Help on replacement transformer for a Cheetah MS6

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Help on replacement transformer for a Cheetah MS6

Postby jjdugan » Sun Nov 14, 2010 4:58 am

I am looking at the schematics for Cheetah MS6,trying to replace 2 bad PSU transformers.
Can anybody look at them and guide me to a proper replacement?
They are located at the link below...
http://www.maad.net/ms6/

I need a 120/240 DP transformer...not sure on the correct output.
I've been looking at the transformers on this page,not sure which one would be the best choice?
http://parts.digikey.sg/1/3/signal-transformer-241-5-16

Any help would be useful.
Thanks,
John
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Re: Help on replacement transformer for a Cheetah MS6

Postby Mooger5 » Sun Nov 14, 2010 6:31 am

120/240 DP? That must mean Dual Primaries for "optional" 120V or 240V AC mains. Depends on the voltage in your country.

One transformer´s secondary should be around 6V+6V, for the +5/-5. I think 9+9 would be safer, but there´s a capacitor before the regulator with a voltage rate of only 10V...
The other transformer should be 15+15 for the +12/-12.

Pay attention to the transformers´ dimensions: too high and they won´t fit inside the case. Look for "Low Profile" encapsulated or R-cores specific for 1U rack units.

Also don´t forget about current ratings. 0,5A each should be fine, I guess.

Edit - I just noticed in the schematic there´s 7 0 7 v near one transformer and 9 0 9 v near the other. 7V-0V-7V for 5V regulators is better. 9V-0V-9V for 12V is too low...
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Re: Help on replacement transformer for a Cheetah MS6

Postby jjdugan » Mon Nov 15, 2010 10:17 pm

Thank You!
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Re: Help on replacement transformer for a Cheetah MS6

Postby Mooger5 » Tue Nov 16, 2010 5:25 pm

You´re welcome.

Just be careful when working with mains transformers because voltages can kill, etc. Also the 9-0-9V trafo for use with 12V regulators is a bit bugging. Weren´t the MS6s known for some reliability issues? That might be one cause. It can even be a schematic error. 15-0-15 is a safe bet IMHO. Email Kristofer, he might be able to help you.

Good luck!
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