How do I take the Mark V apm out of the head shell?

[sean106ESP]

Hi guys,

I am having preamp microphonic noise again. It was such a pain to change the preamps while the amp is in the head shell. Can anyone tell me how to go about doing this so I can tap with a pencil and figure out what is causing all my feedback problems? Thanks in advance!

 

[evilsaint]

1) Unscrew the four wood screws for removing the front grill board.
2) Remove the back grill.
3) Unplug the reverb tank cable jacks.
4) Remove the cable strap for power cable.
5) Loosen the "giant screw" which is supporting the transformer.
6) Unscrew the four chassis screws, then carefully take out the whole chassic out from the headshell.
(Lethal high voltage, DONT touch anything inside with your bare hands.)

p/s: I'll remove the powertubes and rectifier tube before taking out the chassis.

 

[K-Roll]

I'd eventually turn it upside down cause its quite heavy when you want to get it back inside..
after having loosen all the 4 screws I always.. I repeat - I always remove the handle too.. just because I almost crashed my cable running from the EQ to the PCB inside (that broad grey one that looks like IDE) ... the first time i pulled it out and then in, there was some tension while sticking it back inside and I've plugged that broad cable out just because those screws holding the handle are sooo long that they're sticking out of the wood inside the chassis.. the cable got crossed by one of these screws and I unplugged my eq.. of course I found out during the next rehearsal that something is fcked up .. anyway.. I wish the mk5 would come in a nice long head.. these shorter measures are PITA to work with..

 

[sean106ESP]

Thanks guys.

 

[phyrexia]

For me, it is a much bigger pain in the ass to pull the chassis than to fish around for preamp tubes. YMMV.

Victor

 

[MesaGod666]

You can remove the front tweed cover to replace those preamp tubes. Just turn your head upside down when changing those tubes. Otherwise, I would just take it into my Mesa Tech.

 

[thunder100]

Sean

If you dissasemble can you take and post some pictures?
On my Mark V if you take off the front cover( 4 screws) still you have annother plate in front of the tubes.This has annother 4 screws,Can it be removed?(and eventually left out to just take on/off the tweed cover for easy tube swap?)

Roland

 

[K-Roll]

if, for instance, I remove the front tweed on my MK5, there is a solid piece of wood which is a non-detachable part of the chassis

 

[sean106ESP]

Well i ended up replacing the pre amp's no problem without taking it apart and was very careful; so all went well.

But my issue which caused me to do this is still not resolved.

ANY pedal I put in front of the amp (not the FX loop) causes a loud Hiss and scream on the OD channels. I thought it was a preamp issue but it is not as if I just plug straight in it sounds great. Silent but loud when I want it.

This is so frustrating as I cannot narrow down the issue. Each pedal (which is only like 4-5 makes the amp hiss and scream) does it even when alone........ I tried changing cables etc. that connect them and no dice. So annoying :roll: :idea: :idea: :idea:

Maybe it is the simple daisey chain cord I am using to power all the 9 volt inputs of the pedals???? I am going to get a 9 volt battery and see if it does it without any AC power.

This is so frustrating.

 

[thunder100]

Before you give up

What happens if you plug in just the pedal unpowered?
Still hiss-->your signal chain
No hiss at all-->Has you 9Volts DC a ground plug?
If not try annother wall socket more far away-->still the same?

Roland

In my Mark IV days the daisy chain power supply had a shortcut when getting warm

 

[sean106ESP]

Good idea's. cant do it right now but will try that tonight and see.

I am wondering also if it is this:

I have one outlet behind the rig. So I use a power strip and plug the Daisy chain power and Mark V into the strip. Maybe that could cause the issue? Thanks man.

 

[sean106ESP]

Before you give up

What happens if you plug in just the pedal unpowered?
Still hiss-->your signal chain
No hiss at all-->Has you 9Volts DC a ground plug?
If not try annother wall socket more far away-->still the same?

Roland

In my Mark IV days the daisy chain power supply had a shortcut when getting warm

Hey again Roland. OK so I did have time to do a quick test. I plugged guitar---->Tub Screamer (with no power going to it OR battery in it)---->Mark V = no noise. Same as if I plugged direct into the head. No hiss and no feedback.

So sorry for being a pedal noob as I never really used pedals other then a chorus in my FX loop....so what do you mean by if I have a 9Volt DC ground plug?

Could this test mean the daisey chain needs to be replaced as it was working fine up until a week ago; for about a year. So maybe it does need replacing. If so should I step it up and get a Voodoo Labs power brick or something? Thanks again my friend.

Edit:

Maybe something like this could be the solution if it is a ground issue?
http://www.guitarcenter.com/Dunlop-DC-Brick-Multi-Power-Supply-105495402-i1124423.gc

Thanks again.

 

[phyrexia]

power supply for pedals, methinks

 

[sean106ESP]

power supply for pedals, methinks

yup bought the Pedal Power brick and found two things. I had a brand new 12AX7 blown as I had almost no sound.....and the RMC seemed to be the only one causing the screaming. :?: :?: The rest where all fine once I took it out of the loop.


Now I need to build a pedal board. LOL

 

[thunder100]

Super that it works-->RMC will never be hiss free.

Gounding-->I ment a 3 pole DC plug(including ground) instead of 2 pole plug(what is usual)

I had to move to 3 pole(different 9V unit) and make a better ground (new wires) to the wall socket.Because you will get hiss and hum from the induced current into mthe cables as well.On top of this I had to go to the grounded shielded instrument canles.But now even on OCD V4(high gain natural hisser) is almost dead quiet

Roland

 

[sean106ESP]

Super that it works-->RMC will never be hiss free.

Gounding-->I ment a 3 pole DC plug(including ground) instead of 2 pole plug(what is usual)

I had to move to 3 pole(different 9V unit) and make a better ground (new wires) to the wall socket.Because you will get hiss and hum from the induced current into mthe cables as well.On top of this I had to go to the grounded shielded instrument canles.But now even on OCD V4(high gain natural hisser) is almost dead quiet

Roland

Gotcha. I have had the RMC for ages and rarely used it so I never noticed how noisy it is. Gonna look into that Tremonti optical wah. Thanks man!