"Bulletproof" SX-1980

[crooner]

Hi guys,

As a way of further improving reliability, I recommend the use of an inexpensive "muffin fan" to cool the bottom voltage regulator board on the SX-1980.

While my restored unit runs reasonably cool, the fan idea doesn't cost much and gives me a greater peace of mind.

My rack provides ample ventilation already and installation of the fan was a snap.

I used a 220V AC rated fan. This fan running at 120V is extremely silent. You can barely hear it. It is certainly not distracting for regular music listening.

The fan is connected to the "switched" AC outlet on the receiver. This way it turns on and off with the receiver.

Regards,
crooner

 

[crooner]

Here's a shot of the fan in question:

 

[EchoWars]

Very nice. :thmbsp:

 

[crooner]

Thanks EW!

BTW, this unit gives music a "drive" that is simply incredible. The music seems to jump at you, even at moderate levels.

10 watts on the meters on this thing is LOUD!

I guess the 88,000 uf capacitance gives this unit great dynamic performance. It can easily reach 100 watt peaks at 10 watts average level.

I haven't pushed it to the "0" dB mark, and don't intend to. Like Retro Stereo, I don't wan't my house foundation to suffer

The good news is that this "brute" is very well behaved. Judicious use of the volume control is all that's required. I am using speakers rated at 100 watts max!

 

[sixt8mopar]

She is quite the beast Crooner. :thmbsp:

 

[crooner]

Thanks sixt8mopar,

Indeed she is. Too bad they [Pioneer] didn't make a black version. I like the looks of your SX-5580 I bet she sounds as good as she looks!

 

[sixt8mopar]

I could be talked into a trade for a 1980 crooner......LOL

 

[vintagestereo]

Thanks EW!

BTW, this unit gives music a "drive" that is simply incredible. The music seems to jump at you, even at moderate levels.

10 watts on the meters on this thing is LOUD!

I guess the 88,000 uf capacitance gives this unit great dynamic performance. It can easily reach 100 watt peaks at 10 watts average level.

Wow, that's interesting. The SX-1980 has the same 88,000 uf of capacitance as the SX-1250. COOL!!!!!

 

[crooner]

Wow, that's interesting. The SX-1980 has the same 88,000 uf of capacitance as the SX-1250. COOL!!!!!

Yes. But the 22,000 uf cans of the SX-1980 are physically larger and rated at 100V. The SX-1250 filter caps are rated at 80V.

The toroidal is also bigger. My guess is that the 1980 is able to handle more power because of higher rail voltages (suitable for their unique design power transistors), despite the same filter capacitance.

Still, the SX-1250 is an impressive package. A TOTL unit, and it shows!

 

[oscarav098]

Cool....

That is half is of what the A-90 has, 176,000uF. WOW!!!! :scratch2:

 

[VintageNut]

Mine's bigger

The new bragging rights: "My caps are bigger than your caps..so there!"......

 

[oscarav098]

Dude that is so funny....

It really doesn't matter, just coun't help it. Caps..shmaps...

 

[tx1488]

Hey Crooner, glad to see you're enjoying your new 1980! :wave: I've got a fan on mine too, but I had to put it on top 'cause of the solid surface it's sitting on. I've just got it blowing down on the tranny. :stupid:

 

[crooner]

Hey Crooner, glad to see you're enjoying your new 1980! :wave: I've got a fan on mine too, but I had to put it on top 'cause of the solid surface it's sitting on. I've just got it blowing down on the tranny. :stupid:

Well, curiously, in nearly all mid to late 70's Pioneer receivers the power supply pass transistors have rather small heatsinks compared to the generous share of extruded aluminum where the power transistors are mounted.

Once the receiver is correctly adjusted for idle current and DC offset, the output stage runs very cool.

The power supply board is another story, hence the muffin fan.

I don't think the fan on top of the unit is necessary. It hardly gets warm up there