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Helped needed ASAP Tape Deck Jvc-Rc-M90


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#1 prg333

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Posted 20 April 2015 - 07:24 PM

I brought my M-90 to my friend to work on. He cleaned up all the dirt inside and got the switches all cleaned and aligned the radio. The FM stereo now works instead of being intermittent. The radio now sounds very very good, The tape deck is giving him a HELL of a time. He was not able to fully remove the tape deck from the unit. He says it is hanging, but the wires seem to short and the plastic holding it may just break(making the deck useless)   So he could not get at the belts or check, oil the motors.

 

It now plays well and and  at the correct speed. Even with the existing belts.It will play rewind fast forward. The multi   music scanner works well also. The tape deck will work fine thru several tapes

 

The  problem occurs when the box is turned off and on again. The deck will start to make a loud grinding noise. NOT the regular clicking of the deck going thru its normal cycle (with a tape in the deck) the ONLY way to stop the grinding is to unplug the box, the power button will NOT cut the power to the deck.. 

 

So something must be rubbing against something (A metal piece) Has anyone had this same EXACT problem with the tape deck? And how did you fix it?  

 

 

When you unplug then you can hear the motors dis-engage. When the box is powered up then the normal cycle of the deck occurs and the tape plays fine.. 

 

So how do you remove the tape deck completely from the box? The service Manuel says you can do it from the front of the boom-box. But that seems to be very very hard .. So how does one do it from the back of the unit? How do you get at the belts and the motor..

 

Thank you for the advice, I really appreciate it.

 



#2 Superduper

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Posted 20 April 2015 - 08:33 PM

Deck should come out the back.  There should be enough slack to service the deck properly.  Everyone does it this way.  Wires that can't be unsocketed must be desoldered.  Grinding sound might be due to slipping belt, or maybe a mechanical issue introduced by the work?



#3 prg333

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Posted 20 April 2015 - 08:39 PM

The Grinding sound WAS happening before the boom-box was opened up. I will pass along the info to my friend about unsotering the wires



#4 prg333

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Posted 25 April 2015 - 06:57 AM

Well my friend did a GREAT job on my M-90!  He opened it up and cleaned it completely inside. He had to align the FM band which had 21 pots to adjust. He also got the deck out of the box and cleaned and oiled the motors. New fresh belts were installed. Before I had it someone went in there and bent the metal plate in the back.

 

He also made  a tone test tape with a scope.. So he could perfectly adjust the tape deck speed.  

 

The FM sounds fantastic. .Crisp clear with great base. The stereo works now and has a great natural separation.

 

The tape deck sounds great and has NO WOW OR FLUTTER!

 

The only remaining problem with the tape deck is that it still makes a loud chattering sound.It wount stop unless you turn off the radio or unplug it. Mostly when it is first turned on. Ones it warms up it does it less. One of the plastic gears, is slipping and the teeth are worn. He said it is attached to the flywheel so it is impossible to replace. So one would need a ENTIRELY exact same  deck, to fix the problem.. I believe that the M-80 has the same exact auto logic  tape deck as the M-90. So he says if I can get one with a good tape deck and the gears are all good, no wear (like on mine) he CAN swap out the deck from a good M-80 and put in My M-90.

 

Has anyone ever done this? I will post pics of my FINE WORKING GREAT Sounding HANDSOME M-90



#5 prg333

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Posted 30 April 2015 - 09:56 AM

Yes If I could get good cog/gear to replace the one that is worn then ALL would be GOOD!

 

My tech could replace the bad cog. Trick is how do you find the EXACT gear/cog. Best would to get a electronically fried M90 and swap out the deck. Or get the exact specs of the cog put it in a STL file to tell the teleprinter of a 3D-printer "brain" to make the needed cog.



#6 Mike

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Posted 03 July 2015 - 08:10 PM

Are you located in California by chance?  I have a spare M90 deck and would give you this piece if your friend is willing to show me how to open up the box and do general maintenance.

 

I bought the spare M90 deck on EPAY to replace the dead deck on the M90 that I bought.  I (not me...a tech) swapped out decks, but I do want to keep the remainder of the "broken" deck so that I can do future maintenance.  I was very fortunate to find this.  I actually found it as soon as I got home from buying my M90.  I haven't seen anyone part an M90 since.  

 

The "broken" one looks mint.  The problem is something with the board as the motor wouldn't even turn on.

 

-MT



#7 JVC Floyd

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Posted 03 July 2015 - 08:20 PM

could be that red transistor on the back of the deck pc board blew out . it will stop the deck dead when these blow out. might be a resistor either way it will kill the deck if it don't work.



#8 toshik

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Posted 03 July 2015 - 09:50 PM

He also made a tone test tape with a scope..


I'd love to hear how to make a tone test tape with a scope, please share!

#9 prg333

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Posted 18 January 2016 - 02:04 PM

I'll have to ask him my friend made the tone test I know he made it with the tape deck that I brought over

#10 prg333

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Posted 18 January 2016 - 02:06 PM

My tech guy doesn't think it was the Red transistor as he said if it powers up and it plays tapes every time then it probably is not that. Most likely that cog wearing out that's attached to the flywheel. So I have to get an entire replacement deck from and M 90 that might be dead completely electronically but the deck plastic parts are fine. Or get an exact sized cog made with a 3-D printer but that be more difficult to get an exact size cog

#11 caution

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Posted 22 January 2016 - 01:55 AM

Maybe someone here can confirm or deny the type of plastic used for the cogs. If there's a chance they're not Nylon, you might be able to repair the teeth by taking a plastic solvent and dissolving chunks of plastic into it until it's thick, and apply it on the worn teeth, then let it cure and file it back down to original shape.

 

If they're Nylon, which I'm afraid they might be for their resistance to wear, yeah, you'll have to take some measurements and design one and print it with a plastic that has some amount of durability.

 

Find out for sure that it's actually worn, you should be able to figure that out without removing it.



#12 prg333

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Posted 08 February 2016 - 09:27 PM

Maybe someone here can confirm or deny the type of plastic used for the cogs. If there's a chance they're not Nylon, you might be able to repair the teeth by taking a plastic solvent and dissolving chunks of plastic into it until it's thick, and apply it on the worn teeth, then let it cure and file it back down to original shape.

 

If they're Nylon, which I'm afraid they might be for their resistance to wear, yeah, you'll have to take some measurements and design one and print it with a plastic that has some amount of durability.

 

Find out for sure that it's actually worn, you should be able to figure that out without removing it.

 

Sounds like an idea I will look into it.