Help With My RM9 MKII

dhunte21 · « **on:** 12 Feb 2012, 02:14 am »

Ok so this is something new that I noticed. After many many hours of enjoying my RM 9 I noticed the other day that on power on the left channel, as the tubes are warming up if you look at the bias light it flickers on and off and while doing this you can hear a popping in the speaker on that channel. I tried swapping out the power tubes to the other channel, and the input tubes to the other channel and it still continues to do it. What I do notice is that I have to push rather hard on the button on that same channel to get the balance correct.

Have this happened to anyone else? Might I have to change out the bias pot! Its just a thought, any info will be greatly appreciated. Food for thought, once the tubes have been powered up for about 10 mins or so, its completely gone.

HUMMM!

Ericus Rex · « **Reply #1 on:** 12 Feb 2012, 01:45 pm »

My Mk. I used to do that. Changing the bias/balance trim pots, installing new tube sockets and repairing faulty PCB traces did the trick. But I was also getting lots of noise during playback; mine didn't go away after 10 minutes. Since yours does go away I'd say it's hardly worth the hassle and expense to repair.

You haven't been tube rolling the miniatures, right?

dhunte21 · « **Reply #2 on:** 12 Feb 2012, 02:18 pm »

Repairs will not be an issues, I am a tech and have worked on countless amps. I suspected as such as I started to have a little issue with the Bias pots. I did look for loose solder joints already, but I did not change the pots when I was in there.

Thanks for the info.

rbwalt · « **Reply #3 on:** 12 Feb 2012, 03:33 pm »

those push button input balance pots get dirty. spray some contact tuner cleaner in them and move them around. they will move a bit. now the trim pots are not good for many turns. i think about a 100 turns is it. tube rolling on the input tubes will cause the sockets to come lose from the the board and they do. mine did it.

have you changed out the power cord? do you have the amp sitting on its rubber feet? the reason i ask is that many just like to tube roll for tweaking.

let us know how you make out. good luck.

R.

dhunte21 · « **Reply #4 on:** 13 Feb 2012, 01:39 pm »

You know I thought about that. No I have not done any tube rolling, and No I have not changed the power cord. I was thinking about that though. Looks pretty hard to get some spay in those push buttons. I did order the replacement pots from Mouser this morning. But all in all that has been one of my favorite least trouble free amps ever. Love the darn thing, wont part with it for nothing.

rbwalt · « **Reply #5 on:** 13 Feb 2012, 03:02 pm »

yea it is not easy to get the cleaner into the pots. glad you love the amp. i had mine for 11 yrs. i had to have my driver tube sockets gone over, new pots and gain switch. i had a NOS Siemens EL34's in for those yrs without a problem. never switched out the power cord on it. i traded it in to roger so i could get one of his RM9SE's. Had him put on a EC connector. now i can play around with different PC's.

yep the RM9MK1 & 2's are still dam good amps!. i think a little tweaking can make them better. good luck with your repairs. let us know how they come out.

R.

dhunte21 · « **Reply #6 on:** 24 Feb 2012, 01:51 pm »

Just wondering if ther is something in which I must have missed, did change out the pots and I still have somewhat of a slight scratching and popping in one of the speakers. the only thing that I did not do was to change out the input tubes, I did roll the output tubes, and it was still isolated to the same channel.

Any input will help thanks.

rbwalt · « **Reply #7 on:** 24 Feb 2012, 03:05 pm »

did you replace the push button's along with the trim pots and did you check the solder joints of the driver tube sockets on the board?

r.

dhunte21 · « **Reply #8 on:** 24 Feb 2012, 08:06 pm »

To be quite honest, I did not replace the push buttons.... if you happen to know where I can find some, that will be greatly appreciated. I will put it back on the bench tonight and take a look at the solder joint on that side. It only appears to be on the right side, and it sound like small little pops off and on.

Thanks for the input.

Ericus Rex · « **Reply #9 on:** 24 Feb 2012, 09:19 pm »

In addition, take a good close look at all the PCB tracings. They're mighty delicate. I think rbwalt is probably right, though.

rbwalt · « **Reply #10 on:** 24 Feb 2012, 09:41 pm »

if you wiggle the driver tubes around on the one side does it go away, stay the same or get worse? could be a trace on the board as ericus rex mentioned. can you take a pic of the board and post it so we can see.might help in diagnosing the problem.

r.

dhunte21 · « **Reply #11 on:** 26 Feb 2012, 10:58 pm »

Ok, well I did a re-solder the input and output tubes on the channel that is sounding like a scratching popping. Powered it back on and nothing has changed, tried swapping the tubes from side to side, but it appears that it is isolated to that one channel.

So this is all that has been done:

Replaced the pots,
Tried different tubes on the output!! have not changed the input tubes.
Rocked the tubes from side to side.
Re-soldered any cold joint.
Checked for bad traces on the board.

you can hear the issue just as the amp starts to warm up, but it seems to go away in a few minutes. Scratching and static does not change with volume.

Scratching head now.

Gvt1911 · « **Reply #12 on:** 26 Feb 2012, 11:28 pm »

Had 2 of these amps and both had problems with the solder joints around the tube sockets on the board. I took a look at them with a loop and found that almost 6 out of nine solder joints were cracked. I believe this is caused by swapping and rolling tubes. I used WBT solder and my problem was solved.

dhunte21 · « **Reply #13 on:** 27 Feb 2012, 01:23 am »

I am really starting to believe that it is the push button on the right channel that is causing the problem, after playing around with it for a few, the popping went away but came back. If anyone have the spec on that balance button, that would really be well appreciated....

Thanks in advance.

rbwalt · « **Reply #14 on:** 27 Feb 2012, 02:57 pm »

do you get allot of noise from the one channel when you depress the push button? as i mentioned before trying spraying some contact cleaner down into it and work the button around.i know that it is not easy but all you need is a very small amount. mine use to snap, crackle and pop. i think you still have a bad solder joint somewhere in the driver tube socket. here again mine also did the same thing( would go away after it warmed upped). i thought it was a bad driver tube so i sent it back to roger and he tested it. told me it was ok. he sent me a new one and it did the same thing. so off the amp went to roger for a good going over.

R.

ps. make sure you are using a very good solder.none of the 60/40 crap.

dhunte21 · « **Reply #15 on:** 27 Feb 2012, 08:58 pm »

Yes Yes I do!! much more noise on that one button than the other one, Actually I have to press it pretty hard in order for it to balance. I did notice that after playing around with it for a bit the noise did go away but it comes back. Wondering if anyone would know where I can get on to purchase. I am going to try to deox the thing and see.

Thanks will keep you posted.

dhunte21 · « **Reply #16 on:** 3 Mar 2012, 02:00 am »

I am wondering if anyone would be able to point me in the right direction as where to purchase the momentary push button for the balance on the RM9 MKII? Unfortunately there is no marking or indication as to the specs of the button.

Any information will be greatly appreciated.

Thanks.

Freo-1 · « **Reply #17 on:** 3 Mar 2012, 02:04 am »

I would contact Roger directly. He should be able to help you get your amp sorted out.

dhunte21 · « **Reply #18 on:** 3 Mar 2012, 02:14 am »

Thanks,

Would you have any way of contacting him, such as an email address? Or contact number.

Freo-1 · « **Reply #19 on:** 3 Mar 2012, 02:23 am »

Quote from: dhunte21 on 3 Mar 2012, 02:14 am

Thanks,

Would you have any way of contacting him, such as an email address? Or contact number.

Here you go, mate!

Sales: (805) 687 - 2236
Technical Support: (805) 687 - 2236
Yahoo! Store: tubeaudiostore.com
Email: musref.roger@gmail.com

I've talked to Roger about past tube purchases, and found him to be most helpful.