RM100 Power Tubes Won't Light Up!

[Micah7]

I have an RM100 and have searched this forum to try and figure out why all the power tubes won't light up. I found and replaced a broken supply fuse on the inside of the amp. All of the other fuses look fine and I tested the fuses associated with the power tubes and they are working. The preamp tubes and fan are both working. Does anyone have any more things to try?
Thanks

 

[Mattfig]

Don't know if perhaps a dead or even missing 12AX7 input tube or the driver tubes be the culprit? I honestly don't know but it's easy to check....

 

[roszatycki]

It's been a few months since I worked on an RM100 but I am pretty sure the pilot light is hooked to the 6.3v heater voltage from one of the power tubes. Does the pilot light turn on? If the tubes don't light up you don't have power to the heater within the tubes.

 

[Micah7]

Yeah, the power tubes don't even light up. The red light on the front of the amp turns on though. Is this something I could fix myself?

 

[eedude]

the filament supply to the power tubes have their own dedicated pair of fuses: F3 and F4. These are inside the amp.

 

[roszatycki]

eedude,

I PM'd him twice telling him that but got no response. You are correct, I think they are 10A as well. However, I do remember the front lamp being tied right to the heater on one of the tubes which made me think if the lamp doesn't light it may just be a fuse. He did say the lamp lights up though. :?:

 

[eedude]

I do remember the front lamp being tied right to the heater on one of the tubes which made me think if the lamp doesn't light it may just be a fuse. He did say the lamp lights up though. :?:

the lamp is on a different part of the supply. So if F3/4 blow the lamp can still light (and the other filaments as well).

 

[Micah7]

Sorry, I haven't logged on in awhile and didn't see your messages. Yeah I tested F3 and F4 before and F3 was blown. I replaced it and the power tubes still wont light. This is driving me crazy.
Thanks for the replies

 

[Nighon Maiden]

Sorry, I haven't logged on in awhile and didn't see your messages. Yeah I tested F3 and F4 before and F3 was blown. I replaced it and the power tubes still wont light. This is driving me crazy.
Thanks for the replies

Hi, & welcome to my 1st post! I had the same thing with my RM100, it was because the dealer near me were told you could put the amp into standby mode & swap the modules, oh no you can't, I blew some internal fuses. Luckily I got it fixed at Sound Technology here in the U.K. so all was well. So I'm guessing you have had a similar experience of internal blowing of fuses for what ever reason. Hope that answers that, cheers, AD.

 

[crankyrayhanky]

?I swap on or off standby - whenever- no issues

 

[Mattfig]

?I swap on or off standby - whenever- no issues

Same here....Hot swapping seems to be fine for my MTS rig...I try not to do it, but you're playing with tubes and such, it makes things easier...

I know Randall actually referenced the modules as "hot swappable" in their adverts in the past...But I also recall some debate regarding that issue...

 

[Disciple]

Great - started up my amp tonight and same thing that happened to OP is happening to my RM100.

Front light comes on, fan starts up but tubes aren't lighting up and obviously no sound. It was working last night when I played it for a bit before bed and today no luck.

This is my first issue with my RM100 since I've had it in 06. Hope I can fix this myself instead of having to take this in. OP were you able to remedy your issue? If so let me know what you did

 

[bruce egnater]

Did you install 10 amp slo blow fuses? I assume you have a meter since you "checked" the fuses. Bet you are using something other than 5881/6L6 tubes? Check for ~6.3VAC across the green wires. Then check on the other ends of the fuses for 6.3VAC. If you blew the fuses again, install 15 or 20 amp fuses. The issue is that many power tubes have a much higher "cold" surge current than the 5881s. They can blow those fuses even if there is no problem. Report back.

 

[Disciple]

I actually have el34s in my rm100 only have had those and 6l6s in it since I've owned it since 06.

 

[Micah7]

Yeah I have El34s. I will take it apart and check to see if the fuses blew again.

 

[Disciple]

Do I have to discharge capacitors to get inside my rm100 to replace the internal fuses that may be my issue? If thats the case I will have to just take it into a tech