Problems with RM 50 combo

[stratotelepaul]

Has anyone had problems with RM 50 combos (or heads) making popcorn noise when you take the standby off? It also has very little volume, and a distorted sound even on the clean module. I changed all the tubes, re-biased and it's still there. I also have an RM 100, so I installed the modules into the big brother and they work fine. Did I mention this is a brand new out of the box amp (2009 model)? It went back to Randall once, only to have it fail again at the second gig. I was very disapointed.
I'm trying to figure out if this amp can handle the road or I just got a bad one. I've been playing the RM 100 2-3 nights a week for the last 6 years so when this one failed twice, I was shocked.
I've just discovered this forum and I think it is great!!!

 

[wesarvin]

It's funny you posted this. Tonight I had a similar problem with mine. It sounded like a dying preamp tube, but I swapped them and it still doesn't work. Slight popcorn off of standby, then very crackly and distorted with low volume.

Mine had a few suspect solder joints on v3 a while back when it was really making popcorn. I reflows the joints and it worked fine, but now it's doing a different thing, like your issue. Rob DeAntonio here on the board is an authorized tech. Maybe he will chime in.

 

[stratotelepaul]

I'm hoping we can get a bit of advice on this. Now the issue has a new level of complexity...it is intermittent. I fired up the amp again, and it is working fine. Wesarvin, I hope Rob DeAntonio can chime in too. I'm trying to see if Randall will have me send the amp to Rob for the repair. From other posts I've read, he has a great working knowledge of these amps.

 

[Rod]

Rob and Kc2eeb know these Randalls inside and out.

 

[stratotelepaul]

Well, yesterday it finally started acting up again. We're waiting to hear back from Randall on what they want to do with this issue...I'm hoping they just do a board swap now. I know it's not the tubes, there has been 3 sets of new tubes through it now or the modules, they work fine in my 100. Different guitars, cables, ect. It's going to take quite a while before I feel comfortable taking this amp out if we can get it fixed!

Wesarvin, any luck with your situation???

 

[LunatiBSW]

Rob DeAntonio, is owner of Jaded Faith mods. He is a Randall service tech as said up top and He has amazing customer service. Email him and he'll get you up and running if the Randall route doesn't work for you
His website: www.jadedfaithmods.com
will have his contact info.

 

[rvf263]

I have a RM50 that's been doing the same thing lately. It's also intermittent. I was just getting ready to buy new tubes for the amp and my modules but after reading this thread, I'm holding off.

I may have to email Rob....... :?

 

[Mattfig]

What the hell? My Rm50 is beginning to have a similar issue. My cleans at lower volumes are crackling. I did all the common things and it can only be the RM50.

I blame you guys for posting this! I would never have worried it would get worse until now. :x

In all seriousness, this issue seems to be more common than it should. I don't get the popcorn on standby- yet. But I bet that's next.

Rob might see an influx of biz here. Hopefully it can be a board swap and not an entire amp for shipping purposes.

Any of you guys with these issues successfully using EL34s? Just curious as mine won't bias properly either. It drifts and is so sensitive that a slight bump would push it over the edge. Larger glass works fine though and bias right up and hold. Just thinking this may have something more to do with it?

BTW, welcome stratotelepaul!

 

[stratotelepaul]

Thanks Mattfig and sorry to hear about your RM50 acting up too! I've seen a few of your youtube demos of Jaded Faith modules; I like the way you go through them. Keep up the good work!

Well, the amp was shipped back to Randall with a detailed email on the issues I'm having again. I know what's going to happen, the darn thing will work fine when it arrives there...just my luck but they now know it is an intermittent issue so I hope they will keep the amp until it acts up again.

The more posts I'm seeing about the RM50 looks like it may not be a good choice for a main road rig. That's too bad because so far, it is the best (fullest) sounding 1x12 combo I've owned!

 

[kc2eeb]

Hi!
http://mtsforum.grailtone.com/viewtopic.php?t=12785&highlight=lots+pictures+rm50+repair
The pictures show a lot of what to look for as far as shorting on the power amp chassis, i.e. carbon (black) traces on the circuit board around high voltage points.
Sometimes tubes just "cook off" the cathodes and that will cause some popping noise.
You have to check each tube (tap them with a with a small wood stick while the amp is on tho check for micro-phonics.

 

[Jaded Faith]

Sorry this didn't hit my radar sooner guys, the prep for the LA Amp Show and trying to keep customer orders rolling out the door has been killing me all month.

The first thing you should do with any amp when you get odd noises or volume fluctuations that are not obviously tube related is a thorough cleaning of the loop and input jacks. Use Deoxit or a contact cleaner on a guitar cable and work the jack a few times. This is an often overlooked maintenance procedure that fixes many an issue.

If your RM50's won't bias properly with EL34's, you likely have to replace a resistor in the bias circuit. It's well documented here if you search for it.

The arcing on the power board is a possibility, but I'd say it's the least likely issue.

Keep me posted on how you make out and feel free to email me to discuss as well.

Good luck and all the best,
Rob

 

[stratotelepaul]

Rob,
Thanks for commenting here. My RM50 is back at Randall and I'm really hoping they will be patient enough to let it act up. The deoxit is a great idea and will be in my maintenance schedule for all my amps going forward. I will keep you posted on the RM50's 'recovery' when it returns.

 

[stratotelepaul]

How is everyone's RM50 issues going??? Mine is still at Randall. The waiting game sucks. Just wondering if anyone found a common fix for the noise issues of the 50.

 

[withmittens]

just got my RM50 back from my local tech under warranty. he said the main fuse blew but could not determine why. There is strange honky distortion on cleans turned up past 9pm on the master. preamp past 3pm. gain past 12pm. I expect it will go again and when it does I am driving the hour and a half to Jaded Faith. Also, I will ask Rob to go through it and tweak it with his standard upgrades that he outlined in a thread a while back

my only other thought is that because it traversed the country twice handled my UPS that perhaps the tubes have been rattled to death. I have 6CA7's in there now, that could be unstable.

I did have popping but I think I've traced it to a certain pedal

 

[wesarvin]

Well, readjusted the bias (only a millivolt) and replaced the phase inverter tube, and no more issues yet. Odd little beast...

 

[stratotelepaul]

Got my RM50 back from Randall yesterday...I guess they found a bunch of questionable solder joints on the preamp tube sockets. I'll be playing it daily and transporting it in the car as much as possible. It seemed that moving the amp around from gig to gig aggravated the problem. I'll be pouring the screws to this amp before I trust it live again. I have to thank Randall for standing behind their product.
Now I think I'll go after my Top Boost module and have it modded to bring back the Vox chime to it...needs some clean headroom! Any suggestions?
Thanks!

 

[Rod]

Turn that top boost into a JF Voxless!!! Vox or Matchless !! a different animal

 

[stratotelepaul]

Rod, that's what I am thinking. Have heard very good things about it!

 

[stratotelepaul]

Just following up on the RM50...so far, so good. I even had the confidence to take it to my last few gigs. I'm still impressed on how much low end this little combo can toss out! WOW!

I'm thinking about swapping speakers. I play such a variety of styles live that it's tough to begin to search. I think I've seen some posts about WGS products but I need to cover anything from Country to 80's hair metal to Top 40 pop.
Any suggestions would be great!

 

[Rod]

Just following up on the RM50...so far, so good. I even had the confidence to take it to my last few gigs. I'm still impressed on how much low end this little combo can toss out! WOW!

I'm thinking about swapping speakers. I play such a variety of styles live that it's tough to begin to search. I think I've seen some posts about WGS products but I need to cover anything from Country to 80's hair metal to Top 40 pop.
Any suggestions would be great!

statotelepaul.. I've run a few different speakers with my RM50 combo...
Here's my opinion..Also I play a little country, Blues, Classic rock and some high gain tones with my bands.. similar to you I guess..
The stock Celestion GT75 isn't bad. A little loose on the bottom with scooped mids. HIghs are fairly bright for me.
I then went to a Lynch speaker..to much cone cry with odd midrange,,..didn't work.
I tried a Celestion G12H30...To in your face sounding with highs that will peel paint. To hard sounding as well...
I tried a WGS ET65... To muddy and flubby sounding
Then a Veteren 30 WGS .. to much midrange in the high mids area, better than the Vintage 30 but similar.......
Then I discovered the WGS British Lead.. Very balanced and even sounding. Full but tight lows, even mids that aren't obnoxious, and smooth highs.. It does many tones well from very clean to very high gain....
Not trying to be a spammer, but I bought a bunch of them and have an extra one in 16 ohms if you're interested. PM me.. They are about $90 new with shipping..could sell one shipped for $60
At any rate, they are such a great sounding speaker and not congested sounding like their Celestion 80 watt Classic Lead counterpart..