away with the external transformer. I was hoping there may be a way to re wire the taps from the power supply torroid that would not involve too much re-working of the amp. The wires from the primary of the torroid are as follows:
Blue ------- 120 vac \
Joined - connected to power cable
Black--------120 vac/
Yellow---------------\
Joined
White---------------/
Brown------120 vac - through power switch and fuse
Orange - not used
Red - not used
Would appreciate if anyone could offer some advice / help.
Thanks guys,
Chris
Am new to the forums and have a limited knowledge of electronics so have a question that someone may be able to help with...
I have a circa 1990 Adcom GFA-555 power amp that was purchased in the USA, so runs on 120 volts. I live in Australia which has 240 volts. I am running this amp from an external step down transformer, but am interested in seeing if I can convert it to run on 240 volts and do away with the external transformer. I was hoping there may be a way to re wire the taps from the power supply torroid that would not involve too much re-working of the amp. The wires from the primary of the torroid are as follows:
Blue ------- 120 vac \
Joined - connected to power cable
Black--------120 vac/
Yellow---------------\
Joined
White---------------/
Brown------120 vac - through power switch and fuse
Orange - not used
Red - not used
Would appreciate if anyone could offer some advice / help.
Thanks guys,
Chris
The best approach is to contact Adcom and ask them. The description sounds like the transformer can be wired for different mains.
Without info from Adcom, it could probably be done but since you are dealing with main (240v yet!) I recommend this be done by a local tech with more experience wiyh the local power mains than you indicate you have. For one thing, there are so many ways transformers are built (and no standardization on colors - at least that I would trust), that the only sure and safe approach is to 6take some resistance measuresments on the primary side, make an educated deduction, then carefully apply power and measure what comes out the secondary. After that different fusing is required and posibly a different power switch.
Likely it is easy if done right but a potential disaster (not just to the equipment) if done incorrectly.
Without info from Adcom, it could probably be done but since you are dealing with main (240v yet!) I recommend this be done by a local tech with more experience wiyh the local power mains than you indicate you have. For one thing, there are so many ways transformers are built (and no standardization on colors - at least that I would trust), that the only sure and safe approach is to 6take some resistance measuresments on the primary side, make an educated deduction, then carefully apply power and measure what comes out the secondary. After that different fusing is required and posibly a different power switch.
Likely it is easy if done right but a potential disaster (not just to the equipment) if done incorrectly.
Mains Polarity can Be Strongly Important..........
Provided that your extenal step down transformer is generously rated, I find that the mains isolation provided by this external transformer can be sonically a very good thing.
If you want to go the last mile, fit a mains polarity reversing switch at the input connection and the output socket of your external transformer box.
This will give you 4 switch permutations to try, and because of earth leakage in unbalanced systems, expect mains input and output polarity changes to affect/effect sonics.
Further swapping the mains polarity into the CDP with will give you another 4 polarity combinations to try - if you have a CDP fig-8 mains cable this is easy.
Be sure to consult your electrical expert about fitting polarity reversal switches where appropriate if you are not completely clear on this.
Eric.
Provided that your extenal step down transformer is generously rated, I find that the mains isolation provided by this external transformer can be sonically a very good thing.
If you want to go the last mile, fit a mains polarity reversing switch at the input connection and the output socket of your external transformer box.
This will give you 4 switch permutations to try, and because of earth leakage in unbalanced systems, expect mains input and output polarity changes to affect/effect sonics.
Further swapping the mains polarity into the CDP with will give you another 4 polarity combinations to try - if you have a CDP fig-8 mains cable this is easy.
Be sure to consult your electrical expert about fitting polarity reversal switches where appropriate if you are not completely clear on this.
Eric.
Chrish, i`m also in Australia and am currently trying to get my Adcom gfa-585 up and running, it`s got some problems, but on the inside of the front pannel Adcom sticks a label with instuctions on how to wire for 100,120v,200,or 240v, It`s all rewirable on the big terminal block on the relay soft start board. Have a look you may be pleased.
Chris ,ok i`ll give you my GFA-585 wiring block layout maybe it`s the same.
The block has 9 entry points
As it`s wired in mine for 240v i have 1=yellow 2=orange 3=n/c 4=blue 5=black 6=n/c 7=red 8=n/c 9=white.
Black Red and White remain constant in 5,7,and 9 regardless of what voltage you want, only yellow ,orange and blue get moved around for the different voltages.
ps this is about as clear and safe as i can explain it, if it`s the same all should fall into place with no questions.
Cheers George
The block has 9 entry points
As it`s wired in mine for 240v i have 1=yellow 2=orange 3=n/c 4=blue 5=black 6=n/c 7=red 8=n/c 9=white.
Black Red and White remain constant in 5,7,and 9 regardless of what voltage you want, only yellow ,orange and blue get moved around for the different voltages.
ps this is about as clear and safe as i can explain it, if it`s the same all should fall into place with no questions.
Cheers George
If have the GFA 555 aswell, and need to source the wiring layout so I can convert the 120v to 240 - did you manage with yours a yr ago? do you know this post is actually here? I wait in hope that you do. Pls feel free to email me.
I also have a conrad johnson PV-5 preamp that needs the same treatment - anybody tried this? - I can say to anyone who hasn't seen inside one of these - it's beautiful... they don't make them like this anymore (etc..) wish I knew a bit more to do it myself.
I also have a conrad johnson PV-5 preamp that needs the same treatment - anybody tried this? - I can say to anyone who hasn't seen inside one of these - it's beautiful... they don't make them like this anymore (etc..) wish I knew a bit more to do it myself.
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