peter purpose
Well-known member
dmp said:
R13 at 10K got me the zero no problem. Try going smaller.
LA3A 500 BUILD
- Thread starter peter purpose
- Start date
Help Support GroupDIY Audio Forum:
R13 at 10K got me the zero no problem. Try going smaller.
janczmok
Well-known member
Finally got some time to look again at my unfinished module. So, some short questions:
- What's your preferred RLED value ? ( i am using now 3-PIN Led's and one red LED as planned), will try with 22OR, ok ?
- VU Meter: I have 4 (two large, marked with - and + and two small) connectors. Am i assuming right:
- PG/MP use them on the smaller connectors,
- M+/M- according on the meter.
- What heatsinks are needed ? Peter: Which one did you use ?
Thx
- What's your preferred RLED value ? ( i am using now 3-PIN Led's and one red LED as planned), will try with 22OR, ok ?
- VU Meter: I have 4 (two large, marked with - and + and two small) connectors. Am i assuming right:
- PG/MP use them on the smaller connectors,
- M+/M- according on the meter.
- What heatsinks are needed ? Peter: Which one did you use ?
Thx
peter purpose
Well-known member
What's your preferred RLED value ?
That would depend on the leds being used. http://led.linear1.org/1led.wiz
Meter
PG/MP = power ground/meter power
M+/M- = meter positive/meter negative.... so you were assuming correctly.
What heatsinks are needed ?
The driver pair (metal cans) on the output amp need sinking.
I cut up an old pc heatsink and used a double sided, heat transferring pad. Get a super sticky one.
The metal cans carry plus and minus voltage, so must be seperate.
peter
That would depend on the leds being used. http://led.linear1.org/1led.wiz
Meter
PG/MP = power ground/meter power
M+/M- = meter positive/meter negative.... so you were assuming correctly.
What heatsinks are needed ?
The driver pair (metal cans) on the output amp need sinking.
I cut up an old pc heatsink and used a double sided, heat transferring pad. Get a super sticky one.
The metal cans carry plus and minus voltage, so must be seperate.
peter
janczmok
Well-known member
So will check the local computer surplus store for a decent heatsink plus tools 
Also need to file off something off the metal case, as the meter is not fitting in 100% and thereof blocking the buttons.
Also need to file off something off the metal case, as the meter is not fitting in 100% and thereof blocking the buttons.peter purpose
Well-known member
This was addressed earlier.... you just need to file a little around the bottom of the hole at the fold.
janczmok
Well-known member
Thanks for pointing out. Have missed this, despite that i read the whole thread 2 times yesterday.peter purpose said:
dmp
Well-known member
Ok - the meter zeros and bounces happily now as the unit compresses. Thanks for the help.
I haven't measured the accuracy, but it seems reasonable by ear. I'm very happy with it now.
I switched LDRs (although I don't think that was the problem since they had comparable dark ohms)
I have:
R24 NI
R13 10k
R22 47k
RV36 = 3.9k
I haven't measured the accuracy, but it seems reasonable by ear. I'm very happy with it now.
I switched LDRs (although I don't think that was the problem since they had comparable dark ohms)
I have:
R24 NI
R13 10k
R22 47k
RV36 = 3.9k
peter purpose
Well-known member
Marvellous.
mulletchuck
Well-known member
is anyone supplying a complete parts kit for this? ???
Winetree
Well-known member
The TB4 I took apart has a resistor on one leg of the EL Panel.
Should the resistor end go to pin #3 or Pin #4 on the
LA-3A-500 El Panel daughter board? Or does it make a difference?
Wondering which senser is meter and which one is audio? Front or Back?
Should the resistor end go to pin #3 or Pin #4 on the
LA-3A-500 El Panel daughter board? Or does it make a difference?
Wondering which senser is meter and which one is audio? Front or Back?
dmp
Well-known member
Looking at the schematic, 5 & 6 are the meter. They are labeled on the pcb.
Do you realize that the numbering corresponds to the pins on the plug of your T4b? Since you took it apart, you're the only one who knows what pin the resistor was connected to. What value was the resistor?
Do you realize that the numbering corresponds to the pins on the plug of your T4b? Since you took it apart, you're the only one who knows what pin the resistor was connected to. What value was the resistor?
Winetree
Well-known member
No, I didn't realize the pin #,s were the same. Thanks for the tip. I got it figured out.
The cap is a .0047uf@630vdc. Pin #3 goes to panel, comes out into cap to ground.
The cap is a .0047uf@630vdc. Pin #3 goes to panel, comes out into cap to ground.
dmp
Well-known member
You were talking about a resistor in series with the panel. I guess it turned out to be a capacitor?
There is a 4.7nf cap in series with the panel, CT4 on Peter's schematic.
There is a 4.7nf cap in series with the panel, CT4 on Peter's schematic.
gavvyt
New member
mulletchuck said:
I would like to know this as well.
(I am based in London)
kato
Well-known member
Edit to my previous post to clear up confusion - the kits I assembled do not include EL panel, opto cells, or transformers. A T4b and hairball transformer bundle is still required. There is no money savings in my parts kit - nor is there money making on my end - just the convenience of labeled parts, and not ordering from multiple sources. (And for me, the lesson that I never want the pain of running a parts kit business.)
I'm nearing the end of this parts fiasco. I've got two single channels boxed up, and 1 dual channel kit. (Plus extra two dual-channel kits with tall heatsinks that need to be trimmed to fit.)
The latest batch of kits have included these heatsinks (pictured) that fit the close spacing on the board. These are raised up a little with transistor sockets to keep from bumping into the diodes between them. In retrospect I would skip the transistor socket for a more solid connection and solder the transistors above board.
Cost is $56.41 per channel plus $5.20 priority mail for any number of kits.
(You can deduct $2.41 in paypal fees per channel if you choose the "personal tab" in Paypal and send as "payment owed" although you forfeit your Paypal buyer protection by doing this.) Here's what's left:
1-channel kit (61.61 shipped) sold
1-channel kit (61.61 shipped)
2-channel kit (118.02 shipped) sold
I have an additional 2 channel kit assembled that with the larger heatsinks. They require a little filing at the top, and pin cutting at the bottom to fit within the race space width. PM or e-mail.
I'm nearing the end of this parts fiasco. I've got two single channels boxed up, and 1 dual channel kit. (Plus extra two dual-channel kits with tall heatsinks that need to be trimmed to fit.)
The latest batch of kits have included these heatsinks (pictured) that fit the close spacing on the board. These are raised up a little with transistor sockets to keep from bumping into the diodes between them. In retrospect I would skip the transistor socket for a more solid connection and solder the transistors above board.
Cost is $56.41 per channel plus $5.20 priority mail for any number of kits.
(You can deduct $2.41 in paypal fees per channel if you choose the "personal tab" in Paypal and send as "payment owed" although you forfeit your Paypal buyer protection by doing this.) Here's what's left:
1-channel kit (61.61 shipped)
I have an additional 2 channel kit assembled that with the larger heatsinks. They require a little filing at the top, and pin cutting at the bottom to fit within the race space width. PM or e-mail.
Winetree
Well-known member
Got 2 earlier Kits. Got a part's number for the newer heatsinks?
I thought I'd post some progress. This thing has been a breeze so far. Thanks for such a great layout Peter!
I hope to get some matched cells from a friend soon. Until then I'll get the transformers and meters buttoned up.
One question, for the Cinemag 2511 input transformer, am I assuming correctly by matching the red dot from transformer to the white circled pin hole on pcb?
I hope to get some matched cells from a friend soon. Until then I'll get the transformers and meters buttoned up.
One question, for the Cinemag 2511 input transformer, am I assuming correctly by matching the red dot from transformer to the white circled pin hole on pcb?
Attachments
kato
Well-known member
Looking good Duane! I mailed your parts over the weekend so you're kicking some ass.
325705B00000G
Sorry about the extra tall heatsinks. I learned not to assemble a parts kit till I've built the thing myself.
Though the ones I shipped previously have better thermal resistance and reportedly can be made to fit with some grinding. It's always a trade off when working in tight spaces.
Info for all - important things I learned from the beta testers:
• box caps for the unmarked caps do not fit under the amp boards without bending. Later kits shipped with half height dipped caps.
• heat sinks too tall for 1 rack width.
• RV31 and RV23 go on underside of board.
Winetree said:
325705B00000G
Sorry about the extra tall heatsinks. I learned not to assemble a parts kit till I've built the thing myself.
Though the ones I shipped previously have better thermal resistance and reportedly can be made to fit with some grinding. It's always a trade off when working in tight spaces.
Info for all - important things I learned from the beta testers:
• box caps for the unmarked caps do not fit under the amp boards without bending. Later kits shipped with half height dipped caps.
• heat sinks too tall for 1 rack width.
• RV31 and RV23 go on underside of board.
