Grateful Dead Music Forum

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Chat about Equipment Info
 #118375  by 1dallek1
 Fri Sep 07, 2012 10:39 am
this is an interesting tit bit that happened here, this older piece of forgotten amp history the Laney PL100 had a hidden but nasty surprise inside that kept the amp from its true performance

the dropping resistors to the preamp board are mostly the wrong value and the voltage being fed from the power supply was not being handled correctly. in short the two 5 watt dropping resistors were heating to scorching temperatures. together with using the wrong value resistors the final feed voltage to the pre board was too low. I researched the thing and it was a well discussed issue and one person actual designed a new supply as part of turning it into a standalone Preamp.

my conclusion was to get the resistors off the board and substitute " 10 Watt Power Resistor Metal Case" and to chassis mount with compound. the pictures are below and boy did that work all the way around. the amp needed several other parts but this was the main issue and for anyone out there with one this should be done.


hot resistors

locating the new resistors

a few connection mods and

dont try this
 #133424  by Spicksparkle
 Tue Oct 22, 2013 5:12 am

I know this post was a fair while back... but I have a Laney PL100.. and I trying to find out as much as I can about this amp. I stumble across your post.

There are 2 pictures that don't show up in the post. I wondered if you could re upload them?

Was it a PL100 head or combo that you did this mod too?