Quote:
Originally Posted by andypilgrim
If you have noise at both the top and bottom of the picture it suggests that the head to tape contact is poor at the beginning and end of the wrap, this was often caused by low tape back-tension. The back tension is provided by a brake band around the base of the supply spool and the tension is controlled by a guide lever /post that is on the left of the mechanism normally between the first fixed guide as the tape comes out of the cassette and the erase head. Two possibilities, one is that the pivot for that guide lever is gummed up so the guide is not free to move, the other is that the felt lining has fallen off the brake band, both possibilities are equally likely.
I would say twiddling with the entry and exit guides on the drum is a bad idea as the don't tend to go out of adjustment without some human help and re-aligning them requires an oscilloscope and ideally a proper alignment tape to get the envelope flat. As someone has already said, the adjustments affect each other and you cannot really gauge what is happening from a picture alone.
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Thanks for you advice andypilgrim. That machine is now working pretty well with only minor tweaks of the input and output rollers. I have been able to buy the complete JVC tool set on Ebay and have also bought a decent used Tektronix scope. I'm looking out for an alignment tape. (I have a Sony Betamax one I bought in the 70s)
My attention has now turned to a rather sick JVC HR-3330. The subject of another thread.
https://www.vintage-radio.net/forum/...d.php?t=179353