Hello,

My TPR-990 just gave it up.  Inspection shows belt stretched, too loose.  Anybody here know correct main belt size?  I searched and saw some who have replaced belts on this fine box.  Any info, tips, leads, greatly appreciated.  I miss this thing already, please help!

Many Thanks!

I strongly advise taking this to a techie or having someone capable of doing this correctly for you. This is not an easy box for anyone not good technically to replace the deck belts and it be 100% perfect afterwards.

If you know what you are doing then get a hold of the service manual to get you into where you need to be and take photo's all the way. This deck is not easy and some will have you believe they have worked on it successfully but subsequently had problems.

Where are you based ?

I am in USA - Oregon.  Very good advise.  I  replaced all belts on this thing once before about 7-8 yrs ago.  Yes it was a royal pain and I am not looking forward to it again.  I am going to have to learn all over!  I got the replacement belt from a member here but it came in a clear bag with no size info.   I also had to replace the main motor at that time which was dead.  I expected belt to last longer but dont know for sure if main belt I used was correct size now?  I have portables from 1980 with original belts working perfect so this was a disappointment of course.  Especially since this was the hardest unit I have ever fixed.   Any help with correct/best size appreciated!

Take a look here for information and how to calculate the belt size for your box.

The TPR-990 uses Belt SCX4.0.

Page 278 onwards explains sizes for those type of belts.

All measurements are in inches.

This may be for the counter belt since it is smaller square belt.  Looks like they only list one belt type but this unit has 5 belts.  The one I need is main drive belt which is flat style, about 3/16 wide.  I have not removed belt yet but guess it will be somewhere around 8-10" length.   Original Aiwa P/N:  82-562-227-01, only description is:  main drive belt(no size).  

just looked at belts i ordered a while ago and found the main belt flat 0.5 3mm 72 diameter for the 990

Excellent, Thank You!  Can you tell me where you found it?  How did it work?

my first 990 was fine and worked on all tape functions . the second one was a right james hunt !  as docs will tell you           the belts i bought here in the uk , sure there is a source in the usa that members can put you in touch with .

So length is 3.14 x 72 = 226mm or about 8.9"    Is that right?

no the main belt is 3mm wide   length 125 mm folded in half if you get me .

I think so....   3mm wide, .5mm thick and 72mm diam.    So to get length I used pie(3.14) x diam(72mm) = 226mm.  Converted to inches = 8.9   I think I remember belts I ordered before required total length in inches.  Of course I am in the USA so this may not be true for you.  I also remember belts need to be some percentage smaller than actual measured length around pulleys.  Anyone know what that should be?  Still seems like one of us must be wrong though if you have folded length of 125mm, meaning total length = 250mm?  Frustrating how abstract this all seems to be.  The manufacturer didnt help any either.  The factory service manual only gives a P/N which of course is NLA(no indication of correct length).   To go through all the work required to replace a belt on a 990 and end up installing the wrong size is too much to bear for a second time. 

my 990 has servicing receipts for about four belt changes,it has a mind of its own at the minute and needs looking at..it plays ok then slow then nothing?

they are a great radio the 990 but they look very hard to work on..way out of my league

The 990 actually has 5 belts, 2 motors, a gear box with cam lobes...  yes very complex.  You actually need to give it a little time between key presses to finish last request(only a second or two or until LED above button goes out).  So did your unit actually get all belts replaced 4 times or was it one service event with multiple belts changed out?

Hey Bison,  I looked at some earlier posts and the box you got looks awsome!  I could not believe the reciepts you got with it from back to day 1 new!  I did my belts 7-8 yrs ago and yes it was hard.  However that was mostly because bad motor, and lots of cleaning time inside the box.  I got looking at mine and just a belt replacement may not be hard at all.  Hardest part is getting correct size I think.  Sounds like yours is doing exactly what mine was before it quit.  Main belt stretches and slips.  First no power/speed to RR/FF and finally play stops turning.   If I can get main belt size it looks like it may be easy to replace.  It looks to me like a small nylon screw behind the flywheel back out to allow gap for belt replacement!  This means only taking the back off the unit.  New belt would could be slipped around main flywheel and motor pully without removing a single other screw I believe.