First Tube Amplifier, problems already (New Impressions)!

kingdeezie · « **Reply #20 on:** 29 Jan 2011, 03:10 pm »

Quote from: HAL 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.

I didn't think you could use glass where a ceramic fuse was called for. Am I wrong?

Uptown Audio · « **Reply #21 on:** 29 Jan 2011, 03:17 pm »

You should take the amp to a tech and have it looked at. It's not a guinea pig for a newbie to attempt to learn soldering techniques on. There are likely also extremely high voltages present in the amplifier even when it is off. It's just not safe for the average user to work on. The tech should have fuses or be able to get them. You'll want a few spares, they don't need to all match. The tech can go over the operation of the amp to make sure it is repaired and set-up correctly. using a Manley supplied resistor sure would make his life less complicated. The amp should not be having resistors fail every time a tube has a conniption. The tech should also assess the condition of the output tubes at that time. It never hurts to have a spare set handy.

You shouldn't use the amp without a good cathode resistor installed.
-Bill

HAL · « **Reply #22 on:** 29 Jan 2011, 03:22 pm »

If the fuse is used for very high current or very high volatage then the glass fuse should not be used. The current in this case is 1.5 amps so not very high.

The question is voltage rating. If the voltage is higher than 250V, then the ceramic should be used as that is the max rating for the glass fuse at RS.

The long term stability of a ceramic fuse is better, which is why it would be best for a long term application. The glass would work fine in the short term until you can find a ceramic replacement if you do not exceed the voltage rating.

Sometimes places like Lowes or Home Depot have fuse centers where you can find the 1.25" x .25" cartridge fuses. If not Mouser, Digi Key or Newark Electronics carries them.

kingdeezie · « **Reply #23 on:** 29 Jan 2011, 03:24 pm »

Quote from: Uptown Audio on 29 Jan 2011, 03:17 pm

You should take the amp to a tech and have it looked at. It's not a guinea pig for a newbie to attempt to learn soldering techniques on. There are likely also extremely high voltages present in the amplifier even when it is off. It's just not safe for the average user to work on. The tech should have fuses or be able to get them. You'll want a few spares, they don't need to all match. The tech can go over the operation of the amp to make sure it is repaired and set-up correctly. using a Manley supplied resistor sure would make his life less complicated. The amp should not be having resistors fail every time a tube has a conniption. The tech should also assess the condition of the output tubes at that time. It never hurts to have a spare set handy.

You shouldn't use the amp without a good cathode resistor installed.
-Bill

Thank you for your information.

I assumed that running without the cathode resistor working was a bad idea considering that in soft start, the 10th tube was reading some outrageously high voltage. I turned the amplifier off and will wait to get the resistor repaired.

Apparently Manley has clip on resistors that you can just clip the old one out, and plug in the new one. The problem is finding a local tech to do the work.

kingdeezie · « **Reply #24 on:** 29 Jan 2011, 04:59 pm »

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Quote from: zmanastronomy on 29 Jan 2011, 03:45 pm

No, I didn't play the amp while the resistors where not functioning properly.

I figured this was going to be the answer, but I figured I'd check. Did you have previous experience with working on tube amplifiers to fix it yourself?

Ericus Rex · « **Reply #25 on:** 29 Jan 2011, 11:15 pm »

A couple of dumb questions:

Do all the tubes have the lock pins intact? If not, are you absolutely sure you have aligned the missing lock pin in the socket correctly?

Have you checked inside the chassis for anything metallic that may be loose; coins, component leads and the like?

Sometimes, tubes get blamed for going bad when other issues are at play. If a tube is even 1 pin off alignment (missing lock stub) that can do incredible damage. Also, shipping can loosen up debris that then can short out components. I have experience with both scenarios unfortunately.

Your situation is really a case of bad luck. But don't give up on tubes just yet!

Does anyone on this site live close by King and have the expertise to help him with this solder job?

Rocket · « **Reply #26 on:** 30 Jan 2011, 01:49 am »

Hi,

Good luck I hope you fix the problem.

Regards

Rod

TONEPUB · « **Reply #27 on:** 30 Jan 2011, 02:42 am »

Quote from: kingdeezie 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.

It really shouldn't happen every time a tube goes. I have a few friends with this amp and it seems like you and I are the only one it's happened to. My guess is that this will probably never happen again, as the fuse should have popped and that's it.

Here's to you getting back up and running asap!

kingdeezie · « **Reply #28 on:** 30 Jan 2011, 03:12 am »

Quote from: Ericus Rex on 29 Jan 2011, 11:15 pm

A couple of dumb questions:

Do all the tubes have the lock pins intact? If not, are you absolutely sure you have aligned the missing lock pin in the socket correctly?

Have you checked inside the chassis for anything metallic that may be loose; coins, component leads and the like?

Sometimes, tubes get blamed for going bad when other issues are at play. If a tube is even 1 pin off alignment (missing lock stub) that can do incredible damage. Also, shipping can loosen up debris that then can short out components. I have experience with both scenarios unfortunately.

Your situation is really a case of bad luck. But don't give up on tubes just yet!

Does anyone on this site live close by King and have the expertise to help him with this solder job?

Honestly, I was sort of thinking the same thing to be honest.

I looked at the tube that was in the position where the resistor had blown, and visually it looks fine. I don't know as I am new to tubes of this nature, if damage should be apparent. But, if it blew enough to take out the fuse and the resistor I would have to assume the damage would be visible; but perhaps not.

Quote from: TONEPUB on 30 Jan 2011, 02:42 am

It really shouldn't happen every time a tube goes. I have a few friends with this amp and it seems like you and I are the only one it's happened to. My guess is that this will probably never happen again, as the fuse should have popped and that's it.

Here's to you getting back up and running asap!

Perhaps not every time a tube goes, but the original owner who has had the amplifiers for six years has said that he has had to change a few resistors over the years; which makes me think it is more common then I would have liked.

It could also be possible that there is something else wrong with the amplifiers underlying causing the problem, but I would have to get it checked out.

I have my feelers out for any techs in the area. Still haven't had any success.

If anyone on this site is local to me and can help me out I would most certainly compensate as needed.

Thanks again to everyone offering their help.

kingdeezie · « **Reply #29 on:** 30 Jan 2011, 03:35 pm »

I thought the Manley stuff was supposed to be reliable.

TonePub says he has friends with Neo Classics that have never had to change them. I guess its just luck of the draw.

Or maybe there is something wrong with the amplifiers. I am going to have a tech look at them before I send them back out to Arizona to get fixed.

At this point though, I just want to get them working so I can hear how they sound.

SteveFord · « **Reply #30 on:** 30 Jan 2011, 05:15 pm »

Taking these to a tech sounds like a really good idea as from what you said the seller was having the same problem.
I've never heard that Manley gear was unreliable - anything mechanical or electrical can act up, though.
When Good Amps Go Bad:
http://www.analogbros.com/tech/articles/goodgobad.html

Ericus Rex · « **Reply #31 on:** 30 Jan 2011, 07:25 pm »

Quote from: kingdeezie on 30 Jan 2011, 03:35 pm

I thought the Manley stuff was supposed to be reliable.

We have to keep in mind that these resistors have been replaced before in this amp, right? It is possible that they were replaced with improperly spec'd resistors which are now failing. If this is the case, it's more of the prior tech's fault and not Manley's.

I'm not affiliated with Manely, and actually have never owned anything from them. I just like to give people the benefit of the doubt.

Scott F. · « **Reply #32 on:** 30 Jan 2011, 08:44 pm »

Quote from: kingdeezie on 29 Jan 2011, 05:51 am

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?

Should I not be using the amplifiers in this condition?

If by switching the fuse from the good amp to the one that was out fixed it, there is no problem with the cathode resistor. As someone mentioned before, resistors are not self healing. It's a different story if you hear excessive distortion out of one channel. that could mean something else is afoot.

The chances are that one of the tubes you have shorted out, popping the fuse in the amp. Not a big deal.
In shipping and getting slammed around, weak tubes can go bad. Just roll in that replacement set of tubes you have and rebias the amps. I doubt seriously that you will have any issues beyond the blown fuse for a long time to come. Just remember, driver and splitter tubes last for about 8000-10,000 hours and output tubes last about 1500 to 2000 hours. Keep (loose) track of the time your amp is on and be sure to roll in new ones once you get close to their end of life and you shouldn't have any issues.

I'm not sure Radio Shack carries ceramic fuses. I've only seen glass there but I could be wrong. They do carry slow blow fuses though. One other place you could check is your local TV repair shop. I'm fairly sure one of them carries ceramic fuses. If not, there may be a Guitar Center close to you. They might have something too.

While I doubt seriously there is anything truly wrong with your amp (other than a shorted tube that caused your fuse to blow), it may not hurt to take it to a local tech and have it checked. He can also check your bias and should have the ability to check all your tubes too.

Bottom line, don't panic. What has happened (a shorted tube and blown fuse) is completely normal. The fuse did it's job. It's not a design flaw. Remember, tubes wear out. When shaken hard (as they were in shipping) they tend to short out. This is exactly why you should never tap on a tube...especially if it's in an operating amp. Tubes are and will always be a maintenance item in amps. It is something you'll have to accept if you plan on staying with tubes.

Oh and BTW, going from a Pass to a Manley...you are in for a treat (once you get them up and running). As good as the Pass is, I really think you're going to like what the Manley brings to the game. Both are very good amps but both are quite different.

TONEPUB · « **Reply #33 on:** 30 Jan 2011, 09:39 pm »

No, if the Cathode resistor is bad, the amp won't work properly.

Even if you can't find the right fuse, the guys at Manley can probably send you a couple of extra sets overnight pretty inexpensively. Then, just grab a few spare EL34's and you should be ready to roll.

Because the 250's bias each tube individually, they don't require matched tubes.

Hopefully you should be back listening soon.

That amp is pretty easy on tubes, so you will probably get closer to 4000-5000 hours on a set of power tubes.

kingdeezie · « **Reply #34 on:** 30 Jan 2011, 11:22 pm »

The cathode resistor is shot.

The amp makes music.

But, I can't bias the number 10 tube properly; getting readings of like 9 volts or something crazy.

I opened up the amplifier and used an ohmmeter to read the resistance and it was zero across the cathode resistor.

In the Manley manual it says this means the resistor has blown.

Music will still play if the resistor is open; it just will cause a massive failure or the tube and the amp.

Am I wrong?

Quiet Earth · « **Reply #35 on:** 31 Jan 2011, 02:05 am »

Quote from: kingdeezie on 30 Jan 2011, 11:22 pm

I opened up the amplifier and used an ohmmeter to read the resistance and it was zero across the cathode resistor.

In the Manley manual it says this means the resistor has blown.

Music will still play if the resistor is open

king,

When a resister blows, it blows open. "Open" measures as infinity ohms, not zero ohms. A blown resistor would measure many more ohms than it is supposed to be.

Often times, when you measure a resistor while it is still installed in circuit, you also measure the parallel resistance of something else in that circuit. I'm not saying that your resistor does not measure zero ohms, I'm just sayin' that there is a good chance that you are measuring something else too and you might be confusing yourself even further than you already are.

kingdeezie · « **Reply #36 on:** 31 Jan 2011, 06:53 pm »

I talked to Paul from Manley this morning over the phone, and he says that it is for sure the Cathode Resistor, and that the most likely cause was just a bad tube.

I am working with Manley parts to have the resistors and some fuses overnighted to me, and maybe when I get home from work tommorrow, I can get it all working.

I'll keep everyone updated.

Thanks for all of your support over the weekend.

TONEPUB · « **Reply #37 on:** 31 Jan 2011, 07:13 pm »

Sounds good, Paul is a great guy to work with....

Here's to having things sorted out!

kingdeezie · « **Reply #38 on:** 1 Feb 2011, 07:36 pm »

So a weather delay has trapped my resistors in Memphis, TN. With the flow of the storm, I doubt I will see them tommorow.

Hopefully I'll have them before this weekend.

kingdeezie · « **Reply #39 on:** 3 Feb 2011, 06:40 pm »

Resistors came last night.

Surgery was touch and go (read as scary as sh*t), being as the surgeon (me) was completely inexperienced.

However it seems that surgery was a success as the twins have been singing since 8AM this morning (now almost 2pm), while maintaing bias well.

Unless there is an issue that is escaping my unknowing eyes (highly possible), I think I am good for now. Hopefully I don't continue to blow resistors, although I had Manley send me extra in case.

Likely going to completely replace the power tubes shortly to avoid this problem, just looking for a reliable vendor with reasonable prices.