new RM50LB Combo fuse issues

[johnodge]

Good day all!

I've only had my combo for a week, and it has issues...

I put a new set of JJ E34L's in, and let them warm up for 5 minutes, and then biased... from 35 to 38.

I switched the amp into play mode, first with my DF-to-Lynch-spec Brahma, and then my stock Grail, jamming to some classic Dokken....

After about 10 minutes, the amp died... I checked the tube fuses, and they were ok, and then the fuse closest to the power cable. That fuse was blown. So I changed it, and the amp or the modules still don't turn on (no lights, sound, nada)

Any ideas? Tips? Condolences?

Thanks!

 

[Mister Joshua]

My condolences. I'd recheck the power tube fuses. I have read many treads here where people have had similar problem with this when they install new JJ EL34L tubes. I'll see if i can find the old threads about this problem.

Peace, Joshua

Quick Edit. PM Julia. I found some of her old threads about this problem. She probably knows exactly what is acting foolish in your amp.

 

[johnodge]

Well, I dropped the chassis, and checked all 5 or 6 fuses internally, and they all tested good.

I checked the mains fuse again, and it was blown (from just switching it to 'on')... So, I put a new fuse in there, switched the amp on, and blew the fuse... did it again, and blew the fuse... so, I don't know... I ran out of fuses... lol

 

[yigba]

Put in your old tubes and then power up? I won't even use EL34's anymore in my Lynchbox combo.

 

[johnodge]

I'll have to wait until I get new fuses...

The weird thing is... the amp came with E34L's.... errr.....

 

[johnodge]

When I got the amp, there was feedback 'ringing', so, I changed V1, and the power tubes to KT77's biased to a cool 30-32. But still had some feedback 'ringing'. (as a contrast, I don't have that feedback 'ringing' in my RM4/RT2-50 setup, using the same modules).

I played probably 2 hours, low volume like that. Today, I decided to tray a new JJ E34L set, and biased to a cool 38.

 

[yigba]

Mine too. But after reading the horror stories of EL34's I yanked them right out.

TAD 6L6's are now all I use.

 

[johnodge]

I liked the sound out of the KT77's, but no high end 'sparkle' like the E34L's...

But, I have a set of JJ6V6 coming...

 

[Mister Joshua]

http://mtsforum.grailtone.com/viewtopic.php?t=7323&highlight=el34l

http://mtsforum.grailtone.com/viewtopic.php?t=7355&highlight=el34l

Here are two of the old threads about the exact same problem you are having now. Hopefully they provide some insight

Peace, Joshua

 

[Julia]

38 mV is very hot for E34Ls. They are 25W tubes just like EL34s and 5881s. That shouldn't blow your main fuse though.

 

[johnodge]

Hmmm well the Randall manual lists the range as 35-45....

 

[johnodge]

Is there another tube out there that is just as bright (high end sparkle) like the EL34/E34L?

I tried the KT77, and although it has some nice low/low-mid/high qualities, it lacks the sparkle of the E34L...

 

[JKD]

38 mV is very hot for E34Ls. They are 25W tubes just like EL34s and 5881s. That shouldn't blow your main fuse though.

Doesn't JJ claim their E34L as a 30W tube?

 

[eyeball987]

38 mV is very hot for E34Ls. They are 25W tubes just like EL34s and 5881s. That shouldn't blow your main fuse though.

Doesn't JJ claim their E34L as a 30W tube?

I believe that they do. I bias mine up around 31. If I don't they sound a bit harsh. At 31 they sing.

 

[Julia]

You asked for it? You got it.

JJ Electronics spec sheet for E34L

If you look down the column it says 25W.

Sellers may claim 30W, but I'll go by the spec sheet.

Not all 6L6s are created equal either. Check the tube manufacturer's specs for definitive answers. JJ 6L6 GC's are 30W. Sovteks are 25W.

 

[johnodge]

Is the External mains fuse (ie the one beside the power cable going into the unit) supposed to be:

Glass 5x20mm(?) Slo Blo 250V/5A (at 100/120V), 2.5A( at 220/240V)

If so , that might be part of the problem. The one that blew in mine was a 0.315A 250V Fast Blo

 

[JKD]

Is the External mains fuse (ie the one beside the power cable going into the unit) supposed to be:

Glass 5x20mm(?) Slo Blo 250V/5A (at 100/120V), 2.5A( at 220/240V)

If so , that might be part of the problem. The one that blew in mine was a 0.315A 250V Fast Blo

Looks like someone maybe put a tube fuse in the mains slot??? :?:

The voltages and ratings for the mains fuse are on the receptacle...I believe that's where I got those from...I think I pulled the fuse and checked the dimensions too.

 

[johnodge]

Fawk.... lol

I bought the amp 'new'...

Oh well, another trip to Radio Shack ... lol