TC-50 is now Dead...

[bandit2013]

I will not bring the Mark V woes into this one.....If I had I am sorry I did.... Despite the issues I had with it over the years, it finally turned out to be a good amp. I have played though a new one when I tried out the TC-50. That Mark V sounded really good (V4 mod would not be required with that one). Still the TC-50 and the JP-2C are much better for many other reasons and one is neither of them use the Simul Class power section. The same would apply to the RA100 and the Roadster. Not one issue with those to mention. For some reason or another the Simul Class power section tends to cause the tubes to resonant or sing. If it is tube related and perhaps caused by a slight miss-match that may be possible. However the same tubes when used in a Class A/B amp do not do this. Ok, there are differences between the models how they are biased, different plate voltages, etc..... I only bring it up since I had a Mark III and a Mark IV that did the similar thing when used at lower volumes. The louder you play it you do not hear it since it is masked buy the speaker. I did manage to get a matched quad of Mesa tubes that did not exhibit this noise. That just may be a matter of how many thermal cycles the tubes go though. In essence it happens with tubes and is more common than uncommon so no problem really.

Regardless of the Warranty or not, I will be happy to get the TC-50 back from repair. I thought that one had the most transparent FX loop and sounded really good with the Strymon Big Sky reverb pedal. When it failed the first time it did not happen when the amp was in use, it was after powering it up and found no sound. The second time was when it was on.... It happens.. I would not exactly blame everything on lead free solder. If you ever looked at a Mesa PCB in detail, the solder was very good. Proper wetting on both sides of the board. Very little solder flux residue anywhere so ether the board is cleaned or they are using a no-clean flux. I have seen the inside of the Carvin V3MC as I have one. It is okay. The components and workmanship of a Mesa amp is far superior that others I have seen even if the boards are auto inserted and wave soldered. There is still plenty of hand soldering of all of the wires and other parts. It is all about efficiency and repeatability. Perhaps my confidence is just tainted so I am sure all will be good with the repair. No worries.

 

[mace]

Nothing ominous. As we read bandits chain of events, we have a pretty good inkling that his primary issue was something very simple - but his attempted "repair" created further issues. We'll see when it gets here...but we see this often when people attempt their own repairs...

We're very fair, and YES - his warranty is void, as all repairs must be done by an Authorized Technician. - However, regardless of that - a simple repair doesn't cost much.

Agree 100% (where I work we deal with the same thing all the time, customer's doing their own repairs and having it go very bad). You guys are fair with pricing on parts and labor, that's for sure. Little things like straps, feet, even tubes, are even on par with "normal" prices.

And no, I wasn't implying that Mesa is ominous or negative...it was just that that particular post cracked me up since I don't recall another Mesa post here. Just a strange sense of humor on my part.

Later,

Mace

 

[bandit2013]

Since the amp has been gone for a few days I am beginning to realize how much I miss it. It definitely invaded my honeymoon with the JP-2C. Then there is the saturation mod with the Mark V.... too much ear candy..... Sure I have the RA100 to give me a boost on the fix but it is only a substitute. That little amp really grew on me and basically took over. At least it will be fixed properly warranty or not. Perhaps I am the joke here.... I can curb my enthusiasm and be silent for a while... that may be a good thing. Just remember bandit is trolling every thread...never knowing if bandit will strike with a wordy response...not having to read all that crap may be a good thing. Oh well.... not much to say now... so why am I still typing?

 

[bandit2013]

I got a call from Mesa, they will be shipping the amp as of yesterday. They did find the issue and it was not related to the send/return tube. :roll:
Issue was found to be a small IC that is responsible for controlling the mute. :roll: Yes the TC-50 has a mute just like the other amps and its primary purpose is to prevent transient noises occurring in the signal path during channel changes. Mesa did a burn in to ensure the repair was stable. I almost envy the tech who gets to do that part of the job and get paid for it....

I got lucky this time.... But was mention not to do any more work on an amp that is covered under warranty. Mesa honored the repair under warranty , that I was not expecting. :shock: I did request that the part I replaced to be taken out and the correct part installed as I did not have the 39.2K 1% resistor on hand. I did use a 39k 5% carbon film resistor but would prefer the 1% resistor they use as it has a 1W handling capacity even though it is a 1/2W resistor. I found the same parts on Mouser and bought a few of them. No big deal anyway as I need to replace the rework that was done on the RA100 that uses one of the resistors I purchased. (no warranty on that amp since it is much older than my Mark V). I have often contemplated sending that amp or the chassis in for repair as the previous owner had chipped out the ceramic sockets for the power tubes probably to use a tube not suitable that has a larger peg or center post that did not fit the socket. I have to use care when installing tubes as they can be easily indexed improperly. Perhaps just a replacement board is all that is needed.

I should have the amp in a few days. I am eager to get the TC-50 back as I do miss having it. 8)

 

[Daxman73]

Fantastic news bandit2013, great to hear. It's so cool that they did honor the warranty despite your quest to solve the problem yourself. Mesa just rules period.

 

[bandit2013]

I should have the amp in a few days. Looking forward to playing through it again.

 

[bandit2013]

(read this to the tune of Aerosmith "livin on the edge") Something came in the mail to day... and I do know what it is..... they shipped it out in a different box.... but it still looks just the same.... It was wrapped up in a plastic bag... and they changed out the QC tag.... Now there is someone else to blame.... Will it be raw on the edge or will it be just lame? ..... Well I guess I gotta plug it in.... gotta plug it in.... gotta plug it in... and find out for myself..... gotta plut it in...

Have not had a chance to play though it yet but will do so tonight.

 

[bandit2013]

I almost forgot how great this amp sounds. Sweet that it has been returned from service. Sounds just as amazing as it did before I had the initial issue. Now I can get back to my project that I had started the time it went out.

 

[jnoel64]

Glad to hear you got your TC-50 back! That turn around time was pretty good. What was the verdict on the root cause of your issue?

 

[bandit2013]

The issue was with an MAC97 Triac (TO-92 package, common with BJT and MOSFETS). Triac is part of the mute circuit for channel changing. It was either the gate that blew out or for some reason the device became latched on holding the mute active. Could have been the culprit from the start but the resistor I removed was definitely open as I measured it with several meters to confirm before and after removal as I wanted to make sure that was actually open. That could have been a result of component defect as it did not open as a result of current or excess voltage as there was no physical signs of damage. The part I installed did measure correctly in circuit so there was no effect of capacitor loading on the meter. This issue may have coincided with the fuse going out. May have been the Mesa NOS Siemens tubes that blew the fuse. I will have to check them out before they go back into the TC-50. What a far cry better tone than the Mark V..... Do I love that dry sound that makes palm muting sound so good, even with the reverb active.

Even with the Stock tubes, it kills it and sounds perfect. I would find it hard to debate which I like better in my collection of Mesa's as they are all equally fun to play (including the Mark V as it is back up to snuff now that I re-biased the circuit closer to original (using fixed resistors as I have no plans to be biasing the amp every time I change tubes (although that may not be a bad thing if I did use a potentiometer to compensate for drift but why bother, never had an issue with the Mark III or Mark IV on the long term use, tubes wear out and it is not hard to specify what amp the tubes are going in when you place an order. Having a current probe would be a good idea though as some tubes even match may differ with use or may not even be matched. ).

 

[Dreamtheaterrules]

Glad everything is right again!