Mark V No No's!

So I am new to tube amps. Sold my first shitty tube amp for a new Mesa Mark V 90. Well just outside tube warranty which seemed pretty quick. All power tubes and V1 blew out. Amp sounded great a couple days after I replaced them. Now channel 3 has lost complete gain and sounds like dirt. So I just ordered the rest of the pre-amps and rectifier tube today.

So now for the question... Is there any definite No No's I should know about that will kill your tubes? Examples being Cranking Gain to max in any channel or while using 10w, variac power, high compression ect? I want to get the best life out of these tubes as possible.

Tubes will wear out. But you won't make them "fail" immediately buy turning up preamp, or power amp, or whatever. Many guys gig these and as crazy as it sounds, some gig them opened up. They are made to run wide open safely and your ears should fail before the amp. Perhaps something else is amiss and maybe it's time to take it to a certified Mesa amp tech.

The only No-No's would be the obvious and not so obvious....
-Never run your amp without a speaker connected.
-Never run 6L6 power tubes with bias switch set to EL34 (red light on back only turns on for EL34 bias setting).
-Do not run a mixed quad (6L6/EL34) especially with 10W mode.
-Make sure your total load on the output jacks equals or is a bit more than the impedance value. Jacks are wired in parallel so basically divide you load by 2 if you are using both jacks of the same impedance. (you can run two 16ohm cabs using both 8 ohm jacks, if you have two 8 ohm cabs use the two 4 ohm jacks, never combine two 4 ohm loads on the 4 ohm jacks as that will be 2 ohm total load.

One of the must-do's is to read the manual.... if you do not have it download it from Mesa.

Perfect posts so far. I'd add:

Make sure the rear of the head is free from obstruction and well ventilated.

Make sure the internal fan is on.

Always warm up the amp on standby for at least 30 seconds.

Check your speakers are all OK. If you have for example one blown speaker in a 4x12 it will throw off the impedance for the cab (see above post).

Make sure your speaker cable is in good order and of the correct type.

Thanks for the information everyone! I really appreciate all the advice!

This just may be because of my skills in english, but...

All power tubes and V1 blown at once? Doesn't sound right. I wonder if this is about the driver tube V7. It may give the feel that power tubes are gone.

Also effects loop, as in all amps that thing is in, may cause issues. If tube related V4 and V6 are the ones to check.

About what OP asked about possible accelerated wear of tubes just by cranking all up, my vote for that is yes. It is possible to burn your tubes like that. Most of us may just not think that people do that, since it only provides sounds which most of us believe are...

...personal. There are better ways to get long sustained, compressed sounds than putting all pots to the max. What makes Mesa Mark series one of the best amps there are is their exceptionally large range to adjust everything. With MkV you can work every amp there is built in from somekinda jazzy sound to total(ish) mayhem. Sadly that means that you also really can give the amp too much in some cases.

Play hard core, pay hard core ;D

Few no-no's with V

- with head, don't try to change V1 before you've removed reverb tank from your way
- no mixed power tubes (someone did say this already)
- at ch 3 avoid combination of hi gain and hi levels of brightness in tone since you can get a microphonic loop
- don't fix your sounds after played long times with strongly eq:d sounds. Sounds are still ok. You've just experienced eq hangover
- don't try to make your open back combo a mini-disco by givin it all the bass it has. You just wreck the thing, since the pots do not change your cabinet type.
- don't destroy your ears by using all the high ranges eq can give especially at high volumes. It real-ly can be done. Those sliders can brighten your dark sounded jazz guitar to sound like a tele, but with your tele the same setting is a no-no


- avoid also all other kinda extremities. This amp is like highly tuned racing bike. Ride it with skill and thought or it just throws you outta its back ;D

I will add to these ghost stories when i remember more of them.

Well said Bigbadwolf.

Question is, how does one know if V1 is gone if the power tubes are toast?

bandit2013 said:

...how does one know if V1 is gone if the power tubes are toast?

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Depends of how "toast" they are. If completely dead, it gets hard but still doable.

Simply swapping V1 with V2 (or some other tube) can show if something changes. V2 is good for thesting because it limits possibe sound change to ch 2. Just to be sure, one of the reverb/effects loop tubes should be swapped for test too. V7? Yes and no. Althou that one can operate with older tube, that also may be the cause of problem feeling to be in power amp.

If power tubes are completely out, one can always take the signal from effects loop send and use another amp's return to test. If there is need to check pre-amp tubes before going in to music store.

I believe the big question here is how OP knew V1 and power tubes were "blown". Tubes rarely break all at once unless there happens something far from normal. We are talking about time period from one to 3-4 years depending of tube location in amp. And he says "Well just outside tube warranty which seemed pretty quick". Isn't it 6 months in new amp?

Couple of other tips.....
When servicing your amp, say you opted to remove the chassis for ease of tube access (head), this is what I used to do before converting my Mark V to a combo......
(Avoid touching internal parts on the circuit board, especially if you were recently using the amp, power supply caps may still be live. There are bleed resistors in the circuit to drain the capacitors but you cannot rely on them. High potential voltages may be present on the large capacitors so use caution) It is perfectly safe to hold the chassis and even carry it.

Roadster, Road king, all Rectifier amps except combos, RA100 head, and may or may not apply to the Mark Series amps.
The tube retainers or shields on some amps that have the tubes pointing upward where the chassis mounts to the bottom of the shell, there may be some metal dust around the area of the preamp tubes. This may pose issue at times and is caused by removal and insertion of the shields. If enough has accumulated around the preamp tube, best to use compressed air to remove the contaminants from the board surface. I will pickup most of the debris with a Qtip soaked in a weak acetone (wife had some nail polish remover that did not have added oils or other crap) as this evaporates without leaving a film. Q tip will hold the metal dust. Follow up with compressed air to remove what is left. Also before installing shields, clean the surface on the chassis as well as the shields. The O ring should be cleaned and lubricated in a non-conductive lubricant, I found the same product I clean my guitars with worked great with the O-rings. I use the liquid nano wax that works well with plastics, rubber and most clear coat finishes. Do not use on nitro or tung oil.

After returning the Chassis to the shell and make all the wire connections of the reverb. Double check the control settings on the back of the amp to verify they have not been moved. Check all switches to verify they are where they are supposed to be. Always check to see if the speaker or cabinet is connected at both ends before applying power to the amp. I made that a habit to check for load on the output jack and cabinet before I power up.

Power tube failure: Red plate usually caused by running amp at high settings for an extended period, may also be caused buy improper load on output transformer. Bias usually is the assumed cause for this as is a weak tube. Once the tube has suffered and if it blew the fuse, chance that the tube will still be any good is questionable. Tube shorts will take out the fuse, Rectifier tube is more common to have issue on occasion. That loud pop you hear when chaning channels, or when putting the amp into standby is a result of transient energy being dumped back into the Rectifier tube. Watch it for lighting as the discharge usually emits light in the rectifier tube. Once this starts to occur when using the amp it is time to replace the Rectifier tube. General rule would be to replace the Rectifier tube when you replace power tubes. Actually there is good information on diagnosing a tube issue in the manual.

BigBadWolf said:

bandit2013 said:

...how does one know if V1 is gone if the power tubes are toast?

Click to expand...

Depends of how "toast" they are. If completely dead, it gets hard but still doable.

Simply swapping V1 with V2 (or some other tube) can show if something changes. V2 is good for thesting because it limits possibe sound change to ch 2. Just to be sure, one of the reverb/effects loop tubes should be swapped for test too. V7? Yes and no. Althou that one can operate with older tube, that also may be the cause of problem feeling to be in power amp.

If power tubes are completely out, one can always take the signal from effects loop send and use another amp's return to test. If there is need to check pre-amp tubes before going in to music store.

I believe the big question here is how OP knew V1 and power tubes were "blown". Tubes rarely break all at once unless there happens something far from normal. We are talking about time period from one to 3-4 years depending of tube location in amp. And he says "Well just outside tube warranty which seemed pretty quick". Isn't it 6 months in new amp?

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You are exactly correct about using send and return of other amp to test preamp tubes and preamp itself, at least that will cover all tubes except the PI tube. You can plug your guitar into the return to check the output section if needed or the send from another amp. That is assuming one has another amp to use for that diagnosis.

I know this is a dead thread but I thought I SHOULD add the ONE no-no I know of, NEVER switch from full power mode to variac mode without giving a few seconds between the switch and always have it in standby (I was blowing pre amp tubes and this turned out to be the reason, I would flip the switch from full power mode to variac mode without a beat and in standby, but would blow tubes, had to put it in standby and allow a second to pass before going from one setting to the other, this stopped all blown tubes). (I was figuring it cut power so why bother to pause between switches, this turned out to be all wrong and it surges pretty hard a couple times when switching, slowing it down and insulating the tubes with standby was the trick to stop the surges from killing tubes...always remember each switch throw surges something, so not too many too fast!!!! (say duhh, but I have been using these awhile and know how to fix em and still got hit by the stupid bug!! This was advice i wish I had when i bought this amp...too many options and Mesa IS pretty good at making them bullet proof so you get used to doing things you might not do with other amps...like switching settings you might not should be switching on the fly)

That's 6 years old. Dang...

Also if using EL34s in 90w mode you need to run the variac. The manual updated over time to reflect this.

pkdawg said:

Also if using EL34s in 90w mode you need to run the variac. The manual updated over time to reflect this.

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Learned this one the hard way, mine is an early model so it wasn't in the manual.

allbutromeo said:

Learned this one the hard way, mine is an early model so it wasn't in the manual.

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Mine too. But noticed after gig it was really hot then contacted Boogie to ask about it. That’s when they told me it was updated.