Marshall TSL60 problem

[Rod]

Hello

I Have a marshall tsl combo that the front panel ligths up, but all valves dont light up, in the past i had to replace the rectifier bridge after that repair the amp worked fine.

So what can be the problem now? what can i start to check?

Best regards, Rod.

[Rod]

In the attached schematic R14 and R15 dont have any voltage?

[DrGonz78]

Something is open on the filament supply. Perhaps bridge rectifier is not bad but has cracked solder joints. Although if that was the case the power tubes and phase inverter filaments would be still working. Are there any fuses associated with the Fil1 & Fil2?

Edit: Check F3 fuse.

[Jon Snell]

It is common for the spade connectors W12 & W18 to be incorrectly crimped and heat takes its toll on the connection. Caused by out of tollerance crimp machine, (a polite way of saying worn out).
Examine for traces of discolouration and replace as required. Thas also affects the solder side abd can affect the fuse holder.

[Rod]

Hello DrGonz78, the fuse has continuity, i have measured voltages in W18 it as 7,5 volts and W12 doesnt measure any voltage, this no voltage in W12 its normal?

Something is open on the filament supply. Perhaps bridge rectifier is not bad but has cracked solder joints. Although if that was the case the power tubes and phase inverter filaments would be still working. Are there any fuses associated with the Fil1 & Fil2?

Edit: Check F3 fuse.

[DrGonz78]

Hello DrGonz78, the fuse has continuity, i have measured voltages in W18 it as 7,5 volts and W12 doesnt measure any voltage, this no voltage in W12 its normal?

Measure the filament voltage with respect to ground. Right now, I assume, you are measuring across the two filaments. If you measure each node to ground what is your readings? Is that what you’re already doing when you say no voltages?

[Rod]

Im mesuring with one of the probes in the amp chasis "ground", and the other one touches W18 and W12, this way it gives 7,5 volts on the W18 an in W12 im getting no voltage.

Measure the filament voltage with respect to ground. Right now, I assume, you are measuring across the two filaments. If you measure each node to ground what is your readings? Is that what you’re already doing when you say no voltages?

[Helmholtz]

Im mesuring with one of the probes in the amp chasis "ground", and the other one touches W18 and W12, this way it gives 7,5 volts on the W18 an in W12 im getting no voltage.

So you should have 7.5VAC between W18 and W12, which looks ok if unloaded.
What is the voltage between the ends of the fuse?
A fuse with a voltage between its ends is bad/open.
You can't reliably test a heater fuse with an Ohmmeter when in circuit.

[SoulFetish]

It is common for the spade connectors W12 & W18 to be incorrectly crimped and heat takes its toll on the connection. Caused by out of tollerance crimp machine, (a polite way of saying worn out).
Examine for traces of discolouration and replace as required. Thas also affects the solder side abd can affect the fuse holder.

this is absolutely correct. This is an example of the kind of heat damage that can occur. The poor connection causes heat, which causes oxide to build up on the surface of the metal; increasing the resistance, which further increases the heat so on and so forth







this was an interesting one. I wish i had some pictures of the repair.