Some success I hope
OK, at last, something positive.
I disconnected the toroid (three solid core wires) and measured the three diodes that were left in the board (D202 - 4). Two were giving good readings (around 510) and the other wasn't (D203).
To be absolutely sure I removed it from the board and measured it again. Hey presto it has clearly failed and is acting as a short to the system. It basically gave the same reading as when I touch the terminals to one another, 000.
Just need to put her back together with new diodes and the new capacitors and see if all is back to working order.
So the only way to properly measure them is to disconnect the toroid from the motherboard or take them out and measure them out of circuit.
🙂
OK, at last, something positive.
I disconnected the toroid (three solid core wires) and measured the three diodes that were left in the board (D202 - 4). Two were giving good readings (around 510) and the other wasn't (D203).
To be absolutely sure I removed it from the board and measured it again. Hey presto it has clearly failed and is acting as a short to the system. It basically gave the same reading as when I touch the terminals to one another, 000.
Just need to put her back together with new diodes and the new capacitors and see if all is back to working order.
So the only way to properly measure them is to disconnect the toroid from the motherboard or take them out and measure them out of circuit.
🙂
Excellent.
One thing... make sure the FET's you replaced are mounted properly and are correctly isolated from the heatsink and also be prepared to have to reset the bias because the new parts will have different characteristics.
I would still advise the bulb tester for initial powering up.
One thing... make sure the FET's you replaced are mounted properly and are correctly isolated from the heatsink and also be prepared to have to reset the bias because the new parts will have different characteristics.
I would still advise the bulb tester for initial powering up.
Yes, thanks, i will use that pad again just in case, with a little paste to both sides. I will add that to my notes as unfortunately i am not going to be able to do much about reassembly for a few days. But i will update when i have done that.
Thanks again to the various contributors.🙂
Thanks again to the various contributors.🙂
You're welcome. It would probably be better to get hold of new thermal pads. They are supposed to be used without grease. When ever you do use grease, ie with mica, the idea is to use as little as possible, it is to make sure there are no air pockets that reduce thermal conductivity
Just to confirm, I'm refering to the silicon pads. If you use mica mounting washers you must use grease
Sigh... MY bought New D290 Started to blow it's Fuse.
Took it to the Arcam Repair depot.
They Fixed it. Claiming the Diodes were failing.
Still works (I assume) 5 years on.
That said.. shortly after it's repair I substitiuted a DIY Lm3886 amp into my main system.
Absolutely Gob smacked at the Audible differences.
Much more solid Bass, expansive crystal clear highs.
There was a Soundstage... a decently large one..
where the D290 never..ever..delivered a soundstage worth mentioning.
I knew from the moment I got the Arcams home (d290 + power amp) that they were ' dissapointing' But the Dealer (dohhh!) said 'S Good and Arcam implied similar..ie: P*** off mate.. we have your Money.
Arcams went on the shelf.. same day.. still there. Paid to much to take a Baseball bat to them (yet🙂 but that's what they deserve imo.
Last year built/diy a Pass F6. Hey It uses irfp 240s too. Same bits in a genuinely skilled design = a whole world of difference
Similar massive audible improvements /upgrade over and above the lm3886 gizmo.
Just a suggestion 😉 You will Not.. be dissapointed.
Took it to the Arcam Repair depot.
They Fixed it. Claiming the Diodes were failing.
Still works (I assume) 5 years on.
That said.. shortly after it's repair I substitiuted a DIY Lm3886 amp into my main system.
Absolutely Gob smacked at the Audible differences.
Much more solid Bass, expansive crystal clear highs.
There was a Soundstage... a decently large one..
where the D290 never..ever..delivered a soundstage worth mentioning.
I knew from the moment I got the Arcams home (d290 + power amp) that they were ' dissapointing' But the Dealer (dohhh!) said 'S Good and Arcam implied similar..ie: P*** off mate.. we have your Money.
Arcams went on the shelf.. same day.. still there. Paid to much to take a Baseball bat to them (yet🙂 but that's what they deserve imo.
Last year built/diy a Pass F6. Hey It uses irfp 240s too. Same bits in a genuinely skilled design = a whole world of difference
Similar massive audible improvements /upgrade over and above the lm3886 gizmo.
Just a suggestion 😉 You will Not.. be dissapointed.
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I have some upgrades proposed, but nothing drastic. New caps and new acrylic casing. Amps are doing a pretty good job running biamped off Cyrus 8 qx dac into b&w cdm 9nt's.
Vertical FETs really dont do class AB well, IMO. Not without a huge (100+mA) amount of bias. Class A is another matter.
Well I thought all was going to be well, but now the amp sounds distorted, right worse than left, and channels cut out, light goes orange and then resets and then only one channel comes back on, which then cuts out again when volume turned up.
I wonder if the capacitors I upgraded maybe don't suit. They are DNM designed slit foil guided current capacitors (10000uF/80v). I will put back the old Rubycon ones (10000uF/50v) and see how it goes. But not tonight.
At least the fuse is not blowing now. 😕
I wonder if the capacitors I upgraded maybe don't suit. They are DNM designed slit foil guided current capacitors (10000uF/80v). I will put back the old Rubycon ones (10000uF/50v) and see how it goes. But not tonight.
At least the fuse is not blowing now. 😕
Was it ok before you changed the capacitors? Are they 4 terminal caps? Just found this wiring diagram, did you connect them as shown with the 0V link shown in red? http://www.dnm.co.uk/acatalog/4TTN_TransformerDualandSingleRailmed.jpg
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They are just the two terminal variety.
I made the mistake of adding in the upgraded capacitors before checking all was working fine. Just assumed green light meant it would be good. I guess just to save time opening it all up again. Oh well.
I have run with headphones and one channel sounds ok, the other very distorted.
I made the mistake of adding in the upgraded capacitors before checking all was working fine. Just assumed green light meant it would be good. I guess just to save time opening it all up again. Oh well.
I have run with headphones and one channel sounds ok, the other very distorted.
Sounds like loudspeaker protection is tripping probably due to a dc offset. You should be able to measure for any offset at the headphone socket
Oh right, this ones actually an Alpha 9. Auto bias. Ugh.
You've probably got damage which occurred either as a result of the original power supply problem, or from when you ran the amp with no insulating washers on the MOSFETs.
You've probably got damage which occurred either as a result of the original power supply problem, or from when you ran the amp with no insulating washers on the MOSFETs.
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