New to me

My new Fisher 500c hath arrived. Apart from a damaged case, it's in fine feather. The case will need the ministrations of wood glue and clamps.

Two questions:
Is it any kind of problem to have the cable from the 1 speaker terminal touching the com lug on the 2 terminal? I bought these kimber cable n3 spades which they claimed were the correct fit for a fisher 500c. They're not but if that's not going to cause any harm, I figure I'll use the for now.

How does one get the right polarity on the plug and why does it matter?

Thanks!

Congrats

I would not have any terminal shorted to another terminal.

Have those two spades on top point up the way the two on the bottom point down.

If you trace down the AC cable with a finger, you'll find that there's a rib on one side. That's the minus (longer receptacle plug), typically, but not always. Start with that.
I mark 'em with a sharpie.

xanadu1797 said:

Two questions:
Is it any kind of problem to have the cable from the 1 speaker terminal touching the com lug on the 2 terminal? I bought these kimber cable n3 spades which they claimed were the correct fit for a fisher 500c. They're not but if that's not going to cause any harm, I figure I'll use the for now.

How does one get the right polarity on the plug and why does it matter?

Thanks!

Click to expand...

Hi!
It will do no harm for the two (2) COMMON fork terminals to touch on the same CHANNEL pair, 1 & 2, (LEFT SPKR 1 and LEFT SPKR 2 COMMON share the same ground point) and (RIGHT SPKR 1 and RIGHT SPKR 2 COMMON share the same ground point) again on the same channel, they already are (one in the same). If you look at the schematic or underneath the amp itself you will see that both COMMONS are electrically connected with buss wire.
I worried over this too trying to get modern termination to fit vintage terminal strips.
BUT, you CANNOT let any of the HOT terminals touch any other metal other than the terminations on your speaker cables, and don't let anything from one pair (1 and or 2 LEFT) touch (short) with the other (1 and or 2 RIGHT)!

All that matters with the AC cord orientation to the wall duplex is that you determine which way is quieter, marks the cord as such and always plug it in that way.

Have fun!

sony6060 said:

I would not have any terminal shorted to another terminal.

Click to expand...

+1 But it would make interesting music

Reterminate with smaller spades or, better, go bare.

notdigital said:

+1 But it would make interesting music

Reterminate with smaller spades or, better, go bare.

Click to expand...

Hi!
I concur! :yes: Letting wires touch is BAD practice for sure! Not to mention potentially catastrophic!
But, as to his question, no harm will come if the two COMMON do touch ON THE SAME CHANNEL as they are one in the same ground per pair of "1" & "2", LEFT or RIGHT respectively.

Summer's Here! :yippy:

Phyllis

Electrically it might be ok to touch the COM terminals together(depending on how they are wired!), but setting precedent by saying it is ok, ISN'T! Not all brands use a common ground (com terminal),(there have been cases of floating speaker grounds not at chassis potential)and it can conceivably cause blown output transformers, and other disasters!!! Do it right the first time and everytime afterward. KEEP THEM SEPARATE!

As audiodon said, flip 'em. If that ends up being a problem with the case on, try some different spades.

I really really really don't like going with bare wires on those old Fishers. Those screw terminals are so close together they're just a short waiting to happen.

that's why I TIN the ends of my wires and loop it around a screwdriver 1st.

larryderouin said:

Electrically it might be ok to touch the COM terminals together(depending on how they are wired!), but setting precedent by saying it is ok, ISN'T! Not all brands use a common ground (com terminal),(there have been cases of floating speaker grounds not at chassis potential)and it can conceivably cause blown output transformers, and other disasters!!! Do it right the first time and everytime afterward. KEEP THEM SEPARATE!

Click to expand...

Must be an echo!

PShuff said:

Hi!
I concur! :yes: Letting wires touch is BAD practice for sure! Not to mention potentially catastrophic!
But, as to his question, no harm will come if the two COMMON do touch ON THE SAME CHANNEL as they are one in the same ground per pair of "1" & "2", LEFT or RIGHT respectively.

Summer's Here! :yippy:

Phyllis

Click to expand...

I only harp on this as no matter what cables or wire we are are trying to use, the termination fit is always wrong, or so it seems. Bending, trimming adjusting. Dropping the darn screw driver 1/2 a dozen times along the way! :gigglemad.
Not to mention the tight fit with any sort of real interconnect!

It was just nice when I realized that my stress factor over shorting things was reduced by 50% when it came to speaker wires. I go to great lengths to make honest connections but it's just nice to know that if the COMMONS do touch then there's no harm and no foul.

Phyllis

Thanks everyone. I'm going to let them ride for now. Unfortunately, I can't flip them because of the piece at the top of the terminal apparatus. It gets in the way of the spade from the top. Anyway, maybe I'll strip the wires but without tinning them, it just makes me nervous.
This receiver sure sounds sweet though.

Not tinning them will cause the individual wires to spread out under tension from the screw. Best to tin them, as now you have a solid wire, and you can shape it to fit securely around the screw with no fear of cross connection.

You can hammer that bump on the spade terminals flat with a tack hammer.