BIG problems

[Michael F]

Grasshopper....how are you progressing?/ Is your spirit in tune with that of the device and the world around you?/

Greetings Oh Knowledgeable Master of All Things Phase Linear!

While eagerly anticipating the arrival of the Wyoming sourced CARE package, I`m reviewing notes and re-reading all posts to date, and there are many, reading up on the star point grounding scheme and biasing procedure etc. basically preparing myself for the repair.
I hope it gets here soon, I`m starting to get anxious, don't want to loose my nerve
BTW, did you ever find the tracking #?

 

[laatsch55]

Greetings Oh Knowledgeable Master of All Things Phase Linear!

While eagerly anticipating the arrival of the Wyoming sourced CARE package, I`m reviewing notes and re-reading all posts to date, and there are many, reading up on the star point grounding scheme and biasing procedure etc. basically preparing myself for the repair.
I hope it gets here soon, I`m starting to get anxious, don't want to loose my nerve
BTW, did you ever find the tracking #?

No Michael, I'm sorry I didn't. Must have blown out the truck. They said 7-10 days when it left.

 

[laatsch55]

Well Grasshopper??

 

[Michael F]

Well Grasshopper??

Hi Lee, I haven't received CARE package yet I`m hoping it will arrive shortly. I had to put the amp away in the meantime, all 100 pieces of it because I live in a small 4-1/2 room condo and had to use the kitchen table as a workbench.

When the package does arrive, I think I`ll start populating the driver board and then do the drivers and output transistors, that is, unless the initial fire-up (bad choice of term) procedure should be done in stages, please advise.
I`ve couple of questions:
The TO-3 sockets seem prone to being troublesome, can any preventive measures be taken to avoid potential issues?
I will be careful not to over torque the screws and will check for collector to heatsink continuity at every step.
Also, should the old thermal compound be removed?
What type of capacitor is that in the output RC network, Mylar, polypropylene or other?

This down time is playing on my worst fear of a reoccurrence of what got me into this predicament initially ,
the consequences of which are quite obvious now however, I only wish I knew why
in order to avoid history from repeating

 

[laatsch55]

Had the same fears myself in the past. The way to alleviate those is to go about it methodically ad test as each part is done(as much as you can). ALL old grease should be removed. Take the heatsinks off and get it out of the socket recesses, and the lead holes. Pinch the lead tulips on the sockets together VERY carefully to help connectivity. If Don's board is still installed, the RC network is on the board. If not a .1uf/ 250 volt polypro in series with 2 paralled 10 ohm /5 watt MF resistors are what I use.

 

[laatsch55]

To avoid catastropic output failure Joe advises to install the RCA-410 drivers first then bring it up on the DBT and variac if you have one. If not he has a trick way of doing it without a variac. Maybe he'll chime in on his way. With just the drivers in you can still set Bias and check offset before risking any outputs. And like he has said before, if something is terribly wrong the 10 ohm bias resistor will toast.

 

[NavLinear]

Had the same fears myself in the past. The way to alleviate those is to go about it methodically ad test as each part is done(as much as you can). ALL old grease should be removed. Take the heatsinks off and get it out of the socket recesses, and the lead holes. Pinch the lead tulips on the sockets together VERY carefully to help connectivity. If Don's board is still installed, the RC network is on the board. If not a .1uf/ 250 volt polypro in series with 2 paralled 10 ohm /5 watt MF resistors are what I use.

I'd add one more step regarding the TO-3 socket that Scratch does IIRC and is a good idea. That would be to clean the mating surface of the socket with a cleaner such as DeoxIT and a small brush or small Q-Tip or...

http://store.caig.com/

 

[Gepetto]

To avoid catastropic output failure Joe advises to install the RCA-410 drivers first then bring it up on the DBT and variac if you have one. If not he has a trick way of doing it without a variac. Maybe he'll chime in on his way. With just the drivers in you can still set Bias and check offset before risking any outputs. And like he has said before, if something is terribly wrong the 10 ohm bias resistor will toast.

I bring my new conversions up by removing the 5A +/- rail fuses. I then jumper from the tip to ring of each fuseholder with 2 alligator clip jumpers with a 200 ohm 5W cement type fusible resistor (the square ones work fine). Then I bring it up on a variac. If you have no load on the amp, the 200 ohms will bring the amp up fine, allowing you to check the offset and bias without fear of doing major damage in the event that something does not go right.

Picture below.

 

[Michael F]

Thanks guys. Gepetto, will your 200R method work without a variac? I`ve been using a 40 watt bulb for testing, is that adequate? Would only one wattage be required?

 

[Gepetto]

Thanks guys. Gepetto, will your 200R method work without a variac? I`ve been using a 40 watt bulb for testing, is that adequate? Would only one wattage be required?

Yes it will, when I am confident of the transistors on the back wall, I just use the 200 ohm method with no variac. I usually start with just the pre drivers in however.

 

[Michael F]

Yes it will, when I am confident of the transistors on the back wall, I just use the 200 ohm method with no variac. I usually start with just the pre drivers in however.

All right then. I`m pretty sure the driver and output transistors Lee is sending over are worthy of your confidence

So if I understand the initial power up process correctly, with B+/- fuses replaced with 200R resistors and a 40w bulb, working one channel at a time:

Turn amp on with driver board alone. If good, proceed to installing drivers. If good, move on to measuring DC offset and adjusting bias according to service manual. If good, install output transistors, cross fingers, say a prayer to the Audio Gods and turn amp on.

Does that sound about right?

 

[laatsch55]

Joe calls the RCA-410's the pre driver, have those in for the first go. Can ya tell I live in rodeo country??

 

[laatsch55]

The "Care" package is probably held up in customs. They're trying to figure out what a "linear phased" monster is and just how we are going to detonate it. LMOAO!!

 

[orange]

It'll get there...Customs is just having a house party to check Lee's work out.

 

[Michael F]

It'll get there...Customs is just having a house party to check Lee's work out.

LOL. They are probably trying to figure out WTF all that stuff is. Reminds me of the time I was crossing into the US and the Homeland Security officers took a particular interest in a TO3 packaged LM317 that I have on my key ring

 

[Michael F]

Hi guys
Just wanted to update the thread after a couple of weeks of inactivity. Unfortunately, it`s still status quo as I have not yet received the C.A.R.E. package Lee so graciously sent out . I`m beginning to think it`s MIA, which would be a damn shame

 

[laatsch55]

It is a damn shame, cause my care packages are known to contain a LOT more than what was asked for AND surprises beyond that. So, got your other order yet?? And are we gonna fix this puppy??

 

[Michael F]

Damn shame indeed, gives the term "snail mail" a whole new meaning, if it ever does arrive.
Meanwhile, plan B ought to get here in a matter of days. It too, fell off the USPS/Canada Post radar just the other day...
I`m beginning to think that I wasn't ever meant to be a Phase Linear owner

Stay tuned!

 

[laatsch55]

Does seem to be a cursed endeavor, however the forces that are arrayed against us have no F*&^%$# idea who they are dealing with, WE WILL wear the F*&^%$# down!!

 

[Michael F]

Plan "B" arrived this morning, complete but I don't understand why all 24 TO-3s are MJ15024 what's up with that? Are those drivers or outputs? Something tells me they cant be both. I sent the supplier the same question.
I`ll check out the driver board semi`s next..