Roland Acoustic Chorus AC-90 dead

Hello again.
A friend brought me a roland acoustic chorus ac-90. Amp is completely dead (no power when flipping the ON switch).
I opened it up (pain in the butt!) and checked power from the cord to the toroidal transformer primary winding. Tomorrow I will continue to search for the fault. It might be something stupid like a loose connector, or it might be more serious, like a blown secondary winding on the transformer. Who knows? I've seen both scenarios before on Marshall and Fender brand amps made in China.
Any suggestions as what else to look for?

Thanks in advance.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
I got no water at the bathroom faucet.

It is the same problem. You go through the pipes/wires step by step from bathroom through cellar to water meter to main water valve to street/well (or vice versa) until you find the clog/open. It sounds like you know how to check all the steps. Sometimes trouble-shooting is just tedious. (More tedious when products are not designed to be fixed.)
 
I find the simple test is to turn the power switch on, and measure the resistance between the main prongs of the mains plug. Obviously while the plug is not in a wall outlet. That way you are measuring both the primary winding and the power switch and fuse and wiring. If that reads open, then measure right at the primary wires. If the primary reads open, you will have to dig into the transformer to look for a possible thermal fuse that opened. And yes, the joint between winding wire and external lead could have failed.
 

javrolijk

Member
2019-10-07 6:23 pm
Yes, I know. In this case, the fault is in the primary of the power transformer. Sometimes, these toroidals have some type of fuse built in the windings. I know someone who makes transformers for a living, and I just hope that he can rebuild it...

Hello, have you sorted out the issue with the transformer? I have a friend with the same issue. He also has a Roland AC-90 with what seems like a dead transformer. Attached you will find a picture of the actual amplifier with its defect transformer.

If you have found a solution, we'll really appreciate your information.
 

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javrolijk

Member
2019-10-07 6:23 pm
Hello again.
A friend brought me a roland acoustic chorus ac-90. Amp is completely dead (no power when flipping the ON switch).
I opened it up (pain in the butt!) and checked power from the cord to the toroidal transformer primary winding. Tomorrow I will continue to search for the fault. It might be something stupid like a loose connector, or it might be more serious, like a blown secondary winding on the transformer. Who knows? I've seen both scenarios before on Marshall and Fender brand amps made in China.
Any suggestions as what else to look for?

Thanks in advance.

Hello, a friend of mine is also having an issue with it's Roland AC-90. It seems that they were able to narrow the issue down to the Transformer as well. Attached you will find an actual picture of the amplifier with the presumed defect transformer.
If you were able to find a solution, we really appreciate the information.

Kind regards,

Jairo
 

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jeka666

Member
2021-08-09 3:44 am
Hello again.
A friend brought me a roland acoustic chorus ac-90. Amp is completely dead (no power when flipping the ON switch).
I opened it up (pain in the butt!) and checked power from the cord to the toroidal transformer primary winding. Tomorrow I will continue to search for the fault. It might be something stupid like a loose connector, or it might be more serious, like a blown secondary winding on the transformer. Who knows? I've seen both scenarios before on Marshall and Fender brand amps made in China.
Any suggestions as what else to look for?

Thanks in advance.

Same problem can't turn on My ac-90

This amp is more than 2 years but i only use ir no more than 10 times. I think this is a fuse problem, and i rigth, but when I disamble all , cause not easy access to it, and when I See the fuse is a 2.5LA 250v fuse, but the board have printed 5LA 250v . I think many amps of this have problems cause this change of fuse. I Will put a 5A fuse.
 

Tarzan

Member
2004-05-23 6:54 pm
Genk
Ah, add some words you didn't think of.
In one way you're right, the other, hm... no.
Any way, I live in Belgium and my settings are Dutch.
It didn't cross my mind to ad Toroids...
So, you see. We're never to old to learn a few tiny tricks.

Muchos Gracias, Amigo.
 

Tarzan

Member
2004-05-23 6:54 pm
Genk
Wel this is what I get when I search Google with Antec:

Hence my first asking.

We can keep on waisting our time on the fact that some insist that you have to know if a word is misspelled (can happen all the time) and to add some other words.
If the first suggested word is correct, then there are no problems for google to find the site.
And Dotneck corrected the situation.
Problem solved.
For me anyway...
 

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