LuDEF

[Zen Mod]

I've completed a LuDEF!

The pot adjustments for offset and bias all
went as expected with correct values set.

But audio output is extremely low on both channels -
can just barely hear it.

I've checked all the values and part locations.

I'm using an Edcor 600/600.
Is this the right one?
I noticed Sissy and M2 use the Edcor 600/15K.

-Bruce

you didn't forgot jumpers , JP101 and JP201?

check continuity between JP pin marked X and R111

write down resistance

check resistance/continuity between JP pin marked X and GND

 

[banderson546]

you didn't forgot jumpers , JP101 and JP201?

check continuity between JP pin marked X and R111

write down resistance

check resistance/continuity between JP pin marked X and GND

Yessir!! JPX01 jumpers were on!

Resistance between JP pin marked X and R111 - 105 ohms

Resistance/continuity between JP pin marked X and GND - 38 ohms

 

[Zen Mod]

lemme think
need some food then some coffee, then can think

didn't tried those pcbs with Edcors, but did zillion checkups and everything was logical, last time this morning

both channels same behavior?

source can't be blamed/is checked?

 

[nautibuoy]

...need some food then some coffee, then can think...

Now you're sounding mortal! 🙂

 

[Zen Mod]

Yessir!! JPX01 jumpers were on!

Resistance between JP pin marked X and R111 - 105 ohms

Resistance/continuity between JP pin marked X and GND - 38 ohms

your measurement is confirming that autoformers are connected and in continuity

just checked - everything is by the book, Edcor PC 600:600 pinout just snatched from their site

see enclosed

do you have scope, or if not scope , at least some handy signal gene, able to give under 1V of anything between 400Hz and 1KHz - that you can measure directly with DMM set at Vac


if something is about autoformer, it can be only wrong phasing mark on Edcor site

 

[banderson546]

Thanks for the quick reply oh mighty Zenmod!

Yes, both channels have the same problem.

Yes, have signal gen and scope.
Where is a good place to look?

Bruce

 

[Zen Mod]

put , say, 100mV of signal in input of amp

no speaker or load needed

then see what you get on B pin of opened JPx01 jumper

then close jumper and see what you're getting at Rx11

it could be 100mV in, same on B pin, close to 400mV at Rx11

 

[Zen Mod]

I've just checked against gerbers of Pa's M2

PC 600:15K is having same pinout as 600:600, and everything complies between his gerbers and what I did here

now I'm puzzled

check all resistor values, check everything

post pics

 

[banderson546]

I put 300mv of 1khz signal in.

At the B pin of the open jumper I get 300mv.
I closed the jumper and at Rx11 on both channels I get nothing.

On the Edcor I get these readings:

Pin 1 - 584mv
Pin 2 - 300mv
Pin 3 - 0v
Pin 5 - 0v
Pin 6 - 300mv
Pin 7 - 584mv

I will begin double checking everything and take pics.
I have a Cinemag on order - don't know when it will come though.

-Bruce

 

[banderson546]

I did an experiment with a spare Edcor 600/600 transformer on the bench.

It looks like its primary/secondary are reversed from expected.

Configured as it is used on the LuDEF pcb with pins 1 and 7 connected I
put in a 300mv 1khz signal on pin 2 and got nothing on the output (5)

Configured with 5 and 7 reversed I got 1200mv from the output pin (7)

 

[Zen Mod]

well, they suck!!
improvize, xacto knife and tiny wire on pcb
or wait for cmgz
they really suck.... I have 6 or 7 pairs of 600:15k in wshop, but none 600:600, so I just trusted them for their own pinout

 

[Zen Mod]

being on the road to Mountain today,then had to nap
that's why late posting
and now little boss needs my laptop, left her at home
I hate web, typing on phone

 

[banderson546]

Many Thanks for the troubleshooting help Oh Mighty Zenmod!

I reworked the offending Edcor parts and reinstalled them - didn't want to cut up a fine PCB!

I did a quick power measurement and LuDEF
goes right up to around 25 watts into 8 ohms at clipping - very nice!

And now they are playing beautiful music!

Very fine, detailed - magnificent!

Some photos of my build:

-Bruce

 

[twitchie]

Great detective work banderson546! Now just twist those power wires and you'll get an official 'fugly'!

But as this seems to be the first LuDef in existence outside of the OPLDF, you deserve an award.

Fugly! (means awesome job in ZMEngrish)

 

[ra7]

That really is fugly. Love the front plate.

We should hang out. I was in SF last Friday.

 

[banderson546]

I got a little vinyl cutter to make faceplates.
Having lots of fun with it.

I wonder if I'd get extra fuglies from the Mighty Zen if
I twisted my Power Wires like Pippi's Braids?

 

[avitkauskas]

I reworked the offending Edcor parts and reinstalled them - didn't want to cut up a fine PCB!

Bruce, can you please explain how you reworked the Edcors that you did not have to cut vías on the PCB?

Thanks
-Alvis

 

[Zen Mod]

Many Thanks for the troubleshooting help Oh Mighty Zenmod!

I reworked the offending Edcor parts and reinstalled them - didn't want to cut up a fine PCB!

I did a quick power measurement and LuDEF
goes right up to around 25 watts into 8 ohms at clipping - very nice!

And now they are playing beautiful music!

Very fine, detailed - magnificent!

Some photos of my build:

-Bruce

Fugly!

and inventive - including how you decided to take your own care of LU mounting

 

[Zen Mod]

........
And now they are playing beautiful music!

Very fine, detailed - magnificent!

.....

that - you can't expect less, with nice autoformer gain, combined with Berserked OS

 

[banderson546]

Bruce, can you please explain how you reworked the Edcors that you did not have to cut vías on the PCB?

Thanks
-Alvis

The rework I did reversing pins 7 and 5 on the PC600/600's
was not as clean as I would have liked - I'd call it crude but effective.
I snipped off the thin magnet wire on pins 5 and 7. Scraped off
some coating on the end of each wire with an exacto knife.
Then soldered extension wires to extend each pin over to the correct pin.
I covered the wire extensions with a small piece of insulation.

I could have done cuts and jumps on the PCB but I was trying
to keep it original so I wouldn't have to undo things
if sometime I wanted to install Cinemags.

I used Aluminum Oxide Ceramic Thermal Pads from Digikey (4180G-ND) for IRFP240's,
IRFP9140's and the LU1014's.
For the LU1014's I put two pads under each one with each part facing up.
On the Right Channel PCB, extension wires from the two outer pins of the LU1014 part
to the PCB had to be reversed.

It really is a great sounding AMP!
Thanks ZenMod!

But now I'll have to collect the whole set!
Have to look into an Iron Pumpkin and an Old Soul!