All things LA2a related

[Bluzzi]

[quote author="AnalogPackrat"][quote author="Bluzzi"]
The other is C13 at 510pf. I found it but it comes in Ceramic or Mica. Does it matter?

Thanks

Jim[/quote]

I used silver micas for the pf range caps (except for the one trimmer). No problems...[/quote]

Thanks AnalogPackrat (can I call you Analog?). I can order in peace now.
Now I will look further for the trimmers.

Jim

 

[Bluzzi]

[quote author="dissonantstring"]hi,
i read on past post that a 100pf cap works well instead of using the trimmer caps. i'm wondering because i'm having the same problem as Bluzzi finding a trimmer cap with enough range. what is the minimum voltage of the trimmer cap if used?
thanks,
grant[/quote]

I can probably find them but I am trying to order from as few suppliers as possible so as to avoid minimums and transport costs etc.

Mouser is waiting for me to add a few components and I think what I will do is just order a range of values in Ceramic or Mica (50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 all in pf). It may be overkill but this way I know I will be able to find the correct value.

So unless someone can let us know what the usual setting is maybe I can purchase a smaller range. So for example if the trimmer is almost always at maximum pf then probbaly 300 to 500 pf would do.

Jim

 

[rove]

Hey maybe I can help, when I thought my trimmer cap was busted, I was told a cap somewhere between 300pf and 510pf would work fine swapping out for a higher value if you experience too much HF rolloff in testing.

 

[dissonantstring]

here's what i found on another thread:

thats an adjustable trim cap. hard to find and harder to install. you can put in a 100 pf and be alright.
cj

this is in reference to C4 and C14.

i'm still building mine, so i'll try this and see what happens.
-grant

 

[Scenaria]

hmm

if you are building from the kit the trim cap should be in there.. look for a small ceramic trim type cap with a couple of solder lugs on it.. they arent that small

if you are talking about the one for the stereo link then yes.. I dont include that one unless someone orders a pair and specifies that they intend on using them in an actual stereo link.

 

[dissonantstring]

hi steve,
you're right!
i do remember the trimmer cap being in one of the bags.
thank you for reminding me!
(lack of sleep)
i guess no worries for me since i got your wonderful kit!
:grin:
thank you steve!

 

[Bluzzi]

Does anyone have a source for the trimmer caps in the required value?

Thanks

Jim

 

[Scenaria]

seriously...

just drop a 100pf cap in there and be done with it..

if you need to tweak it up then increase the value.

I know theres a few places out there that have the trimmer caps.. (cant remember the URL)

but in all honesty.. it is not needed...

as a matter of fact I was just talking to ssltech about the trimmer cap earlier today with that fact that im thinking in the future of just including a few values to test and try instead.

 

[Bluzzi]

Yeah, sounds good. I'll get a few more values in case.

Thanks Scenaria

Jim

 

[rove]

Couple of Bloo LA2A transformer questions for anyone with the time:
Re: input transformer (Sowter) I am not sure where to connect R5 and the Grey wire.
Re: output transformer (Sowter) where do I connect the Green wire?
Re: power transformer, where exactly do the 2 black wires and the Grey wire connect (unclear on which is "live" and which is "neutral").
Searched the group for this info and haven't been able to turn it up, so forgive me if this is old hat! Also I have the Sowter schematic, but it isn't helping at this point.
thanks

 

[SSLtech]

On the IEC power socket, there are three pins. the one at the top is ground. The one just below it is Neutral. The one (should be on the right looking inside the box) which doesn't some straight out, but ducks down to the fuseholder part at the bottom, then re-appears on the left side is the live.

So: from top to bottom:

Top = Ground
Middle = Neutral
Bottom = Live

Keith

 

[DrFrankencopter]

Regarding the trimmer cap, why not just take a rotary switch and put say 6 different values on it, add the control to the front panel, and label it 'colour', and have it range from dark to bright.

Cheers,

Kris

 

[Bluzzi]

[quote author="DrFrankencopter"]Regarding the trimmer cap, why not just take a rotary switch and put say 6 different values on it, add the control to the front panel, and label it 'colour', and have it range from dark to bright.

Cheers,

Kris[/quote]

Kris, good idea! I just ordered a few values last night. I still have a ways to go before even starting to solder but I will be trying each value to see its effect. If it is very noticable it may be a good thing, otherwise just having the value that seems to leave the frequency response intact would be enough.

Jim

 

[rove]

[quote author="SSLtech"]On the IEC power socket, there are three pins. the one at the top is ground. The one just below it is Neutral. The one (should be on the right looking inside the box) which doesn't some straight out, but ducks down to the fuseholder part at the bottom, then re-appears on the left side is the live.

So: from top to bottom:

Top = Ground
Middle = Neutral
Bottom = Live

Keith[/quote]
So maybe what is confusing to me is that the "live" and "neutral" refer to the IEC power socket and not to the black wires coming out of the Power transformer? Does the grey from the power transformer then attach to ground on the IEC?
Thanks!

 

[CJ]

I was just tweaking around with that trimmer and thinging the same thing as Kris.
You can change the freq rep on that box quite a bit with one of that trimmer. Then you might take off the cap on the T4 so you could reach down itno the lows a bit more.

cj

 

[SSLtech]

rove,

Which transformer are you using? -The only ones that I've built (and I'm buildinig another at the moment) are all 110/120/220/240V multiple primaries...

Check with the transformer information sheet/wire color info for your paricular transformer, with specific reference to the primary wires.

Keith

 

[Scenaria]

Hey Rove,

If you look on the transformer you will see sticker that tells you everything you would ever want to know..

I believe you have a 110/120 tranny right?

if so then you should have this:

the two BLK come from the IEC power socket (this is your primary)
the two reds are your 600vt winding
the two greens is your heater winding
the yellow stripped and grey wire all need to be tied to chassis ground (the same ground that is tied to the IEC socket)

:guinness:

 

[wave]

[quote author="rove"]Couple of Bloo LA2A transformer questions for anyone with the time:
Re: input transformer (Sowter) I am not sure where to connect R5 and the Grey wire.
Re: output transformer (Sowter) where do I connect the Green wire?
Re: power transformer, where exactly do the 2 black wires and the Grey wire connect (unclear on which is "live" and which is "neutral").
Searched the group for this info and haven't been able to turn it up, so forgive me if this is old hat! Also I have the Sowter schematic, but it isn't helping at this point.
thanks[/quote]
Rove,
Sowter input :Gray, black, and one side of R5 go to ground bus
Sowter output : Green and black go to ground bus
If you search back in the thread you can find one of cayacosta's handy diagrams for the sowter input wiring

 

[CJ]

I ate the reds. What should I do with the greens and blacks?
Never mind.

 

[rove]

Thanks everybody, things are becoming more clear to me now regarding the transformers. I keep second guessing my ability to read the schematics, but so far it seems I shouldn't have.
I dug up that Sowter input diagram by cayacosta and it was also helpful.