Hi there, I don't know if I'm too late for the kits but I've ordered PCBs to get a stereo SA-3A and I dont even know if there're some left... I tried to contact them and still no answer so to all of you out there, where could I find at least the front panel for this little stereo baby?
SA-3A (LA-3A Clone) Support Thread
- Thread starter ruckus328
- Start date
Help Support GroupDIY Audio Forum:
sage
Well-known member
Hi there
could you please get a bit more in detail to what the 600 ohm load does to the circuit and on how to connect it?
I would really appreciate it - i do not see an optional space on the board, it looks like it is all populated!
Sage
could you please get a bit more in detail to what the 600 ohm load does to the circuit and on how to connect it?
I would really appreciate it - i do not see an optional space on the board, it looks like it is all populated!
Sage
Harpo
Well-known member
Already described by rob61, lift one side of R46 to get the switch in between.sage said:
Hi everyone!
I'd be grateful if someone could give me some ideas how to continue with my stereo SA-3A.
The problem is that when I reduce gain I only get more and more distortion. When gain reduction is on zero the sound is clean. This happens in both channels!
I pulled out TB's during investigation and it didn't change the sound but the meter in G/R mode stopped reacting.
Any hints are very much appreciated!
I'd be grateful if someone could give me some ideas how to continue with my stereo SA-3A.
The problem is that when I reduce gain I only get more and more distortion. When gain reduction is on zero the sound is clean. This happens in both channels!
I pulled out TB's during investigation and it didn't change the sound but the meter in G/R mode stopped reacting.
Any hints are very much appreciated!
Harpo
Well-known member
Mixed up wires at gain pot CW and wiper connection maybe ?Thego said:
Harpo said:
Thanks for the tip, but unfortunately case is not that. Very frustrating when knowing that the problem is probably something as simple as that.
I think it's about two years when I started putting this together before I put it gathering dust and Im not sure of all the things I'v tried.
I'd be happy to hear some more suggestions before I start rewiring the machine.
jason baliban
Active member
Here is a time-lapse video I did while building the SA-3A.
http://youtu.be/Z3UfptIswE4
Hopefully it helps somebody along the way.
jB
http://youtu.be/Z3UfptIswE4
Hopefully it helps somebody along the way.
jB
sage
Well-known member
here the schematics :
http://www.waltzingbear.com/Schematics/Urei/LA_3A.htm
Sage
http://www.waltzingbear.com/Schematics/Urei/LA_3A.htm
Sage
salomonander
Well-known member
- Joined
- Aug 28, 2011
- Messages
- 915
hey guys
im trying to figure out the following:
if i do not need most of the mods - can i simply not connect their molex connectors? i can't tell since there is no shematic of the actual serpent audio circuit. cheers
im trying to figure out the following:
if i do not need most of the mods - can i simply not connect their molex connectors? i can't tell since there is no shematic of the actual serpent audio circuit. cheers
charlievela
Member
- Joined
- Nov 15, 2008
- Messages
- 13
So I wired up my Dual La3 and got a smoked resistor at r17.
I replaced it and hunted down a couple of cold joints and was about to rewire all the switches/pots when i realized that i soldered T3 TOO CLOSE TO THE BOARD!
I was very careful to give plenty of space to transistors, but just made a bonehead mistake.
Is there any way i can lift it up just a hair without having to buy new xfrmrs? usually lifting a component isnt too big a deal, but since this one has so many legs i've been trying for the last 20 minutes with no luck at all. any tips? or is the component likely fried anyway since i powered the unit up already.
I replaced it and hunted down a couple of cold joints and was about to rewire all the switches/pots when i realized that i soldered T3 TOO CLOSE TO THE BOARD!
I was very careful to give plenty of space to transistors, but just made a bonehead mistake. Is there any way i can lift it up just a hair without having to buy new xfrmrs? usually lifting a component isnt too big a deal, but since this one has so many legs i've been trying for the last 20 minutes with no luck at all. any tips? or is the component likely fried anyway since i powered the unit up already.
rainton
Well-known member
First use a solder sucker to carefully remove the solder from the pins.
It takes some practice to get good at this...
Then extra carefully to get something like a flathead screwdriver between the pcb and the xfmr.
If that's not possible take the xfmr between thumb and pointer and try to put the soldering Iron on all pins of the same row at once and then try to slightly lift up only this one side of the xfmr and then do the same for the other side.
A better way would be using a desoldering station but I assume you don't have one at hand...
It's kind of a drag without one but still doable.
You need to be careful and patient though
It takes some practice to get good at this...
Then extra carefully to get something like a flathead screwdriver between the pcb and the xfmr.
If that's not possible take the xfmr between thumb and pointer and try to put the soldering Iron on all pins of the same row at once and then try to slightly lift up only this one side of the xfmr and then do the same for the other side.
A better way would be using a desoldering station but I assume you don't have one at hand...
It's kind of a drag without one but still doable.
You need to be careful and patient though
sr1200
Well-known member
FWIW, I've used a heat gun to remove transformers from boards also, just gotta be REALLY careful you dont get too close, just enough to melt the solder joints all together.
salomonander
Well-known member
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- Aug 28, 2011
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- 915
hey
does anyone have a wiring diagram for this. it would really help. supposedly there was one at some point. its gone for some reason... thx
does anyone have a wiring diagram for this. it would really help. supposedly there was one at some point. its gone for some reason... thx
Harpo
Well-known member
Brotastic said:
Instead of the resistor R46 soldered in between the pcb holes for the R46 position (x)--[ R46 ]--(x)
you will have an additional switch in series to the one side lifted resistor leg (x)--[ R46 ]-----./.--(x)
for a 600R termination with the switch closed (for connecting to modern gear)
or for an unterminated connection with the switch open (for connecting to 600R impedance historic gear).
Next to drilling the mounting hole for the switch, the most difficult part is choosing the correct colour for the hook up wire in order to not insult your eyes. ;D
Harpo
Well-known member
In series to the resistor between the thru holes. SPST will do for mono. Edited pic shows a SPDT switch. For stereo either use two SPST switches or one DPST switch.Brotastic said:
salomonander
Well-known member
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- Aug 28, 2011
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hey
i just finished my first unit. everything seems fine but id like to make shure that its safe to plug in the urei opto before i do so.
i measure 27.5v on pin5 in output mode of the gr meter and 11.5v in gr mode. cant be right i guess... please help an idiot
i just finished my first unit. everything seems fine but id like to make shure that its safe to plug in the urei opto before i do so.
i measure 27.5v on pin5 in output mode of the gr meter and 11.5v in gr mode. cant be right i guess... please help an idiot
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