D-LA2A Support Thread

[justinheronmusic]

I am definitely making progress with this piece. I've got the Rondo power transformer pretty much wired up, I just need to connect it to the power switch and the IEC inlet. I am not sure how to wire it up, but I need to wire it up for US/120V mains - I will not be using a voltage switch.

Can someone help me?

 

[[silent:arts]]

For 115V bot primaries must be in parallel,
so both yellow cables come together, and both white cables.

Am I missing the very important fuse

I just need to connect it to the power switch and the IEC inlet

since it is part of the IEC inlet? 

 

[justinheronmusic]

For 115V bot primaries must be in parallel,
so both yellow cables come together, and both white cables.

Am I missing the very important fusesince it is part of the IEC inlet? 

Ah yes! The fuse! I will be sure to put that in as well. What is the yellow and green spotted wire for? The one that looks like a reptile?

 

[[silent:arts]]

The yellow / green wire is the transformers screen. Connect it to your Chassis / Safety Ground.

 

[justinheronmusic]

The yellow / green wire is the transformers screen. Connect it to your Chassis / Safety Ground.

For the Rondo, are the colors of the leads still the same? Mine seem to be in a different order.

 

[[silent:arts]]

no color changed

 

[Zander]

Can sombody confirm you need 1.1V at pin 8 of V2A referred to gnd?

 

[Barton]

So, I finally finished my D-LA2A.  Unfortunately, I'm still having several issues.  It will pass audio, but I'm only getting about 2 to 3 dB of gain reduction max.  Was wondering if anyone out there would be willing to diagnose and do any repairs to get it fully operational.  I'm more than happy to pay a reasonable amount, as I really don't have the time to mess with it right now.  No real rush either.  Any takers?

 

[Deepdark]

Can sombody confirm you need 1.1V at pin 8 of V2A referred to gnd?

Pin 8 of V2 should be around 90 to 100v, or so.
Pin 8 of V1 should be around 1.1 to 1.5 or so

 

[justinheronmusic]

If swapping the T4B doesn't solve the meter problem,
check R226, R227 and R225.
There aren't much more components in the meter circuit ...

Comparing voltages in that arear with the working channel might be a good idea as well.

Just when I thought I was finished...

In Output mode, my VU meter is working properly. In GR mode, the VU meter does not go to zero, and does not display gain reduction. I did a quick test and saw that R227 was not receiving any volts in DC mode. I swapped out R227 for another 10K and still it's not getting anything. I touched up all the solder joints on R225, R226, and R227. Still nothing.

Where should I look next? Does anyone have any suggestions?

UPDATE: I touched up the solder joint that connects the T4B to R227. Nothing. However, R227 receives voltage when increasing gain reduction, as does R225, and R226. All pass continuity test as well.

I double checked my VU wiring, my switch, my wires, and my solder joints. I wasn't sure about my rotary switch wiring so I checked that with a multimeter and that's all fine too.

The NE2 has been bumped a few times. It lights up and changes brightness with the Zero Adjust meter. It does, however, look like only one side is producing light, is that normal?

Is there anywhere else I should be looking?

 

[justinheronmusic]

I got it figured out

The Gain Reduction molex pads on the pcb had solder flowing from + and - thus causing a short. This was causing the VU meter in GR to be completely unresponsive - the needle was all the way to the left and it would not calibrate.

I solder pumped (scary!) the pads and cleaned them off with solder wick and re soldered them. Now it is working smoothly and I have no issues.

I am, ideed, finished!

 

[schrobbelbop]

Tip!

when building this in a 2HE case add a fan

i've the V-case from don-audio and a 80x80mm fan fits on the side panel.

I've used a NB-multiframe 1200rpm 12v fan connect to the 12V circuit (on the cap after the diodes)
you can't hear this fan, doesn't cost much and your unit will be happy.

Mine started to drift in callibrations on the meter 0 and i think it gets too hot for the components inside when racked.

 

[PeteC]

Hi everyone,
I am almost finished with my build 
I am using EDCOR WSM ( i.e. no screens ) input and outputs for now ( until I have the cash for something more ) and might even stay with them if they sound good.

My question is - do I need to shield the 4 wires going from the board to each Transformer. What have others done who have used EDCORS ?

cheers
Pete

 

[hugo]

Hi everyone,
I am almost finished with my build 
I am using EDCOR WSM ( i.e. no screens ) input and outputs for now ( until I have the cash for something more ) and might even stay with them if they sound good.

My question is - do I need to shield the 4 wires going from the board to each Transformer. What have others done who have used EDCORS ?

cheers
Pete

On all pictures i saw, those wires were shielded, so i went with shielded.

 

[[silent:arts]]

Many used transformers with flying leads (me included).
Those wires are unshielded.
For transformers with solder tags I would use shielded cables.
It doesn't hurt.

 

[PeteC]

OK thanks

but if i use shielded should I run the ground wire and terminate the shield at the star earth ?

thanks
Pete

 

[[silent:arts]]

You terminate the shield at one side, why not to the Edfors metal frame which is connected to chassis anyway?

 

[PeteC]

Thanks Volker - I'll do it that way.
Cheers
Pete

 

[desol]

when building this in a 2HE case add a fan

Yep. I've been thinking of adding a fan to mine. It gets pretty warm in there, and my zero adjust goes whacky.

 

[justinheronmusic]

Single channel version of the D-LA2A board. I cut it down the middle, and kept the right channel to use as a single channel.

All carbon comp resistors from Kamaya
Panasonic ECA, Nichicon UHE & UPM for electrolytics
Solen, Sprague, and Wima caps
Bournes pots (Gain pot with 75k resistor)
Alpha Rotary
Sowter Input Transformer
Carnhill Output Transformer
Hairball Meter
Rondo Power
Kenetek T4B
All vintage & NOS RCA tubes dated between 1965 and 1968. 12AX7's are long plate.
That about sums it up! Feel free to ask any questions.