Help, Roland AC90 Mic Input Problem
 

I’ve got a Roland AC-90 in which the microphone has a combo xlr/trs jack. My young kids like to sing through it for fun and I’ve been using a cheap mic that came with one of their keyboards that uses the std 1/4 jack. I decided to buy them a little better mic that is XLR based. The problem I’m having is when using the XLR connection I’ve got very little output. Pretty much have to turn it up to 10 on both the mic volume and master vol to get any output at all. I went to the store and purchased an XLR/TRS adapter and boom, volume is normal. I’ve found one site online with another person having the same issue but no updates as to what they have found. If anyone has this amp or any of the AC series for that matter, have you experienced a similar problem?

Chris

Roland AC-90 Mic Problem
 

Hi:

What is the impedance of the mic you bought to replace the inexpensive mic? Did it come with a cable? If so, what kind? (xlr to quarter inch jack or xlt to xlr)? Are you able to try the mic and xlr cable in another amp for comparison?

The mic is a EV cobalt 9. Not sure what the mic imped is off hand. The mic is xlr out. Cable is xlr both ends. Just to rule out the mic and cable, I went over to GC and test both together there an all worked good. The one site I found with a similar problem mentioned trying the xlr/trs adapter as the mic input is a combo jack. That seems to work as it should. I can't say I know much about these type of jacks or how they are wired. My first thoughts are things should be common on the inside. I'm wondering if there could be a bad connection on the xlr side of the jack. May just have to bite the bullet and order a service manual off eBay.

its not your mics.....I had a AC 90 also and it done the same thing..I took it back to Guitar Center to trade and two other ones had the same problem.so I traded for a fishman, the fishman works great, but the roland sounded alot better

Roland AC90 Mic XLR troubleshooting update
 

So, after doing some reading on the old www, I decided to buy a service manual online for a few bucks just to see what exactly I was up against. I’m not an electronics tech but I’ve torn apart enough consumer electronics over the years to know how to take some screws out and hopefully remember where to reinstall them. :) Anyways, below is my project to get the XLR mic input working again
[IMG]http://i966.photobucket.com/albums/a...a/4a5421e0.jpg[/IMG]
Note to Roland: Why not engineer the speaker wiring to be about 8” longer so one can remove the electronics without the need to remove speakers just to get things in the open? Sure it saves on the front end costs, but it wasted a few minutes of my time to have to dink with that oversite. Must have been the project of an summer engineering intern.

http://3.bp.blogspot.com/-H2qxvDVPbp.../s640/1095.jpg

I assure you that I took no proper grounding precautions nor is my carpet rug not full of static electricity. But a swipe of the cat across the electronics should help with any of those issues right?

http://i966.photobucket.com/albums/a...a/641942ab.jpg
I think the problem is in this xlr combo jack by itself. Tweaking and yanking on a little bit yielded positive results in getting the jack to work correctly. So I think I can rule out anything later in the signal path. I was able to get my cheap mic working without the need to turn the mic and master vol’s up to 11. I was also able to get my SE2200ac to fire up and mic as it should also after giving the board a tech tweak.

What I find quite sad from reading the components breakdown in the manual is the fact that this tiny little XLR board is not a service part in itself but only available with the Main circuit board assembly. (See picture below of the main board). From a service standpoint its dumb since the mic input board is not built onto the main board but only attached by the main wire connector plug. I guess its a good design for Roland so they can sell you 500$ in replacement parts you don’t need.
http://i966.photobucket.com/albums/a...a/3a047e81.jpg

Luckily there is a brand name tattooed to the XLR combo jack so I think I may be able to just buy the jack and solder a new one in, crossing my fingers that is the only problem. Now I just have to go through Neutricks catalog to match up the correct jack assembly. One thing that I found on their site is a nice little cover cap for these jacks so that crap doesn’t settle in the hole when its sitting in the corner.

http://www.neutrik.com/website/uploa...0x/scf.jpg?v=1

So, off to the Neutrik site to see what I can find and to try and get this working better than Roland could.

A follow up post to my Rolland AC90 fix. I’m fairly certain that the problem lies in the jack itself. Just out of curiosity to see if Rolland sold the XLR board by itself, I gave them a call. Just like the manual states, you would have to order the main board just to get that little board that fits in the palm of my hand. The cost from Rolland direct is 400.00. I told her for that much money I’d rather spend it on buying a new Fishman. I ordered a new Neutrick jack on ebay for 4.00, and worst case even if I had to replace all the caps/resistors etc, I’d probably only be into the parts for about 15.00.

So for any folks who may be having a similar problem, More than likely its in the jack itself and nothing else in the amp. Looking at the schematic, the signal line for both the XLR side and TRS side of the jack share the same signal path. If it were a problem elsewhere in the amp, then signal should be dead on both sides of the jack. If anyone needs a copy of the service manual for the AC90, shoot me a PM.

Hi Xtremca,
could I ask you ... Do you remember impedance of AC-90's speakers? 4 or 8ohms? Now I have AC-33 and I'm thinking about upgrade to get more headroom. AC-33 has a 4ohm speakers.

Thank you for answer.

I had the same problem with my AC-90. It did not work with an XLR cable, but did with a 1/4-inch adapter. I took it to the dealer and they switched out the component, on warranty. The tech guy knew right away, as if it was a common problem. No issues since.

I'll see if I still have the service manual. I'm not sure if it covered that. You could pull one out and put a digital multi meter on it so see where they spec at. If you are also looking at speakers, make sure to check what the sensitivity of them are. Speaker specs usually state for example 89db @ 1watt. The higher the db the more efficient the speaker. Also, you could find yourself going in reverse as the speaker enclosure is usually designed around the speakers theil-small parameters. So just throwing a speaker in there could have less headroom or have a skewed EQ.

Chris

Thank you! I saw your disassembled AC photos above and thought that you explored speakers too ;) I'm surprised that AC-90 speakers looks different than from AC-33, not only bigger but middle cone is missing.

The AC90 has seperate tweeters which is why it probably doesn't need the cone on the mains.

Oh, sorry, I didn't mentioned that, thank you. So only AC-60 6.5" speakers are suitable for me.

Need AC-90 Schematics
 

Any chance you can email me a copy of the service/schematic manual for the AC-90? [email protected]

Hi
Just having exact same input XLR issue with my Roland AC90. Can get it to work with a bit of jiggling. Thanks for your post..yup totally agree about the length of the speaker cables. Not good design practice, I was wondering how the heck the module came after undoing the side screws out but your post helped as I didn't think that Roland would do that.
Did you ever get round to replacing it if so what Neutrik part is the one that solders in ?
Rob

My AC-60 has a Line/Mic switch for the XLR input and there is a major volume difference between the two. I don't know anything about the AC-90.