Randall RH 100 amp head issue

[ShaneShreds]

Hey guys, this is obviously my first time posting on yall's forums, but I am having a big problem with my Randall amp head right now and would be appreciative beyond measure if I could get a fix for it. I have a randall rh 100 amp head and one day I went to turn it on and jam as usual and when I hit the switch  it was as if the sound started to slowly dim out and it blew the fuse. So my next step in trouble shooting it myself was, practically, just putting another fuse in the power switch. Well the same thing happened and I cant seem to find out what is happening exactly thanks a plenty to who ever gets back to me guys. :dbtu:

[J0K3RX]

Hey guys, this is obviously my first time posting on yall's forums, but I am having a big problem with my Randall amp head right now and would be appreciative beyond measure if I could get a fix for it. I have a randall rh 100 amp head and one day I went to turn it on and jam as usual and when I hit the switch  it was as if the sound started to slowly dim out and it blew the fuse. So my next step in trouble shooting it myself was, practically, just putting another fuse in the power switch. Well the same thing happened and I cant seem to find out what is happening exactly thanks a plenty to who ever gets back to me guys. :dbtu:

Might have a blown component? I would examine the board for any obvious place that look like they have been exposed to heat or burnt components etc... I would also check for cracked solder joints especially around the power amp section, that is very common... You can run from your effects send output direct into something and see if you get any signal... this will just be coming from your preamp section, if you get signal then you know it's not anything in the preamp section.  Check all of the solder joints around Q8 thru Q16.

[DrGonz78]

First thing first unplug the speaker before turning on the amp at this point. Nothing on the preamp side of things should be blowing fuses. My concern is first for the speaker and then being able to run the amp without blowing fuses. So it would be nice to build/use a light bulb limiter which there is a sticky thread and many threads about building one located on this site. Once you have the amp through a limiter then see if there is any DC voltage on the speaker leads so use a DMM to check. Got to figure where the short is on the amp and at this point a light bulb limiter will hopefully keep the amp from blowing fuses. Sure there could be bad solder joints and things going on, and an inspection of power amp area of the board is very important.

Got to make sure we didn't fry the speaker and using 9 volt battery touched on speaker leads listen for a pop.

[Blacksack]

What'd you find out on this issue?  I have the same exact amp doing the same exact thing.

[Roly]

With no more postings since Feb his problem has been resolved, one way or another.

You have an identical problem?  Pick up the thread starting with @DrGonz78 post #2 above, grab the schematic so we are all looking at the same thing, and we'll proceed from there.

First thing (with the amp unplugged) is a good visual inspection looking for anything obviously broken or burnt.  You will also need to make up a limiting lamp.