Sanyo 9994

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Superduper

Member (SA)
Belts:
5.4" large square belt (main)
Other belts to complete the job:
10.5", 7.0" and 10.0". These are combination of orbicular and transital but small square belts should work.

=====================

(1) Remove the back cover, note the locations of all tethered wires, disconnect them.
(2) Remove all the knobs
(3) Disconnect the speaker connectors.
(4) Remove the chassis from the front case. Note the location of all screws. If any wires remain tethered, note their locations and disconnect them.
(5) From the front, Carefully unclip and remove the tuner dial -- set it aside and protect from scratches during the procedure. Masking tape works wonders.
(6) Remove the screws securing the mechanical assembly.
(7) Carefully lift out the mechanical assembly -- carefully turn it around. It is tethered with wires. They are soldered and not easily disconnected. It is easier to work with the assembly desoldered and removed but is more work. It can be rebelted tethered but you'll need to be careful not to fatigue any wires and snap them. Because if you do, it will be hard to find where they were originally connected to.
(8) Place a cloth or other protective material between the mechanical assembly and the chassis in such a manner that you can work on it without scratching or damaging any cosmetic parts.
(9) Remove the backing plate that secures the flywheel. This should expose the flywheel and rotating assemblies. Be mindful that there is a bushing below one of the screws. If you lose it, then you're in deep doo doo. Can't remember right now but I think the other side might be spring loaded. If so, count the turns or check flywheel end play and try to duplicate this amount. The spring is used to adjust flywheel endplay. When replacing screws, replace screw set compound. Fingernail polish might work.
(10) There is a main belt that is hidden under the flywheel. It is a 5.4" Large square belt and not normally visible. Lift off the flywheel but be advised that a small washer will fall from the capstan needle from the front side. Find and keep this washer -- you will need to replace it when done.
(11) If you suspect that the clutch is worn (slipping), then the clutch will need to be removed, cleaned, and the friction surfaces slightly abraded to improve friction (there are no replacements).
(12) Clean all belt and pulley surfaces with 100% (or as near as possible) isopropyl alcohol.
(13) There is at least 2 belt routing methods for this model depending upon when it was released so the method you employ will depend upon your boombox. Best for you to note the original routing.
(14) Replace all belts with proper sized belts. A belt installation hook tool is almost required to do the inner belt.
(15) Reassemble, reversing the entire process.

This is a simplified description of the process. You must exercise common sense and possess good mechanical aptitude to do this. Not every step is enumerated here. You will need to note and document along the way as necessary in such a manner as to allow you to reassemble. Please don't take short cuts because then you'll be back asking where does this wire go, or what screw goes where and such. The best reference that you're going to have are the photos you took of the process to guide you back to the beginning. Think of them as bread crumbs.

Tips:
(1) Lube the capstan needle shaft near the base with a teeny bit of silicone grease. Also slightly lube the flywheel rear shaft to nylon bushing on the backing plate.
(2) It is easy to get grease on the belts when slipping them on since they are likely to contact one of the greased locations. Make sure you go over everything when done with 100% isopropyl alcohol to remove any trace of grease or you'll just spread the grease over the entire pulley assembly and A: cause belts to deteriorate faster and B: cause potential slippage.
(3) The flywheel backing plate might include a freeplay adjustment screw (it would have a spring). If you did not count the turns to begin with to restore to original spot, adjust to remove freeplay but allow fre movement of flywheel. It should spin like a bike wheel. Too tight and it will affect playback speed.
(4) If it continues to slip or eat tapes -- suspect a slipping clutch.
(5) There is a tendency to overgrease parts. If parts that originally slid freely are greased, the part may not function properly when the grease gets old and thickens up preventing free movement of that part.
(6) A lot of the greased parts will have turned to wax. Try to loosen up and free the sliding parts with a Q-tip soaked in 100% isopropyl.

And if worse comes to worse, and you feel like you can't do this on your own -- send it to me and I'll replace them for you for a few $$'s.
 

Tacooooooo

Member (SA)
May 5, 2010
110
0
0
31
Texas
I've opened it and I've notice that its missing some screws that keeps the chassis in place. I could see that it does have belts, but one looks rather thin. When I press play, nothing ignites. Spindels don't move or anything. I could try to replace the belts myself, but I rather not mess anything up. Also, is it normal for the speakers to "pop" on the 9994? At high volume and bass output, the speakers tend to make a popping sound. Is that normal?

Let me know what you know.
Thanks.
 

Superduper

Member (SA)
If the motor is good and you don't feel comfortable doing it yourself, then send me a PM if you want me fix for you. How many belts can you see? There are 4 and they can't be accessed from the backside. At least that's not the way I would recommend. At least one is buried beneath the flywheel and is almost totally hidden. You can tell if the motor is good by pressing play and see if you can hear or feel the motor working.

As for the speakers popping -- I don't notice that on my examples and I hardly play the boombox at 100% volume, especially with bass full on. The M9994 is more of a good sound quality type of box at reasonable sound output levels -- it's not a bass monster. However, if you deem the condition abnormal, there could be many reasons. The first of these that comes to mind is the amplifier bias levels are out of whack, a voltage regulator is toast or the capacitors are worn out.
 

Tacooooooo

Member (SA)
May 5, 2010
110
0
0
31
Texas
I can see two belts without tampering with it. When I press play, I hear nothing. Motor dead? And as for the speakers, At a reasonable volume level it sounds great. Only when its at a higher level is when the speakers kinda make that loud "boom" sound.

I'm just curious as to how much you would charge to fix it.
 

Jedidiah

Member (SA)
Aug 26, 2014
21
0
0
Metro Detroit
Superduper said:
Belts:
5.4" large square belt (main)
Other belts to complete the job:
10.5", 7.0" and 10.0". These are combination of orbicular and transital but small square belts should work.

=====================

(1) Remove the back cover, note the locations of all tethered wires, disconnect them.
(2) Remove all the knobs
(3) Disconnect the speaker connectors.
(4) Remove the chassis from the front case. Note the location of all screws. If any wires remain tethered, note their locations and disconnect them.
(5) From the front, Carefully unclip and remove the tuner dial -- set it aside and protect from scratches during the procedure. Masking tape works wonders.
(6) Remove the screws securing the mechanical assembly.
(7) Carefully lift out the mechanical assembly -- carefully turn it around. It is tethered with wires. They are soldered and not easily disconnected. It is easier to work with the assembly desoldered and removed but is more work. It can be rebelted tethered but you'll need to be careful not to fatigue any wires and snap them. Because if you do, it will be hard to find where they were originally connected to.
(8) Place a cloth or other protective material between the mechanical assembly and the chassis in such a manner that you can work on it without scratching or damaging any cosmetic parts.
(9) Remove the backing plate that secures the flywheel. This should expose the flywheel and rotating assemblies. Be mindful that there is a bushing below one of the screws. If you lose it, then you're in deep doo doo. Can't remember right now but I think the other side might be spring loaded. If so, count the turns or check flywheel end play and try to duplicate this amount. The spring is used to adjust flywheel endplay. When replacing screws, replace screw set compound. Fingernail polish might work.
(10) There is a main belt that is hidden under the flywheel. It is a 5.4" Large square belt and not normally visible. Lift off the flywheel but be advised that a small washer will fall from the capstan needle from the front side. Find and keep this washer -- you will need to replace it when done.
(11) If you suspect that the clutch is worn (slipping), then the clutch will need to be removed, cleaned, and the friction surfaces slightly abraded to improve friction (there are no replacements).
(12) Clean all belt and pulley surfaces with 100% (or as near as possible) isopropyl alcohol.
(13) There is at least 2 belt routing methods for this model depending upon when it was released so the method you employ will depend upon your boombox. Best for you to note the original routing.
(14) Replace all belts with proper sized belts. A belt installation hook tool is almost required to do the inner belt.
(15) Reassemble, reversing the entire process.

This is a simplified description of the process. You must exercise common sense and possess good mechanical aptitude to do this. Not every step is enumerated here. You will need to note and document along the way as necessary in such a manner as to allow you to reassemble. Please don't take short cuts because then you'll be back asking where does this wire go, or what screw goes where and such. The best reference that you're going to have are the photos you took of the process to guide you back to the beginning. Think of them as bread crumbs.

Tips:
(1) Lube the capstan needle shaft near the base with a teeny bit of silicone grease. Also slightly lube the flywheel rear shaft to nylon bushing on the backing plate.
(2) It is easy to get grease on the belts when slipping them on since they are likely to contact one of the greased locations. Make sure you go over everything when done with 100% isopropyl alcohol to remove any trace of grease or you'll just spread the grease over the entire pulley assembly and A: cause belts to deteriorate faster and B: cause potential slippage.
(3) The flywheel backing plate might include a freeplay adjustment screw (it would have a spring). If you did not count the turns to begin with to restore to original spot, adjust to remove freeplay but allow fre movement of flywheel. It should spin like a bike wheel. Too tight and it will affect playback speed.
(4) If it continues to slip or eat tapes -- suspect a slipping clutch.
(5) There is a tendency to overgrease parts. If parts that originally slid freely are greased, the part may not function properly when the grease gets old and thickens up preventing free movement of that part.
(6) A lot of the greased parts will have turned to wax. Try to loosen up and free the sliding parts with a Q-tip soaked in 100% isopropyl.

And if worse comes to worse, and you feel like you can't do this on your own -- send it to me and I'll replace them for you for a few $$'s.
thank you for this !!!! i will need it soon
 

Michiel

Member (SA)
Dec 29, 2012
209
41
28
Netherlands
Tacooooooo said:
I can see two belts without tampering with it. When I press play, I hear nothing. Motor dead? And as for the speakers, At a reasonable volume level it sounds great. Only when its at a higher level is when the speakers kinda make that loud "boom" sound.

I'm just curious as to how much you would charge to fix it.
It's wise to turn off the loudness (or turn the midtone on) at high volume levels. It's easy to oversteer the woofers on this box. Full bass, loudness and high volume will make the speakers distort for sure, it's normal. Like sd says, this box is all about quality, not quantity :)
 
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