Purusha
Well-known member
Yap, the fuse was dead :thumb:
Will try to power it again tonight :grin: ...this time with correct wiring :green:
Will try to power it again tonight :grin: ...this time with correct wiring :green:
All things LA2a related
- Thread starter Scenaria
- Start date
Help Support GroupDIY Audio Forum:
You might want to ohm out that first cap, I think it took a hit, which took the fuse out.
Purusha
Well-known member
I checked all four and most of the time I see around 20M. Only the second cap has around 300K resistance.
good deal.
self healing, ya know.
self healing, ya know.
Purusha
Well-known member
The Hammond works Ok :thumb: Many thanks to Matta and CJ!
I connected everything and it looks fine. I see around 500VDC and 6.7V out of the Xformer. I powered the thing but with no tubes and no T4B. No smoke came out so far. :green: Is there anything I need to measure before installing the tubes and T4B. I think I checked all things a few times by now. :wink:
Oh, I quickly checked on 12AX7 #1 tube socket and pin 1 and 6 have 320VDC on... is this a good thing? I really can't check the rest as it's hard to come near the pins.
I connected everything and it looks fine. I see around 500VDC and 6.7V out of the Xformer. I powered the thing but with no tubes and no T4B. No smoke came out so far. :green: Is there anything I need to measure before installing the tubes and T4B. I think I checked all things a few times by now. :wink:
Oh, I quickly checked on 12AX7 #1 tube socket and pin 1 and 6 have 320VDC on... is this a good thing? I really can't check the rest as it's hard to come near the pins.
dripelectronics
Well-known member
hey there with no tubes or t4 , the 12ax7#1 voltage should be around 370 plus or minus
(im here in the states so i could blame my power company)
320 sounds good enough ,
im showing 388v before r29
and most of the tubes pin 6's read 380v
sound like the moment of truth :twisted:
g.
(im here in the states so i could blame my power company)
320 sounds good enough ,
im showing 388v before r29
and most of the tubes pin 6's read 380v
sound like the moment of truth :twisted:
g.
Purusha
Well-known member
OK, made some progress :thumb:
After I wired the heaters I powered up the unit. Everything looked fine so I set the meter scale to 0 in GR
mode and run some audio through. Sound goes through so this is a good sign but...
... the meter doesn't respond to audio in +4 or to gain red. in GR mode. Gain knob works fine but the GR
knob lowers the volume at last 15% when turning it CW. What could be the problem and where should I check first?
Is there any way to check my T4B if it works OK? Are there any other wires to be soldered under the PCB beside the heaters?
After I wired the heaters I powered up the unit. Everything looked fine so I set the meter scale to 0 in GR
mode and run some audio through. Sound goes through so this is a good sign but...
... the meter doesn't respond to audio in +4 or to gain red. in GR mode. Gain knob works fine but the GR
knob lowers the volume at last 15% when turning it CW. What could be the problem and where should I check first?
Is there any way to check my T4B if it works OK? Are there any other wires to be soldered under the PCB beside the heaters?
dripelectronics
Well-known member
http://driprecords.com/dripelectronics/pcb_manual1.pdf
Purusha
Well-known member
[quote author="drpat"]
This isn't a problem. The GR knob is supposed to reduce gain as you turn it clockwise, thereby lowering the volume. Check your wiring to the meter...[/quote]
know this :wink: but is it OK that I notice the GR so late at 80 on the scale of 100 and not before?
This isn't a problem. The GR knob is supposed to reduce gain as you turn it clockwise, thereby lowering the volume. Check your wiring to the meter...[/quote]
know this :wink: but is it OK that I notice the GR so late at 80 on the scale of 100 and not before?
Purusha
Well-known member
I checked my meter wiring and it is wired OK so something else must cause the problem :?
Can someone tell me also what is the proper comp/lim wiring to the switch?
Can someone tell me also what is the proper comp/lim wiring to the switch?
dripelectronics
Well-known member
http://www.driprecords.com/pcb/la2_hook_up_notes.pdf
a little essay on the pots/switch
g.
a little essay on the pots/switch
g.
Purusha
Well-known member
Hi Gregory, I have all your PDF pots/switch notes :wink: but in the comp/lim notes there is nothing mentioned about when is either of these two engaged. For example when you short those two wires is LA-2A working as comp. or limiter?
Purusha
Well-known member
Hi Gregory, I have all your PDF pots/switch notes :wink: but in the comp/lim notes there is nothing mentioned about when is either of these two engaged. For example when you short those two wires is LA-2A working as comp. or limiter?
I will check again my wiring to be sure it's done 100% correct but other than that is there anything else I should check regarding my problems with meter? It shows 0 when in GR mode but it doesn't show either the output signal nor GR when I crank the GR knob fully CW. I hear signal going down at the max GR but don't hear any pumping effect so I doubt the GR really works as it should.
I will check again my wiring to be sure it's done 100% correct but other than that is there anything else I should check regarding my problems with meter? It shows 0 when in GR mode but it doesn't show either the output signal nor GR when I crank the GR knob fully CW. I hear signal going down at the max GR but don't hear any pumping effect so I doubt the GR really works as it should.
matta
Well-known member
Took me 2 seconds to work out by looking at the LA-2A schematic... maybe you should try doing the same instead of being spoonfed with every little thing, You are are taking the DIY out of DIY with all your projects :?
Cheers
Matt
Cheers
Matt
Purusha
Well-known member
You are right, this one was easy :green:
dripelectronics
Well-known member
hi there ,
the meter section can be a bit of a problem ,
one of the common mistakes can be the meter switch it's self.
if it's an on -off - on with a midle position in the throw , those often don't
work.
the wireing is easy , but can be confussed .
your meter might need the diode rectifier configuration.
the most common mistake is a wire is loose, or the shield jacket
is shorting one of the pots .
check for solder or tiny wires shorting the pots or switches.
check your HAX GND make sure its soldered.
turn your stereo adjust pots / limiter response pots full clock wise or
full counter clock wise , one of those positions will bring on the juice.
g.
the meter section can be a bit of a problem ,
one of the common mistakes can be the meter switch it's self.
if it's an on -off - on with a midle position in the throw , those often don't
work.
the wireing is easy , but can be confussed .
your meter might need the diode rectifier configuration.
the most common mistake is a wire is loose, or the shield jacket
is shorting one of the pots .
check for solder or tiny wires shorting the pots or switches.
check your HAX GND make sure its soldered.
turn your stereo adjust pots / limiter response pots full clock wise or
full counter clock wise , one of those positions will bring on the juice.
g.
Purusha
Well-known member
Thanks for the tips. BTW, I am using Sifam AL29. Don't know what meter you usually use in yours.
Will check everything what you mentioned twice and if I still can't get it fixed then you will hear from me again :wink:
matta
Well-known member
Purusha,
Your meter doesn't need a bridge rectifier, it is built into the Sifam. Happy troubleshooting, hope you get it all up and running, you are 90% of the way there already :thumb:
Cheers
Matt
Your meter doesn't need a bridge rectifier, it is built into the Sifam. Happy troubleshooting, hope you get it all up and running, you are 90% of the way there already :thumb:
Cheers
Matt
jho-audio
Well-known member
Happy new year folks!
I'm using the drip boards and I need some help figuring out edcor wsm connections.. I have some loud hum and oscillation going on, likely more than incorrect transformer hookup but I want to get the in/out correct.
CJ style rendering of my current setup..
Is this okay?
Also, I'm using the edcor power transformer which has no ct on the heater secondary.. i will go buy some 100ohm 1 watt resistors to get reference to ground as im sure that this is creating some of my hum.
Cheers, Jason
EDIT: the xlr connections in the image are incorrect.. i have pin 1 to gnd and pin 3 is going to the transformers in place of pin 1. I am actually using 1/4" jacks and TR to transformer S to gnd.
I'm using the drip boards and I need some help figuring out edcor wsm connections.. I have some loud hum and oscillation going on, likely more than incorrect transformer hookup but I want to get the in/out correct.
CJ style rendering of my current setup..
Is this okay?
Also, I'm using the edcor power transformer which has no ct on the heater secondary.. i will go buy some 100ohm 1 watt resistors to get reference to ground as im sure that this is creating some of my hum.
Cheers, Jason
EDIT: the xlr connections in the image are incorrect.. i have pin 1 to gnd and pin 3 is going to the transformers in place of pin 1. I am actually using 1/4" jacks and TR to transformer S to gnd.
