Other Amps

Amp tech help needed - Music Man 210RP-100 died yesterday…BUT LIV

1

Well, I guess my beloved Music Man 210 RP heard me considering the Parkel and decided to throw a hissy fit last night mid gig.

I was getting down and digging in to a solo when I heard a high level distortion noise. I was trialling a pair of ETY electronic noise plugs for the first time and kind of assumed it was those and didn't think too much about it, just back off a little and finished the song. Next song started and the amp is dead; nothing. I had to plug my Line 6 into the PA to finish the gig. The amp has blown an internal fuse once in the past so I assumed it was that again, but having opened it up today there's nothing wrong inside, all fuses are intact.

My guts are telling me output transformer or tubes. I doubt both tubes would die at once, so my question is this; if one tube dies would it take out the whole output? If the answer is yes then it could be a dead valve. If the answer is no I guess I'm looking at a new O/P transformer...

Any other help or advice on offer would be gratefully received.

2

Deke: I can't help you myself (you certainly wouldn't want me poking around in your amp) but there are a couple of places in North Kent -- Tube Tone and Vintage Amp Repairs -- who do this sort of stuff. You probably know of them already. Best of luck.

3

I'm no help but I will express my sympathy. I know there are plenty of people here that may have an answer. I dread the day it happens to me.

4

Deke, Transformers rarely fail, but tubes short out all the time. You probably just need a set of tubes and a bias. If I were closer, I'd have you rocking again in an hour!

5

Not to cast a dark shadow - and I hope JB is right (from the description I concur it could well be a “valve”) - but the hybrid Music Mans (while very robust) are sometimes subject to mystery gremlins. Possibly, I’m told, related to heat-and-age induced brittling of PC boards and associated intermittent uglies.

The heck of it is, such problems can escape the notice of even a careful visual inspection. (And I only mention it because you say you can’t see anything amiss.)

I hope I’m wrong. Tubes are a much more honorable problem to have in an amp than brittle boards...and more easily fixed.

Good luck. My MMs defy my every intention to downsize the ampery. Great amps.

7

Thanks guys, all very helpful.

The 210RP is a great amp, I mean a GREAT amp. It's heavy - 54lb or so - but when I plug that thing in I forget how much I cursed carrying it to where it is. It's been my right arm since around the turn of the millennium (sounds awfully pretentious, but there we are), and I can't imagine what I'd do if it were no more.

There is one confession I have to make that I neglected to mention before. The effects loop is on a single TRS socket. This means that you need a Y-cord in order to use it. Our bass player wanted to take a line out of my amp last night to put into his monitor and I suggested he put a cable in there to see what comes out. We tried it for a few seconds, but it was clear very early on that putting a plug in there cut the signal to the main power amp so we took it out. I now worry that we have maybe shorted out the return sides of things and blown something serious (expensive) up, but I played for the next hour with no problems so I really don't think that could be it, but who knows; maybe I did.

Josh, more than ever before I wish you were my next door neighbour

8

Me too, my friend!! At least I may manage a visit to your area someday! You can't hurt much by plugging things into the effects loop. If the loop's jack get dirty or corroded, it will cut off your output. But if you put a patch cable between the send and return, it will bypass the loop entirely. Marshalls are famous for loop jacks getting dirty and then the amp's owner thinks that it has died. A cleaning of the jacks is all it takes.

You might need tubes, but I'd try this first.

9

One bad tube can blow the fuses, internal or both. Transformers almost never fail, unless they're modern crappy ones. Filter caps will blow the fuses too. Which version do you have, the one you can't get tubes for, or the one you can't get transistors for? Almost nobody understands how those amps work. It's a transistor amp with tubes between the collectors and the B+, and they run positive bias voltage on the tubes. The only adjustment is for the crossover symetry of the class B driver transistors, which must always be replaced with a matched pair. The ones with 6CA7/EL34 tubes run 700 volts on the plates, which is a lot for modern tubes to handle., although running them on half power lowers to voltage to a normal 450 volts. The other trim pot is for the Tremolo, but those usually won't stay in adjustment anyway.

10

Well, I guess my beloved Music Man 210 RP heard me considering the Parkel and decided to throw a hissy fit last night mid gig.

I was getting down and digging in to a solo when I heard a high level distortion noise. I was trialling a pair of ETY electronic noise plugs for the first time and kind of assumed it was those and didn't think too much about it, just back off a little and finished the song. Next song started and the amp is dead; nothing. I had to plug my Line 6 into the PA to finish the gig. The amp has blown an internal fuse once in the past so I assumed it was that again, but having opened it up today there's nothing wrong inside, all fuses are intact.

My guts are telling me output transformer or tubes. I doubt both tubes would die at once, so my question is this; if one tube dies would it take out the whole output? If the answer is yes then it could be a dead valve. If the answer is no I guess I'm looking at a new O/P transformer...

Any other help or advice on offer would be gratefully received.

– Deke Martin

WS beat me to it. The amp gods have spoken Deke. Have someone local pick up the Parkel and ship it to you!

11

What's a Parkel? I assumed it was a typo meant to be Park, but you're all spelling it that way.

12

Thanks again guys, I appreciate the input.

Billy, wow, lots of tech stuff there I don't understand . I don't know which one I have, it's a 210RP-100 is all I know, board is dated July 1980 if that helps. There are no blown fuses inside, so it's not a bad fuse. I've ordered a new pair of 6L6GC and they should be here early next week, so fingers crossed that will solve it. Josh, you mention biasing, will it need readjusting after the new tubes go in?

Billy, the Parkel is a Bud Park built Standel clone that's for sale on another thread:

Parkel

13

Deke,

Billy's spot on with his comments. The tube change to 6L6 power tubes occurred around 1979/80 at the time of the white to black logo change although that is not a definitive designation as, like most makers, old parts were used up until they ran out.

If you have a black logo amp with 6L6 tubes then it's the later version which I personally prefer and the tubes are easier to find.

Yes, if one power tube fails, you will get no sound. And yes, these amps drive the power tubes really hard. They all came with Sylvania 6L6 tubes originally and many still have them installed.

So, I'd start with the power tubes. If you get sound, then you're on the right track and can spend time searching for a good NOS set. Believe me, it makes a difference in tone as well as reliability.

Since I don't really believe in coincidence I am also suspicious of you running a monitor from the effects loop. Yes, that will cut the main amp signal as the loop is now the primary signal path. If you've never cleaned any of the jack sockets get a can of Caig DeoxIT and treat them all. I treat all of my amp sockets and tube sockets every six months or so and it really does keep down noise and crackle as well as improving the sound.

https://www.amplifiedparts....

If you still don't get any sound then it might be a preamp circuit board problem but, like transformer failure, that's pretty rare.

Lastly, it seems that you had a fuse blow on a previous occasion. That was a warning right then that something was going amiss.

As you say, these are great sounding amps, although damned heavy, more so with the Electro-Voice speaker option.

If you do need more serious help, this thread indicates some good guys who you can contact.

http://www.tdpri.com/thread...

Let's know how you fare with getting it running again.

14

I had a 65 watt / 2-10 MM amp in 1980 and it was the loudest screamer for that size, like in history)

Johnny Winter was faithful to MM right up to the end. In this vid one of his several 4-10 MMs catches fire. What kind of things can cause an out-and-out fire?

He was hot player, no doubt. No joking here btw

15

Roadies are the cause of amp failure on the road.

16

Ah, Billy...how true! My crew dropped my 4 week old Vox AC30 12 feet on to a concrete floor in 1965. Times and construction methods were different. I still have it and it plays great.......not least due to Vic Mason at Mojave Amp Works in Apple Valley, CA.

17

No matter what precautions you take, they'll find a way.

18

Well, a quick update. I found a how-to-test-your-tubes-without-a-tube-tester video on YouTube and it seems my tubes are, prima facie, OK. In truth the video only shows you how to test for shorts between pins so I don't really know how "OK" my tubes really are. The replacements should arrive tomorrow, so I guess I'll know in about 22 hours. I kinda want the tubes to be OK as they look like the originals, but by to same token that means something else is poggered so maybe a dead valve is prolly the lesser of evils.

Dave_K, I'd not heard Tube Tone, but I Googled them and lo, they appear to be somewhere in the region of 1 mile from my house. That's pretty awesome so I'm going to take that as a good omen and if the new tubes don't fix it they will be the people I call.

But only because Josh is in Chicago.

19

Mojave, I have the later logo and 6L6GC valves, so I assume my amp is a 2nd generation model. As I mentioned before the board is dated July '80.

I don't get the familiar thump when I switch it out of standby, so I'm assuming the problem is definitely on the power stage.

20

Don't assume anything, and don't try to mess with it yourself. Take it to a really good tech with MM experience.

21

Hi Deke,

I go with Billy on this one. You can certainly clean the sockets and install the new tubes but beyond that track down a vintage MM tech.

If you haven't already done so, check out this link.

http://pacair.com/mmamps3/

22

Hi Deke,

I go with Billy on this one. You can certainly clean the sockets and install the new tubes but beyond that track down a vintage MM tech.

If you haven't already done so, check out this link.

http://pacair.com/mmamps3/

23

Well, a quick update. I found a how-to-test-your-tubes-without-a-tube-tester video on YouTube and it seems my tubes are, prima facie, OK. In truth the video only shows you how to test for shorts between pins so I don't really know how "OK" my tubes really are. The replacements should arrive tomorrow, so I guess I'll know in about 22 hours. I kinda want the tubes to be OK as they look like the originals, but by to same token that means something else is poggered so maybe a dead valve is prolly the lesser of evils.

Dave_K, I'd not heard Tube Tone, but I Googled them and lo, they appear to be somewhere in the region of 1 mile from my house. That's pretty awesome so I'm going to take that as a good omen and if the new tubes don't fix it they will be the people I call.

But only because Josh is in Chicago.

– Deke Martin

Deke, the only continuous connection in a tube would be the heater. Don't worry about keeping the original tubes. Mir they're bad, replace them. They're made to be easily removed and replaced for a reason.

Always have the amp rebiased when changing tubes.

24

Thanks again everyone. Sorry I've not responded to all in person, but your input is no less valuable.

I have a quick update, but it's not good.

I changed the valves today and still nothing. I had a y-lead made up at work today with a TRS plug on one end and a pair of mono plugs on the other. This is what is needed for the effects loop S&R. The insert point is just after the pre-amp and just before the power amp, so I figured with this I could a) see if there was a signal coming out of the pre, and b) see if I could feed an external pre-amped signal into the loop so the power stage was acting as a slave. Sadly neither produced any noise at all, so I still don't know if its the pre-amp of the power amp that's playing up.

One thing I did do though is to measure the output coming out of the pre-amp. There are 2 S&R insert points; one labelled 100mV and one labelled 3V. The 100mV one reads about 100mV immediately on power-up, but straight away starts to tails off, down to pretty much nothing after 15 secs or so. Similarly, the 3V insert reads 3V immediately then slopes off to nothing in a similar timeframe. What's going on here? Is it a faulty cap?

WS; yes, only heaters have continuity, that was the basis of the rudimentary test. They should, but no other pins.

Other than changing the valves and/or fuses I'm certainly not going to go poking around in there, much less do any actual surgery. I am very aware of the super high voltages in valve amps, and at 700V it seems Music Man even took that idea and ran with it. With that in mind I called Tube Tone this evening (the amp builder less than a mile from where I live) and was told he had passed away. I think it was his widow I was speaking to. That put my little amp problem into perspective, that's for sure.

25

Deke, the only continuous connection in a tube would be the heater. Don't worry about keeping the original tubes. Mir they're bad, replace them. They're made to be easily removed and replaced for a reason.

Always have the amp rebiased when changing tubes.

– wabash slim

You don't bias Music Man amps. They're different. They run a positive voltag on the grids, and the signal input is the cathodes, which are attached to the collectors of the driver transistors. There is a trim pot to adjust out the crossover notch on the driver transistors. These are NOT tube amps. They're class B transistor amps with tubes between the collectors and the B+, which flows from the driver transistors, to the cathodes, and then to the plates and back to the power supply. The tube grids are NOT the signal input, and they are run at a positive voltage. These have nothing to do with normal tube amps. Find a tech who understands that.


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