M90 Bass Rattle / Rattling Fix Creaks HELP

Hello everybody! I just acquired a JVC M90 and noticed a problem when heavy bass hits. I've never had an M90 before so I was wondering if anyone has had similar issues. When I crank up the bass and play some old school hip hop with 808 kicks or what not, one side of the unit rattles / creaks. It only happens on the right side of the unit. It's a medium rattle, but loud enough to be annoying. The weird thing is that if I tilt the unit back at a 45 degree angle the rattling vanishes. Or If i stand the unit up on its side at a 90 degree angle, there is no rattle either. This is very irritating. I just want to unit to not rattle when its in its natural upright position or being carried by the handle. I feel like I'm being robbed of the true M90 listening experience I hear about, because when it doesn't rattle the bass sounds buttery.

I guess my main question is should I open the back casing to investigate, and is this an easy task? I know nothing about electronics so I'm a little nervous. What can be causing the rattling and is this typical? Any suggestions or input would be great.

Thanks!

You should open up the back and check if there is something loose inside. Are all the rear case screws present and tight? If so, then you may have bought an M90 that's been dropped and may have broken screw posts.

Pull the back off and investigate.

Let us know how you go.

Welcome to the site!

Jimmy I think you're right. It sounds like there something sliding around or broken off inside the unit. The case screws are present and tight. It's possible it may have been damaged during shipping

I'm going to go for it and open it up, I'll let you know how it goes...Thanks!

Will be good to show some pictures of this boombox.
If is a problem inside, it is good to show.

I've had this with a couple of boxes. Almost always the battery cover. Take it off and see what happens.

I always open them up

Could be a wire touching the back of the speaker as well...

Sent from my VS986 using Tapatalk

Almost all boxes have an inch or less wide fine felt layer with adhesive back up stuck along the edges of the rear cover where it meets the joining section. For some reason it that is lost box will rattle. Basically all around or partially around the edges where two individual sections meet has got a layer to lower any vibration and give a nice fit. That is the first thing to look for.

Screw posts break and fall inside the box. In some cases it is a part of the plastic screw post. This can also cause rattling especially when it is caught at the back of the woofer cone and metal frame.

You need to open the back cover and investigate. Make sure to remove all the back cover screws and gently pull the cover out evenly. When you put the screws back turn it clockwise until you feel a click and then turn clockwise. This way the chances of cross threading is minimized.

****UPDATE****

Thanks for all the input and feedback!

I just got done opening the unit up and completely resolved the rattling issue. While I was taking the screws out I noticed a slight crack on the back casing which lead me to believe it was dropped at one point. There was a strange little rubber piece (pictured) that was floating around behind the speaker which was causing most of the rattling (I couldn't figure out where it came from). I believe that was the main issue and when I was tilting the box as mentioned, it was most likely getting lodged between some metal. Also, the right speaker was mounted loosely so I tighten up those screws real good. Problem solved!



On another note, I think I may have damaged the antenna connection. I'm pretty sure it's not supposed to just dangle like this...



Any suggestions? The fm radio seems to work fine, but knowing the chord is hanging inside the box is going to bother me. At least I get to enjoy the sound quality now, and it thumps pretty hard without creaks or rattling.

That cord dangling for the antenna hookup plugs into the radio tuner board. You didn't damage it.


Also, that black rubber block likely came from under the power supply area on the rear case. It adds support to that heavy transformer, but in most cases it can be dislodged. It is ok to leave it out.

blu_fuz said:

That cord dangling for the antenna hookup plugs into the radio tuner board. You didn't damage it.


Also, that black rubber block likely came from under the power supply area on the rear case. It adds support to that heavy transformer, but in most cases it can be dislodged. It is ok to leave it out.

Click to expand...

Thanks for the info! Do you happen to know what the radio tuner board looks like, and i would just plug it right in I assume?

Here it is ..

On the right side looking from the back of the M90 you will see a board shown in the pic. It is the tuner board. Right next to the ferrite rod you will find that male connector with 3 pins sticking up.

Do not do any cleaning or tampering on that radio board. There are parts that are buried in molten wax. After tuning and aligning manufacturer sealed it with wax or else it will mis-align tuning.

I have circled the place on the board "CN2-P" which is the place for the antenna lines to connect.

BoomboxLover48 said:

Here it is ..

On the right side looking from the back of the M90 you will see a board shown in the pic. It is the tuner board. Right next to the ferrite rod you will find that male connector with 3 pins sticking up.

Do not do any cleaning or tampering on that radio board. There are parts that are buried in molten wax. After tuning and aligning manufacturer sealed it with wax or else it will mis-align tuning.

I have circled the place on the board "CN2-P" which is the place for the antenna lines to connect.

Click to expand...

Amazing, thank you so much! I love this forum.

JC Slater said:

Amazing, thank you so much! I love this forum.

Click to expand...

Best forum on the web, homie.

Success! I located the pins and it is now connected. Huge shout out to everyone who walked me through this, I truly appreciate it.

JC Slater said:

Success! I located the pins and it is now connected. Huge shout out to everyone who walked me through this, I truly appreciate it.

Click to expand...

I'm glad it all worked good for you.

In future when you open up any box remove the cover very slowly. Some boxes will have several connectors like this one which needs to located and disconnected. Make sure to take pictures of those connectors before you disconnect and save it under that boom box file. This will really help a lot!

There are so many friendly and very knowledgeable members here! Enjoy this friendly site!

Cheers!
~Royce

Glad that you got the rattle sorted out, you are a lucky owner of such a grail & beauty