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tsl60 filament fuse issue
Hello,
I'd say if the fuse is discolored, you might be dealing with a very low resistance connection between the fuse & the fuse clip. We've seen this over & over again with this kind of arrangement.
The fuse being a slo blow gets pretty warm owing to the resistance in the internal coiled fuse element. this inturn heats the fuse ends & the clip. this seems to lead to the oxidation of the clip. once the clip becomes discolored or oxidized, this creates a low resistance between the fuse end & the clip....resistance + high current = power dissipation hence heat.
The heat generated will eventually melt the solder inside the fuse & hence disconnecting the fuse element & bad fuse. If this is the case with your amp, you can file the oxidation off the clip then actually solder the fuse in the clip...this will resolve the issue at hand...it does of course make it a bit inconvenient to replace the fuse when needed.
I do recall that the TSL100 originally had heater fuses...Marshall issued a bulletin to remove the fuses & hard wire across them and those were 10a SB fuses.
My take on the heater fuse issues is that since the circuit draws current consistently as opposed to most devices which vary their current draw with the demands of the operation, they tend to be problematic as described. There are so many amps out there that do not have filament fuses & just use the mains fuse...I've never seen an issue that resulted from not having a filament fuse....still I'm not advocating removing the fuses...
Try soldering in the fuse & see what happens, esp since you are having the overheating fuse clip issue. If there is no evident problem ie:shorting power tubes, then you could also try a slightly larger fuse value...say 7amp SB (if you can find one). My take is if there is a major short, even an 8amp fuse will blow.
glen
Hello,
I'd say if the fuse is discolored, you might be dealing with a very low resistance connection between the fuse & the fuse clip. We've seen this over & over again with this kind of arrangement.
The fuse being a slo blow gets pretty warm owing to the resistance in the internal coiled fuse element. this inturn heats the fuse ends & the clip. this seems to lead to the oxidation of the clip. once the clip becomes discolored or oxidized, this creates a low resistance between the fuse end & the clip....resistance + high current = power dissipation hence heat.
The heat generated will eventually melt the solder inside the fuse & hence disconnecting the fuse element & bad fuse. If this is the case with your amp, you can file the oxidation off the clip then actually solder the fuse in the clip...this will resolve the issue at hand...it does of course make it a bit inconvenient to replace the fuse when needed.
I do recall that the TSL100 originally had heater fuses...Marshall issued a bulletin to remove the fuses & hard wire across them and those were 10a SB fuses.
My take on the heater fuse issues is that since the circuit draws current consistently as opposed to most devices which vary their current draw with the demands of the operation, they tend to be problematic as described. There are so many amps out there that do not have filament fuses & just use the mains fuse...I've never seen an issue that resulted from not having a filament fuse....still I'm not advocating removing the fuses...
Try soldering in the fuse & see what happens, esp since you are having the overheating fuse clip issue. If there is no evident problem ie:shorting power tubes, then you could also try a slightly larger fuse value...say 7amp SB (if you can find one). My take is if there is a major short, even an 8amp fuse will blow.
glen
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