Hi. And thanks for taking the time to read this post.
A few weeks ago i upgraded the power supply smoothing capacitors to panasonic fm's in my firestone fubar dac and noticed an improvement in sound quality. I then upgraded the rest of the capacitors on the board keeping the same capacitance and voltage values, checking the soldering job as well.
And the darn thing never worked again.
Later, I upgraded the capacitors in my zero dac and that stopped working as well.
Has anyone else had similar problems to this. Is this capacitor upgrading not as simple as it looks. Does the different specifications (impedance, ripple current values etc) of replacement capacitors change the current or something in the circuit creating a dangerous situation.
Could really use some help here guys on which direction to go, £400 worth of dacs just bit the dust.
Many thanks in advance. John.
A few weeks ago i upgraded the power supply smoothing capacitors to panasonic fm's in my firestone fubar dac and noticed an improvement in sound quality. I then upgraded the rest of the capacitors on the board keeping the same capacitance and voltage values, checking the soldering job as well.
And the darn thing never worked again.
Later, I upgraded the capacitors in my zero dac and that stopped working as well.
Has anyone else had similar problems to this. Is this capacitor upgrading not as simple as it looks. Does the different specifications (impedance, ripple current values etc) of replacement capacitors change the current or something in the circuit creating a dangerous situation.
Could really use some help here guys on which direction to go, £400 worth of dacs just bit the dust.
Many thanks in advance. John.
Changing the caps for others with the same value and voltage rating shouldn't cause a DAC to totally stop working.
IMO, there's two things that might have gone wrong. Either you put in an electrolytic or tantalum cap backwards, or there's a problem with the soldering.
Possible soldering problems include overheating and damaging other components on the PCB or accidentally short-circuiting something with a stray splash of solder.
IMO, there's two things that might have gone wrong. Either you put in an electrolytic or tantalum cap backwards, or there's a problem with the soldering.
Possible soldering problems include overheating and damaging other components on the PCB or accidentally short-circuiting something with a stray splash of solder.
At the first step, you noticed a difference with certain caps replaced. Some of that difference might have been due to cap brand, but some of it might just be from fresh caps versus old ones. But regardless of the reason for the difference, that is the sort of thing different caps will do.
ESR, ripple ratings, temperature specs, etc etc all may have some subtle effect, but none of those will just up and prevent the system from working. AT least not usually. There is a difference between working but not well, and not working at all.
A common rule of thumb in the repair game is that if a system functioned before and now has a new problem since you worked on it, it is likely because of something you did.
So look closely at your work. ANy caps installed backwards? Most boards I encounter have a dot or circle or maybe a shaded segment silk screened on the board to indicate the negative pole of the amps with polarity. but not all. I have seen the positive pole marked. SO if you must, remove some remaining cap to make sure which way the markings are printed. Of course the ones with a "+" symbol are pretty consistent.
I had a client who tried to learn to overhaul video monitors on his own. He purchased "cap kits" for his arcade monitors. He installed a kit, and it now blew fuses. He brought it to me. I found he had neglected to clip off the excess lead wire on a couple caps, so power supplies were being grounded to the metal chassis. Make sure on your boards you don't have any excess lead touching anything, and look CLOSELY at each joint to make sure no wires touch adjacent pads.
Excess solder and loose solder globs make "solder bridges." Look closely to see if anywhere you soldered, a blop of solder is shorting two traces together.
ESR, ripple ratings, temperature specs, etc etc all may have some subtle effect, but none of those will just up and prevent the system from working. AT least not usually. There is a difference between working but not well, and not working at all.
A common rule of thumb in the repair game is that if a system functioned before and now has a new problem since you worked on it, it is likely because of something you did.
So look closely at your work. ANy caps installed backwards? Most boards I encounter have a dot or circle or maybe a shaded segment silk screened on the board to indicate the negative pole of the amps with polarity. but not all. I have seen the positive pole marked. SO if you must, remove some remaining cap to make sure which way the markings are printed. Of course the ones with a "+" symbol are pretty consistent.
I had a client who tried to learn to overhaul video monitors on his own. He purchased "cap kits" for his arcade monitors. He installed a kit, and it now blew fuses. He brought it to me. I found he had neglected to clip off the excess lead wire on a couple caps, so power supplies were being grounded to the metal chassis. Make sure on your boards you don't have any excess lead touching anything, and look CLOSELY at each joint to make sure no wires touch adjacent pads.
Excess solder and loose solder globs make "solder bridges." Look closely to see if anywhere you soldered, a blop of solder is shorting two traces together.
Friend Needs Help.
Hi. Many thanks for the replies.
It is genuinely appreciated.
One last thing. Some of the caps i replaced were 2200uf with a tolerance of 20 percent. It is possible the new caps were 1760uf ie 440uf lower due to the tolerance and this may have caused a problem perhaps with current levels all of a sudden being too low for some parts of the circuit.
Also do you think it is a good idea to replace like for like ie panasonic caps with higher grade panasonic caps, rather than using any old brand. On the power supply i used panasonic fm's for the rest of the board i used sanyo os con and vishay which i used replace rubycon za's. On the capacitor it just said "ZA" only after i had replaced them then i did a google search finding out these were rubycon caps and were actually pretty good - Doh!
Many thanks. John.
Hi. Many thanks for the replies.
It is genuinely appreciated.
One last thing. Some of the caps i replaced were 2200uf with a tolerance of 20 percent. It is possible the new caps were 1760uf ie 440uf lower due to the tolerance and this may have caused a problem perhaps with current levels all of a sudden being too low for some parts of the circuit.
Also do you think it is a good idea to replace like for like ie panasonic caps with higher grade panasonic caps, rather than using any old brand. On the power supply i used panasonic fm's for the rest of the board i used sanyo os con and vishay which i used replace rubycon za's. On the capacitor it just said "ZA" only after i had replaced them then i did a google search finding out these were rubycon caps and were actually pretty good - Doh!
Many thanks. John.
A bit of a shame to see those two pieces of gear out of action.
I doubt the capacitor change has done the damage to either of the devices. Low impedance capacitors like FMs and ZAs shouldn't be used everywhere, but using them in an inappropriate place might cause oscillation or poor performance, not cause the whole device to fail. It much more likely to be a workmanship issue.
Almost certainly not. The original designers would have specced an electrolytic capacitor with tolerances just as loose, and hence designed it to allow for that possibility.
The ways you may have damaged them that spring to my mind are:
- Solder bridging, where a solder blob joins two pins that shouldn't be joined.
- Damage to the PCB. Both devices you mentioned use double sided through hole plated PCBs. In each hole there is a copper liner that joins the upper and lower copper layers. When you removed the old capacitors you may easily have torn out some of these liners. You may have also lifted some tracks or pads.
- Static discharge damage, did you observe anti-static precautions when you worked on the devices?
Maybe some photos of the work you've done might help. Could you also clarify what you mean by 'stopped working'. I'd break most failures into three groups; 1) you try to turn it on and it blows a fuse, 2) you turn it on but nothing happens, 3) you turn it on and it lights up, but no sound comes out. Which one is each device?
I doubt the capacitor change has done the damage to either of the devices. Low impedance capacitors like FMs and ZAs shouldn't be used everywhere, but using them in an inappropriate place might cause oscillation or poor performance, not cause the whole device to fail. It much more likely to be a workmanship issue.
Almost certainly not. The original designers would have specced an electrolytic capacitor with tolerances just as loose, and hence designed it to allow for that possibility.
The ways you may have damaged them that spring to my mind are:
- Solder bridging, where a solder blob joins two pins that shouldn't be joined.
- Damage to the PCB. Both devices you mentioned use double sided through hole plated PCBs. In each hole there is a copper liner that joins the upper and lower copper layers. When you removed the old capacitors you may easily have torn out some of these liners. You may have also lifted some tracks or pads.
- Static discharge damage, did you observe anti-static precautions when you worked on the devices?
Maybe some photos of the work you've done might help. Could you also clarify what you mean by 'stopped working'. I'd break most failures into three groups; 1) you try to turn it on and it blows a fuse, 2) you turn it on but nothing happens, 3) you turn it on and it lights up, but no sound comes out. Which one is each device?
Friend Needs Help.
Hi. Many thanks for the replies.
I'm afraid i didn't take before photos as i thought : I'm just replacing a few capacitors, what could possibly go wrong?
At the moment when i turn the dac on it gives off a burning smell from a LM1117T 5.0 regulator, apart from that the thing is totally dead, no lights or sounds.
What do i need to measure the values of the components on the board, i've tried a multimeter but the other components are interfering with the component i am tring to measure and i am getting a wrong reading from the resistor and capacitance values printed on the side of the component.
Many thanks in advance. John.
Hi. Many thanks for the replies.
I'm afraid i didn't take before photos as i thought : I'm just replacing a few capacitors, what could possibly go wrong?
At the moment when i turn the dac on it gives off a burning smell from a LM1117T 5.0 regulator, apart from that the thing is totally dead, no lights or sounds.
What do i need to measure the values of the components on the board, i've tried a multimeter but the other components are interfering with the component i am tring to measure and i am getting a wrong reading from the resistor and capacitance values printed on the side of the component.
Many thanks in advance. John.
Hi,
The spec sheet of LM1117 says: "The ESR of the output capacitor should range between 0.3Ω - 22Ω." Did you change it to something else by chance?
Good luck!
Satoru
The spec sheet of LM1117 says: "The ESR of the output capacitor should range between 0.3Ω - 22Ω." Did you change it to something else by chance?
Good luck!
Satoru
Were the leads of the old caps "clean" after you removed them? That is,they didn't have any 'lumps' or what looked like blobs of solder on them?
Some PCB's can be kind of tricky,and it's easy to pull the plated-through-holes right out along with your component leads. (Not that I've ever done this,of course. 🙂 )
Some PCB's can be kind of tricky,and it's easy to pull the plated-through-holes right out along with your component leads. (Not that I've ever done this,of course. 🙂 )
I actually meant photos of it as it is now, so I can see what the soldering you have done is like. Given that a regulator is burning, it seems likely you created a short somewhere. By the time a component has made smoke or odour it's usually pretty dead.
Often you can't measure components in place, as like you said, other components in parallel effect the measurement. The first thing I would measure is the resistance between the +5V regulated rail and ground (between pins 1 and 2 of the LM1117T-5.0), this will tell you whether the output of the overloaded regulator is shorted to ground.
Other than that test, take a few photos of the unit and post them here. Show both the parts you worked on and the rest of the unit.
Often you can't measure components in place, as like you said, other components in parallel effect the measurement. The first thing I would measure is the resistance between the +5V regulated rail and ground (between pins 1 and 2 of the LM1117T-5.0), this will tell you whether the output of the overloaded regulator is shorted to ground.
Other than that test, take a few photos of the unit and post them here. Show both the parts you worked on and the rest of the unit.
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