Most likely a fine instrument but to me, nothing beats a good CRT scope.
You could do a search around here, there are a few excellent threads about o’scopes.
/Hugo
You could do a search around here, there are a few excellent threads about o’scopes.
/Hugo
barchetta said:
Let's be honest.
I was upset with you because I knew you were never a newbie.
I thought you had the result already.
I thought you were kinda scorning people around here.
I thought you might be that famous Fred!
Because I thought the mods were treating you special way.
If I was entirely wrong, I would be sure you would finish this
rebuilding in good result.
Netlist said:
You're right.. this is way off topic.. I apologize.. I'll keep this limited to finishing this repair.. which BTW.. I am very excited about.. I also noticed this morning no hum whatsoever.. it used to have a small amount of hum before I went over the right channel solder joints..
Guys, before I forget.. I will be heading out of town this weekend.. be back tuesday.. but will be here next 2 days.. so if you dont hear from me thats why... (will be a nice break for you all!).
I just want to say thanks again for all your patience on this.. obviously I could not have done this by myself and I do have a new appreciation for working on old gear like this.. rebuilds require more than fixing the original problem that is for sure!
Again bias tonight.. I want to make sure I get some really good Class A electrical bills every month! 🙂
Babowana said:
Let's be honest.
I was upset with you because I knew you were never a newbie.
I thought you had the result already.
I thought you were kinda scorning people around here.
I thought you might be that famous Fred!
Because I thought the mods were treating you special way.
If I was entirely wrong, I would be sure you would finish this
rebuilding in good result.
I continue to struggle understanding you.. I can't tell if you are being nice or a wisea$$ like me 😉 Maybe a little of both. Anyway.. I have no grudges. I have read many of your posts and am very impressed with your technical skills. You have really motivated me to build a Aleph 5 one day.
EDIT: Me not a newbie? Are you kidding? LOL.
barchetta said:
OK, fair enuf. I was over-sensing. Sorry about it.
It's not Aleph 5, but Zen V5. Am I correct?
Maybe, you r a newbie LOL.
As a matter of fact, I love ZV5 very much, particularly
with the sound. Mmm . . . and I am thinking about
modification of PSU with a series reg having the negative
feedback. Acceptable, Nelson?
All the best!
Babowana said:
OK, fair enuf. I was over-sensing. Sorry about it.
It's not Aleph 5, but Zen V5. Am I correct?
Maybe, you r a newbie LOL.
As a matter of fact, I love ZV5 very much, particularly
with the sound. Mmm . . . and I am thinking about
modification of PSU with a series reg having the negative
feedback. Acceptable, Nelson?
All the best!
Sorry z5. See, I am a newbie... actually I am really bad with names.. they go in one ear and out the other.
I am also eyeing the Aleph 3. The reviews on it are amazing.
Babowana said:
. . . and I am thinking about
modification of PSU with a series reg having the negative
feedback. ............
why?
tighter regulation?
better put more caps after existing reg.........if I'm not mistakin' as usual
Papa:
"Regulation Rules
The Mosfet regulators in this
circuit are simply followers, driven
by the voltage appearing at their
Gates. On a long term DC basis
this is determined by the value
of the Zener diodes, but fairly
large capacitors C10 and C11
are provided not only to help
filter noise, but to provide a very
slow startup voltage. ZV5 can
draw quite a bit of extra current if
awakened rapidly due to C1 and
C2, and so the 2200 uF values for
C10 and C11 give it a gentle wake-
up call.
You might imagine that large
capacitance would not be needed
coming off the output of the Mosfet
regulators, but in fact they are.
Q3 and Q4 are operated without
feedback, and their intrinsic
“resistance” (the inverse of their
transconductance) is about .25
ohms, enough to create some
undesirable modulation at AC
frequencies. This is squashed by
the 30,000 uF of C8 and C9 so that
it doesn’t become an issue until
down about 10 Hz or so, and by
then your woofer has much bigger
problems than the amplifier. "
Zen Mod said:
Just for another experiment, squeezing further down the
regulator output impedance, to remove the ac modulation in
the +V rail at the low frequencies.
Let's stop here, and return the thread to Joe.
Zen Mood,
I was very noisy local time tonight. Time to go to bed . . .
O, still I could not get JFET . . . But I did not forgot . . .
Babowana said:
.............
Let's stop here, and return the thread to Joe.
..........
"of topic" is my middle name.......
I told you : do not worry and don't feel any obligation to me
Joe,
I'd recommend you go for a standard crt scope as well. Buy one in the 60 to 100mhz range...
The issue with the fluke is the lcd speed. You want a display that is very fast resolution wise and I'm not sure about the portable units. A good crt is very fast...
Check out your local craigslist as I see them on mine fairly often.
Don't buy a digital storage scope, just a good (brand name) analog scope would be fine.
Yeah, I know if doesn't fit with the minimalistic lifestyle...
Perhaps others with experience with the portable units would have better advice.
I'd recommend you go for a standard crt scope as well. Buy one in the 60 to 100mhz range...
The issue with the fluke is the lcd speed. You want a display that is very fast resolution wise and I'm not sure about the portable units. A good crt is very fast...
Check out your local craigslist as I see them on mine fairly often.
Don't buy a digital storage scope, just a good (brand name) analog scope would be fine.
Yeah, I know if doesn't fit with the minimalistic lifestyle...
Perhaps others with experience with the portable units would have better advice.
Apogee said:
I read about that fluke and apparently it emits noise. Yeah I will stick with a small CRT. 🙂 If I can find one.. there is an HP on my craigslist.. might pick it up.
Hi Joe,
I used to calibrate scopemeters. I hate them. They aren't really very good at anything, but they will get better.
-Chris
I used to calibrate scopemeters. I hate them. They aren't really very good at anything, but they will get better.
-Chris
Well I spent many hours last night adjusting bias on the right channel only.. The good news is the amp appears to operating much better.. for one the pot is no longer touchy.. so whatever was loose was causing the bias adjustment to be very unstable.. now I can adjust it very nicely (voltage across emitter).
But.. I experienced what was in the factory manual I have read.. after several adjustments it "locked"... I could not increase the temp.. so I did what the manual suggested .. power down and cool and start over.. however.. when I powered up the transformer screamed bloody murder because the bias was set to high from my attempts to raise temp.. luckily on variac and fuse and no issues.. powered down and set the bias to 0..
Anyway.. I am now getting close to the goal of 45c. I am at 41c after one hour idle.. one or 2 more tweeks and I should be there and then I can adjust the left channel to the same setting cold and watch it come up to temp...
Can I be done then? PLEASE? 🙂
Unfortunately I leave for out of town saturday morning.. so I wont get this done until middle of next week when I get back.. I cant wait to hear it on my vandersteens and compare to my other 400a.. which by the way the bias is not even close to right on my "good 400a".. so I cant wait to adjust that too.. Jon from vintage says it can really help with the treble.. I hope so.. cuz thats all that amp is lacking (could be my vandersteens too though).
EDIT: I asked before but it got lost.. what filter caps should I be using? It looks like one might be orginal (gasp). One is not labled just silver and the other is 9800mfd 100v.. Should to try for more like 22000mfd 75-100v??
Joe
But.. I experienced what was in the factory manual I have read.. after several adjustments it "locked"... I could not increase the temp.. so I did what the manual suggested .. power down and cool and start over.. however.. when I powered up the transformer screamed bloody murder because the bias was set to high from my attempts to raise temp.. luckily on variac and fuse and no issues.. powered down and set the bias to 0..
Anyway.. I am now getting close to the goal of 45c. I am at 41c after one hour idle.. one or 2 more tweeks and I should be there and then I can adjust the left channel to the same setting cold and watch it come up to temp...
Can I be done then? PLEASE? 🙂
Unfortunately I leave for out of town saturday morning.. so I wont get this done until middle of next week when I get back.. I cant wait to hear it on my vandersteens and compare to my other 400a.. which by the way the bias is not even close to right on my "good 400a".. so I cant wait to adjust that too.. Jon from vintage says it can really help with the treble.. I hope so.. cuz thats all that amp is lacking (could be my vandersteens too though).
EDIT: I asked before but it got lost.. what filter caps should I be using? It looks like one might be orginal (gasp). One is not labled just silver and the other is 9800mfd 100v.. Should to try for more like 22000mfd 75-100v??
Joe
Hi Joe,
Make sure you choose caps that are rated at the same voltage or higher than the originals.
Yes, I'd be looking somewhere around 30,000 uf each for the replacements. Just make sure the physical size will fit in the original locations.
Just my opinion...
Make sure you choose caps that are rated at the same voltage or higher than the originals.
Yes, I'd be looking somewhere around 30,000 uf each for the replacements. Just make sure the physical size will fit in the original locations.
Just my opinion...
Apogee said:
That's my problem.. I dont know what the originals were.. I have looked at schematics available to me.. mine are 9800mfd and I am told those are not correct... at least ONE of them is.
I was told here that they might have been 15k.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1142750#post1142750
Oh when you say originals maybe you mean whats in there now.. okay I see.. Now I am studying the quality issue.. gaaads...
Hi Joe,
To make life easier for you, measure the diameter and height of the existing capacitors. Note what you feel the maximum height and minimum height might be for your chassis. Look for replacement caps that are at least the voltage rating of your current capacitors and the same diameter. The height of the can must be within your min and max specs. Then just choose a capacitance value that isn't grossly high.
-Chris
To make life easier for you, measure the diameter and height of the existing capacitors. Note what you feel the maximum height and minimum height might be for your chassis. Look for replacement caps that are at least the voltage rating of your current capacitors and the same diameter. The height of the can must be within your min and max specs. Then just choose a capacitance value that isn't grossly high.
-Chris
anatech said:
Help me here: the higher the MFD the more power available in reserve for peak power requirements.
Is that pretty close?
That's correct.
Essentially, in this case bigger is better to a point. The problem is, if you go too large, then when you turn the amp on it will blow fuses until the caps charge.
The empty caps act like a dead short to the transformer. If you want to have lots of capacitance, then you add a soft start circuit that gives a few seconds to allow the caps to charge instead of a hard hit on the transformer.
You shouldn't have any trouble with ~30k of capacitance, and you shouldn't need a soft start circuit.
As I wrote earlier, technology has changed and it allows much more capacitance in the same physically sized unit - hence why upgrading makes sense.
Essentially, in this case bigger is better to a point. The problem is, if you go too large, then when you turn the amp on it will blow fuses until the caps charge.
The empty caps act like a dead short to the transformer. If you want to have lots of capacitance, then you add a soft start circuit that gives a few seconds to allow the caps to charge instead of a hard hit on the transformer.
You shouldn't have any trouble with ~30k of capacitance, and you shouldn't need a soft start circuit.
As I wrote earlier, technology has changed and it allows much more capacitance in the same physically sized unit - hence why upgrading makes sense.
barchetta said:
Yes. Also, Chris gives good advice. Determine the size that will fit, pick a safe voltage/temp range, and see what values are available. Newly manufactured caps have much more capacity for a given size. Be careful to not get too many MFD. If you do, you can hurt the rectifier bridges and cause your household circuit breakers to trip due to the turn-on surge. 😀
You might want to consider installing a CL-60 thermistor on the primary side of the transformer to limit surges.
The RIFA caps mentioned in the other thread are great but damn near impossible to find here in the US. I've had good results with Mallory CGS, Sprague 36D, and United Chemi-Con.
Bill