Marantz 7 question

[DoctorD]

Searching ebay I noticed some Marantz 7's have Selenium Rectifier's and the one I have looks nothing like it. Was this a product up grade during manufacturing?

Can someone please explain.

Thanks,

[speakerdave]

In the seventies, when I last saw a Marantz 7 in person (I was handing it to the person who bought it from me) the hot topic about those selenium rectifiers was getting rid of them, so if you have not owned yours since new, maybe that was done to it.

[crooner]

I believe all Model 7's came equipped with selenium rectifiers. What serial number (or range), is yours? The latest serial number I have in my database is 22014 which corresponds to late 1965. Right before the solid-state 7T was introduced.

My own model 7 still runs on its original selenium rectifiers and I don't plan to change them anytime soon. Collectors in the Orient claim selenium has certain euphonic characteristics that are pleasant to the ear. I tend to agree.

If the selenium(s) are changed, it becomes necessary to add a series resistor to compensate for the lower voltage drop of silicon rectifiers.

You may want to post a picture of your unit so I can attempt to ID your rectifiers.

[DoctorD]

Here is a picture of the one I have. I have noticed several for sale that look similar to mine and just thought it might have been somthing that was changed during the manufacturing process. The ser # is 13438. My father bought it new and then gave it to me in 1979. So if they were never built like this then I guess since he was a repair tec he would have changed it to what it looks like now. Can you give the approx manufacture date?

Thanks for the help,
Dennis

[crooner]

Your unit is relatively early in the model run. Most likely made between 1961 and 1962. I'm sure the silicon diode was a replacement. Could also have been done by the dealer (or their service dept.) which was common. A five minute job.

Unfortunately, there doesn't seem to be any additional series resistor added to the diode.

Given the value of the unit, it may be worthwhile to check the B+ (HV) voltage against the schematic. If too high, add a corresponding resistor after the diode.