Converting an older Receiver with spring loaded speaker terminals to RCA?

[barfle]

It's not the resistance of the solder. It's turning the wire end into a rigid cylindrical pin. The spring clamp is two flat edges that clamp the wire. Two flat edges only contact a cylinder on two pin points. It's that reduction of the conductor mass in that spot that acts like a resistor.

Now there are different spring clips and some of them have larger surface area contact. But the cheap ones exist and that would be the maybe not obvious at a glance concern.

Banana plugs are good for speaker connections! Recognized as the speaker plug looking connector and everything. +1 to that

If you want a super power with electronics, computers, and anything that needs wires connected? Recognize that these connections are not trivial and use the proper wires and connections. Shielding. Ground draining. Follow the design and don't alter it with substitutes.

Treat the cables and connectors like the most delicate equipment you own. Don't treat cables like rope and put any tension on them! That means no coiling like rope with little tugs and tight coils. 99/100 of the first failures or weird and intermittent malfunctions are some connection failing. Treat your cables and connectors religiously and 30 years of heavy use later... everything still just works like always.

Solder is pretty soft, but, of course, it depends on the strength of the spring clamping down on the wire and the total surface area. That's why I don't much like those knife-edge clamps in most electrical outlets, either. Having something like that carry 15 amps seems risky.

 

[barfle]

Guys the plan is in place and I linked the binding posts I bought in post 14.
Might get to the plan this weekend, or at least after the posts arrive.
I will be removing the plate the current speaker terminals are in and fabbing a new plate out of aluminum sheet and installing the binding posts in it...desoldering the old ones and soldering in the new ones..

Appreciate all the feedback.

Watch polarity, make sure the filter caps are discharged, and give your soldered terminals a tug to make sure they're solid. I believe those binding posts have shoulders to make sure the conductors don't short to the mounting plate, so make sure they're properly placed.

But you probably knew that already.

 

[Owen Smith]

Solder is pretty soft,

Traditional solder with lead in it is pretty soft, modern lead free solder less so (I hate the stuff).

 

[barfle]

Traditional solder with lead in it is pretty soft, modern lead free solder less so (I hate the stuff).

I never bother with lead-free. Some places might require it, though.

I’m going through my Marantz CD400B, replacing the RCAs with gold ones and replacing all the aluminum capacitors. Man, there’s a bunch of them, and the solder side of the board is confusing as all heck. Good old Kester 60/40 doing the job, though.

 

[mandrix]

Watch polarity, make sure the filter caps are discharged, and give your soldered terminals a tug to make sure they're solid. I believe those binding posts have shoulders to make sure the conductors don't short to the mounting plate, so make sure they're properly placed.

But you probably knew that already.

Good advice.
There will be pictures and notes taken as soon as the cover is removed. lol.
The speaker outputs, at least 4 of them, are stacked (+ - - +) in two rows. The center has a a separate output but I won't be changing that one.

But yes, the posts I bought are insulated. I will have to drill appropriate sized holes in the replacement mounting plate to fit the insulators. Conveniently they state what size hole should be drilled to fit the insulators.... .20 - .27 inch so I'm thinking a 1/4 inch hole likely but I have a good variety of drill sizes so I'm covered either way.

I don't remember how physically close the large caps are but as long as they are untouched by me should be no problem with soldering the wiring.

 

[barfle]

I don't remember how physically close the large caps are but as long as they are untouched by me should be no problem with soldering the wiring.

That part of the recommendation was just to avoid any “shocking” surprises. If you have a 10k resistor or two, just put them across the capacitor terminals for a few minutes to insure they’re discharged. Smaller values will work, too, but might heat up a bit. With the unit unplugged, of course!

 

[mandrix]

I never bother with lead-free. Some places might require it, though.

I’m going through my Marantz CD400B, replacing the RCAs with gold ones and replacing all the aluminum capacitors. Man, there’s a bunch of them, and the solder side of the board is confusing as all heck. Good old Kester 60/40 doing the job, though.

About 3'ish years ago I bought some solder off Amazon, I guess no name made in China stuff, that included a little tin of some of the best solder paste I ever used.
I usually keep a small bottle of rosin, if it hasn't become hard as a rock.

 

[mandrix]

That part of the recommendation was just to avoid any “shocking” surprises. If you have a 10k resistor or two, just put them across the capacitor terminals for a few minutes to insure they’re discharged. Smaller values will work, too, but might heat up a bit. With the unit unplugged, of course!

Oh I totally get it! I have, or at least had, a small box of resistors all separated by resistance and watt I bought for some project. Also bought some diodes for.....hmm...oh yeah, I had some device that was not properly handling PWM and had to rig up a mini circuit right at the pc fan wiring connector to bring the voltage up on one line to +5V, tapped off the 12V line.
(4 wire, or PWM for pc fan's is hot, ground, speed sensing, and PWM) Some older devices don't exactly adhere to the Intel standard for PWM.

 

[jimfisheye]

Solder is pretty soft, but, of course, it depends on the strength of the spring clamping down on the wire and the total surface area. That's why I don't much like those knife-edge clamps in most electrical outlets, either. Having something like that carry 15 amps seems risky.

Some designs that are really questionable in hindsight...

How about the 1/4" connector? I think it was military surplus after WWII that led to designing it into all kinds of audio products. For all the size and heft of the plugs and jacks these also only connect at two points. The point that the flat spring clip contacts the cylindrical plug at the tip and the point that the cylindrical shaft base contacts the larger diameter cylindrical jack hole. They look big and robust but have the poorest connection.

Then there's the part where they get used for instrument level, line level, and wait for it... amplified speaker level! Someone at Apple took a page from this playbook with the USB-C port infecting everything today. Can't tell by the plug if it's USB or thunderbolt or which versions of either are supported. And hey, lets remove the charging ports and use a USB-C port for charging too! Another reason to hate on post-Jobs Apple!

 

[audiomaster]

Some designs that are really questionable in hindsight...

How about the 1/4" connector? I think it was military surplus after WWII that led to designing it into all kinds of audio products. For all the size and heft of the plugs and jacks these also only connect at two points. The point that the flat spring clip contacts the cylindrical plug at the tip and the point that the cylindrical shaft base contacts the larger diameter cylindrical jack hole. They look big and robust but have the poorest connection.

Then there's the part where they get used for instrument level, line level, and wait for it... amplified speaker level! Someone at Apple took a page from this playbook with the USB-C port infecting everything today. Can't tell by the plug if it's USB or thunderbolt or which versions of either are supported. And hey, lets remove the charging ports and use a USB-C port for charging too! Another reason to hate on post-Jobs Apple!

But, back in the day, the military used solid brass 1/4" plugs and long frame jacks in all the equipment which were much more reliable. You could use the same Brasso to polish the plugs you used on your belt buckle before inspection! The jacks were a little more difficult to clean, but a bore brush from your rifle cleaning kit would work also, depending on caliber. Been there, done that!

 

[barfle]

Some designs that are really questionable in hindsight...

How about the 1/4" connector? I think it was military surplus after WWII that led to designing it into all kinds of audio products. For all the size and heft of the plugs and jacks these also only connect at two points. The point that the flat spring clip contacts the cylindrical plug at the tip and the point that the cylindrical shaft base contacts the larger diameter cylindrical jack hole. They look big and robust but have the poorest connection.

Then there's the part where they get used for instrument level, line level, and wait for it... amplified speaker level! Someone at Apple took a page from this playbook with the USB-C port infecting everything today. Can't tell by the plug if it's USB or thunderbolt or which versions of either are supported. And hey, lets remove the charging ports and use a USB-C port for charging too! Another reason to hate on post-Jobs Apple!

That USB-C thingy was more to be in compliance with European regulations than the just-to-be-different Lightning cable was.

Those 1/4" phone plugs are still on my headphones, and I recall more than a handful of audio patch panels full of them. And they were used for "phantom power" on the microphones.

 

[jimfisheye]

That USB-C thingy was more to be in compliance with European regulations than the just-to-be-different Lightning cable was.

Those 1/4" phone plugs are still on my headphones, and I recall more than a handful of audio patch panels full of them. And they were used for "phantom power" on the microphones.

Well, Apple started that one and it's infecting everything now! Not just the post-Jobs Apple stuff. It's even on my cheap Android phone!

A 1/4" TRS jack with phantom power?
Well, that's not standard and would be pretty frowned upon!! Plugging into a unit powered on would cause a short as the plug traveled across the connectors in the jack. Could end up sending power down the cable to the mic and frying that too. Powering off before making or breaking ANY connection would be a hard requirement!

What unit are we talking about here? Must be something older.
These are the ones where you REALLY want to read the manual first!

 

[mandrix]

I plugged in a 1/ 4 connector into an electric guitar many times while the amp was powered up. Made some racket but never killed anything. LOL.

 

[audiomaster]

Well, Apple started that one and it's infecting everything now! Not just the post-Jobs Apple stuff. It's even on my cheap Android phone!

A 1/4" TRS jack with phantom power?
Well, that's not standard and would be pretty frowned upon!! Plugging into a unit powered on would cause a short as the plug traveled across the connectors in the jack. Could end up sending power down the cable to the mic and frying that too. Powering off before making or breaking ANY connection would be a hard requirement!

What unit are we talking about here? Must be something older.
These are the ones where you REALLY want to read the manual first!

I have seen mike level jacks on patch bays. But don't recommend phantom powering thru a bay or having DC power on 1/4" jacks. Can cause corrosion at the contact points. Or phantom powering thru the "normal" connections on patch bays.

 

[jimfisheye]

I plugged in a 1/ 4 connector into an electric guitar many times while the amp was powered up. Made some racket but never killed anything. LOL.

I was talking about the use as a speaker output. Connect an amp speaker output to a line or instrument input. Same connectors.

 

[mandrix]

I was talking about the use as a speaker output. Connect an amp speaker output to a line or instrument input. Same connectors.

I get it. I been around a few years. lol. Old folks got stories.

 

[mandrix]

Well I've decided to move some "stuff" around in the audio room again so I can mount the new TV and not interfere with my big honkin' Center speaker, which will get moved a little higher.
Music is not static, and neither is the pursuit of good A/V.
Or so I tell myself. My wife just shakes her head.

 

[barfle]

Well, Apple started that one and it's infecting everything now! Not just the post-Jobs Apple stuff. It's even on my cheap Android phone!

A 1/4" TRS jack with phantom power?
Well, that's not standard and would be pretty frowned upon!! Plugging into a unit powered on would cause a short as the plug traveled across the connectors in the jack. Could end up sending power down the cable to the mic and frying that too. Powering off before making or breaking ANY connection would be a hard requirement!

What unit are we talking about here? Must be something older.
These are the ones where you REALLY want to read the manual first!

I was responsible for (among plenty of other things), a conference center that had three joinable rooms with somewhere over 100 floor boxes with XLRs for phantom-powered mics. Every cable went to a patch bay that was populated with TRS 1/4” phone jacks, eventually going to one of three Yamaha mixing consoles.

On one of the XLRs, I left a bit of the shield wire exposed, and when it contacted the metal floor box and shorted the phantom power, it was quite the racket. IIRC (and it’s been ten years+), those phantom power sources are current-limited, so nobody’s going to get zapped.

Glad I don’t have to worry anout that stuff any more. But I still have so many projects in my house, I’m thinking of calling the place “The Projects.”

 

[barfle]

Well I've decided to move some "stuff" around in the audio room again so I can mount the new TV and not interfere with my big honkin' Center speaker, which will get moved a little higher.
Music is not static, and neither is the pursuit of good A/V.
Or so I tell myself. My wife just shakes her head.

Yep. I’ll stop working on my room when I’m carried out.

 

[mandrix]

I hope sometime this summer to build an A/V rack. I was going to move my old audio cabinet out of the living room but it's a tad too wide. The advantage to using the old one is because I basically rebuilt some of it years ago, put in a new backing and cut out holes for ventilation fans. It was once part of a big entertainment center but as tv's got bigger it just wasn't feasible to use any more.

Probably/maybe just build a simple open shelved rack but elevated off the floor enough for easier old man access.

My speaker binding posts for the Receiver should be here today, though it may be dark thirty before delivery with the vagaries of the postal service these days.