This little ITT-KB cassette recorder is from 1971, it looked to be in very good condition. I bought it a while ago now, and just got around to putting it on the work bench with the idea of cleaning it to photo for the museum.
I also took a look inside and saw that as expected the belts had broken into pieces and were laying around inside the case.
I fished them out before they all turned to black goo as they had started to already. I had a small belt for the idler to re-wind capstan which I had made before. But I only had larger ones that were slightly too large to use for the main drive belt.
This is how I did it;
Cut the belt you are going to resize, place it around the pulleys and mark where the ends overlap.
Put the belt on a firm surface and with a very sharp craft knife cut at the mark at 45 deg across the belt, (the narrower the angle the better). Then cut about 1cm off* the other end to match the angle of the first cut, this shortens the belt slightly to give it some tension.
Place the belt on a non-stick surface, I use a small sheet of clear polythene, and match the ends together. Next get the tiniest drop of superglue, I use a very small jewellers screwdriver, and place the drop on one end of the cut belt then push the the two ends together, lining up the two 45 degree cuts and whilst maintaining the smooth curve of the belt. Hold it for about 10 seconds, wipe of any surplus glue and job done.
On reassembly and testing the recorder it worked very well except that when I tapped the bench it gave the most awful crackles ending in a rather loud hum. This turned out to be a loose earth wire to the volume and tone controls bracket, it must have pulled the solder of the spring mounting for the VU meter when I was moving the main chassis around.
When soldered back on the recorder worked perfectly, and when the case was resembled I was very impressed with the tonal quality of the tape I had used. Engelbert's rich tones came out very well and I was impressed at the good high frequency response, far better than I remember cassette recorders sounding.
*How much to cut off depends on the total length of the belt, but for this one I estimated about 1cm to be about right. If in doubt cut slightly less and if the belt is loo loose then redo the join.
Mike
I also took a look inside and saw that as expected the belts had broken into pieces and were laying around inside the case.
I fished them out before they all turned to black goo as they had started to already. I had a small belt for the idler to re-wind capstan which I had made before. But I only had larger ones that were slightly too large to use for the main drive belt.
This is how I did it;
Cut the belt you are going to resize, place it around the pulleys and mark where the ends overlap.
Put the belt on a firm surface and with a very sharp craft knife cut at the mark at 45 deg across the belt, (the narrower the angle the better). Then cut about 1cm off* the other end to match the angle of the first cut, this shortens the belt slightly to give it some tension.
Place the belt on a non-stick surface, I use a small sheet of clear polythene, and match the ends together. Next get the tiniest drop of superglue, I use a very small jewellers screwdriver, and place the drop on one end of the cut belt then push the the two ends together, lining up the two 45 degree cuts and whilst maintaining the smooth curve of the belt. Hold it for about 10 seconds, wipe of any surplus glue and job done.
On reassembly and testing the recorder it worked very well except that when I tapped the bench it gave the most awful crackles ending in a rather loud hum. This turned out to be a loose earth wire to the volume and tone controls bracket, it must have pulled the solder of the spring mounting for the VU meter when I was moving the main chassis around.
When soldered back on the recorder worked perfectly, and when the case was resembled I was very impressed with the tonal quality of the tape I had used. Engelbert's rich tones came out very well and I was impressed at the good high frequency response, far better than I remember cassette recorders sounding.
*How much to cut off depends on the total length of the belt, but for this one I estimated about 1cm to be about right. If in doubt cut slightly less and if the belt is loo loose then redo the join.
Mike
