675a card

[Frank Raia]

What is the spare 675a card slot for in the cp500?

[Ryan Gallagher]

Directly from manual, states the additional 675A provides AC3 decoding. (Page 3-11)

[Frank Raia]

I see that now, thank you for your response! I plugged an extra 675a card in there and the unit errors and will not boot. I changed the jumper on the card and same thing happened. Was it a totally different card?

[Frank Raia]

So Ryan, the card that you speak of is in the J19 slot. That is not what I was inquiring about. I was wondering about the spare J13 slot

[Ryan Gallagher]

I would think the one marked "SPARE" is merely a place to park a spare/backup card. But they could have meant "spare" slot, as in "reserved for future use". Someone more familiar with the CP500's design might have an answer, cause the manual says nothing about the spare slot or J13 (as you probably found when looking).

Apologies, I read your OP as "2nd 675A card" not the actual spare slot. It doesn't seem from your testing that it was intended to house a hot-spare 675A! ;-)

[Frank Raia]

Ryan, I guess it is just a spare slot not used. I plugged an extra 675a card in and the unit would not boot up. Oh well I guess it was never used

[Frank Cox]

Probably a motherboard designed for something else and repurposed; the extra slot was for whatever it was originally.

I don't imagine too many outfits are going to design and manufacture a custom motherboard if they can use one off-the-shelf.

[Frank Raia]

Being curious I did find 2 jumpers on the backplane. One to bypass j13 and one to include it

[Ryan Gallagher]

Being curious I did find 2 jumpers on the backplane. One to bypass j13 and one to include it

That seems pretty intentional. When you tested with the extra card had you tried the J13 include jumper config?

[Randy Stankey]

I think it's an "Exclusive-OR" decision. You place the jumper bar on the left header if you have the option installed or place it on the right side if you don't have the option installed. You leave the other side empty. If you leave both sides empty, you'll get nothing. The jumpers just reroute circuits through or around a PCB connection, depending on whether the slot is empty or not.

[Frank Raia]

Ryan, I did not know the jumpers where there when I plugged in the extra card. I changed the jumpers on the card not the backplane. But I am going to try changing the backplane jumper and see if anything changes. I hope I don't kill the card or the backplane.