WOPL update for PL400

BlueCrab

BlueCrab

Journeyman
#61
Joined
Nov 10, 2019
Messages
229
#61
I thought duct tape was for keeping things from moving. Use a hammer when things are stuck.

Were the transistor covers for the PL400 just friction fit? ie, just slip them on and slip them off?
 
Gepetto

Gepetto

Administrator
Staff member
#62
Joined
May 15, 2011
Messages
13,560
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#62
BlueCrab said:
I thought duct tape was for keeping things from moving. Use a hammer when things are stuck.

Were the transistor covers for the PL400 just friction fit? ie, just slip them on and slip them off?
Click to expand...
They snap on under spring pressure created by the shape of the cover. It has a minor bend in the middle of the cover which acts as a spring to expand the small grab bends at each end of the cover. It snaps into a machined groove you can see at the top and bottom of your heatsinks.

If you are handy with a pair of tin snips, you should be able to fabricate covers fairly quickly using aluminum roof flashing rectangles (Home Depot). They won't be anodized unless you can find anodized rectangles (they do exist) but they will be functional. Just don't short unanodized covers (anodize coating is an insulator) to the transistors or you will be blowing fuses.
 
Last edited:
J!m

J!m

Veteran and General Yakker
#63
Joined
Dec 24, 2019
Messages
9,457
Location
Connecticut
Tagline
BOT
#63
I don't know I'd trust the anodize to provide insulation... It's REALLY thin!

Maybe brush some tool-dip or liquid electrical tape (probably the same stuff?) on the side that may/will contact the transistor?
 
BlueCrab

BlueCrab

Journeyman
#64
Joined
Nov 10, 2019
Messages
229
#64
Jim, I don't think the cover actually touches the output transistor. There is some clearance between the cover and the top of the transistor.

I now see the groove the cover fits in. Was the cover anodized aluminum? Aluminum is so soft and not particularly springy. If someone removed them, I could see where it would be easy to deform them enough that getting them to properly fit when trying to reinstall.
 
Gepetto

Gepetto

Administrator
Staff member
#65
Joined
May 15, 2011
Messages
13,560
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#65
The covers use air space as the primary insulator, the anodize is secondary and also for appearance.

Thin Aluminum is quite springy and does quite an effective job, the spring stresses in this application stay within the elastic deformation range and get no where near the plastic deformation stress levels.

They are not that easy to deform
 
laatsch55

laatsch55

Administrator,
Staff member
#66
Joined
Jan 14, 2011
Messages
74,282
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#66
No, not aluminum, a thin sheet metal that was fairly stiff. With a bend on the ends to form an 1/8" clip to go in the groove, then it went out from the backwall enough to gain lenght enough to unclip them when pushed back towards the backwall.
 
laatsch55

laatsch55

Administrator,
Staff member
#68
Joined
Jan 14, 2011
Messages
74,282
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#68
God, I have a box of those in the garage....maybe even the 2 large for a 400....

Blue Crab, I'll check tonight...
 
laatsch55

laatsch55

Administrator,
Staff member
#72
Joined
Jan 14, 2011
Messages
74,282
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#72
In theory yes, but I don't think it does. Ed had this figured out one time. I think it's more like 150 to 160 watts.. it was suggested that the factory liked the figure below rated output at 0 db thinking it would deter more turning to the right...
 
BlueCrab

BlueCrab

Journeyman
#78
Joined
Nov 10, 2019
Messages
229
#78
laatsch55 said:
In theory yes, but I don't think it does. Ed had this figured out one time. I think it's more like 150 to 160 watts.. it was suggested that the factory liked the figure below rated output at 0 db thinking it would deter more turning to the right...
Click to expand...
Trying to understand the small numbers below dB numbers - which show 100 at 0dB, 80 at -1.5dB, 60 at -4.5dB. Doesn’t seem to match wattage unless +3dB is 200 watts, but then 50 should be at -3dB.
 
You must log in or register to reply here.
Top