Thanks, I took a look through. Think you can share this directly on mouser to make it easier.
For the Kemet bypass capacitors, EPCOS B32521E6104J 0.1uF 200V 13x5 10mm lead spacing (fit to underside of board).
The same as you've listed to replace all the 10 Metallized Polypropylene Film Capacitors that MF use as rectifier snubbers.
C20, C23 C120, C123, etc.
Also check C133 value (if you haven't already). C133 & R156 for left channel form ground loop breakers, can't see the values in the images. Can you tell me what value R156 is please?
C31 is likely a smoothing cap prior to voltage regulator, so low ESR and leakage, high ripple rejection Panasonic FC 667-EEU-FC1E222S will work nicely. No need for the more expensive audio grade Nichicon here.
Panasonic SU bi-polar 667-ECE-A1HN100UB - I'd look to see if you can get WIMA MKPs (as @NickKUK recommended) that physically fit as they couple the output stages, metal film caps will be a significant upgrade in terms of clarity.
If not, the Nichicon Muse UES 647-UES1H100MPM audio grade non-polars will almost certainly be a better choice, ideally bypased with TDK EPCOS B32529D6104J 0.1uF 200V (fit to underside of board).
C9 and C109 Jamicon SK 1uF 63V - these are important in the VAS balancing. I used Panasonic NHG 667-ECA-2CHG010 1uF 160V. The Wurth Elektronik will probably be good, just no experience with them.
C13 Jamicon SK 100uF 100V - I used Nichicon Muse KZ 100uF 100V 16 (10-14) UKZ2A101MHM
C113 as above. The Nichicon Muse KZ are Premium Grade Type for audio but twice the diameter, check if you can squeeze them in. The UFW 647-UFW2A101MPD it looks like you've selected will be good if there's insufficient space.
Nichicon 647-UES1C101MPM 100uF 16v, which caps are these replacing?
The rest looks good.
For the Belden 19364 – 83803 cable, it would be remiss if I didn't mention that it is difficult to work with!
Awkward for tight radius bends if needed and needs a lot of heat to solder quickly.
With regard to desoldering, did the MF X10v3 also have plated through holes and such a high quality double sided PCB? These boards are flow soldered so pads both sides and also component legs through the holes are soldered. Insertion machine bends the legs when stuffing the board too, so will make for some fun. If it's what you've dealt with before then all good, if not then maybe have a think about a low cost desoldering station.
Mine is just a modestly priced KATSU Desoldering Rework Station, but makes your life so much easier.
Deoxit is great for Hi-Fi use, contact cleaning, connectors, mains plugs, etc. If you already have the grease then should be good to go.
For the Kemet bypass capacitors, EPCOS B32521E6104J 0.1uF 200V 13x5 10mm lead spacing (fit to underside of board).
The same as you've listed to replace all the 10 Metallized Polypropylene Film Capacitors that MF use as rectifier snubbers.
C20, C23 C120, C123, etc.
Also check C133 value (if you haven't already). C133 & R156 for left channel form ground loop breakers, can't see the values in the images. Can you tell me what value R156 is please?
C31 is likely a smoothing cap prior to voltage regulator, so low ESR and leakage, high ripple rejection Panasonic FC 667-EEU-FC1E222S will work nicely. No need for the more expensive audio grade Nichicon here.
Panasonic SU bi-polar 667-ECE-A1HN100UB - I'd look to see if you can get WIMA MKPs (as @NickKUK recommended) that physically fit as they couple the output stages, metal film caps will be a significant upgrade in terms of clarity.
If not, the Nichicon Muse UES 647-UES1H100MPM audio grade non-polars will almost certainly be a better choice, ideally bypased with TDK EPCOS B32529D6104J 0.1uF 200V (fit to underside of board).
C9 and C109 Jamicon SK 1uF 63V - these are important in the VAS balancing. I used Panasonic NHG 667-ECA-2CHG010 1uF 160V. The Wurth Elektronik will probably be good, just no experience with them.
C13 Jamicon SK 100uF 100V - I used Nichicon Muse KZ 100uF 100V 16 (10-14) UKZ2A101MHM
C113 as above. The Nichicon Muse KZ are Premium Grade Type for audio but twice the diameter, check if you can squeeze them in. The UFW 647-UFW2A101MPD it looks like you've selected will be good if there's insufficient space.
Nichicon 647-UES1C101MPM 100uF 16v, which caps are these replacing?
The rest looks good.
For the Belden 19364 – 83803 cable, it would be remiss if I didn't mention that it is difficult to work with!
Awkward for tight radius bends if needed and needs a lot of heat to solder quickly.With regard to desoldering, did the MF X10v3 also have plated through holes and such a high quality double sided PCB? These boards are flow soldered so pads both sides and also component legs through the holes are soldered. Insertion machine bends the legs when stuffing the board too, so will make for some fun.
If it's what you've dealt with before then all good, if not then maybe have a think about a low cost desoldering station.Mine is just a modestly priced KATSU Desoldering Rework Station, but makes your life so much easier.
Deoxit is great for Hi-Fi use, contact cleaning, connectors, mains plugs, etc. If you already have the grease then should be good to go.
It you’re taking the output transistors off the heatsink then you will want to use new thermal pads. I don’t know the pad sizes but only handle them when you’re ready to fit (after cleaning the heatsink and transistor). The last thing you want with obsolete matched output transistors isto have dirty or the burr from the screw hole lift the transistor away from the HS leading to early failure.
I have one wurth cap (same red) and that is in the mute delay circuit so not on the signal path/power. There are better caps out there but wurth are relatively cheap (I assume they are rebranded).
WIMA MKP4 are good and wima recommend these for audio, I didn’t like the sound of MKP10. The key is checking the lead spacing to fit or you will have wires and those can act like antenna in certain situations.
I have one wurth cap (same red) and that is in the mute delay circuit so not on the signal path/power. There are better caps out there but wurth are relatively cheap (I assume they are rebranded).
WIMA MKP4 are good and wima recommend these for audio, I didn’t like the sound of MKP10. The key is checking the lead spacing to fit or you will have wires and those can act like antenna in certain situations.
Just for clarification, the EPCOS B32521E6104J is listed as a 400VDC cap at 0.1uf Capacitance 13x5 10mm lead spacing, and not 200VDC. Is this incorrect? The entire bottom half of the amp has the (15) 104J 250v being replaced with EPCOS B32521E6104J and the 224J film caps on either side towards the middle of the amp are being replaced with (2) WIMA MKS4-.22/400/10P10 caps
I have attached a picture that I took earlier where C133 and R156 just happen to be (otherwise I have to open her up again for a better view)
A lot of the caps chosen were either not available locally or on back order, so I went with what I thought would be the next runner up based solely on specifications.
How does the WIMA MKS2B051001N00JO00 (10uf, 50 volts, 5% tolerance) look for replacing the Panasonic bi-polars?
As per your suggestion, I will change to the Panasonic NHG 667-ECA-2CHG010. There were no other options for a 63v 1uF and I forgot a good way out of that situation is to just up the voltage rating slaps head
For the 100uF 100V caps, they are indeed right next to each other, so if they are twice the diameter, it won’t work unfortunately.
Finally, the two Nichicon 647-UES1C101MPM 100uF 16v caps are hidden in the middle/rear of the amp where the input board is located. I figure I may as well go to the trouble of doing those, especially if what seems to be the signal path.
Thanks again to you both – you’re heroes!!
I have attached a picture that I took earlier where C133 and R156 just happen to be (otherwise I have to open her up again for a better view)
A lot of the caps chosen were either not available locally or on back order, so I went with what I thought would be the next runner up based solely on specifications.
How does the WIMA MKS2B051001N00JO00 (10uf, 50 volts, 5% tolerance) look for replacing the Panasonic bi-polars?
As per your suggestion, I will change to the Panasonic NHG 667-ECA-2CHG010. There were no other options for a 63v 1uF and I forgot a good way out of that situation is to just up the voltage rating slaps head
For the 100uF 100V caps, they are indeed right next to each other, so if they are twice the diameter, it won’t work unfortunately.
Finally, the two Nichicon 647-UES1C101MPM 100uF 16v caps are hidden in the middle/rear of the amp where the input board is located. I figure I may as well go to the trouble of doing those, especially if what seems to be the signal path.
Thanks again to you both – you’re heroes!!
The problem is that I cannot find any MKP4's that are 10mm lead spacing with 10uF capacitance. I can however source a few MKP4's in 37.5mm lead spacing... Any solution to this?
Correct, that was my bad. I'd copied it from my BoM spreadsheet and had the AC ratings listed.
The photo is not quite in focus so I couldn't make it out, but no worries. If you can maybe get the values next time you're in there that would be great.
I'm curious to see what MF implemented for ground loop prevention.
Yep, I'd try those. Polyesters get good reports. You could get some Nichicon UEP 647-UEP1J100MED as an alternative in case you don't like the sound.
They look like a good solution.
Rather than the Nichicon UFW2A101MPD 100uF 100V, I'd recommend the UKW2A101MPD, characterised for audio, same dimensions and not much greater cost.
Attached is a Bill of Materials in excel that I slapped together. It's in 7zip format as that's what the forum accepts.
Will make it easier to keep track of what/where everything goes. Have a look it should be useful.
Caveats: I could only pick out limited component numbering from the photo's and be aware information for purpose is interpreted from the work
I've completed on the A308 int. It is probably accurate, just bear it in mind if something doesn't look right.
Also, it isn't verbatim to the .pdf, I left some of the component alternatives listed in there for information under the right hand channel listings, plus additional decoupling cap spec's.
Keep us up to date on progress, looking forward to hearing about your experience!
There's also a good reference by Carlson's lab on his YouTube channel. The general rule for audio seems to be the largest voltage rating (and depending where/purpose increase capacitance) results in the lowest distortion for couple etc.
There's ESR and ESL etc but there's also linearity, temperature stability of capacitance and phase shift of the AC signal going through it to the other side. Then there's also other effects such as piezo electric acoustical noise, sensitivity to over voltage or reverse voltage etc.
My general rule are:
What I have found is that the caps stake a little time on the first use to sort out any self healing (any pin holes burn out to prevent shorts) etc. I found putting some power across them for an hour and then discharging before using helps reduce the time. Most modern caps don't need attention and can be used immediately but may sound a little off from their normal sound which should appear after a few hours (also temperature of the system, scubas the A220, needs to be right before you make a comparison).
There's ESR and ESL etc but there's also linearity, temperature stability of capacitance and phase shift of the AC signal going through it to the other side. Then there's also other effects such as piezo electric acoustical noise, sensitivity to over voltage or reverse voltage etc.
My general rule are:
- no electrolytic on the signal path (MUSE ES is perhaps an exception for large capacitances)
- Foil film caps where possible, MKP4 seem to be decent if size becomes an issue (now MKS I've not got experience of)
- Low ESR for power supplies (consider inrush and startup stability)
What I have found is that the caps stake a little time on the first use to sort out any self healing (any pin holes burn out to prevent shorts) etc. I found putting some power across them for an hour and then discharging before using helps reduce the time. Most modern caps don't need attention and can be used immediately but may sound a little off from their normal sound which should appear after a few hours (also temperature of the system, scubas the A220, needs to be right before you make a comparison).
There are some good tips in here! I have modified some of the caps on my list which would allow for higher voltages (but same capacitance) and although they are physically larger, I've made sure they will fit. In the meantime while I wait for parts to come in and psych myself up for the job, I have a small gift for you Musical Fidelity owners, specifically a308 Integrated owners - I've managed to get the schematics! Not sure if it will make much a difference at this point, but it's nice having this for the record
There are differences between PSU and signal requirements for caps. I should have been clearer that the golden rule is for the audio path, although a good bump often helps PSU.
If they are power caps you can trade the increase in voltage for extra capacitance/extra temperature tolerance/hour life/esr etc.
In a power supply the caps capacitance will act as a low pass filter (reduces noise) but also provides a energy reserve for fast current delivery.
MF had a reputation for using parts very close to their limits. The A220 uses 50V 85degC 10mF (10,000uF) main PSU caps but the A220 gets scorching hot and uses voltages near the upper voltage.
So for my A220 I would look at the caps that provide low esr, support the required current draw, will be happy with 50hz ripple (not all caps are designed for rectification and it shortens life), boosts 85degC to 105degC temp tolerance and boosts capacitance (10mF to 15mF) voltage rating (63V). Then finally decent life (3000+ hours depending on what will fit and expected use).
If they are power caps you can trade the increase in voltage for extra capacitance/extra temperature tolerance/hour life/esr etc.
In a power supply the caps capacitance will act as a low pass filter (reduces noise) but also provides a energy reserve for fast current delivery.
MF had a reputation for using parts very close to their limits. The A220 uses 50V 85degC 10mF (10,000uF) main PSU caps but the A220 gets scorching hot and uses voltages near the upper voltage.
So for my A220 I would look at the caps that provide low esr, support the required current draw, will be happy with 50hz ripple (not all caps are designed for rectification and it shortens life), boosts 85degC to 105degC temp tolerance and boosts capacitance (10mF to 15mF) voltage rating (63V). Then finally decent life (3000+ hours depending on what will fit and expected use).
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Does anyone know how to get rid of this glue? The large caps are glued on to what seems to be a very hard resin type substance - not your standard, silicone/rubber type. It is quite hard with very little give and the only way I've managed to get the other caps was with basically brute force via wiggling the caps slightly over time until they 'crack' off (which is terrifying). The last cap shown is a real bugger and Musical Fidelity, in all of the genius, decided really go all out so that these boards cannot be serviced easily.
I have tried to so far cut away as much as I can with an xacto knife to not much benefit as the caps are really close to the board. I have tried a small amount of heat with a hot air gun, with little benefit. I have also made sure that all of the solder has been removed from the pins as best I can for removal. If there's any way to dissolve this plastic-like hard substance, please let me know
I have tried to so far cut away as much as I can with an xacto knife to not much benefit as the caps are really close to the board. I have tried a small amount of heat with a hot air gun, with little benefit. I have also made sure that all of the solder has been removed from the pins as best I can for removal. If there's any way to dissolve this plastic-like hard substance, please let me know
Edit: I just tried some acetone and I'm still having issues. I tried using a Q-Tip doused in acetone and running around the capacitor to no avail. I have also tested some acetone on top of the portion of material that was left from the removed cap to see what it would do... very little happened. What in the hell is this stuff?
Am I applying it incorrectly?
Am I applying it incorrectly?
So unfortunately, this build has been kicking my butt and I very much jinxed myself by "fixing something that wasn't broken". I have completed the full recap and the amp does start up and play music, but has developed a nasty buzzing sound. It does not change at all when adjusting the volume. When playing music but at "0" level, it will cleary demonstrate I have a cracking/screeching sound and so I have posted a video as a sample of the issue:
At first I thought it was (and could still be) a ground loop issue, so I made sure the AC cable was routed properly and copied exactly how it was before to no change. I made sure the ground wire was hooked up correctly to the chassis and I must have checked all connections, capacitors, and wiring at least 10 times.
I then found out that the humming significantly reduces when I switch the Input selector from 'A' to 'B'. I tried again with 'A' selected but removed the RCA cables with the same effect. So it seems it some sort of grounding issue and/or interreference problem with the board listed in this picture:
I did change the two small bipolar capacitors with an equivalent rating Nichicon caps and changed the 'birds nest' wiring exactly how it was but with slighter thicker copper signal cables. Needless to say, this was not easy to change out and solder in. I am confident my preamp is not the issue or my cables as they were working just fine prior to starting this project. Any input on what to check or change is highly appreciated - please help!
At first I thought it was (and could still be) a ground loop issue, so I made sure the AC cable was routed properly and copied exactly how it was before to no change. I made sure the ground wire was hooked up correctly to the chassis and I must have checked all connections, capacitors, and wiring at least 10 times.
I then found out that the humming significantly reduces when I switch the Input selector from 'A' to 'B'. I tried again with 'A' selected but removed the RCA cables with the same effect. So it seems it some sort of grounding issue and/or interreference problem with the board listed in this picture:
I did change the two small bipolar capacitors with an equivalent rating Nichicon caps and changed the 'birds nest' wiring exactly how it was but with slighter thicker copper signal cables. Needless to say, this was not easy to change out and solder in. I am confident my preamp is not the issue or my cables as they were working just fine prior to starting this project. Any input on what to check or change is highly appreciated - please help!
You could never test on speakers immediately - a pair of omite 8R 100W planar resistors. Then a small cheapie 8R speaker drivers (ie £5-10) and only then go for the expensive speakers.
Hum usually means a cap problem (perhaps a cap is backward), lack of shielding or grounding loop.
Did you clean the board (solder balls) and checked the solder joints?
I see you have added heatsinks to the transistors on the board. Are they shorting?
Hum usually means a cap problem (perhaps a cap is backward), lack of shielding or grounding loop.
Did you clean the board (solder balls) and checked the solder joints?
I see you have added heatsinks to the transistors on the board. Are they shorting?
The hum and crackle is made to be much worse than it seems in the video, but nonetheless, it shows an issue that wasn't there before. I have noticed however there is very little crackle when no music is being played, if that should matter at all. It should also be noted that the issue is in both left and right channels.
The heatsinks are not touching anything else but the transistors themselves as far as I can see.
Again, I'm leaning towards that input board somehow being the problem given that there is very little audible noise when the cables are removed and it seems there is audible pickup from nearby devices (ground loop). For example, when starting music from my streamer and the device is buffering, you can audibly hearing clicking and pulsing noises just before it begins to play. If you press pause it stops. If you load the next song, it has a similar procedure.
The only other point of interest would be the transformer soldering onto the posts near the bottom of the board. It was very difficult getting a clear path to solder in that area and it's possible that I may have a poor connection there.... but before I spend the agonizing task of redoing that bit out of precaution, I am curious if there are other area's that could be the issue.
The heatsinks are not touching anything else but the transistors themselves as far as I can see.
Again, I'm leaning towards that input board somehow being the problem given that there is very little audible noise when the cables are removed and it seems there is audible pickup from nearby devices (ground loop). For example, when starting music from my streamer and the device is buffering, you can audibly hearing clicking and pulsing noises just before it begins to play. If you press pause it stops. If you load the next song, it has a similar procedure.
The only other point of interest would be the transformer soldering onto the posts near the bottom of the board. It was very difficult getting a clear path to solder in that area and it's possible that I may have a poor connection there.... but before I spend the agonizing task of redoing that bit out of precaution, I am curious if there are other area's that could be the issue.
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