WOPL 400 Linda Linda

[laatsch55]

I've had a few turn to hummers on me. I would turn em on and start tightening the bolts till they quit...

 

[Gepetto]

Well I think I found the source of the excessive hum. Tapping around the plates I found a few other spots that sound hollow. Has anyone repaired something like this? First thought is using electrically insulating varnish or lacquer to fill the space and adhere the loose bit of plate together. Maybe two part epoxy?
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Any of those solutions will work for you. There is an insulating varnish on each layer of the E-I laminates anyway for eddy current reduction purposes so there is no downside. Make sure the bobbin is secure as well. Often the hum is because the bobbin core became unattached from the transformer E-I core and vibrates.

 

[girbob75]

Any of those solutions will work for you. There is an insulating varnish on each layer of the E-I laminates anyway for eddy current reduction purposes so there is no downside. Make sure the bobbin is secure as well. Often the hum is because the bobbin core became unattached from the transformer E-I core and vibrates.

I have some MG Chemicals 4226A clear on the way. Just checked the bobbin and that seems good, thanks for the tip. It's a good time to isolate the transformer from the chassis. Obtained some stainless bolts and nylon washers. I'll be using a layer of Kapton tape for the pass through.

 

[girbob75]

I've had a few turn to hummers on me. I would turn em on and start tightening the bolts till they quit...

I tried that without any luck. I could only get the top two bolts tighter and not the bottom. I think the end plate popped loose when I removed the covers for the transformer.

 

[girbob75]

Nice to see another Phase Linear 400 rebuild in progress. I've been slowly working on mine, replaced the output transistors and power capacitors, then moved into a house, that was four years ago and the PL 400 hasn't had the bias adjusted yet. Also found after I moved the PLL 400 started making a screech sound when turned on, I believe it maybe due to a foil trace and wire coming off from the Drive Board Assembly, Model PL400C. I have a replacement used Drive Board but haven't installed it yet. And also have the Speaker Protection Relay Board. but haven't installed that either. The past few years was attending university for a master in business administration while working 80 hours or more per week, only got one to three hours sleep per night, almost killed me several times, a walking zombie. So, now I'm slowly regaining my health and clearing out and cleaning up the house and workshop-office for a continuation of work on Phase Linear equipment, as I'm also a collector of Phase Linear, have more than a few pieces, several amplifiers, pre-amplifiers, equalizer and, delay. Anyways, will try to participate and follow along. Thank you all for the input and fellowship.

That's rough man. My wife and I are raising three boys and I commute three hours out of the day for work. Any time at home is prioritized for family. Finding time for my projects can be tough some times. I've learned to be really patient.

 

[J!m]

I'm right there with ya. I am at least two hours a day on the road.

 

[VSAT88]

And I am never at home. As in is there anybody IN there.....

 

[Bob Boyer]

I'm right there with ya. I am at least two hours a day on the road.

Ain't living in the northeast fun?

 

[Bob Boyer]

I'm right there with ya. I am at least two hours a day on the road.

Before my father-in-law retired to a golf course in South Carolina, he commuted 1.5 hours each way, every day, from the Jersey shore to Newark. Didn't matter if he used his car or the train. 1.5 hours.