All things LA2a related
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AnalogPackrat
Well-known member
Oh yeah...he's almost there. I made two wiring mistakes on the meter stuff. Miswired one of the leads from the output XLR at the rotary and reversed the leads on the meter adjust pot (so GR mode reads backwards). Another Bloo is born...
Analog Packrat
Analog Packrat
What did I say our next problem was going to be?
Post 5 on page 43.
Get a hi liter pen out and check each and every connection, one by one.
Trace it out on a schematic as you verify.
Good practice.
Start with the VU meter.
Post 5 on page 43.
Get a hi liter pen out and check each and every connection, one by one.
Trace it out on a schematic as you verify.
Good practice.
Start with the VU meter.
AnalogPackrat
Well-known member
It's a three pole three position (throw) switch and you only need two of the pole and contact sets. It doesn't matter which two you use, but you need to pay attention to which connections are associated with each pole.
I'm going to assume you have the same switch that I have since we're both looking at Bloo kits. Looking at the back of the switch you should see three connections that have little wipers that contact the metal ring toward the center of the switch. These are the poles. The three position contacts that go with each pole are the three immediately counterclockwise from the pole.
I'm going to assume you have the same switch that I have since we're both looking at Bloo kits. Looking at the back of the switch you should see three connections that have little wipers that contact the metal ring toward the center of the switch. These are the poles. The three position contacts that go with each pole are the three immediately counterclockwise from the pole.
AnalogPackrat
Well-known member
[quote author="CJ"]What did I say our next problem was going to be?
Post 5 on page 43.
[/quote]
No doubt. Rotary switches are easy to F up
CJ, I think he's got it working and can't stop using it to give us a victory post. Whaddaya think?
Post 5 on page 43.
[/quote]
No doubt. Rotary switches are easy to F up
CJ, I think he's got it working and can't stop using it to give us a victory post. Whaddaya think?
AP You said it!
My dumb ass had the twin shield wired 1a-3a instead of 3a - 3b :shock:
I'm surprised I actually got it (actually I looked at photos of AP's build and caught my mistake-)
Mass beers for everyone!
:guinness: :guinness: :sam: :guinness: :guinness: :sam: :sam:
This thing SOUNDS GREAT.
Reminds me of everytime I've used one (or had to rent one) in the studio.
The meter is behaving correctly now. I'm sure some people would probably really calibrate the thing but I think it's good enough for ROCK!
Let me also just say thanks alot for all the help from AP,CJ, and Scenaria.
I'm way green and this was my first DIY project except for an Electra distortion pedal made from Shack parts :wink:
I couldn't have done it without you guys, Cayacosta's great layout and Scenaria's awesome kit!
Cheers :sam:
Wave
p.s. I'll take this bad boy to work tomorrow and have our photographer snap some shots for you.
My dumb ass had the twin shield wired 1a-3a instead of 3a - 3b :shock:
I'm surprised I actually got it (actually I looked at photos of AP's build and caught my mistake-)
Mass beers for everyone!
:guinness: :guinness: :sam: :guinness: :guinness: :sam: :sam:
This thing SOUNDS GREAT.
Reminds me of everytime I've used one (or had to rent one) in the studio.
The meter is behaving correctly now. I'm sure some people would probably really calibrate the thing but I think it's good enough for ROCK!
Let me also just say thanks alot for all the help from AP,CJ, and Scenaria.
I'm way green and this was my first DIY project except for an Electra distortion pedal made from Shack parts :wink:
I couldn't have done it without you guys, Cayacosta's great layout and Scenaria's awesome kit!
Cheers :sam:
Wave
p.s. I'll take this bad boy to work tomorrow and have our photographer snap some shots for you.
AnalogPackrat
Well-known member
Cheers back at ya! :guinness: And congrats on your first "real build." You did good. Now make some music with it before you get hooked into another project :green:
Analog Packrat
Analog Packrat
Coolsville!
Drop a 6072 in for V1 and then tell us how you like it.
:thumb:
Drop a 6072 in for V1 and then tell us how you like it.
:thumb:
AnalogPackrat
Well-known member
Hmmm...I need to try that, too. Have a few 12AY7 in the collection. It's not like the thing is short of gain, eh?
QNote
Active member
Ok... I finally finished construction and...it's blowing fuses. It seems at this point, without me doing a lot of troubleshooting (lack of time today), that the problem may be the two FRED's that I used instead of 1N4007's. They are in correctly, but they may be underrated--voltage (600V PIV).
Anyone used any FRED's for the two rectifiers? Which ones did you use? I'm gonna try a couple of 1N4007's on Saturday, after I take a peak of what the FRED's are doing on an oscilloscope. I'm thinking they might be breaking down on reverse peak voltage, causing an ac load at the caps. I ordered these in a hurry and should have selected a much higher PIV rating. ??
Just in case your wondering, I did correct their orientation as the table in Bloo's manual is incorrect. Also, there are NO shorts anywhere--isolated and checked thoroughly. It's at the rectifiers and caps.
Anyone used any FRED's for the two rectifiers? Which ones did you use? I'm gonna try a couple of 1N4007's on Saturday, after I take a peak of what the FRED's are doing on an oscilloscope. I'm thinking they might be breaking down on reverse peak voltage, causing an ac load at the caps. I ordered these in a hurry and should have selected a much higher PIV rating. ??
Just in case your wondering, I did correct their orientation as the table in Bloo's manual is incorrect. Also, there are NO shorts anywhere--isolated and checked thoroughly. It's at the rectifiers and caps.
Just did a fix on this for wave if you look back a few pages.. Which way is the bar on the diodes facing?
AnalogPackrat
Well-known member
I used UF100x fast recovery diodes in my Bloo kit with no problems. I can't remember if they're 600 or 1000PIV parts. Which part # are you using (there are several flavors)? Seems like 600 PIV would be enough. Check CJ's debug of wave's fuse blowing episode.
Analog Packrat
Analog Packrat
SSLtech
Well-known member
The positive side of both diodes should be on the 'B' row (the row nearest the front panel) and should be joined together.
I was not aware of an error in the Bloo instructions, everyone else has built theirs following the orientation as marked, and they've worked?
FWIW, if you're going to see +380Volts or so at the output, then the peak must be at +350V. This means that when the AC is at its most negative part of the cycle, it will be at -380VDC.
+380VDC at one end, with -380VDC (instantaneously) at the other end means instantaneous 760V reverse bias. I'd have gone with 1000V.
My thoughts FWIW: Fast Recovery diodes in tube gear? Sounds a little over the top to me! :wink:
Keith
I was not aware of an error in the Bloo instructions, everyone else has built theirs following the orientation as marked, and they've worked?
FWIW, if you're going to see +380Volts or so at the output, then the peak must be at +350V. This means that when the AC is at its most negative part of the cycle, it will be at -380VDC.
+380VDC at one end, with -380VDC (instantaneously) at the other end means instantaneous 760V reverse bias. I'd have gone with 1000V.
My thoughts FWIW: Fast Recovery diodes in tube gear? Sounds a little over the top to me! :wink:
Keith
AnalogPackrat
Well-known member
Keith,
Just checked--I used UF1007 which are 1000 PIV parts. I vaguely remember doing the voltage calc before ordering so I blew it on the 600PIV statement. These FREDs were $0.38US parts and seemed worth it for the potential noise reduction. I'm not going to start a FRED war here... :razz: They do work fine in the Bloo, though. Oh, and I also recall no errors in the manual regarding the rectifier orientation. Can you clarify what you meant, QNote?
Analog Packrat
Just checked--I used UF1007 which are 1000 PIV parts. I vaguely remember doing the voltage calc before ordering
so I blew it on the 600PIV statement. These FREDs were $0.38US parts and seemed worth it for the potential noise reduction. I'm not going to start a FRED war here... :razz: They do work fine in the Bloo, though. Oh, and I also recall no errors in the manual regarding the rectifier orientation. Can you clarify what you meant, QNote?Analog Packrat
SSLtech
Well-known member
Cool. there's nothing I can find actually wrong with using FReDs, but I can't measure an improvement, so it's a bit of a non-issue for me. -At under a buck for something that can't make anything worse, there's nothing wrong with using them though.
However, 600V is too low. And if Qnote has "corrected" their orientation, then they're very likely the wrong way round also. Replace them with 1000V diodes and put them the right way round... I reckon you'll stand a better chance of not sending quite so many fuses to meet their maker... :wink:
Keith
However, 600V is too low. And if Qnote has "corrected" their orientation, then they're very likely the wrong way round also. Replace them with 1000V diodes and put them the right way round... I reckon you'll stand a better chance of not sending quite so many fuses to meet their maker... :wink:
Keith
QNote
Active member
My Bloo manual reads on page 15 (of 27)...
A23, B23[+]
To me, this indicates that the anode should be on B23, but this cannot be the case, since the anodes should connect to the transformer secondary. In retrospect, I'm assuming the [+] actually indicated the cathode band marking--confusing? Yes. But, anyway you look at it, now the anodes are connected to the transformer wires, and the cathodes tie together to a 2W resistor--confirmed!
As for the FRED's, they are Fairchild ISL9R460P2, 4amp 600volt.
Also, from my memory, voltage peak across these diodes would be calculated at...
PIV = 2 x Vpk - Vd,
...which would NOT be based on the +380VDC figures, but the AC peak voltage values from the secondary. This would indicate higher values than you originally suggested.
After a few more minutes this evening in troubleshooting, I should find the reason and I will post it here.
Thanks guys! Oh, I did go back and read the "fuse blowing" chat earlier. :wink:
A23, B23[+]
To me, this indicates that the anode should be on B23, but this cannot be the case, since the anodes should connect to the transformer secondary. In retrospect, I'm assuming the [+] actually indicated the cathode band marking--confusing? Yes. But, anyway you look at it, now the anodes are connected to the transformer wires, and the cathodes tie together to a 2W resistor--confirmed!
As for the FRED's, they are Fairchild ISL9R460P2, 4amp 600volt.
Also, from my memory, voltage peak across these diodes would be calculated at...
PIV = 2 x Vpk - Vd,
...which would NOT be based on the +380VDC figures, but the AC peak voltage values from the secondary. This would indicate higher values than you originally suggested.
After a few more minutes this evening in troubleshooting, I should find the reason and I will post it here.
Thanks guys! Oh, I did go back and read the "fuse blowing" chat earlier. :wink:
cathode always needs a higher potential in order to forward bias the diode... think of the arrow pointing in the direction of current flow.. increase the potential at on the side that has the line (cathode) and it allows current to flow... a higher potential or the +
in either case I guess I could see how its confusing..
:guinness:
or the + in either case I guess I could see how its confusing..
:guinness:
QNote
Active member
[quote author="Scenaria"]cathode always needs a higher potential in order to forward bias the diode... think of the arrow pointing in the direction of current flow.. increase the potential at on the side that has the line (cathode) and it allows current to flow... a higher potential or the +
in either case I guess I could see how its confusing..
[/quote]
You're close, but no cigar!
It's the anode that must have a higher voltage potential than the cathode, by the amount of voltage as it's Vf, or forward voltage rating, which for most silicon diodes is approximately 0.7V. Diodes can be biased in the reverse direction, but this is usually not a good thing (except for zeners). This value is the diode's Vrb, reverse breakdown voltage.
If you have a higher voltage potential on the cathode than on the anode, then a normal diode would be biased off, assuming the reverse breakdown voltage hasn't been met or exceeded. If you have to bias the cathode on a particular diode in order to acheive current flow, then either it is defective, incorrectly marked (with the band), or a zener, but this is unlikely, since it (a zener) behaves like a normal diode in the forward bias direction.
<<school bell rings>>
:thumb:
or the + in either case I guess I could see how its confusing..
[/quote]
You're close, but no cigar!
It's the anode that must have a higher voltage potential than the cathode, by the amount of voltage as it's Vf, or forward voltage rating, which for most silicon diodes is approximately 0.7V. Diodes can be biased in the reverse direction, but this is usually not a good thing (except for zeners). This value is the diode's Vrb, reverse breakdown voltage.
If you have a higher voltage potential on the cathode than on the anode, then a normal diode would be biased off, assuming the reverse breakdown voltage hasn't been met or exceeded. If you have to bias the cathode on a particular diode in order to acheive current flow, then either it is defective, incorrectly marked (with the band), or a zener, but this is unlikely, since it (a zener) behaves like a normal diode in the forward bias direction.
<<school bell rings>>
:thumb:
