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Old 1st December 2011, 03:22 PM   #1021
Atilla is offline Atilla  Norway
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jtktam, man you'll be amazed what I've managed to do while working on things

But the important thing is that with the BOM, acquired trough Jokener, I haven't had any issues with the amp at all. Just watch where you place what and you will be fine.
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Old 1st December 2011, 03:53 PM   #1022
konga is offline konga  United States
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I am one of the people with a sudden failed regulator.

I have my build running on AC only no batteries, all parts with the exception of a couple of out of stock resistors are exactly from the BOM.

The amp had been working fine for about a week. Yesterday I turned it on with my TF10's attached, there was a squeal and then silence. The U6 regulator starts to heat up a lot, U5 remains cool.

I shut down unplugged everything for an hour to allow it to cool. Started it up and with the same result, no audio and uncontrolled heat up of U6.

Someone else reported the same problem on the same day. I'm starting to think there maybe some QC issues with On Semiconductor. When I replace them I will go back to the slightly pricier TI, National, or Fairchild regs I'm familiar with.

Funny thing is a couple of weeks ago I was responding on head-fi with a suspected failed regulator, about how generally difficult it is to kill a regulator...this is karma I guess.

Last edited by konga; 1st December 2011 at 04:00 PM.
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Old 1st December 2011, 04:54 PM   #1023
qusp is offline qusp  Australia
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Quote:
Originally Posted by jtktam View Post
I don't know how anybody can blow anything up doing this amp

it's like 1 on a scale of 1 to 5

if you are not careful and put stuff in the wrong place, or don't check for shorts or fitment issues, then don't blame the board

I built over 10 now and every one works 100%

no rectifier issues!

-joe
see, its exactly this sort of dismissive and condescending comment that will stop people (particularly new people just starting diy and not confident in describing technicalities, possibly in a second language) coming and asking for help if they are having problems, same as over at the other forum. from the stories of the identical problems, it appears to have nothing to do with being careful, not checking for bridges etc, functional amps all of a sudden become dysfunctional amps. perhaps it is something all are doing wrong, but that itself needs to be looked into and fixed as its unlikely to be coincidence

see i started to question my own comments in that thread, i found myself confronting a particular builder immediately stating that it had to be user error because the design has been built, tested and is sound. but really this still leaves quite a few variables that dont include user error and it does the project a disservice to assume it from the get go.

and btw, i assume you mean regulator, not rectifier.. get it right!! hehe

anyway i'm off to bed, hopefully you guys can get to the bottom of it; put wicked headphones rather than fingers in your ears.

btw i'm really not just trying to cause trouble or argument here, i just think the vibe in that thread has been pretty bad from both sides and theres no need to continue here

Last edited by qusp; 1st December 2011 at 05:04 PM.
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Old 1st December 2011, 05:04 PM   #1024
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Thanks everyone for your comments. This seems, so far, to be isolated to just a few people at head-fi (hysteria-fi?) and exactly one (out of more than 1000) who is concerned enough to even post here. To summarize what I know so far:

I'm only aware of 3 or perhaps 4 people with the problem. Deadlylover doesn't seem to have the regulator problem, he just seems to be stirring up the pot as he's done in the past (example making a big deal out of the turn-off transient and then, after I published a scope photo of the actual transient, saying it was no big deal).

Cheapskateaudio has been an O2 detractor all along and seems to have started the hysteria. Given all some have invested in "esoteric audio", it's hardly surprising a few choose to build the O2 mainly to shoot it down however they can. It's obvious when someone is more concerned with trying to justify their own highly subjective positions at all costs, keep Santa Klaus and other myths alive, has financial interests to protect, is a H-F shill, etc.

Mikeaj and Konga (same person?) seem to have a problem but it may not be the 7912 as suspected. Both said the amp was working then stopped and the 7912 got hot. That likely means there's a short (or near short) somewhere on the negative rail and it's simply in shutdown. He/they may only expect its a regulator problem because of the other hysteria created by only a couple other people.

It is difficult to kill a regulator. To whoever posted on head-fi they're not protected against sustained operation outside their specifications should know they're being operated well within their specifications in the O2. They're not even close to being run too hot, with too much current, etc. Someone should post this on H-F:

Max Input Voltage = 35V, O2 voltage with 16 volt transformer = 23V
Max Current 1A continuous, 2.2A peak, O2 peak current < 0.4 amps
Max Junction Temp = 125C, O2 junction junction temp 45C - 65C

There are implied claims BOTH regulators somehow failed. The odds of that are near zero unless there's a problem upstream of the regulators like too high of a wall transformer voltage or bad/wrong diodes (D3/D4). The correct 1N4002 diodes are bulletproof but if someone put the 1N5818 in those locations by mistake, they may well fail shorted.

Someone else pointed out the regulators touching the top of the enclosure could be a problem if they're soldered in too "high". I agree with that although it's still unlikely to kill the regulators.

Someone might point out the regulators do not have reverse bias diodes around them, but that's because they have diodes isolating them and only small 0.22 uF caps on their outputs. Reverse diodes across the regulators are not required per the manufactures.

The BOM has specified On Semi regulators since well before the group buys but there's talk of "off brand" regulators. Either someone is horribly mistaken and considers On Semi (formerly part of Motorola and one of the biggest linear/analog IC companies on the planet) "off brand" or they're using some other unspecified parts. Konga above said On Semi but there's no proof his regulator is even bad.

FOR THOSE HAVING PROBLEMS: I would suggest the following:

Hopefully your op amps are in sockets. Remove all 4 of them, and the batteries, and see if the voltages across the battery terminals return to normal and the regulators are both barely warm. If so, you have at least one bad op amp. Replace them one at a time to find the bad one, or for less than $2, just replace all of them. If not, you likely have a solder bridge, something touching the case, or (unlikely) another failed component somewhere--the most likely suspects are the 0.22 uF caps (C17, C18).

If your op amps are not socketed, heat and lift up (desolder) one end of D1 and D5 and measure the voltages across C6 and C7. If they're normal, see above about dead op amps, solder bridges, etc.

If with no load on the regulators the voltages are still not normal, measure the DC voltage across both C4 and C5. It should be around 18 - 29 volts on each cap. Set the DMM for AC voltage and measure again. Each should be under 1 volt. If you measure high AC, replace D3 and D4. If you measure more than 30 volts DC you need a different wall transformer.

IMPORTANT: If anyone has had a regulator fail and deliver over 15 volts to the entire board (it's not clear anyone has), you should replace all the op amps after verifying the power supply is working correctly per the test procedures in the O2 Details article.

REMOVING OP AMPS: For socketed op amps carefully pry them up from each end a little bit at a time with a very small flat screwdriver. For soldered in op amps (hopefully there are not any), cut the chips out with small diagonal cutters and de-solder each pin individually.
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Last edited by RocketScientist; 1st December 2011 at 05:07 PM.
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Old 1st December 2011, 05:18 PM   #1025
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Thanks for giving the folks with problems something to look for. I myself haven't had any problems at all in the 3 weeks since I built mine. The regulators touching the top of the enclosure is really hard to do since they're shorter than the caps and mosfet in to-220. Jumping to conclusions in what could be wrong leads to missing the obvious way too often.
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Old 1st December 2011, 05:51 PM   #1026
qusp is offline qusp  Australia
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perfect, thanks RS. i hope you know what i mean; its things like this

Quote:
The BOM has specified On Semi regulators since well before the group buys but there's talk of "off brand" regulators. Either someone is horribly mistaken and considers On Semi (formerly part of Motorola and one of the biggest linear/analog IC companies on the planet) "off brand" or they're using some other unspecified parts. Konga above said On Semi but there's no proof his regulator is even bad.
with this number of builders and different avenues for kits landing in peoples hands, many maybe not buying their own parts or even knowing how to identify parts past the label on the snaplock baggie. things like this need to be looked at in exactly the way that you have just done RS with the comprehensive checklist above, the BOM that lands in peoples hands may in some cases look like the right bom, but something goes amiss.

but dismissive and divisive comments do not help anyone, they only serve to scare people from bringing up issues that may be real problems, not with the design so much as the supply chain. i think the big sanctioned GBs are likely to all be perfectly fine, but there will be kits, part finished amps, pcbs with scribbled or printed BOMs that are old etc etc. the world is full of people wanting to make a few bucks and they dont all know what they are doing
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Old 1st December 2011, 05:55 PM   #1027
tschuss is offline tschuss  United States
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Quote:
Originally Posted by Jokener View Post
I think I'll go out and buy a new soldering station first, though.
A Weller station from the 80s is good and well, but I think a shiny new Ersa i-Con 1 is in order...
(Or would you guys recommend strongly against it or strongly FOR something else?)
I'm no expert when it comes to these things, but I ordered this one from Amazon two years ago and have LOVED using it.

Amazon.com: Aoyue 937+ Digital Soldering Station: Home Improvement

Not sure if you can find it in Deutschland, but if so, I'd highly recommend it for electronics work.
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Old 1st December 2011, 06:07 PM   #1028
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@qusp, good point that many may not know who On Semi is--especially among the H-F crowd. I need to do better keeping that sort of thing in mind. Here on diyAudio it seems safe to assume a bit more general knowledge. The O2 was never really intended as a total novice DIY project. Those warnings have been in the documentation from the start. The idea was someone would step up and offer at least assembled boards and that's happened nicely. To my knowledge none of those boards have had any problems at all (and MrSlim just confirmed that's the case for the ones he's built).

Of the 2000+ PC boards I know were manufactured at least many hundreds should be assembled boards by now. You can count the group buys on one hand and, at least those in the North America, Europe and Australia/NZ, were done by what seem like reputable guys who followed the correct BOMs, etc.

Out of those many hundreds of assembled boards, only a couple people have reported this issue and at least one or two of them have a track record of zealously highlighting negative things--factual or otherwise--about the O2. The other few have not even demonstrated the regulators failed. Their boards may have a bent over lead shorting something out somewhere.
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Old 1st December 2011, 06:09 PM   #1029
konga is offline konga  United States
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Quote:
Originally Posted by RocketScientist View Post
Thanks everyone for your comments. This seems, so far, to be isolated to just a few people at head-fi (hysteria-fi?) and exactly one (out of more than 1000) who is concerned enough to even post here. To summarize what I know so far:

I'm only aware of 3 or perhaps 4 people with the problem. Deadlylover doesn't seem to have the regulator problem, he just seems to be stirring up the pot as he's done in the past (example making a big deal out of the turn-off transient and then, after I published a scope photo of the actual transient, saying it was no big deal).

Cheapskateaudio has been an O2 detractor all along and seems to have started the hysteria. Given all some have invested in "esoteric audio", it's hardly surprising a few choose to build the O2 mainly to shoot it down however they can. It's obvious when someone is more concerned with trying to justify their own highly subjective positions at all costs, keep Santa Klaus and other myths alive, has financial interests to protect, is a H-F shill, etc.

Mikeaj and Konga (same person?) seem to have a problem but it may not be the 7912 as suspected. Both said the amp was working then stopped and the 7912 got hot. That likely means there's a short (or near short) somewhere on the negative rail and it's simply in shutdown. He/they may only expect its a regulator problem because of the other hysteria created by only a couple other people.

It is difficult to kill a regulator. To whoever posted on head-fi they're not protected against sustained operation outside their specifications should know they're being operated well within their specifications in the O2. They're not even close to being run too hot, with too much current, etc. Someone should post this on H-F:

Max Input Voltage = 35V, O2 voltage with 16 volt transformer = 23V
Max Current 1A continuous, 2.2A peak, O2 peak current < 0.4 amps
Max Junction Temp = 125C, O2 junction junction temp 45C - 65C

There are implied claims BOTH regulators somehow failed. The odds of that are near zero unless there's a problem upstream of the regulators like too high of a wall transformer voltage or bad/wrong diodes (D3/D4). The correct 1N4002 diodes are bulletproof but if someone put the 1N5818 in those locations by mistake, they may well fail shorted.

Someone else pointed out the regulators touching the top of the enclosure could be a problem if they're soldered in too "high". I agree with that although it's still unlikely to kill the regulators.

Someone might point out the regulators do not have reverse bias diodes around them, but that's because they have diodes isolating them and only small 0.22 uF caps on their outputs. Reverse diodes across the regulators are not required per the manufactures.

The BOM has specified On Semi regulators since well before the group buys but there's talk of "off brand" regulators. Either someone is horribly mistaken and considers On Semi (formerly part of Motorola and one of the biggest linear/analog IC companies on the planet) "off brand" or they're using some other unspecified parts. Konga above said On Semi but there's no proof his regulator is even bad.
Here we have the exact reason why you get so many hateful replies. I reported an issue I was having just like you requested a few posts back and I get 8 paragraphs of derisive drivel before you offer any thing remotely helpful.

Deadlylover, mikeaj, and I just so happen to have the same issue in a very same span of time. We all reported the issues just like you asked and this is how you reply. I only suggested that based on the evidence that maybe there was a bad batch of components. Is that so beyond the realm of possibility? Like that's never happened to any builders on here in the past.

Not in any way have I been a "detractor" and poo-poo your design or even blame the amplifier itself.

No, Mikeaj and I are not the same person. My sn on head-fi is FrancisDemarte. We just happen to have the same problem on the exact same day.

Quote:
Originally Posted by RocketScientist View Post
FOR THOSE HAVING PROBLEMS: I would suggest the following:

Hopefully your op amps are in sockets. Remove all 4 of them, and the batteries, and see if the voltages across the battery terminals return to normal and the regulators are both barely warm. If so, you have at least one bad op amp. Replace them one at a time to find the bad one, or for less than $2, just replace all of them. If not, you likely have a solder bridge, something touching the case, or (unlikely) another failed component somewhere--the most likely suspects are the 0.22 uF caps (C17, C18).

If your op amps are not socketed, heat and lift up (desolder) one end of D1 and D5 and measure the voltages across C6 and C7. If they're normal, see above about dead op amps, solder bridges, etc.

If with no load on the regulators the voltages are still not normal, measure the DC voltage across both C4 and C5. It should be around 18 - 29 volts on each cap. Set the DMM for AC voltage and measure again. Each should be under 1 volt. If you measure high AC, replace D3 and D4. If you measure more than 30 volts DC you need a different wall transformer.

IMPORTANT: If anyone has had a regulator fail and deliver over 15 volts to the entire board (it's not clear anyone has), you should replace all the op amps after verifying the power supply is working correctly per the test procedures in the O2 Details article.

REMOVING OP AMPS: For socketed op amps carefully pry them up from each end a little bit at a time with a very small flat screwdriver. For soldered in op amps (hopefully there are not any), cut the chips out with small diagonal cutters and de-solder each pin individually.
This was you need to say and it would have been the end of it.
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Old 1st December 2011, 06:33 PM   #1030
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The post wasn't aimed at you Konga, it was intended as a summary of everything I know so far about this issue and you're just one small part of that. I'm sorry if you're offended but put yourself in my shoes. Something seems not quite right with at least some of what's been posted. I tried to divide the issues up by what I know about them.

You and mikeaj obviously have a legit problem. But we don't know that it's the 7912 unless I missed something?

Yes, it's possible there's a bad batch of 7912's. But haven't others claimed the 7812 has also failed? What are the odds two completely different, normally bulletproof, parts suddenly start failing the same week when there have been O2's in the wild since August?

I admit I'm prone to being defensive, but it's been my experience in the past, the only way to sort the truth from the spin at H-F is to spell out the facts. That's all I'm trying to do.
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