Has anyone converted an Ampeg SVT2 PRO from 110v to 240V?

[jimmykebab]

Hi guys! 1st post and all that, i was wondering if anyone could help?

Just bought an Ampeg SVT 2 Pro from the US, it is possible to change the taps on the Transformers, and i have the schematics, problem is, it doesn't tell you which taps are the right ones, has anyone done this before?

I really don't want to blow the amp up, as i've been waiting for delivery for 3 MONTHS.

Please help a fellow bass player in need of some warm tubes on a cold winters night.

Ps. Im based in the UK.

 

[punkbassistfc]

I do not know much about swapping the tgranny and that but what i would like to know is how much did you save all together?

 

[jimmykebab]

About £550 quid, that $1100.

I paid £780 for the amp, and about £165 for tax. But i need help on this cos if i blow it, then it's gonna cost me another £600 to get it fixed, can anyone help?

 

[punkbassistfc]

Wow, thats alright of a saving. 550 pound in aus dollars is like 1300 i think. Good luck

 

[jimmykebab]

Yeah, there are rip off bastardos in the UK.

 

[T-Bird]

Hi.

I'd take the head to a tech. It should be a simple procedure with an oscilloscope.

Regards
Sam

 

[jimmykebab]

The tech for the UK is miles away and will keep it for donkeys, i work in a company who builds m/c for the US and one of the electronics guys said he's do it, just that on the drawings everything says tab, tab, tab.... what the bloody hells a tab?

Cheers

J

 

[T-Bird]

Hi, J.

Tap/tab/lug is the reinforcement that the end of the windings are attached to AFAIK. And where You solder/screw/insert a connector (Abiko for example). Or a jumper post-block to make the connections.

The schematics aren't really necessary if there's a positive identification that the primary windings can be configured to operate on both voltages. Only if there's multiple (more than two) primaries, things will get a bit more interesting, but a person with an el-ed should be able to figure it out with basic measurement devices.

Regards
Sam

 

[jimmykebab]

So your saying use an oscilloscope to find out the voltages then?

The connection part seems easy, unsoldered lugs, also i have the information for a svt 3 pro, would that be the same connection settings for uk and us you think?

 

[rodl2005]

My tech & I converted a SVT2 (non pro) over to 240v from 110v & it was a intricate li'l job......... as I described it at the time......"looked like a mass of dead spiders" legs going everywhere-wires!!!!!!!!! Wasn't that hard according to my man but we had the circuit diagrams-wiring diag. for the PT & even then it was INTRICATE............IIRC there were 2 OT's a big 'un & a little'un & had to wire 'em both correctly........ as always I could be totally & completely in the wilderness-well actually I am here, but luckily I had a guide with GPS!!! was done in a cuppla hrs but the fan was on it's own tap??? is that right?? & it burnt out in about 10 mins of running at 240V instead of 110v but a quick trip to elec. store had another inserted onto a 240v 'tap' & works good now.
Dunno how much of this relats to the IIPRO tho

 

[jimmykebab]

Jeeeze! That sounds like a mission and a half!

It's less complicated i think, but i just need to know what nuumber taps i take the connectors off and which ones i put it back on again.

Hmmmm

 

[i_got_a_mohawk]

It was done to my SVT-II.

Where abouts in the UK are you?

There are plenty of great techs out here.

If it turns into another £600 to get it fixed, buy one from here . . .

Either way tho, give your location, maybe someone can help you with a tech.

If your in Scotland, or even if your not, id highly recommend Dennis Marshall:

Invalid Link Removed

 

[jimmykebab]

I live in Barnsley, South Yorkshire, UK

If anyone lives near here i can drop it off, the only thing is that i could do with it being fixed pretty quickly.

Cheers guys

Jamie

 

[i_got_a_mohawk]

Cant help you in that area.

What about localish music stores? They might be able to give you details of a tech?

And quickly depents on the tech, the good ones usually have a bit of a backlog, turnover ive experienced has generally been about a week to two, so even then its not too much time.

 

[Jerrold Tiers]

Generally yes you can.

There MAY be some early 2-PRO units that have US-only transformers.

But if the transformers have part numbers ending in "-30" or "-40" the unit can be changed over internally. The "-30" is 115V and 230V only (4 wires). The "-40" can be connected for 100V, 120V, 230V, or 240V (6 wires).

The basic principle is that there are dual mains windings on the power and filament transformers. The dual windings are connected in "parallel" for 100 and 120V, and "series" for 240V etc. For voltages other than 120 or 240, the "taps" must be used, but you won't need that for 240V.

BOTH the (smaller) filament AND (larger) power transformers need to be reconnected, then the fan, which is 120V only, gets connected across one of the power transformer primary windings (so it still gets 120V). That means the fan will NOT be on in standby.

The above info, and the schematic/pictorial, are enough for any decent technician to do the job. If it takes much more than 1/2 hour, the tech is questionable.

 

[mattwear]

I am currently having my SVT-2 Pro rewired from 120VAC to 240VAC. The first step for my technician was to ascertain whether it had a multi tap transformer. It does so my gamble has, to this point, paid off!

The next step is to get my hands on the schematics so my tech can do the job. Jimmykebab, or anybody… Do you have an emailable version of your schematics and would you mind please sending them to me? [email protected]

Thank you

 

[T-Bird]

Hi, J.

So your saying use an oscilloscope to find out the voltages then?

Mainly the phase as there's obviously two ways to connect the ends of the windings together (when in parallel or in series), in phase, CORRECT and out of phase, NOT GOOD.

As Jerrold above said it's an easyish job for a tech, but one has to know what he/she is doing.

Regards
Sam

 

[jimmykebab]

Yeah man. The new ones have multi tap transformers on them, you can see the taps for connection.

I think i'll just double check with my tech friend that he feels confident before i let him do anything, or BOOM!

Also, anyone know how to discharge tubes without turning the amp on?

 

[i_got_a_mohawk]

Why would you need to discharge them?

Its the caps that need to be discharged, and if your tech friend isnt aware of what needs discharged and what doesnt, and isnt aware how to do it. Then id strongly recommend taking it to someone who def. knows what to do.

While it is a fairly simple job, there are some pretty dangerous land mines in there . . .

 

[T-Bird]

Hi.

I think i'll just double check with my tech friend that he feels confident before i let him do anything, or BOOM!

A wise call.

Its the caps that need to be discharged, and if your tech friend isnt aware of what needs discharged and what doesnt, and isnt aware how to do it. Then id strongly recommend taking it to someone who def. knows what to do.

While it is a fairly simple job, there are some pretty dangerous land mines in there . . .

+ whatever amount of money the possible repair is worth to You.

Some (most?) of the El-techs I know are quite self concious about their profession. With the title they can accomplish anything etc...

So if the conversation goes a bit like this:

You: Do You know what You're doing?
Tech: Yep, sure.
You: Are You really sure You know what You're doing?
Tech: Yep, it's just another piece of el-equipment, piece of cake.
You: You do realize that if something smokes by mistake, You'll pay for it.
Tech: Err, can't guarantee that, and if it smokes there's probably something else wrong with it, not my fault.
You: (whatever comes to Your mind, really )

run away and search for a real tech.

If I was You, I would have searched for the tech BEFORE buying an amp that needs a mod, but it's a bit late now.

Good luck
Sam