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

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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 :-)
 
Thate your RM Steve?
I used to have tons of issues with blowing fuses on one of the RM100's I owned.
 
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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