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Dec 23, 2021
Swanage, UK
Hello one and all, as a long time collector of records I recently got into quad by chance of picking up an EMI SQ1500 decoder very cheaply and, as I had plenty of spare equipment and a few SQ records, I decided to set up a four channel system to see what I had been missing since having zero cash back in the heyday of quad in the mid 70s.

Since that first foray I decided to delve a little deeper and now have a reasonable set up that handles SQ, QS and CD-4 although I am generally disappointed with the later due to the well known issues of record wear and tear and I have an odd problem with one of my decoders and although this is probably not the place to do so would also like to pose my first question, if that is acceptable.

I am currently using a Pioneer QD-240 decoder for my CD-4 records which works OK but I also have a JVC 4-DD5 which has a rather odd issue that someone might also have come across. Basically, it has no front – rear separation. Using the JVC adjustment record, the Radar beacon lights as it should but adjustment to the separation pots just increases or decreases level on the channel being adjusted. Both front and rear stay at a similar read out as the level goes up and down (as viewed on the VU meters of my Sony SQ decoder). When I originally bought the decoder it seemed to work, at least as far as the left channel is concerned, but it soon became obvious that something was wrong. The carrier adjustment tone also cannot be heard.

I’m not at all familiar with demodulators of any kind but like most of us that value our vintage equipment am perfectly capable of exchanging components and using a multi meter/scope if need be. I’m really just asking for suggestions as to where to start looking, I assume a semi conductor has decided to fail or partially fail but I suppose it could be any one of a number of things that have decided to call it a day after almost 5 decades, NOS or not.

If anyone has any ideas or can suggest the way to proceed I would be grateful.

May I wish you all a Merry Christmas and a Happy New Year.

Kind regards