Superstar 3900 Channel Selector Board

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486dx4
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Superstar 3900 Channel Selector Board

Post by 486dx4 » 11 Jul 2018, 01:13

Hello,

I have an old Superstar 3900 with the EPT3600-11z main board which is the same board as a Galaxy 2100 I was writing previously about . The 3900 radio which was in pieces has an EPT360022Z channel selector board. I am trying to bring the radio back to life and on an identical board model Superstar 3900 I have that is intact it has this EPT360021Z board for the channel selector. The wiring is different between the 21Z and 22Z boards as well as the board layout.

Is the EPT360022Z board the substitute for the 21Z model by chance? I know this is very old stuff so if anyone knew what channel selector would work in this old model radio other than the EPT360021Z or know where to maybe purchase a used working EPT360021Z that would be great.

Thanks in advance for any information.

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14CS06
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Re: Superstar 3900 Channel Selector Board

Post by 14CS06 » 11 Jul 2018, 11:55

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cb4ever104
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Re: Superstar 3900 Channel Selector Board

Post by cb4ever104 » 13 Jul 2018, 09:32

486dx4 wrote:
11 Jul 2018, 01:13

Is the EPT360022Z board the substitute for the 21Z model by chance? I know this is very old stuff so if anyone knew what channel selector would work in this old model radio other than the EPT360021Z or know where to maybe purchase a used working EPT360021Z that would be great.

Thanks in advance for any information.
Hi .

It uses the same 501 channel selector , so yes . It'll work , but you may have to rewire it a bit to suit the main pcb . The output of the channel selector is binary 91 to 135 . If you do the maths on your 11Z then you'll see that that's the case . Ch1 LOW = 25.615 - 10,695 IF = 14.920 - 14.010 (your low bands Xtal) = .91 Mhz , which is your downmix signal . That gets divided by your 91 channel selector to give the 10khz spacing .

Anyway . If your replacement EPT360022Z ch.sel pcb has already been removed then you'll need to power it up temporarily to an 8V supply and find out which wires are which . So put it on CH 1 and you'll have 01011011 on your 8 program wires somewhere . 135 will be 10000111 . Now the mapping from the channel selector pcb to the main board might be 1 to 1 . Or they might be mixed up . I haven't had to mess with my 11Z channel selector so I don't know . Anyway . The ch. sel. wires will go to the same binary adder pins from any other 3900 , so it shouldn't take you long to figure it out .

Good luck.

Sammy
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