I want to White Oak a Phase Linear 400 Series I

[mlucitt]

Agree with Lee. What is the rule Lee, if you don't know what the meter source is - start on the highest AC range (although yous might be an auto-ranging meter) because it puts diodes and caps in the meter circuit? Then adjust the voltage and switch to DC to check for a DC signal? Same with Current measurements, you have to place the meter "in" the circuit not just in parallel with it and start at the max range and work your way down. In any case never check diodes or Ohms with any power applied - bad news for the meter and maybe for you too.

Nice work on the bridge, as long as that green wire on the "+" side of the bridge goes to the "+" side of the capacitors you are in good shape.

Your resistors are fine, that is just burnt flux. You will be replacing them anyway with the DC protect board. Keep the capacitors, those are very nice high-quality caps that PL used on the outputs.

Lee, what do you think about those diodes on the back of the board, was this guy on to something close to the Gepetto Mod?

Mark

 

[laatsch55]

Yeah or had caught word of what we were doing and tried it. I have done the Gepetto mod on 7 local amps withoput the White Oak board, just the diodes and the 470- caps and they respond very well.

 

[laatsch55]

If you have trouble holding PS caps in try velcro, works well

Excellent Skratch!!! Good idea. Might be just the solution to some cap mount problems.

 

[ksrigg]

OK...

I'm ready to do something. I have new AC cable in the amp. Ran 16/2 exactly like the previous AC. Replaced the broken fuse holder and think I have looked at every connection I can see. Have Joe's led lighting installed, and the new caps, BR.. installed I am ready to do something...

Am I safe plugging the amp into wall current using the DBT? Or would you recommend any other testing.....or would you go ahead and just install Joe's new PCB and the new driver and output transisters?

I guess you could say I am lost.

Don't know what to do next..

I did have to put some new, longer wires on the BR to connect to the new caps. I'd like to post a pic and make sure I have everything hooked up correctly. Had to change some wire colors...and although I took pictures, I'm not 100% sure everything is where it should be..

Oh, is the wring one the new PCB the same as on the original PCB? can I put the wires in the same place on the new board?

I do have the scope and sig gen and all the connectors sitting here but haven't a clue what to do....

H E L P

 

[Gepetto]

Wrong area of the board for the Gepetto mod Mark. Looks more like fixing butchered traces. The Gepetto mod works just fine on the stock PL board as well.

 

[ksrigg]

How does this look guys? Look like everything is in the right place? If so, I'm tempted to DBT it....I hope she doesn't blow..

 

[mlucitt]

Sutton,
It could be the camera angle, but it looks like the red wire coming off the positive capacitor bank is touching one of the transistor buss wires. Just check to make sure it is OK. Use your variac to power up the amp slowly through the dim bulb anf you should be OK. Did you want to remove the output transistors? It looks like they are still installed. Or do you wan to leave them in. You can cet an output signal and sounds for just having the drivers (bottom row) installed.

Mark

 

[laatsch55]

Yep the B+ feed to the fuseholder is definately touching the base bus bar. Bad, Bad thing.
While the old board is in it now is the time to make mistakes learning how to probe with the scope. When hooking up the proibes ---POWER OFF----CAPS DISCHARGED through a 3-5 watt 50-100 ohm resistor. When changing probe locations ---POWER OFF ---=---CAPS DISCHARGED----I can not stress this enough. I have gotten in a hurry and not discharged the caps, and shorted base bus bar to collector bus bar, it's not pretty and it's a lot of work to fix. It takes components out on the board too, besides some outputs. When removing the probes---POWER OFF -----CAPS DISCHARGED----Is this starting to sink in?? You can elimin ate a months work in a half a second, and there really is no excuse.

 

[laatsch55]

Sutton----you WILL make mistakes, we're just trying to keep them to a dull roar. Not as easy as it looks, is it??

 

[mlucitt]

That's why I like alligator clips on the ends of the wires that connect to my test leads...

 

[Gepetto]

Hi Sutton
A little while ago, you were asking about the screws on the TO-3 transistors. It took me a bit to dig them out of my cabinets but what I replace the original hex headed screws with are Stainless Steel, phillips Pan head, #6 x 5/8 sheet metal screws. The ones I got are Midwest Fastener 10351 and are sold at various hardware stores (ones that are actually hardware stores that is, getting harder to come by these days The pitch is the same as the originals and the diameter is very close. It is much easier to deal with phillips head screws than those hex heads in the tight quarters of the heatsink channels.

 

[laatsch55]

Amen Joe, and if you use a magnetized driver bit it has to be grond down quite a bit to get between the hex head and the TO-3 case.

 

[Gepetto]

Hi Sutton
Albany County Fasteners has 304 stainless steel pan phillips #6 x 5/8" for $4.00 per hundred. BTW this is a great and low cost source for SS hardware of all sorts. Better selection of sizes and lengths than I have ever found. It's a relatively new business and Bob Cominos that runs it is a great guy to deal with.

 

[kevin]

LOL.... Id say Sutton is now pulling the few hairs on his head out !!!!!!

 

[ksrigg]

Joe,

Do the leads on your replacement PCB replicate the ones on the original PL 14 board? The boad in this 400 are all in place and look to be original. Can I simply move each lead to the new board as they exist on the old board? Front and back? I my just try my luck, and change out the board and put the protect circuit in and cross my fingers....unless there are changes to the wiring of the PCB. I assume the led board is the same also? I took pictures and can do masking tape labels for each wire, if I know they are going back to the same spots on the new boards..

 

[ksrigg]

Also Joe, you may want to look at the hook up wire at MCM Electronics... Prices are lower than Amazon which you told me about..Reallly good pricing on a lot of things... Plus with an order of some BNC to RCA female connectors they recently sent me...I ordered 2 and got 2 BAGS.....so I think I have 200 of them for 98 cent per hundred...(I told them aobout the mistake and they told me to just keep them...)

 

[ksrigg]

OK....You were right....the red wire was touching....but I moved it, and tightened the connections to the new caps...I got up my nerve and plugged the amp into the DBT. The lightbulb glowed very brightly and then dimmed slowly. The amp apparently came up, the leds glowed, and no fuses blew...so I guess that is all good news. So what do you all suggest I do next? Put Don's Protect Circuit into the amp? Or, I will could get voltage measurements if someone will tell me how to do that. Remember,,,,I don't know how to do any of this stuff...so talk as though to a 10 year old....and a not very bright one...

YEA ME!!~!! I am so happy....Now I want to move on to the next thing, but I would like to get some measurements to see if everything is alright....if I knew how..

 

[Gepetto]

Don
Follow the picture instructions for the light board. 2 of the wires are in reverse location compared to the original so unless you follow the wiring instructions your meters will be reversed.

 

[Gepetto]

Sorry not Don, I meant Sutton...but you knew that.

 

[Skratch]

Men I replaced the bias transistors and wanted to use something flexible. I was looking around and found an old ethernet cable and cut it apart. I think it is 28 gauge and it worked great. Now I have an extra 49 feet of bias wire.