Sears SR2100 cassette issue 304.21922250

[Ape92]

Hi,

I am working on a Sears SR2100 and when you push play on the deck is goes for about 3 seconds and auto stops itself. The belts look good and I have cleaned everything and I do not see any gear damage. What I have found is that the two gears that are driven by the belt spindle do not have teeth all the way around. When the get to a certain spot the gear gets "stuck" and stops the tape. I noticed that the belt spindle has numbers on it so I was wondering if there is a specific way to align the gears and the spindle. Thanks

 

[Superduper]

I’ve never known any capstan flywheel to require clocking when meshing with gears. However I suggest you recheck your belts. If not new, they might be stretched or lost their grip. There is a significant effort hump in the rotational cycle during start and reset operations. Your belts are all thin ones so they are more critical than large or flat ones. If they slip, the mechanism won’t work right and can’t overcome the effort hump.

 

[Transistorized]

@Ape92 The gears are fine. They aren't supposed to have teeth all the way around. The break in the teeth are where it stops to lock in the function of that gear. Looking at it from the back, play gear cam is on the right and pause cam gear on the left. As a side note, this deck will not stay engaged in play mode if the push button keys and bracket are not in place as the key assembly assists with locking the deck into play. If the push button keys and bracket are not installed and installed correctly it will not stay in play either.

But this deck is well known for the head mount issue. They do this exact thing when it cracks. This is the same style deck as the GE Blockbuster 3-5259a and the Realistic SCR-8. You can find a replacement on eBay or by contacting member superduper above.

Head assembly

Here is my old cracked head mount assembly with replacement installed.


Superduper is correct. These decks are very sensitive to belt tension.

I will make life easy for you with belt sizes (pictured below). Go ahead and replace them. You already need to order part(s) to fix it and since you already have it torn down it only makes sense.

If you need a pinch roller, the exact size is: (13 X 8.3 X 2.5mm). If it looks shiny or is hard, do yourself another favor and replace that too. I've had to open my radio way more times than I should have because I thought I was going to skimp by with minimal cost. Nope. Bit me in the a$$. Actually just got through putting it back together again today for another issue

There are two other things to check with this deck. Make sure the idler tire that engages the take-up spindle is in good shape. If it is cracked or hard you can get a replacement but it is not an exact fit. Its in the photo with the belts at the top left. Then if you are really unlucky, there's a gear that drives that idler pulley that can crack. This will be apparent when you get the deck to stay in play if you hear a clicking noise. It's pictured in the center of the belt photo. Again, this gear if needed is available through member superduper.



If you do all of this, you will have a proper working deck that may only need speed calibration. I have put literally 100 hours on mine since I rebuilt it with all of this. Mine also needed a new motor because I have such great luck (sarcastic) but it is now holding up great.

Hope this helps.