FIXED (MOD50) like 90% of tube amp issues, bad tube and fuse

jkdsteve

jkdsteve

Active member
Turned Egnater MOD50 on, getting humming noise but with amp signal, no bias reading from test point at one side only - is this likely a screen grid resistor?

Heaters are both on, no sign of arc'ing above ground (tube sockets)
 
Well, I pulled the chassis...no obvious signs of issue, all fuses checked and seems like SGR are working..need to find somewhere else to read the bias voltage from.

I measured PV on Pin3 of the power tubes and it's present

Could just be one side of bias power supply?
 
So, fixed it....tube must have failed...I put in what I assume were good tubes and no dice.....so I pull the bias fuses again, lo and behold the fuse is flaky and then gone!

So i put in third set of tubes, ned fuse and bam-a-lam back in business.

Lesson in always double checking the easy stuff :)
 
Mailman1971":3qydhhgs said:
Thate your RM Steve?
I used to have tons of issues with blowing fuses on one of the RM100's I owned.
Click to expand...

Was my prized MOD50.

The RM100s were totally fickle like that..especially the earlier ones without the HT/Wire mod...thankfully seems to have been addressed by the time the LB came out.
 
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