Przem's Phase Linear 700 Series II White Oak Conversion

[laatsch55]

Joe, why do ya suppose there are no 220K resistors on the 700II's inputs??

 

[Gepetto]

Joe, why do ya suppose there are no 220K resistors on the 700II's inputs??

I am guessing some previous owner removed them along the way Lee because the S2 documentation calls for them.

The more humorous side of me however is picturing a group of bean counters in 3 piece suits walking down the hallway into the engineering department and shouting, "The Japanese and Sony are crushing our market. You engineers have to find a way to slash our costs and do it quickly. No more expensive analog meters, no more expensive PL20 control boards, no more inlaid back illuminated front panel AND no more 220K resistors on the input jacks."

 

[laatsch55]

LMOAO!! Joe I love your humorous side, they will be remounted!

 

[laatsch55]

No, they provide a pathway for static electricity to discharge through when plugging in the IC's...

 

[gadget73]

Where are these 220k resistors typically found? If its across the direct/indirect switch, I'm reasonably sure my friend's 700-II did not have them either. The Pro doesn't have the switch at all, and no resistors over in that area either.

 

[laatsch55]

The 220's are put between the input copper ground plane and the plus tab of the input RCA's

 

[gadget73]

can't recall if his had them or not. I want to say no, but I wouldn't bet a sandwich on it. The Pro does not though, but it also used 1/4" jacks instead of RCA.

 

[Gepetto]

Not me ...

Would that be the reason to hear a slight hum in any volume pot position, except going for max.?

No, it is common knowledge that all PL amps hum according to the TX guru

 

[laatsch55]

yes..."inherent in the desgn" i believe were the words... and "NOTHING CAN BE DONE ABOUT IT"

 

[Gepetto]

yes..."inherent in the desgn" i believe were the words... and "NOTHING CAN BE DONE ABOUT IT"

Bah...humbug

 

[gadget73]

I guess both of the ones through here were broken. Either that, or someone had already taught them the words.

 

[Gepetto]

But with WOPL upgrade I leave the issue behind forever, as I understand. Right?

As long as nothing fails...

Unfortunately, hardware does fail.

 

[laatsch55]

As Joe says...it's a team effort...

 

[laatsch55]

Nice speaks Przem!!

 

[laatsch55]

And got Przem's 700 back on the bench , reclaiming it from the paperwork wars it had to be sacrificed to...

 

[laatsch55]

New BR, properly bypassed....

 

[laatsch55]

Looks like a nice cast frame on the woof. Don't know what to say about cleaning the aluminum horn though...

 

[JustMike]

As I expected, he cabinets have never been opened. I looked inside - could not resist... - and took some pictures. The x-over seems to be in a perfect shape, no need to upgrade I suppose. The two drivers are original, but there are aftermarket / new subs available at simplyspeakers.com (HF drivers) and parts-express.com (LF woofers) made by Eminence in case of WOPL amp accidental overloading. What I don't like is the damping material on the back cabinet's wall. Have to think what istead...

My 'cleaning questions' of on of previous posts still without any advice .... ?

Hello Przem.
There are products available for cleaning Aluminum mag wheels. These are spray and rinse chemicals .
Check your auto parts stores.
the best method to bring back to like new would be to have them blasted in a sand blasting cabinet but not with sand.
Walnut shell or baking soda is the blasting media to use, or plastic bead which is a little more aggressive.
Look for someone in your area under auto restoration.

 

[laatsch55]

Mike, we have a bead blaster at the shop, seems pretty gentle. We use those soft beads that turn to dust...

 

[laatsch55]

We have run into a snag on the backplane installation. The chassis appears to bo not as tall as the "B"s"......Whether it was bent in the wrong place , I dont know. The platic bushings are tight up against the lip , but they did go. The holes must have been slightly undersize also as the bushings had to be exactly straight to go. A couple took some rotary motion to go, hence the seal pic.. It looks like a trip to the shop belt sander is in order.......

Question Sir Joe.....how much material can i take off the top or bottom of the backplanes?? I only need .010-.015 total....1/2 off the top and half off the bottom...