Tremoverb... Why wont the chassis slide out?

[gambit]

I am attempting to change a pot myself.

I undid the four screws from the bottom, it still wont slide out.

I also understand I am supposed to do something so I dont shock myself... turn the amp on with the ac unplugged and play?

 

[gambit]

?

I am tolexing my amp so I at least need to know how to take the chassis out.

thx guys

 

[Elpelotero]

If you're asking questions about what you need to do so you don't electrocute yourself, you shouldn't be changing pots in my opinion.

 

[gambit]

agreed. however, i still need to be able to slide the chassis out so I can do tolexing. Is it safe for me to slide the chassis out for that reason if I dont touch electronics?

Thanks (Im doing 2 amps so I'll have to do this on a marshall too)

 

[fluff191]

If you're asking questions about what you need to do so you don't electrocute yourself, you shouldn't be changing pots in my opinion.

+1

I agree. The first time I discharged caps, I had a seasoned technician standing right next to me showing me every step.

DO NOT just "go for it", get someone to actually show you. Seriously dude, you can have a real bad day if you dont do everything right.


If you dont plan on messing with the electronics, just slide out the chasis after removing the 4 bolts and slide it out from the back and place it somewhere safe.

 

[gambit]

I absolutely am not going to do the pot myself... but the thing wont come loose....

were talking about the four bolts on the bottom right?

I un-did them and tried to slide the thing every which way, not budging! anything im forgetting?

 

[fluff191]

I un-did them and tried to slide the thing every which way, not budging! anything im forgetting?

Nope! If you are looking at it from the rear, it comes towards you.

I usually set the amp on the floor face-down and grip the transformers and pull it straight out.

If that doesnt work then I don't know what to tell ya!

 

[94Tremoverb]

I put this in the other thread, but if you missed it - on the combo, the chassis is trapped against a foam strip under the top front edge, so it may be similar even if yours is a head. To get it clear, you need to take off the grille - there are screws inside the cabinet. This will allow the chassis to drop/lift about half an inch and come clear of the foam. It's even more important when you're putting it back - you won't get it in without chewing the foam up otherwise. I also put some stuff about filter caps in the other thread. You're basically safe with this amp, but since that isn't *always* true with other amps, make sure you know what to do.

 

[gambit]

thx man... so basically as long as i dont try to mess w the electronics im safe removing the chassis for tolexing?

So I have to remove the four bolts from the bottom and then how do I remove the grill? I see the four screws in the TOV behind it, but I dont see how that will let me remove it.

Ill try to remove the chassis this way, hopefully it works thanks!

 

[MrMarkIII]

Look for a long screw sticking out of the bottom of the chassis. It may look like it is too long and needs to be tightened. Back this screw out about a 1/4" and see if the chassis isn't easier to slide out.

 

[fluff191]

Look for a long screw sticking out of the bottom of the chassis. It may look like it is too long and needs to be tightened. Back this screw out about a 1/4" and see if the chassis isn't easier to slide out.

Wow I had no idea Tremoverb's had those! Learn something new everyday!

 

[gambit]

Sorry I just want to clarify this again b4 I do anything..

I am pretty much safe opening the TOV because its a relatively modern amp.

Regardless, to drain the pots... I hit the standby switch and play for a few minutes (with the amp unplugged of course), theres no need to hit the power switch. This will drain the pots if there is any charge left.

To remove the chassis, which I cant figure out how to do yet... I remove the bottom four long screws (did that) and then remove the front piece?

I have to remove the chassis either way for tolexing so I have to figure how to get this thing off.

 

[fluff191]

Regardless, to drain the pots... I hit the standby switch and play for a few minutes (with the amp unplugged of course), theres no need to hit the power switch. This will drain the pots if there is any charge left.

Dude. Just take the amp in somewhere. Potentiometers do not store a charge, they just vary the amount of voltage going through them. Putting the amp off of standby and playing is the same as clicking your heels together and saying there is no place like home. It doesn't do anything. You want to drain the CAPS and even then there can still be a static charge elsewhere on the board.

And if you can't even get the chassis out, just take the entire amp somewhere and have them remove it for you.

That way you don't have to worry about touching anything inside, cause you just don't sound that qualified to be removing anything on a tube amp in the first place. :wink:

 

[94Tremoverb]

Sorry, but the post above is wrong.

First, putting the standby switch to 'play' *absolutely* does do more than "clicking your heels" - it connects all the main filter caps in the amp to the first stage, which in this amp is a stacked pair with divider resistors and hence has a built-in drain. If you look at the schematic this should be obvious. Second, there is no 'static' anywhere else on the board. The only other charged circuits are the bias supply and the low-voltage switching supply, and these are firstly not high enough voltage to be dangerous, and secondly both have built-in drain resistors - or in the case of the 6V switching circuit in this amp, the filament of V1 which has a DC supply to reduce hum. This is also in the schematic. If you turn the amp off and unplug it, and leave the standby switch in the play position, there will be no measurable and certainly no dangerous voltage anywhere inside the chassis after no more than a minute or two at the most.

There is absolutely no reason someone with a little basic knowledge - and who is willing to ask questions first - can't change a simple pot on the back panel of an amp. If the chassis won't come out it's because it's physically stuck in some way, nothing to do with electrical risk. I know it's good to be cautious and safety conscious... but it isn't necessary to be afraid of things when there is no risk, once the right method is understood. No offense intended!

I'm not certain about later models or the head version, but mine does not have the tension screw in the chassis either.

 

[gambit]

Sorry, but the post above is wrong.

First, putting the standby switch to 'play' *absolutely* does do more than "clicking your heels" - it connects all the main filter caps in the amp to the first stage, which in this amp is a stacked pair with divider resistors and hence has a built-in drain. If you look at the schematic this should be obvious. Second, there is no 'static' anywhere else on the board. The only other charged circuits are the bias supply and the low-voltage switching supply, and these are firstly not high enough voltage to be dangerous, and secondly both have built-in drain resistors - or in the case of the 6V switching circuit in this amp, the filament of V1 which has a DC supply to reduce hum. This is also in the schematic. If you turn the amp off and unplug it, and leave the standby switch in the play position, there will be no measurable and certainly no dangerous voltage anywhere inside the chassis after no more than a minute or two at the most.

There is absolutely no reason someone with a little basic knowledge - and who is willing to ask questions first - can't change a simple pot on the back panel of an amp. If the chassis won't come out it's because it's physically stuck in some way, nothing to do with electrical risk. I know it's good to be cautious and safety conscious... but it isn't necessary to be afraid of things when there is no risk, once the right method is understood. No offense intended!

I'm not certain about later models or the head version, but mine does not have the tension screw in the chassis either.

You seem to really know your stuff and I trust your opinion. Step one will be to figure out how to get the chassis out... as of right now the four bolts arent releasing it.. maybe theres an extra screw or I might possibly have to remove the grill.

Thanks man

 

[cscotto]

I had a chance today to take the chassis out of my Tremoverb. Sorry to say, take out the four bolts, unplug the reverb wires, and it practically jumped out of the head shell. It was even easier to take out than the Roadster chassis. There isn't much head room for the tubes, so make sure the chassis isn't getting hung up by the tubes. The only other thing I can think of is the chassis is stuck on a piece of tolex. That has happened to me before. Good luck.

 

[weissach r&d]

just had a tremoverb head out 'o chassis about one month ago. remove 4 long cap screws from bottom corners. look between the output tubes and preamp tubes about center of head INSIDE enclosure. on some there is a tensioning/anti vibration cap screw that runs through chassis to the bottom of the enclosure. i does indeed protrude about two inches and looks like it doesnt belong. if your head has one of these it will absolutely cause it to stick. loosen it a couple turns. sometimes they are still a little sticky from seal strip. apply rearward pressure alternating from side to side. it SHOULD come out. also, leaving stdby switch on ac disconnected and speaker connected will drain off MOST stored dc charge in the caps. good luck!

 

[94Tremoverb]

You don't need the speaker connected to drain the caps! The speaker circuit has nothing whatever to do with the power supply circuit - it's on the other side of the output transformer.

With the Tremoverb, just put the standby switch to 'play' and unplug the amp, and the caps will drain *completely* - there's an exact technical reason why this is so, there is no magic or voodoo about it. This doesn't apply to *all* amps, so in some other cases you may need to do it differently, but it certainly does to the Tremoverb, and to all other amps with stacked filter caps and divider resistors. In all other cases it can still be done safely and the best method can be determined from the schematic.

It is true that there is some risk from stored charge with *some* amps if you don't know the correct method, but it isn't necessary to be afraid of working on any amp providing you understand what to do and why. The fallback method is always to switch off the power and unplug the amp with the standby set to play.