Stereo amp for mono use?

[Sal1950]

Quick question for the tech pro's here, I've poked around the net but not sure I'm comfortable with the answers.
I picked up a Adcom 5400 that I'll be using for the center channel. Since it's not bridgeable what to do with the unused channel? Many say to just ignore it but I remember back in the day it was standard practice to put shorting plugs on unused analog rca inputs.
So, to short or not to short, that is the question.
TIA

 

[RayDunzl]

Shorting the input won't hurt anything, and will prevent the amplifier from having any input to amplify.

Service Manual and Schematic.

Inputs are PJ1 and PJ2.

There's also a pair of fuses that could be pulled on the output section, if you really feel like saving a few watts.

 

[TBone]

... fuses easily accessible, to bad it's not bridgeable.

 

[DonH56]

Way back when when I was never quite sure the stability of any given amplifier I would disconnect the unused channel from the power supply. A less invasive approach was to use a shorting plug on the input and a 100-ohm resistor on the output as a bleeder just in case.

 

[Sal1950]

Thanks guys for the input!
I had read somewhere claims that under some condition that blew the 5400's rail fuses would set off another unstable situation that would take out the output transistors? Sounds a bit shaky to me but think I'll leave them in for the immediate future till I can get more solid info on that. I would like to shut down that channel as the amp runs quite hot, at least in contrast to my GFA 545s? Well see.
Think I will short the input of the unused channel just a protection against some unseen outside RF could set off a unstable condition, can't hurt.
Ciao

 

[Sal1950]

Way back when when I was never quite sure the stability of any given amplifier I would disconnect the unused channel from the power supply. A less invasive approach was to use a shorting plug on the input and a 100-ohm resistor on the output as a bleeder just in case.

Old habits die hard. LOL
I can't remember now which component it was, maybe my Crown IC-150a preamp way back in the day, that came with a big of shorting plugs and a recommendation to short any of the unused inputs? Days of Future Past.

 

[RayDunzl]

I would like to shut down that channel as the amp runs quite hot

There's probably a little potentiometer to set the bias level of the output transistors. You can turn the idle heat up and down there.

(looks at schematic)

VR603 and VR604 would seem to be them.

 

[Sal1950]

There's probably a little potentiometer to set the bias level of the output transistors. You can turn the idle heat up and down there.

(looks at schematic)

VR603 and VR604 would seem to be them.

Yep, I have the service manual with bias values, etc. may check into it later
Thanks!

 

[RayDunzl]

I would like to shut down that channel as the amp runs quite hot

The picture is hard to see if they have slip-on connectors, but it looks like you might be able to simply pull the connectors that feed from the transformer to the rectifiers for that channel.

On the schematic, AC1 AC3 DC1 DC3 for one channel, AC2 AC4 DC2 DC4 for the other.

The big chip bridge rectifier feeds the output section, little diodes on the board rectify for the low voltage driver section.

 

[Sal1950]

The picture is hard to see if they have slip-on connectors, but it looks like you might be able to simply pull the connectors that feed from the transformer to the rectifiers for that channel.

On the schematic, AC1 AC3 DC1 DC3 for one channel, AC2 AC4 DC2 DC4 for the other.

The big chip bridge rectifier feeds the output section, little diodes on the board rectify for the low voltage driver section.

Thanks Ray, I'll look into it.

 

[Blumlein 88]

Way back when when I was never quite sure the stability of any given amplifier I would disconnect the unused channel from the power supply. A less invasive approach was to use a shorting plug on the input and a 100-ohm resistor on the output as a bleeder just in case.

Yes, this is the foolproof method. Covers all the bases.

Now for the foolish things to do:

Connect the extra channel to some super tweets scattered about. Low pass the input to 20 khz and above.

Connect a series of colored 120 v floods to the extra channel and use a y-connector at the input. Gives it that late 70/early 80's disco vibe.

Connect the extra channel to one of these RS power meters.
http://www.retrothing.com/2013/01/radio-shack-apm-200-power-meter-lets-you-see-the-music.html
That way the unused channel is used.

Connect the unused channel to a power resistor bathed in scented oil. That way the music will slowly track the smell emitted by the warm oil for that hippie/new wave atmosphere.

Connect the unused channel to a peltier positioned at the listening chair so it can keep the appropriate beverage either chilled or warm.

 

[Sal1950]

Yes, this is the foolproof method. Covers all the bases.
Now for the foolish things to do:

You missed using the channel to power some type of "buttkicker" sub arrangement. For Thomas we could devise an anal-og vibrator to buzz and throb to the beat of the music.

As a serious followup I did talk to Rick at Big Sky Audio that specializes in Adcom amp upgrades/repairs and he said it would be fine to run the undriven channel with the rail fuses pulled. So I'm running it that way and with a shorting plug on the input to protect the driver stage just to be sure. Amp is biased to run HOT so anything that will save on heat pumping into these Florida digs is well appreciated.

 

[Thomas savage]

Stop trying to legitimise your fantasies of pleasuring me with your equipment!

As I told you many times its ok to daydream about me but I don't want to know about it least I have to spend 2 hours in the shower scrubbing in vain to stop myself feeling dirty..

 

[Blumlein 88]

Stop trying to legitimise your fantasies of pleasuring me with your equipment!

As I told you many times its ok to daydream about me but I don't want to know about it least I have to spend 2 hours in the shower scrubbing in vein to stop myself feeling dirty..

Is that in vain, or wow, scrubbing in veins? That is a bad habit you two have there.

 

[Thomas savage]

Is that in vain, or wow, scrubbing in veins? That is a bad habit you two have there.

It should of been a 'a' . Vain.

Doh!

 

[Sal1950]

 

[TBone]

Is that in vain

in Bane ...