D-LA2A Support Thread

Hi Bernd,

I will check but I don't think so. When the unit is turned on audio passes through fine and the gain and vu meter work correctly (although only when the switch is set to Bypass?)  Surely this wouldn't happen would it if the xlr's where wrong - or am I missing something?

Ian

Let us know the exact relay type

Here is the close up of the relay.

It is an Omron G5V-2

Many thanks for the assistance

[silent:arts] said:

jonathanmorbin said:

have other people taken the 5v for their VU Meter LED's from the 5v supply on the board that is meant for the relays?

Click to expand...

yes, I do - with no problems (and I have light bulbs in the meters, your 20mA LEDs shouldn't be any problem)
do you have a proper heatsink on the 5V regulator?

Click to expand...

I have this attached to my 5v Regulator however i have not screwed it to the chassis.

http://uk.rs-online.com/web/p/heatsinks/1898094/?searchTerm=189-8094&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D424552267573743D3138392D383039342677633D4E4F4E4526

Should i maybe do this? Could this be a cause of the flickering LED's also?


g9Builder where abouts in the midlands are you? I am in birmingham myself and i recently built one of these units. Would be happy to help out if you live close.

g9builder said:

Here is the close up of the relay.

It is an Omron G5V-2

Many thanks for the assistance

Click to expand...

The relay seems to be correct.
Check:

- D3-D6 orientation
- grounding of the 5V psu via jumper next to C8
- wiring from 5V psu molex connector to both relais molex connectors
- orientation of the diodes above the relais

I suppose the 5V grounding could cause the issue.
regards
Bernd

Found my problem! I swapped the input xlr cable and all now works! There was a problem with the bl**dy cable nothing wrong with the DLA2A!!!

Channel 1 works great - no compression on channel 2 though so need to trouble shoot this now!? Gain knob works and passes audio fine just no gain reduction. Disconnected the stereo link but this did not solve the problem.

Anyway glad i am nearly there - thing is quiet as and channel 1 sound great! Thanks for all the help.
Ian

did you swap the T4B?

No not yet shall try this tonight and also tubes. Ran out of time last night!!

I think it's safe to say 80% of the problems people have with this build are wiring related. 

Could someone tell me exactly where the six mini toggle switches 3-SPDT & 3-DPDT (BOM lines 64 & 65) go and what they are supposed to do?

THanks a bunch!
-= Cash

One more stupid question... I can only find seven switches on the BOM... the six between the two large Gain pots, and the On/Off switch.  I can't seem to see where the Dual/LINK switch is specified.  Can someone tell me exactly what the specifications are for it... and perhaps a source.

Thanks in advance for your help!
-= Cash

Cash the link is a SPST. Only one wire goes to the switch from each channel.

I highly recommend you donwload the pdf on the first page compiled by a forumite as it has a great diagram on wiring possibilities

soooooo...  i have finally saved up enough money for iron for my D-LA2A.  I've decided to go with Sowter, but i need some advice on the different models.  All of these are listed on their site as usable in an LA2A.

1009 = input transformer -  1:9.1, 600/50k, "f" Mumetal - Mumetal can  UTC A10 replacement - can type
4383 = input transformer - 1:4  600/10k - Can type

8940 = Output transformer - 5K/600 Line output Ratio 3:1  5k/600 ohms
1290 = Output transformer - 15K/600 Line output Ratio 5:1  15k/600 ohms UTC A24 replacement - can type
1010 =Output Transformer - Teletronix LA-2A 1968 15K/600 Line output Ratio 5:1. 15k/600 ohms UTC A24 replacement - open type

I have a BOM that says to use 4383 and 8940, but i'm thinking that the orig replacements would be more accurate to the original's sound.  I see the differences in impedances and ratios, and i've read the thread a few times, but I'm learning about all this stuff as i go, and i don't have a ton of money to experiment with.  Just looking for a little advice.
Thanks for your help, and hopefully i'll understand more after i get through a few of these projects.

If it were me, i'd probably go with the Sowter 1009 inputs and the Edcor XSM outputs to save on $!

http://www.edcorusa.com/p/164/xsm15k-600

I used Edcors in and out on my build and they sound good...but the Sowter inputs would be better with the mu metal cans, etc. When i looked at the output on my build with an analyzer...i could see a tiny bit of noise down in the 50/60hz region...although you can't hear it (in certain cases, i think you can, just barely...if you crank the makeup and the unit is in a rack with toroids above/below)...and i attributed it to the fact that the edcor inputs aren't shielded.

I haven't used the unit in a little while, so i have a hard time remembering...but i am still considering swapping to better inputs.

Desol, I got the WSM (or is it xsm? the one with smaller wattage rating) as my pair of I/O trafos.
If you do change to sowters, can you please do a couple of samples before and after (different material, driven harder?)

Very interested in hearing the difference I fill I'm barely beginning to scratch the surface when it comes to trafos.

Sure...if/when i do it...i'll certainly try to remember. I just like inputs that are shielded well, to reduce any noise being fed into the front end of the unit.

desol said:

I think it's safe to say 80% of the problems people have with this build are wiring related. 

Click to expand...

I think you might be right there Desol. Both channels are now compressing nicely on my unit after finding a wiring fault. Just carn't get channel 2's VU to work properly. Checked the wiring on this though and all ok  ???

Interested in this project, but i'm wondering if the only source for T4B cells are from studioelectronics, since Drip doens't seem to be producing them anymore..

Anyone build this recently, and source T4B's from anywhere else?

Thanks
GdS

Drip still sells them.  Just email him. I think he may have a hundred in stock.  That's what I was told a few days ago.

Kenetek as well...although i don't know his current situation.