Trainwreck Express New Build Transformer Help!!

[dano-rator]

The OT in your original post is listed as a 25-40 watt unit... and if you look back at a previous thread "will I blow a speaker w/ my express" (or something like that) you'll see that the general idea is that these amps put out a solid 35w clean. But when pushed it looks like they can reach 50 or 60w or maybe even more. That might be pushing a $25 trans a little too far.

It looks like that OPT is manufactured by this guy: http://musicalpowersupplies.com/index.html

and it's his most powerful one. I'd look for a little more beef, but if you try it and it works well than poo on us...

Dan

[prslespaul]

Thanks again guys, I think im going to go with the Tonesluts OT, and that Antek PT. Looks good to me, and its a good deal for the pair. Last question, where is the best place to buy turret boards, and amp components. I want to stay as close as possible to the original as possible, it seems like theyre using mallory brand orange drops.. Are those the same as the Sprague's or are the current Mallorys the same as the old Mallory Orange drops in a new body? Also the original wrecks dont really even look like turrets, theyre a different type of turret, what are those called? Anywho, thanks so much to everyone who helped. I am still a noob. I really appreciate all your answers.

[soma_hero]

look in the Trainwreck Files forum, Ron has compiled excellent excell sheets listing all the information for ordering that you could possibly need.

I used Mallory 150s in my Liverpool and Rocket and like them. Have used Orange Drops and cheaper Xicons in Marshall and Fender builds and they sound good too. A lot of options there, I'd stick to what Ron lists in the file for a base build. You can change parts around later.

[gearhead]

I want to stay as close as possible to the original as possible, it seems like theyre using mallory brand orange drops.. Are those the same as the Sprague's or are the current Mallorys the same as the old Mallory Orange drops in a new body? Also the original wrecks dont really even look like turrets, theyre a different type of turret, what are those called? Anywho, thanks so much to everyone who helped. I am still a noob. I really appreciate all your answers.

Like soma said, look to the BOM for part numbers/manufacturer.

As far as the turrets, those are called "flea clips". Haven't been made in the dimensions needed for years. Effectively Unobtanium. I prefer fork turets myself, but that's personnel preference. Others use various turret types and/or eyelets that work well too.

[prslespaul]

I ended up getting the Antek for the PT. 45 bucks shipped, cannot be beat.
https://www.antekinc.com/details.php?p=58

For the OT i got a webber tranny. $58 bucks for that one.

https://taweber.powweb.com/store/wot45sch.jpg

I do have a question, it can be wired 3400 or 6800 ohm.. How would i wire it to the 6800 ohm? Also i am going to try to wire it without the inpedence switch and wire it to 3 seperate 1/4 jacks. For each jack have a different output rating, 4 ohm 8 ohm and 16.. etc. How would I wire it to do that? and to be at 6800?

[paulster]

I do have a question, it can be wired 3400 or 6800 ohm.. How would i wire it to the 6800 ohm? Also i am going to try to wire it without the inpedence switch and wire it to 3 seperate 1/4 jacks. For each jack have a different output rating, 4 ohm 8 ohm and 16.. etc. How would I wire it to do that? and to be at 6800?

Blue and brown to the tube sockets, white 4ohm, green 8ohm, yellow 16ohm, black ground for the three output jacks, grey capped off. Take your NFB connection direct from the 8ohm jack.

[prslespaul]

Thx you!!

I am wiring up my PT.

https://www.antekinc.com/details.php?p=58

There are 2 sets of everything. 2 sets of 115V primary 2 sets of 300v sec. 2 sets of 6.3v secs.. Do i just wire one set up and cap off the rest or what? How do i know what primary goes to what secs? Thanks in advance guys!

[paulster]

You want to parallel the primaries (tie the two reds together and two blacks together) as they've been designed so you can use them in parallel for 115V or in series for 230V.

You want to parallel the heater secondaries too, so you get an 8A 6.3V supply rather than 2x 4A ones (blue to brown and green to orange).

Fit a small value mains fuse before firing up the transformer with no load connected though, just in case they've got these round the wrong way on the drawing (it doesn't specifically indicate winding direction). It'll blow the fuse if they need swapping.

Note that you've got no centre-tap so you'll have to add the 2 100R resistors as in the Francesca pictures.

For the high-voltage secondary, you need to put the two secondaries in series. You need to figure out which pairs are related using a multimeter to measure the resistance, so you end up with what we'll call secondary A (white and yellow) and B (white and yellow).

Tie secondary A white and tie it to secondary B yellow. That'll be your centre-tap, that gets connected to the chassis. Secondary A yellow and secondary B white will be your 300V supplies.

Hope that makes sense.

[prslespaul]

Okay.

1. Tie the Primaries together, (Red and Red, Black and Black)

2. Tie the Heaters together, (blue to brown and green to orange)

3. Fire up the transformer with a fuse.
I dont really understand where to put the fuse in this situation.?

4. Okay so i understand how to find what white and yellow to pair together, But i dont understand how to make it a center tap.

So use the white and yellow and connect to the diode entrance correct?
The other set not being used you say tie together and the ground? Did i say that correctly? Where do the 2 100 Ohm resistors come into play?

Thanks paulster youve been a real help! I dont really know a lot about transformers! I really appreciate!

[MBD115]

I agree with the above. If the project is worth doing its worth trying to do it right.

Start with the right transformers and the build should turn out worth the $$ and the effort.

[paulster]

Okay, you've got your primaries and your heaters right.

Normally on a Toneslut transformer the heater winding would have a centre tap (white and brown striped) that you would connect to the chassis to reference the heaters to ground. Francesca didn't have this, so two 100ohm resistors were added at the first power tube socket between the heater pins and the chassis to create a 'virtual' centre-tap. You need to do this as well on your transformer.

Because you are paralleling the two heater secondaries there is a possibility that the manufacturer's drawing doesn't correctly show the relative coil winding direction, which could then give you a magnetic short as a consequence. If you put a low value (500mA) fuse in the hot primary lead and power the transformer on with nothing connected to the secondaries (but already having tied them together as described), the fuse will blow if one of the heater secondaries is round the wrong way before it has had time to damage the transformer.

If you look at the high voltage secondaries on a Toneslut transformer (ignoring the 260V taps) there are two 300V secondaries (yellow) and a centre-tap (red and yellow striped).

Your yellow will be one of the 300V taps, white will be the other, and the join between the two windings (white and yellow) will be equivalent to the centre-tap, which gets tied to the chassis.

Hopefully that'll make sense.

[prslespaul]

Okay I am looking at the francesca pics.
1. I see the 2 - 100 ohm resistors being grounded at the first power tube heaters. I understand now.

2. Power up the transformer with the heaters combined running a fuse through the hot side of the primaries. Red is the hot side correct?

3.Ground 1 pair of white and yellow as in place for the center tap? That part is confusing me because wont it be like running 300V to my chassis?

I almost got it!! Thanks so much haha, And to be honest MBD115 I was going to buy the tonesluts OT but he was sold out at the time so i got the next best thing. And why waste money on a power transformer when it doesnt really effect the sound? Thanks again paulster!

[M Fowler]

The best trannies would have been Pacific and then toneslut's.

[Structo]

Does your OT have dual primaries?

That diagram doesn't make sense if it only has the one set of wires unless you juggle the secondaries for the reflected impedance.

[soma_hero]

Yeah you're just running the speaker into a different tab to reflect the correct impedance