Another dead Arcam delta 290
Hi DIY'fellows
I have a dead ARCAM delta 290, one channel has two bad SM042A.. I have read thet they might be substituded for IRFP240, but some mods have to be done.
I haven't been able to get the SM, I have been googling around, and there are some offering here at the DIY forum, but I don't have the permissions yet to post a PM.
any help will be deeply appreciated
regards
Alexander Rubli
Hi DIY'fellows
I have a dead ARCAM delta 290, one channel has two bad SM042A.. I have read thet they might be substituded for IRFP240, but some mods have to be done.
I haven't been able to get the SM, I have been googling around, and there are some offering here at the DIY forum, but I don't have the permissions yet to post a PM.
any help will be deeply appreciated
regards
Alexander Rubli
Hi
Well my Delta 290 went back to Arcam and after a long wait it came back with a new selector switch and some new phono input sockets in the back. Sadly, a few weeks in, the same problem came back. It's intermittent, mostly noticeable at low volumes, and when it happens is during the quiet bits of songs.
It's almost the opposite of clipping, where the loud bits of the music come through, but the rest is chopped out. The result is a cutting in and out of your music on the left channel.
Arcam have very kindly said they'll take it back at no cost to resolve the issue. I'll let you know what they come back with.
Best regards,
Phil
Well my Delta 290 went back to Arcam and after a long wait it came back with a new selector switch and some new phono input sockets in the back. Sadly, a few weeks in, the same problem came back. It's intermittent, mostly noticeable at low volumes, and when it happens is during the quiet bits of songs.
It's almost the opposite of clipping, where the loud bits of the music come through, but the rest is chopped out. The result is a cutting in and out of your music on the left channel.
Arcam have very kindly said they'll take it back at no cost to resolve the issue. I'll let you know what they come back with.
Best regards,
Phil
Hi Phil,
What a pain with the switch - but good news that Arcam are going to sort it for you. I've found their after-sales service to be very good - I've had a few service manuals from them, sent gladly.
Did Arcam replace the phono sockets because the metal comes adrift (does on a couple of my amps, unless you twist the interconnect off)?
I've just recapped one of my D290Ps, with promising results. Still burning in at the moment......
Cheers
Jon
What a pain with the switch - but good news that Arcam are going to sort it for you. I've found their after-sales service to be very good - I've had a few service manuals from them, sent gladly.
Did Arcam replace the phono sockets because the metal comes adrift (does on a couple of my amps, unless you twist the interconnect off)?
I've just recapped one of my D290Ps, with promising results. Still burning in at the moment......
Cheers
Jon
Almost 2 years later.. How did the Recap work out?
I've found (a few years back now) that the Pre section of my D290 is ..the.. weak link.
Using a DIY tube pre (doesn't actually need it as the Delta is a High gain amp with tone circuit stuff inserted).. it's more of a buffer stage, the sound is wayyy beyond it's previous quality.
Switching the wee internal switch back to inboard 'preamp', honestly makes it sound like there are towels inserted in the speakers.
D290 is by my observation a very good amp with a truly crappy pre /tone section.
Hope that helps someone.
I've found (a few years back now) that the Pre section of my D290 is ..the.. weak link.
Using a DIY tube pre (doesn't actually need it as the Delta is a High gain amp with tone circuit stuff inserted).. it's more of a buffer stage, the sound is wayyy beyond it's previous quality.
Switching the wee internal switch back to inboard 'preamp', honestly makes it sound like there are towels inserted in the speakers.
D290 is by my observation a very good amp with a truly crappy pre /tone section.
Hope that helps someone.
Hi,
The recap on both of my 290P amps went very well. The amps retained their overall character (soft-ish and typically Arcam), but certainly felt the benefit of new the caps. I used a mix of low ESR FM and FC caps generally, with Philips caps after the 3-pin regulators. Well worth doing, especailly as these amps are around 15 years old or more.
Happy New Year!!
Jon
The recap on both of my 290P amps went very well. The amps retained their overall character (soft-ish and typically Arcam), but certainly felt the benefit of new the caps. I used a mix of low ESR FM and FC caps generally, with Philips caps after the 3-pin regulators. Well worth doing, especailly as these amps are around 15 years old or more.
Happy New Year!!
Jon
The arcam delta 290 got problem with the clamp (broken).
Could anyone help to tell what type of transistor/mosfet can be used in place of these output clamps?
pls see pic.
Could anyone help to tell what type of transistor/mosfet can be used in place of these output clamps?
pls see pic.
An externally hosted image should be here but it was not working when we last tested it.
That looks like some kind of liquid was spilled into the unit at some point....
The service manual has a process for replacing the output mosfets with IRFP240 devices - these are a different package, so some rework is required, also some other parts must be changed to suit. Arcam should be happy to e-mail you a copy of the service manual.
The service manual has a process for replacing the output mosfets with IRFP240 devices - these are a different package, so some rework is required, also some other parts must be changed to suit. Arcam should be happy to e-mail you a copy of the service manual.
Service Manual of Arcam Delta 290 Amplifier can be downloaded from here:
ARCAM Delta 290 Service Manual free download
Photo of this amplifier with alternative mosfet output devices mounted can be found here:
http://www.dcaudio.pl/delta.htm
ARCAM Delta 290 Service Manual free download
Photo of this amplifier with alternative mosfet output devices mounted can be found here:
http://www.dcaudio.pl/delta.htm
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Yes, page 2 of the service manual - The notes specify the switch as SW205. It's shown in sheet 3 of the schematics, all in the same download.
Arcam Delta 290 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
Arcam Delta 290 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
Basically, one amplifier is driven with the inverse phase signal of the other so that the output voltages add when the speaker is connected between the positive output terminals of either amplifier. The negative terminals are ignored.
To do this properly, you need to build a simple, unity gain inverter using an op-amp at the input to one of the amplifiers. The power can come from the amplifier's own op-amp power supply and this whole simple circuit built on a tiny scrap of stripboard for little cost. You can simplify it further by omitting the switch which allows a choice of bridged or not.
This ESP article may have been suggested earlier.
To do this properly, you need to build a simple, unity gain inverter using an op-amp at the input to one of the amplifiers. The power can come from the amplifier's own op-amp power supply and this whole simple circuit built on a tiny scrap of stripboard for little cost. You can simplify it further by omitting the switch which allows a choice of bridged or not.
This ESP article may have been suggested earlier.
I don't think you can actually bridge the D290P. You can use the shorting link and run them in mono, but this does not increase the power.
This link to the manual refers - page 8, para 3.
HTH
Jon
This link to the manual refers - page 8, para 3.
HTH
Jon
As above: remove case cover .. there is a clearly identified slider switch.
Did that years ago, it turns off the Pre section, including Phono Card and ALL the front panel controls ... except for power switch and Speaker on/off pushbuttons
I fitted a bespoke Triode type Pre amp, for basically zero gain so I guess it's working as a buffer ? Doesn't matter why to me at this point, as it works Exceptionally pleasingly.
Result was/is a night and day sound improvement
Much as I still miss the Phono card function, switching the Arcam's Pre section back on is simply unpleasant (I succumb and try every year or so.. Briefly.
A shame it needs defeating though.
But for me, turning it off really makes owning the Amp.. worthwhile.
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You certainly can't bridge amplifiers without a bridging adaptor that inverts signal phase to the second amplifier. Domestic hi-fi amplifiers seldom include this, so it must be added here or (not recommended) the input could be fed direct to one amplifier's inverting input. These are circuit-level changes, not covered by the user manual or warranties.
However, any stereo amplifier or 2 similar ones can be bridged, provided their current rating is high enough for the increased output demand.
ordered mundorf 10000uf 63v caps to replace stock psu caps , one last boring question , anyone replaced opamps in the delta 290 ?
