PL 3300 preamp and weird driver travel

[scottonnob]

I just acquired a 3300 preamp and set it up to test all the functions. I used a known amp and known speakers, then played a CD through all the inputs. However, even though the music seemed to play fine, when I took the grill covers off, one of the woofers was pulsing, waffling, or traveling extremely far, back and forth, seemingly on its own, and through all the inputs. The other channel was fine. I did everything necessary to determine that the problem is coming from one channel on the pre, but I don't know where to start to look for the cause. The woofer waffles this way even when the volume is all the way down. It may be pulsing to the music that's being played, but I can't really tell. Another weird thing is that the power light stays on as long as the unit is plugged in. It never goes off until the pre is unplugged. Yet another thing is, I can't seem to get the headphone jack to produce a signal, regardless of whether I use Switched or Unswitched. Any ideas?

 

[laatsch55]

Do you have the service manual?

 

[scottonnob]

No. I thought I did, but no luck.

 

[scottonnob]

Okay, found one online. Something I should look at, specifically?

 

[laatsch55]

Look for a cap and resistor on the on/off switch....

 

[laatsch55]

And read the troubleshooting section....

 

[laatsch55]

The troubleshooting section is very concise and well written....

 

[scottonnob]

I'll give it a read and identify those parts. Thanks.

 

[scottonnob]

Would what you are suggesting likely be the source of the odd speaker behavior, or just the light failing to turn off? There's something wrong with the left channel, apparently somewhere before the output jack. I'm tempted to just take the thing apart and give it a full overhaul. But I'd like to get it working properly first. Thanks for the input, Scott

 

[scottonnob]

I now realize I'm also getting significant on/off thumps that this amplifier never generates with my other preamps. I've heard the Phase Linear turn-off thumps, but this is also occurs when I power up. I have another 3300 paired with a Series II 400 Phase amp and this just doesn't happen with them.

 

[laatsch55]

The cap and resistor on the power switch can be part of the problem, I suspect caps and op-amps for the other problems.

 

[scottonnob]

Sounds like it may be time to just rebuild the thing. A friend just gave it to me, so I don't mind putting some time and money into it.

 

[laatsch55]

They don't cost that much to restore, 100.00 in parts maybe. And the low frequency response can be helped a lot. I'll see if I can link the thread where we did that...

 

[scottonnob]

That would be great. I planned to upgrade it anyway, I'll just put that at the top of my list, rather than toward the bottom. Time to start ordering parts.

 

[laatsch55]

Here's one, I may have another with more info....http://forums.phxaudiotape.com/showthread.php/2722-Absolutely-Gorgeous-Phase-Linear-3300-Ser-II

 

[scottonnob]

Thank you. I'll start compiling a parts list from the thread.

 

[scottonnob]

I just put a meter on it, and the On/Off switch is not disconnecting the power. There is voltage from the switch, regardless of the switch position. I'd sure like to troubleshoot this problem before tearing the whole unit apart for a rebuild. How likely is it that the switch has failed?

 

[laatsch55]

Tear out the switch and check it out. Navo did one on a 3000 Ser II that was pretty much the same....be very, very careful of small springs and tiny levers....

 

[NavLinear]

The PL 3000 Series II uses CMOS switching logic and to remain in the same state a voltage level is required at the ICs power pins after the power switch was switched to the off position. The power switch is shunted by a resistor that provides this power. I suspect this may be the way the 3300 Series I is configured but I don't have a schematic or service manual.



http://forums.phxaudiotape.com/showthread.php/3830-Phase-Linear-3000-Series-II-Preamplifier-Repair

 

[orange]

It's like it never existed, manual wise...at least on the usual suspect websites.