HI All
Little problem with a Musical Fidelity F16 power amp.Keeps coming through distorted on one side and occasionally completely cuts out.Takes a while to happen suggesting temp related but if you raise the input level it cures it possibly suggesting a dodgy capacitor somewhere.Have checked for dry joints.Also does anyone have a schematic for the above.Musical Fidelity will not sell me one.Thanks for any help.Smiffy
Little problem with a Musical Fidelity F16 power amp.Keeps coming through distorted on one side and occasionally completely cuts out.Takes a while to happen suggesting temp related but if you raise the input level it cures it possibly suggesting a dodgy capacitor somewhere.Have checked for dry joints.Also does anyone have a schematic for the above.Musical Fidelity will not sell me one.Thanks for any help.Smiffy
Thanks for the advice Hugo
Still hoping for a schematic but it shouldn't be to hard to work out signal/power caps.There are only about 7 caps on the power amp boards.May replace them with Black gates at the same time really.There is a 220uf non polarised right on the input.Shame MF are so tight with their circuit diagrams.\Lovely amp though.
Smiffy
Still hoping for a schematic but it shouldn't be to hard to work out signal/power caps.There are only about 7 caps on the power amp boards.May replace them with Black gates at the same time really.There is a 220uf non polarised right on the input.Shame MF are so tight with their circuit diagrams.\Lovely amp though.
Smiffy
I hope this helps...
Hi Smiffy,
The F16/F19 circuit is apparently a tidied up version of the MF P270/A370 circuit.
The original amps ran VERY hot and were unreliable (I can attest to that! There is nothing quite like the smell of smoke coming from your amplifier to convince you that things might not be quite right!).
The Mk II versions cured the overheating (and some of the reliabilty) problems, while the F16/F19 were the best implementation of the circuit MF could possibly achieve, finally taking advantage of the oppotunity to incorporate acres of heatsinking and space for a huge supply. (400w AB/50w A in an elegant, good-looking chassis is no mean feat! Its also one of the few commercial amps I would buy in a flash).
I've a copy of the A370 circuit (the P270 is the same, with just 3, rather than 5 pairs of output devices).
I'll dig it out and post it here.
Hi Smiffy,
The F16/F19 circuit is apparently a tidied up version of the MF P270/A370 circuit.
The original amps ran VERY hot and were unreliable (I can attest to that! There is nothing quite like the smell of smoke coming from your amplifier to convince you that things might not be quite right!).
The Mk II versions cured the overheating (and some of the reliabilty) problems, while the F16/F19 were the best implementation of the circuit MF could possibly achieve, finally taking advantage of the oppotunity to incorporate acres of heatsinking and space for a huge supply. (400w AB/50w A in an elegant, good-looking chassis is no mean feat! Its also one of the few commercial amps I would buy in a flash).
I've a copy of the A370 circuit (the P270 is the same, with just 3, rather than 5 pairs of output devices).
I'll dig it out and post it here.
Good afternoon!
Is there somebody who has a service manual or even schematic diagram of NAD 314 Integrated Amp?
I have scratching sound coming out of either the left or right speaker about 2 years ago. Later, it worsened with distorted sound from either left or right channel when music passages are low yet when the volume control was cranked up the music would be normal.
I suppose I have same symptom similar to Smiffy (Musical Fidelity F16 problem/Schematic ).
I started replacing capacitors when the bass sounded thin. The sound improved for a few days before the bass sounded anemic again.
thanks for any helping hand you can extend.
Is there somebody who has a service manual or even schematic diagram of NAD 314 Integrated Amp?
I have scratching sound coming out of either the left or right speaker about 2 years ago. Later, it worsened with distorted sound from either left or right channel when music passages are low yet when the volume control was cranked up the music would be normal.
I suppose I have same symptom similar to Smiffy (Musical Fidelity F16 problem/Schematic ).
I started replacing capacitors when the bass sounded thin. The sound improved for a few days before the bass sounded anemic again.
thanks for any helping hand you can extend.
MF schematic - better late than never...
Here you go...
http://www.audiodesignguide.com/doc/ampl/musical_fidelity_a370.jpg
Here you go...
http://www.audiodesignguide.com/doc/ampl/musical_fidelity_a370.jpg
Hi Smiffy,
after a decade I have the same problem with my F16!!! Did you manage to solve your problem and how have you done it. I am really thankful for any help or advice.
Predrag
Hi
Not yet
However it seems to be worse now with lots of hum from the left channel as well.I have taken it apart and am going to compare readings from right channel which is fine to left channel.
Smiffy
Would hate to dump it and guess Musical Fidelity will want an arm and a leg to fix it plus cost of courier or journey to Wembley will be expensive.
I can personally recommend John Sampson of JS Audio.
The former service manager at MF, John is also the UK service agent for too many high-end US brands to mention.
The man is incredibly knowledgeable, personable and honest - a true gent - who actually spent days convincing me to spend LESS (yes, that's right) than I was panning to on an upgrade. What he has done to my amplifiers is nothing short of miraculous.
Contact him for a chat - you wont regret it.
The former service manager at MF, John is also the UK service agent for too many high-end US brands to mention.
The man is incredibly knowledgeable, personable and honest - a true gent - who actually spent days convincing me to spend LESS (yes, that's right) than I was panning to on an upgrade. What he has done to my amplifiers is nothing short of miraculous.
Contact him for a chat - you wont regret it.
Blimey.
At long last I found the fault.A very weird one.It actually in the end turned out to be the speaker output wire connected to the output relay.
I swapped the power amps over from one side to the other but the fault stayed on the left.
So I poked around the input wiring from the input board to the power amp..It then started cutting out on the left.
However as I had not put back the supply voltage and speaker wires in their right place I noticed that the speaker wire was resting on the cable from the input board to the power amp.
So I then started moving this wire.Result!
It turns out the speaker wire to the relay and from the relay to the outputs has crimp connectors on which had been insufficiently crimped.
Removed both sides,crimped them up.put them back on.All cut out problems now gone and been running with no faults for 6 weeks now
Smiffy
At long last I found the fault.A very weird one.It actually in the end turned out to be the speaker output wire connected to the output relay.
I swapped the power amps over from one side to the other but the fault stayed on the left.
So I poked around the input wiring from the input board to the power amp..It then started cutting out on the left.
However as I had not put back the supply voltage and speaker wires in their right place I noticed that the speaker wire was resting on the cable from the input board to the power amp.
So I then started moving this wire.Result!
It turns out the speaker wire to the relay and from the relay to the outputs has crimp connectors on which had been insufficiently crimped.
Removed both sides,crimped them up.put them back on.All cut out problems now gone and been running with no faults for 6 weeks now
Smiffy
I had once one of those... gave me everlasting headache, kept blowing up every week or so (mostly due to HF oscillation)... Extremely unstable design, stay away from anything using LM318 opamps! Finally I replaced them with LM 6171-s, was working OK with those, and sold it before blew up again...
Yes, another of MF's long line of variations on a simple design from the 80's with skimped component ratings and disfunctional quality control. I haven't seen a professional terminal crimp done that badly in an amplifier, though.
Still, it's consistent with their most reliable quality, which is their unreliability
Still, it's consistent with their most reliable quality, which is their unreliability
Yep
Wouldn't try changing the LM318s as most Muical Fidelity PCBs seem to evaporate at the mere sight of a soldering iron.
And it had to go back(like 3 others I know of)to Musical Fidelity in its first 6 months because of leaking electrolytic from
the main power supply caps.The highly professional cure was to glue felt pads over the cap vent to soak up the electrolytic fluid.Really!
Smiffy
Wouldn't try changing the LM318s as most Muical Fidelity PCBs seem to evaporate at the mere sight of a soldering iron.
And it had to go back(like 3 others I know of)to Musical Fidelity in its first 6 months because of leaking electrolytic from
the main power supply caps.The highly professional cure was to glue felt pads over the cap vent to soak up the electrolytic fluid.Really!
Smiffy
Well after many years I found the problem
After poking around and touching bits I never discovered it till I accidently touched the output wire.
I followed it and it goes to the black relay on the control board.
Presumably there to settle the amp and not let a dc turn on thump go to the speaker
The same problem before that started on the right channel as well
So every time it cut out a small tap on the relays cured it
I cleaned the wires and crimped the connector tighter but still happened.Then started moving the relay.It felt loose on the pcb.So after 5 years I have now taken the control board off(pITA job)and resoldered the relay connections
Perfect.Cured the problem
At last.Only taken 15 years to sort this.Ha ha
Smiffy
Same issue. Just to re-liven this thread after another 4 years...
I have an F16 - love it - not suffered any of the issues until recently. RIght channel crackles into silence, can be quieter, sometimes no sound at all.
Will open it up to check the issues described above with the hope of an easy fix.
The power caps are not marked on value. As 30 yr old electrolytics measuring them is pointless. Any one know the value to replace?
I have an F16 - love it - not suffered any of the issues until recently. RIght channel crackles into silence, can be quieter, sometimes no sound at all.
Will open it up to check the issues described above with the hope of an easy fix.
The power caps are not marked on value. As 30 yr old electrolytics measuring them is pointless. Any one know the value to replace?