Phase 400 rebuild

[Gepetto]

One of the major difficulties I had with the whole WOPL400 rebuild was the task of inserting the output transistors into their respective positions on the backplanes. Mark had warned about this task on his video but I had no idea how frustrating this could be. For some reason, I had only a little difficulty getting the first 14 devices to seat correctly but then I ran into the 2 outputs from Hell. Those last 2 took me hrs to finally coax into their inserts and it was the problems I had with these last 2 specific transistors that eventually led to my mix up and my inserting each into the wrong column and the resultant short that nearly caused me to blow a blood vessel. So, upon mentioning this to Joe, he indicated that some of you experts have a neat tool that takes the pain out of this part of the rebuild called a magnetic pick up tool. He was also kind enough to send me a photo of this miracle tool and I ordered one on the spot from Sears. So could one of you who have experience with such a tool provide some insight on exactly what is the proper technique when inserting output transistors into WO backplanes using the magnetic pick up tool ?

Sure
Orient the amp face down on the bench.

Make sure the transistor leads are straight and burr free.

Attach the strong magnet to the top of the steel can on each transistor. The diameter of the magnet is almost exactly the same size as the transistor can. Center the magnet.

Carefully align the transistor in the socket to be populated. You will be able to feel when the leads find the socket holes by holding the handle on the magnetic pick up.

Once aligned, gently press the leads all the way in. Slide the magnet off sideways and install the 2 6-32 screws.

Pretty simple. The tool makes short work of it.

To remove a transistor, use the tool in a similar way.

 

[NavLinear]

Sure
Orient the amp face down on the bench.

Make sure the transistor leads are straight and burr free.

Attach the strong magnet to the top of the steel can on each transistor. The diameter of the magnet is almost exactly the same size as the transistor can. Center the magnet.

Carefully align the transistor in the socket to be populated. You will be able to feel when the leads find the socket holes by holding the handle on the magnetic pick up.

Once aligned, gently press the leads all the way in. Slide the magnet off sideways and install the 2 6-32 screws.

Pretty simple. The tool makes short work of it.

To remove a transistor, use the tool in a similar way.

Wouldn't it be simpler to put hair around it?

Oh yeah - nice explanation.

 

[laatsch55]

Whatever works Navo!!!!!

 

[Dchristie]

Intermittent Shutdown

I have been playing PAM (WOPL400) for a couple of days now and she seems to be functioning correctly for the most part, but I have run into what appears to be small problem with her. Twice, she has shut down for a few seconds with no apparent reason. Once on vinyl and once on CDs. Comes immediately back on after a few seconds and then continues to play fine for hours.

Any thoughts from anyone would be appreciated ?

 

[WOPL Sniffer]

how hard were you pushing it? What speakers are you running? Details.....

 

[MarkWComer]

Twice, she has shut down for a few seconds with no apparent reason. Once on vinyl and once on CDs. Comes immediately back on after a few seconds and then continues to play fine for hours.

Any thoughts from anyone would be appreciated ?

How hot is it getting? Thermal cutoff kicking in?

...Or even a defective thermal cutoff?

 

[Northwinds]

Relay have an issue? Sounds like it is tripping and resetting?

 

[laatsch55]

The DC protect has to have power recycled to reset.. sounds like the thermoswitch...

 

[Dchristie]

Pam Shutdown

Not running her hard at all ( moderate levels at most and VU meters barely moving). Heat sinks are cool to touch. Speakers are easy load (vintage restored Avid 100s) .

 

[WOPL Sniffer]

If it was my amp, I'd bypass the thermo-switch temporarily, put a fan back there, and test it. I've been trying to source a thermo switch replacement but have not had time. They still make them in that package but haven't got any farther. It would be nice to get a replacement instead of the 40 year old trons stuff. Not too hard to replace but pulling a new amp apart sux.

 

[WOPL Sniffer]

or, you can go old school and unplug the unit and get out the hairdryer and the laser thermometer.

 

[Dchristie]

Well, the good news is that it should be relatively easy to get to since I believe the thermo switch is right behind the control board connected to the AC line and one of the wires from the transformer and Joe put phoenix connectors on the control board for the left band right channel 3-wire hook up. Once the 3 wires are disconnected from each channel, the control board should just lay back. And IF the nuts and screws holding the switch onto the chassis are not frozen, then removing it should also be relatively straight forward.

I guess, I just need some direction as to where I can get another one to replace this one - anyone have any guidance regarding where I can get a new replacement ( assuming we all agree it is the thermo coupler).

I would rather just replace it now with a new switch and be done with it.

Thanks

Dean

 

[laatsch55]

I would test it before I took it out....

 

[Dchristie]

Thanks Lee and Perry, the one thing that is not quite clear to me is that when this drop out occurs, the amp is still acting as if nothing is wrong as the meters are still lit and nothing else shuts down ( the amp still appears to be fully on). If the thermal switch kicked in, wouldn't the amp shut down as the AC line to the switch would be interrupted as well ?

It is almost as if there is a loose solder joint or something similar that just does not quite connect for just a few seconds but affects both channels output simultaneously.

 

[laatsch55]

If it was the thermoswitch everything would be dark, yes.What is your DC offset?

 

[Gepetto]

Thanks Lee and Perry, the one thing that is not quite clear to me is that when this drop out occurs, the amp is still acting as if nothing is wrong as the meters are still lit and nothing else shuts down ( the amp still appears to be fully on). If the thermal switch kicked in, wouldn't the amp shut down as the AC line to the switch would be interrupted as well ?

It is almost as if there is a loose solder joint or something similar that just does not quite connect for just a few seconds but affects both channels output simultaneously.

First thing to note in troubleshooting is whether the needle movement goes dead at the same time the cut out occurs. If the meter needles are still moving then it is isolated to the DC protect relay as the amp still thinks it is putting out sound. Observe that before you do any tearing apart.

The meters on the PL400 will go dim pretty quickly if you lose AC power either due to the amp being turned off or the thermo switch going open. You will notice that if it is cutting out for a couple of seconds. You can observe that if you remove AC power to the amp and look at the meter illumination LEDs. Observe how dark the LEDs go with the removal of the AC for only a couple of seconds.

 

[Dchristie]

WOPL 400 speaker connection problem

My meters were still functioning during the drop outs so I went back and revisited the wiring connections on the DCP board (as per Gepetto's post) and that did indeed fix the problem. However, within 1/2 hr, lost the channel again so this time I completely removed the DCP board, checked for anything amiss and then inserted the wires very carefully, making sure that each was getting good contact with the Phoenix connector. Reinstalled the board and everything is working again. Hoping it continues to work!

So, my question to all of you folks who have been doing this for a while, why not just remove the phoenix connector blocks off of the DCP board and just directly solder the speaker leads , AC, DC and ground wires directly to the board. I may just have a "lemon" set of connectors but while they do make sense for the control board (in case you ever want to remove it) they seem somewhat quirky on my DCP unit and direct solder makes sense here since there are so few connection points. But, maybe the clamp downs are more than adequate and I am just having a "bad hair" day.

 

[MarkWComer]

So, my question to all of you folks who have been doing this for a while, why not just remove the phoenix connector blocks off of the DCP board and just directly solder the speaker leads , AC, DC and ground wires directly to the board.

I personally like being able to remove a faulty component easily- and I mean without desoldering. The Phoenix connectors make that easy. Like you, I believe that directly soldering the wires makes a more trusty connection. There's really nothing wrong with removing the connectors, but swapping out the DC protection board isn't as PIA free.

In your photos you didn't have the relay mounted on the board. Perhaps it isn't pressed all the way into the socket?

 

[Dchristie]

I personally like being able to remove a faulty component easily- and I mean without desoldering. The Phoenix connectors make that easy. Like you, I believe that directly soldering the wires makes a more trusty connection. There's really nothing wrong with removing the connectors, but swapping out the DC protection board isn't as PIA free.

In your photos you didn't have the relay mounted on the board. Perhaps it isn't pressed all the way into the socket?

Mark, I completely agree with everything you said. The faulty connection appeared to be with the AC input connector and I would prefer to be able to easily swap out boards/etc as well. With all of the DCP boards in the field, I am sure if this were a continual problem, then Watts Abundant would have modified it accordingly.

However, for the critical inputs ( primarily power associated) I guess I would sleep better with a solder joint. But as I said, after diligently reconnecting all of the DCP associated wires, everything is now working. So, with fingers crossed, I assume this will no longer be an issue.

 

[laatsch55]

Out of all the amps I've done, I've only soldered one DCP board in. I thought it would look less cluttered with the wires coming up from the bottom and soldered on the top. It achieved that objective, but it was a pain in the ass. I've had no problems with the others.