First Tube Amplifier, problems already (New Impressions)!

kingdeezie · « **on:** 29 Jan 2011, 03:30 am »

So, I finally broke down and purchased a tube amplifier. I bought a set of Manley Neo Classic 250s from a seller of of audiogon.

I was super excited, and upon opening them was extremely impressed by their awesomeness.

However, as has been my experience with this hobby; nothing works right....ever.

Now, assuming that these weren't busted when they were shipped to me, I am getting no sound out of the left channel.

When I first turned on both amplifiers, everything seemed to be working okay, and then the left channel made a little "popping" noise.

I turned on some music and there was absolutely no sound out of that same channel.

I changed the input tube, and the two other smaller tubes, and all of the EL34s seem to be lit.

Or course when I went to get my multimeter, the GD battery was dead. I am heading to 7/11 to see if I can grab some batteries, but outside of batteries I can't figure out what else could be wrong with them.

I have some extra tubes that the seller sent me for output....

I'm worried at this point that something bad happened to the amplifiers during shipment and that a solder joint or something somewhere has gone to shit, and these amplifiers are screwed, and will need repair from Manley.

My biggest fear was in all honesty was unreliability, and so far that seems to be the exact problem. My Pass amp was plug and play.

Any thoughts? I would love to hear these make music, but so far only the right has.

Tyson · « **Reply #1 on:** 29 Jan 2011, 03:39 am »

Either an output tube or a signal tube most likely. Just swap the tubes on the left side over to the right side and try it again.

TONEPUB · « **Reply #2 on:** 29 Jan 2011, 03:42 am »

You might have a bad tube, even though all the EL34's are lit. Give manley a call on Mon, they will help you troubleshoot even if you bought it used, they're pretty nice.

I know when we had the 250's in for review, one of them blew a cathode resistor when a tube croaked. Also, have you checked all the fuses too? Even if the tubes are glowing, you might have blown a high voltage fuse.

Here's a link to their site that might shed more insight:

http://www.manley.com/tech_page.php?product_type=hifi&product_code=n250&tech_page=Cathode_Resistor

Its a lot of screwing around, but you might want to swap all the output tubes in the working one for the the ones in the non working one too.....

A tube amp will never be quite as bulletproof as SS, but the Manley stuff is well made and they really stand behind it.

Here's to you getting back rocking sooner rather than later!

kingdeezie · « **Reply #3 on:** 29 Jan 2011, 03:50 am »

Could one bad output tube cause no sound at all to be made??

The cathode resistor scares me. I don't have the ability to fix something like that.

TONEPUB · « **Reply #4 on:** 29 Jan 2011, 04:08 am »

Even if you don't want to fix it yourself, you should be able to see a fairly burnt resistor on the circuit board...

Might at least give you a little piece of mind for now....

Check those fuses too! If you don't have any spares, you can swap the ones from the working amp and see if it makes a diff.

kingdeezie · « **Reply #5 on:** 29 Jan 2011, 04:35 am »

Of all the goddamn luck...

Its a freggin Resistor....

What are the odds that the first time I turn the amplifier on, the freggin resistor blows right out of the gate?

What a mess, and a horrid nightmare.

Guess I'll have to ship it to Manley; somehow I knew this was going to happen.

TONEPUB · « **Reply #6 on:** 29 Jan 2011, 05:29 am »

Do you know of a good local tech that can handle it?

S Clark · « **Reply #7 on:** 29 Jan 2011, 05:49 am »

A resistor is a pretty easy fix. If you can see the one that's bad, nearly anyone with some electronics background can change it out. Local is certainly easier than messing with shipping. Now the question is, why did the resistor burn out? Are you located somewhere where there is an electronics repair shop?

kingdeezie · « **Reply #8 on:** 29 Jan 2011, 05:51 am »

So the saga continues, and I am more confused then ever now...

So my multimeter was reading very low bias for most tubes, and next to nothing on tube number 10. So, I replaced tube number 10, but was still getting nothing there and very low on every other tube.

I switched the meter to OHMS, shut the amplifier off, and measured across all pots and got 11 except for the last one which I got 0. I figured it was the Cathode Resistor causing the problem here.

For giggles, I switched the B+ Fuse from the good amplifier to the bad amplifier...

SUCCESS!! Sound from the left channel....

So, my next question is, would I still get sound from the amplifier if I blew the Cathode Resistor? Would it just cause that tube to be unable to BIAS, but still play music?

TONEPUB, did you remember if the amplifier still played music after the cathode blew? Is it extremely dangerous to play the amplifier in this condition?

I don't know a good technician at all who can do it. Apparently Manley sells plug in resistors for those of us who can't solder well or at all.

I live in the PA/NJ/DE area if anyone knows a good tech there that wouldn't mind helping me out for probably a 10 minute swap out with the plug in resistor if I get a hold of Manley.

I am going to get another fuse hopefully tommorrow at Radio Shack for the other amplifier, but I am curious as to what it all means....

Should I not be using the amplifiers in this condition?

kingdeezie · « **Reply #9 on:** 29 Jan 2011, 05:53 am »

Quote from: S Clark on 29 Jan 2011, 05:49 am

A resistor is a pretty easy fix. If you can see the one that's bad, nearly anyone with some electronics background can change it out. Local is certainly easier than messing with shipping. Now the question is, why did the resistor burn out? Are you located somewhere where there is an electronics repair shop?

Manley says its a safety mechanism if a Tube shorts out; it doesn't screw the entire amplifier in this instance. Perhaps I am naive, but damn, I feel like this is a HUGE design flaw for your common person.

Maybe it isn't common, but I had the amplifiers plugged in for thirty seconds and it seems one might have went.

After the fuse change, I am getting sound from it, but I wonder if the resistor is still shot, and thus I won't be able to properly bias the tube in question.

S Clark · « **Reply #10 on:** 29 Jan 2011, 06:08 am »

Quote from: kingdeezie on 29 Jan 2011, 05:53 am

... but I wonder if the resistor is still shot, ...

If it measured open before, it certainly won't repair itself, even if it now carries a current intermittently. It will need replacing. By the way, it occurs to me that if you are new to tubes, be aware that just turning the amp off doesn't discharge capacitors. Poking around in a tube amp can result in very, very bad things happening. I'm sure that you are probably aware of this, but thought I might mention it.

dangerbird · « **Reply #11 on:** 29 Jan 2011, 06:09 am »

are you close to Pittsburgh

SteveFord · « **Reply #12 on:** 29 Jan 2011, 10:38 am »

If the Harrisburg area isn't too far to travel R.T. Grim Electronics in Camp Hill does really good work and the turnaround time is fast as well.

I believe that Tonepub nailed the fix, though.

It sounds like a tube didn't take too kindly to shipping. I have two sets of VTL monoblocks and both gave me some agita shortly after arrival but they've been going like champs ever since.

Chin up, once that resistor is replaced you'll have one hell of a pair of amps!

Niteshade · « **Reply #13 on:** 29 Jan 2011, 11:32 am »

Does the damaged amp heat up as much as the working one?

Rocket · « **Reply #14 on:** 29 Jan 2011, 11:52 am »

Hi Kingdizzie,

Don't worry too much you can fix the problem with the amplifier and if necessary you may have to send it to manley for further investigation. When you purchased the amplifier from the dealer did you obtain a warranty?

You could be in my shoes and have spent $6500US (2009) and purchased an amplifier and shipped it to australia. I have had so many problems with it. I sent the transformer back to the US and shipping cost me $250US. In total I have spent $1500 on repairs and I still have problems with it.

I understand your situation but you can fix this.

Regards

Rod

Alexdad54 · « **Reply #15 on:** 29 Jan 2011, 01:14 pm »

Kindeezie,
Give Community Audio in Philly a call, they carry Manley and they put me in touch with their repair tech who specializes in vacuum tube amps. Their number is: 215-242-4080. The tech (whose name escapes me now and I can't find the original receipt)) is extremely reliable and does a great job. He lives near New Britain which is not too far from Jersey, NE of Philly.
Good luck!

kingdeezie · « **Reply #16 on:** 29 Jan 2011, 01:30 pm »

Thank you everyone for your words of encouragement.

Obviously this is not an ideal situation, but this stuff happens in this crazy hobby, and hopefully I can get it fixed eventually.

I would love to get it fixed locally as opposed to shipping it back to Manley. Ultimately I would love to learn to fix it myself considering it appears that this will happen every time a tube goes.

I am going to try and email or get in contact with someone over at Manley on Monday to see if they can send me the plug in resistors; which should make changing to resistor a relatively quick process.

kingdeezie · « **Reply #17 on:** 29 Jan 2011, 02:39 pm »

Anyone know of any store that carries Slo-Blo ceramic fuses that might be local to me?

I need a MDA 1-1/2 fuse, and I can't find anything online locally.

HAL · « **Reply #18 on:** 29 Jan 2011, 03:04 pm »

If you cannot find the ceramic version you can use the Radio Shack Slo-Blow Glass fuse while you are looking:

http://www.radioshack.com/product/index.jsp?productId=2102748

Just put two new ones in to have both channels the same.

kingdeezie · « **Reply #19 on:** 29 Jan 2011, 03:09 pm »

Quote from: zmanastronomy on 29 Jan 2011, 02:52 pm

I just went trough the same problem. My Almarro A318B takes 6C33C's for output tubes. I put a bad one in and cooked my cathode resistor on the right channel. Almarro sent be a new one and I fixed the problem.
Once the resistor cooked, it would still play music but would not bias on the right channel correctly.
Hope this helps.

This seems to be the problem, and yes it helps a lot. Did you continue to listen to music with the cathode resistor out, or did you stop till the resistor came to you from Almarro?

How hard was the repair? Did you solder it? It looks like Manley has a "clip" on solution.