Mkiic+ problem: Can't get a clean tone

[GeoBull]

I have an '84 Mkiic+ [1]. I just got it back from Mesa where Mike B. did the '+' mod. (BTW...Mesa was great to deal with and Mike B. spent a lot of time on the phone with me talking about amps, etc. Great customer service). I sent all the tubes with the amp and Mike said he thought they were ok; however, when I got it back and fired it up here's what happens:

-Can't get a clean tone no matter what the setting on Volume 1
--The sound isn't bad; just dirty; I used to be able to get a strong clean sound up to around 7 on Volume 1
-Tube situation (looking at back of amp)
--Far right tube -> I can't distinguish a light in it; it is cold
--Middle two tubes -> not very hot
--Far left tube -> Hot

Any thoughts? Could it be the difference between the Celestion and the EV? Could I have blown the Celestion? (I think I tried it on 100W) Does it sound like a tube issue?

Also, could anybody tell me if I've plugged the reverb tank in correct?
Looking at the back of amp should the plug with the metal wings on it go toward the front of amp or back of amp?

Thanks as always,
George

[1]
1984 Mkiic (#12,275)
Just modded to '+'
60/100
EQ
Reverb
Stock was EV speaker
Recently swapped out with Celestion C-90

 

[Russ]

White goes closest from the input of the tank to the jack closest to the transformer/ closest to the back of the amp. Gray/Black goes from output of the tank to the jack closest to the front of the amp.

 

[Elpelotero]

judging from what you're describing about the tubes, that's my first guess. See if you can plop any old tubes you have laying around to test things out. If not, you may have to buy new ones.

 

[Restless Rocks]

I would try another set of power tubes, if you're in simulclass or the 100 watt setting all four tubes should be lit up and burn your fingers. Tubes don't like being shipped around the country.

 

[visualrocker69]

How do you think they get to the store then? lol

 

[Russ]

I would try another set of power tubes, if you're in simulclass or the 100 watt setting all four tubes should be lit up and burn your fingers. Tubes don't like being shipped around the country.

Nor across the pond...

 

[Dasein]

First --- nothing about the speaker change other than a bad speaker would do this...

Have you checked your guitar or power cord? Does it do it on different guitars/cord combos?

R

 

[Restless Rocks]

How do you think they get to the store then? lol

I visited the Groove Tubes website earlier today and noticed they would not ship their 6L6 GE tubes by UPS ground. Go figure!!! I meant to say that tubes should be removed from the amp and properly wrapped and packed before turning them over to the "lettuce tossers" I've had lot's of tubes get rattled to bits in the band truck.

 

[Boogiebabies]

Oh Jeeeeez,

I just saw Pirates of the Caribbean III and it had less drama than the V1 in this amp.

Swap some pre's. If the tube is still cold after 10 minutes of playing, it's not getting plate voltage. Then I would be looking for a loose wire or resistor. Until them, try a new V1, saavy.

 

[Russ]

Or just release Calypso

 

[GeoBull]

Oh Jeeeeez,

I just saw Pirates of the Caribbean III and it had less drama than the V1 in this amp.

Swap some pre's. If the tube is still cold after 10 minutes of playing, it's not getting plate voltage. Then I would be looking for a loose wire or resistor. Until them, try a new V1, saavy.

Thanks for the reply. Do you mean I should swap out the pre-amp tubes one at a time before I change out the power tubes? You probably understood this but it is the power tube (far right looking at back of amp) that isn't lighting up.

To reply to another post: guitar cord, etc. are working fine through an Evans amp (nice amp, BTW)

 

[Boogiebabies]

Pull the chassis. It may have a broken contact on the power board for the heater supply or perhaps another pin. They weaken over time and just snap from decades of tube wiggling or the trace lifts from the board. It's worth a look as you may find the culprit.

 

[GeoBull]

Pull the chassis. It may have a broken contact on the power board for the heater supply or perhaps another pin. They weaken over time and just snap from decades of tube wiggling or the trace lifts from the board. It's worth a look as you may find the culprit.

So, I would be looking down into the circuitry once I pulled the chassis? I.e. as if I'm looking down through the top of the amp? The only wierd thing about that would be that it just got back from Mesa.

Boogiebabies, are you thinking it's not the power tubes and that the power tube is not lighting due to some other reason? I ask because I want to avoid buying new tubes if possible (although it wouldn't hurt).

Also, I notice that my small tubes are all a little wiggly in their sockets. Is that normal.

Thanks as always for your expertise.

 

[Elpelotero]

you can always wiggle a tube around, but only if you force it a little. They shouldn't be wiggling on their own.

 

[Boogiebabies]

Pull the chassis. It may have a broken contact on the power board for the heater supply or perhaps another pin. They weaken over time and just snap from decades of tube wiggling or the trace lifts from the board. It's worth a look as you may find the culprit.

So, I would be looking down into the circuitry once I pulled the chassis? I.e. as if I'm looking down through the top of the amp? The only wierd thing about that would be that it just got back from Mesa.

Boogiebabies, are you thinking it's not the power tubes and that the power tube is not lighting due to some other reason? I ask because I want to avoid buying new tubes if possible (although it wouldn't hurt).

Also, I notice that my small tubes are all a little wiggly in their sockets. Is that normal.

Thanks as always for your expertise.

They should wiggle, but still have a firm grip on the pins. I don't inderstand why this would not pop the fuse if it were a dead tube unless it was a totally discombobulated dead tube and the voltage goes nowhere. A virtual internal dead end.

 

[GeoBull]

They should wiggle, but still have a firm grip on the pins. I don't inderstand why this would not pop the fuse if it were a dead tube unless it was a totally discombobulated dead tube and the voltage goes nowhere. A virtual internal dead end.

I went out this AM and really looked at the tube (should have done that right away ). The top is white not silver and if I put the tube in another socket it doesn't light up whereas the tube I move to the socket it was in does. My apologies, I should have done this experiment first, duh!

Sounds like a bad tube to me. Do you agree?

 

[Boogiebabies]

Yes, it's lost it's vaccum and probably just toasted the innards in seconds.

 

[Restless Rocks]

I would try another set of power tubes, if you're in simulclass or the 100 watt setting all four tubes should be lit up and burn your fingers. Tubes don't like being shipped around the country.

 

[Buddy]

I would try another set of power tubes, if you're in simulclass or the 100 watt setting all four tubes should be lit up and burn your fingers. Tubes don't like being shipped around the country.

Chili dogs with 'slaw , macaroni & cheese And lot's of cold beer !
Gotta love it ......

 

[Boogiebabies]

I would try another set of power tubes, if you're in simulclass or the 100 watt setting all four tubes should be lit up and burn your fingers. Tubes don't like being shipped around the country.

Chili dogs with 'slaw , macaroni & cheese And lot's of cold beer !
Gotta love it ......

It's a dawg with slaw en chilly. Yawnt wun ?