Bulk Capacitor Replacement Procedure for the PL 700B

[Gepetto]

Not critical Lee, I used 200 ohm 5W. It is enough to bring the full amp up with all the output devices installed and to set the bias and check offset. The board is fed by a separate unfused line so it gets full voltage.

 

[laatsch55]

Nice!! Back to the field, see ya in a few.

 

[Phase Linear Phanatic]

Alright fella's. You're not going to believe this, but I have isolated the problem. A STUPID simple issue! I WAS correct in the way I hooked up the caps. I WAS correct in making sure all the fuses were good. I WAS correct in wiggling the RCA's and even swapping them out with different ones. What I NEVER tried doing was man-handling the damn cables at the RCA jack on the amp! It seems the RCA jack's themselves are going bad. Because all the sudden I got my channels back. I am not sure about the cap forming. Would the caps not form themselves after hours of the amp simply being on at standard operating voltage? They seemed to work well now. It looks as if it's back to ebay to get some RCA jacks. Jeeze. New WOA light board, new bulk caps, shiny new gold RCA jacks.....all I need NOW is a WOA Driver board to give it that new forest green look, and a whole new set of fast responding transistors, and I have me a whole new amp! (and a whole empty wallet). I feel dumb on those RCA's. I swore I jiggled those things on her all day. (Nav that one's for you). I suspected the caps are working well, because I saw Joe's blue meter lights power down slowly and take about two minutes to fully discharge through the LED's.

On the topic of calibrating the VU's I mentioned earlier. I am aware of the eye socket on the meters. I attenuated the meters to read directly to zero on the VU. But one side seems to respond accuratly to each bass note thump, and the other behaves wildly oversensitive. Too fast. Is there something else I am missing? Or ten years ago when my Right channel transistors exploded and pinned the VU, did I stress out my windings? DOH! Otherwise........ I'm going to re-assemble this thing after I get my new RCA's and call it a day.

 

[orange]

Swap the meters if you can do that (are they plugged in?) and isolate that potential fault to either the movement or some other point first.

 

[laatsch55]

Take the leads off of both meters and run a resistanve check on them. Post what ya got. Did you repair the red wire??

 

[Phase Linear Phanatic]

Being the obvious novice that I am; I couldn't even get my multi meter to function. "LOW BATTERY" Of course. The ONE tool I have at this location needs a button cell I don't have. So I am unsure of whether I can give you anything accurate. As I also have a pinched wire on that Multimeter. Ugh.....replacement time. (It's a tiny pocket basic radioshack cheapie I had at the bottom of my toolbox. My Full sized fluke is at my Fathers.) Grr. But before it died on me, I checked the right meter. It started at 100-plus ohms and started slowly rising. Unending. I then checked the sensitive one (LEFT), and it started out at 115-120 ohms, and also steadily rose. I have no clue if my meter is being stupid or what, but I THOUGHT I knew how to use one? :-/ The wires were not connected during the brief test. When they are hooked up, they are feeding into a new WOA light board. (for reference. Because I assume you are familiar with the components on that board). Why would a more resistive meter act faster? Seems it should be the other way around? I'll get a new meter and re post.

Lee, I DID get that red wire fixed on the back of the PL20 board. I cut that melted piece off and pulled the wire slightly more towards the board, through the existing tie wraps, with still slack in the wire. I soldered it to the board. It seems my handi-work looks better than the factories? Not the best solder work I have seen from a manufacturer to be honest? I guess they were smoking a little something at the factory in the 70's? LOL! I'm sure you have gotten your hands on one of Joe's latest driver boards? Have you found a noticeable difference aside from physical? And what are your results? I've been considering it. Also I was thinking about using the Germanium transistors with it. One for Joe: double sided better than single? What are the differences mainly? A newbie question, but I like what I hear on this forum about the upgrades. I may zip over to the WOA discussion topic and browse for info. Thanks for the time fella's!

 

[laatsch55]

We beta tested on the 400 Guinea pig. check that thread out.

 

[Gepetto]

Being the obvious novice that I am; I couldn't even get my multi meter to function. "LOW BATTERY" Of course. The ONE tool I have at this location needs a button cell I don't have. So I am unsure of whether I can give you anything accurate. As I also have a pinched wire on that Multimeter. Ugh.....replacement time. (It's a tiny pocket basic radioshack cheapie I had at the bottom of my toolbox. My Full sized fluke is at my Fathers.) Grr. But before it died on me, I checked the right meter. It started at 100-plus ohms and started slowly rising. Unending. I then checked the sensitive one (LEFT), and it started out at 115-120 ohms, and also steadily rose. I have no clue if my meter is being stupid or what, but I THOUGHT I knew how to use one? :-/ The wires were not connected during the brief test. When they are hooked up, they are feeding into a new WOA light board. (for reference. Because I assume you are familiar with the components on that board). Why would a more resistive meter act faster? Seems it should be the other way around? I'll get a new meter and re post.

Lee, I DID get that red wire fixed on the back of the PL20 board. I cut that melted piece off and pulled the wire slightly more towards the board, through the existing tie wraps, with still slack in the wire. I soldered it to the board. It seems my handi-work looks better than the factories? Not the best solder work I have seen from a manufacturer to be honest? I guess they were smoking a little something at the factory in the 70's? LOL! I'm sure you have gotten your hands on one of Joe's latest driver boards? Have you found a noticeable difference aside from physical? And what are your results? I've been considering it. Also I was thinking about using the Germanium transistors with it. One for Joe: double sided better than single? What are the differences mainly? A newbie question, but I like what I hear on this forum about the upgrades. I may zip over to the WOA discussion topic and browse for info. Thanks for the time fella's!

"One for Joe: double sided better than single? What are the differences mainly?"

Well it all depends on the artwork layout on the single sided board versus the double sided board. Either type can be substandard. Single sided boards "generally speaking" have longer trace runs because you do not have the luxury of routing on either the top or the bottom, you only have one surface to work with. That extra trace run generally does not help signal integrity, more opportunity for crosstalk and noise pickup susceptibility on longer runs. Single sided boards are mechanically inferior as well because in most cases, there are no plated through holes to help mechanically secure the trace to the PCB substrate material. As single sided board age, the trace sometimes peels away from the base material around solder connections due to long term mechanical stress from the component leads that are soldered to them. You will see many Phase Linear amps displaying this condition (esp the PL-36 board where the zener regulator ballast resistor would discolor the board and separate the trace).

The plated through hole helps to provide mechanical structure to the solder joint, rather than just hanging on by the trace to board glue bond. The White Oak layout is meticulously laid out to avoid crosstalk situations and eliminate long runs. The low level processing is carefully segregated from the higher power sections of the board. The performance results speak to these improvements. The WO board incorporates a precision, low noise +/-20V regulator section in the center of the board that powers both channel low level sections further improving the noise floor. The L and R channels are isolated from each other by separate filtered and decoupled connections to this low noise regulator section.


Single sided boards are cheaper which is why manufacturers use them. They trade off performance for cost saving.

On meters, there is a thread in the PLWO section on how to check out your meters.

 

[Phase Linear Phanatic]

I fully understand. Now I am only hung up on whether or not I should go with the hand solder method for the board, or the screw terminal option. Obviously, the screw terminal will be a faster and easier procedure, but is it my understanding that you can get a better connection and better integrity from the solder joint? Just asking for some opinions on that one. I am looking forward to installing the new WOA boards in my 700B's this week down in the man cave! Thanks Joe!

 

[laatsch55]

If you are leaving the board in, solder it. Joe's board has holes for the wires, might take 15 more minutes to solder as opposed to terminals

 

[Phase Linear Phanatic]

Will do. On my way to the e-store to pick up a Rev D board! Exciting!

 

[Phase Linear Phanatic]

THIS is the current PL 700B that will get more of Joe's love and attention with the Rev D board. Opinion results soon to post! I have a third PL 700B on the way too. Thinking of going Tri-Amp. And I resolved the meter calibration issue. Thanks for the great procedure posts on that in the WOA section Joe!

 

[Gepetto]

Glad that those meter procedures helped you out Dave.

 

[laatsch55]

Whatcha got for an electronic crossover???

 

[Phase Linear Phanatic]

A VERY good question Lee. And a valid one. I assume you're asking because of my tri-amp comment? I should laugh at myself for wishful thinking. Something I forgot about. I'm not properly equipped for that. But right now as it stands, I have a Bozak N106B (c) Bi-Amp electronic crossover filter. (400HZ). Something my father was very successful with. This version was redesigned and built new for me last month using upgrades in components and filters designed by Bob Betts. An engineer who worked at the Bozak factory on Norwalk Connecticut in the 60's and 70's. I guess he is the "Joe" of the Bozak users group forum my father is a part of. The speakers have custom made internal two-way crossover networks for the mid's and highs, (of which I just replaced, from some universal network) designed by my local vintage audio shop, using the specifications also called for in the Bozak concert grands. For replica like sound. Paired with the Linear's, the sound is fantastic. I will be installing one of Joe's light boards in a 700B to fix a bad board with destroyed solder traces. Once that's done, I may be offering it up to you guys on the forum. Along with a PL400. WOA light board converted.

I have a question for you guys. Are you aware of a guy on ebay who's been selling Renewed PL amps for years? He claims his father "ED" used to work with Dean at the factory................this by chance wouldn't happen to be Ed Blackwood would it????? Just tryin to put two and two together here?

 

[NavLinear]

I have a question for you guys. Are you aware of a guy on ebay who's been selling Renewed PL amps for years? He claims his father "ED" used to work with Dean at the factory................this by chance wouldn't happen to be Ed Blackwood would it????? Just tryin to put two and two together here?

That's the one - he put two sons through college.

 

[laatsch55]

He did not work with Dean at the factory. Ed works in the metrology lab at Boeing. He MOVED NEXT DOOR TO DEAN 25 years ago and that's when Ed got started fixin PL gear. A very nice guy and a Gentleman deluxe. I got a 2000 watt load bank that was used in the engineering dept at the factory, still has the PL equipment inventory sticker on it, and the PL testing dept's phono stage tester. Ed stayed in touch with ex employees and usually before they died they would call him to sell their PL pieces they had. I would love to pick through his garage.....

 

[NavLinear]

What Lee said.

 

[laatsch55]

I have a Pioneer SF-850 in the Buy/Sell/trade forum......

 

[Phase Linear Phanatic]

I second Dennis. Well it all makes sense now. I checked my PayPal statement, and two months ago I bought that PL 400 from "jblackwood". Hello? Ding ding! (duh to myself) Well in a photo I provided in this post, I show a stack of PL gear, and there's a 400 in there. That one came from ED. I have the very list of the things he did to it. The ONLY thing I did myself was put a WOA light board in there. I have the original still, with new lights. That amp, I will be selling soon, and offering to the Phoenix guys first. My desire is to simply have two 700B's in bi-amp configuration. (one WOA'd out). I have no need for a third 700B (also on upcoming auction block; and that 400). Ed did a fine fine job to the internal components! Even new transistors. New caps on the original driver board and new bulk caps etc. Flawless in my opinion. Just waiting to finish upgrading some PL's with WOA gear, before I start parting way's with amps. To make sure I have working stuff. That's a fine crossover you got there Lee. You're way more serious than I. Sadly.....my money is tied up in WOA at the moment.