Toroidal wiring help! Jaycar MT2086

[johnwmclean]

I’m really out of my depth here, wiring really gets me. I bought and built a jaycar headphone amp KC5417 and a power supply KC5418.

I also have a MT2086 toroidal transformer... but am at a loss on how to wire this thing up. There’s 6 wires protruding form the transformer:
2 x orange
1 x yellow
1x red
1x white
1x purple

Heres some specs regarding the transformer
http://www.jaycar.com.au/products_up...20Modified.pdf

Also attached a schematic and layout of the power supply.

I can’t read a schematic

Any help would be great!!

 

[Wilf]

Hi JohnWMclean,

Orange leads = one each to live/neutral from the mains inlet.
Yellow = one of the ac inputs (~) on the psu board.
Red/White = both to the CT connection on the psu board.
Purple = the other ac inout (~) of the psu board.

I've built, and then modded (LM4562, cap multiplier, courtesy of the RG) this amp, and it sounds simply amazing, way better than the pimeta/m3 I've built, and the mini3/ppav2 I've heard. Anybody put of by the relative low cost is missing out big time.

Hope to see you there!

Alps now replaced with stepped attenuator.

 

[johnwmclean]

Hey Wilf, this is my second project, my first being the mini3 (no wiring

). Once it’s built I’ll put it through it’s paces against my balanced M^3 (not my build) and the mini3.
Big thanks for your response, this is exactly what I need.

 

[Wilf]

Glad to be of help.

It's a good, solid amp un-modified, but to get the best out of it, and to beat off the competition, you need those extra mods.

On the PSU change the rectifier diodes/strap a cap across the inputs. Insert JLH ripple eater (bottom left pcb), change op-amp to lm4562 and change output trannies to toshibas.

Happy Building!

 

[nickyboyo]

Ditto what wilf has said, the guys at rockgrotto are very very helpful and very enthusiastic. Just drop sandy k a line and before you know it you will have all the information you need explained with clear concise instructions and diagrams.

Just waiting for my jlh to be delivered and a to buy a few bits and bobs and i will be on a soldering mission myself.

wilf, did swapping the output transistors to the toshiba's make that big a difference?

 

[Wilf]

Hi Nickyboyo,

I made my scha during the time when Jaycar had sold out of the kit, so I bought the pcb (and the components) separately. This led me get the 2SA1930 and 2SC5171 straight away. The other guys, who built stock and then swapped over from the BD139/140 say it made a definite positive difference.

Two things to remember with the toshies.
1. mount the toshies 180 'round from the original.
2. try and match hfe, for best performance. (this also applies to the JLH trannies.)

And you are quite right about SandyK, he is THE man, and originally brought the SCHA/Jaycar, and the major mods, to our attention.

 

[nsx_23]

Where do you guys buy the JLH board and components? I'm tempted to build one of these since it doesn't look too difficult.

Looks like it might be a slight bitch to wire, but anyway, I'll get over that by just buying a massive case and having plenty of room to work with.

 

[nickyboyo]

Try making the amp in it's stock form, it is supposed to sound very good in it's designed state. You can get hold of the jlh board later from other members over at rockgrotto. The jlh mod would be a simple mod- just build the pcb and wire in.

 

[fordgtlover]

I think I am finally going to jump on this bandwagon.

 

[nickyboyo]

Compare notes in a couple of weeks ford, hny bud

 

[minivan]

the stock amp sound very ordinary, with frequency roll off at both end, lack of clarity with high noise floor. it's only when it's modded according to what sandyk (alex) did that it really shine.
my suggesting is: change the diode on psu to the fast first, that will bring the noise floor down and making improvement of the rest of the other mod become more obvious.

the topology of this amp look very similar to this expensive amp,
costing 1000 euro?


i have a clone of this expensive amp, did some tracing of the circuit and it look similar enough to me, signal go through the opamp with current boost by the 2 stage of transistors.


a/b with the sandyk modded SCHA, i prefer the scha one more , better dynamic and musical.

ps: i still have not install the jlh yet, ordered mine from the guy from rockgrotto on 14 dec, still have not received them yet, xmas/new year delay?

 

[Wilf]

CJ is a goodguy, Minivan, dont worry. He's been really busy in 'the real world', but he'll come through with your goods.

It's worth the wait anyhow.

PS, did you get your JVC RCEZ51?

 

[minivan]

wilf , thanks for the reassurance

the last time i upgrade the diode on the psu, the improvement is very obvious, so i am pretty sure the jlh will improve thing even further.
nope, i think i will try to buy a squeezebox instead.

 

[nsx_23]

My question is: What parts do I need to wire in the transformer to the mains and the jaycar power supply board?

As you can probably tell, I'm noob, and am slightly worried about 240V......

Where can I get detailed assembly instructions for this amp, and the subsequent mods?

 

[Wilf]

*edit*