How is this build thread different from any other build thread? Bill isn't trying to sell anything. He bought some boards and wants to share his experience of putting together an amp based on those boards. Jeez...
~Tom
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At least one thread was moved to the vendors section when the designer requested a schematic to be removed. It seems to be a grey area where these threads should go. Personally I dislike having to look in all the different places. I will shut up now or the thread might get moved to the LOUNGE.
Dear all,
The project is progressing, but I failed the first testing as I blow-up the fuse when I start... This seems to be in relation with the way the tranformer is wired. It is an Hammond. I have followed the instruction in accordance with the color coding. The fuse blows up even when the secondary of the transformer is not connected to the board.
The hammond datasheet is here: http://www.hammondmfg.com/pdf2/1182P22.pdf
And some photos to show my wiring:
Brown and white are connected together for the 230 volts configuration. Any idea ?
Dominique
The project is progressing, but I failed the first testing as I blow-up the fuse when I start... This seems to be in relation with the way the tranformer is wired. It is an Hammond. I have followed the instruction in accordance with the color coding. The fuse blows up even when the secondary of the transformer is not connected to the board.
The hammond datasheet is here: http://www.hammondmfg.com/pdf2/1182P22.pdf
And some photos to show my wiring:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Brown and white are connected together for the 230 volts configuration. Any idea ?
Dominique
That seems to be a 225VA transformer.
On 220Vac you can close rate the fuse @ T1A, but this will need a soft start to not blow the fuse at start up.
If you don't use a soft start then expect to need a T2.5A or T3.1A for reliable starting over many years.
Let's see how many cold re-starts the T1.6A can manage till it blows.
On 220Vac you can close rate the fuse @ T1A, but this will need a soft start to not blow the fuse at start up.
If you don't use a soft start then expect to need a T2.5A or T3.1A for reliable starting over many years.
Let's see how many cold re-starts the T1.6A can manage till it blows.
Nice chassis. Do you have a link to the manufacturer/vendor where you purchased it?
One little detail: Sand off the anodization (the black stuff) on the chassis under the lugs for the ground connection to the chassis. The anodization is not conductive and your chassis is likely floating.
~Tom
One little detail: Sand off the anodization (the black stuff) on the chassis under the lugs for the ground connection to the chassis. The anodization is not conductive and your chassis is likely floating.
~Tom
Thank you Tom,
I plan to continue working on the details tomorrow... It is the first time I am assembling an amplifier. Your kit is great!
http://www.ebay.fr/itm/151362612775?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Dominique
That looks great, Dominique! Nice chassis and cool speakers! 
Should the amps be earthed to chassis? You already have the chassis earthed directly to IEC as required. I think that is the only earth you need.
Putting an earth connection in the middle of the amp ground leads will increase the ground resistance. The amps should benefit from lowest resistance ground possible, which would be a direct unbroken wire. Think of this if you find any hum, especially if you connect the balanced input ground wire to the amp board rather than just to chassis, since hums are caused by voltage on the ground. If you have a noisy earth, or cableTV ground earthed which may inject noise onto your amp ground.
Hopefully you won't have any problem and it will sound perfect just as it is!!
Should the amps be earthed to chassis? You already have the chassis earthed directly to IEC as required. I think that is the only earth you need.
Putting an earth connection in the middle of the amp ground leads will increase the ground resistance. The amps should benefit from lowest resistance ground possible, which would be a direct unbroken wire. Think of this if you find any hum, especially if you connect the balanced input ground wire to the amp board rather than just to chassis, since hums are caused by voltage on the ground. If you have a noisy earth, or cableTV ground earthed which may inject noise onto your amp ground.
Hopefully you won't have any problem and it will sound perfect just as it is!!
Don't confuse earth and ground. Earth is just for safety (and static charge drain.) Ground is a return that allows current to flow. The IEC earth to the chassis is your "earth" connection. That's the only earthing you need, but you definitely do need it for safety to prevent you from getting shocked if a hot wire touches the chassis on the inside.
The ground wire from Mod86 J1 goes to your negative speaker binding post.
The ground wire from Mod86 J3 goes directly to the J2 ground on Power86. You have this link earthed to the chassis in the middle of the wire rather than direct from J3 to J2 with one wire.
The IEC ground connects directly to the chassis. The terminal on the Power-86 board marked "GND" connects to this chassis connection as well. Those are the only two connections to the chassis.
The wires coming out of the Power-86 board go directly to the MOD86 boards.
The speaker connectors connect directly to the output terminals of the MOD86 boards. The input connectors connect directly to the input terminals on the MOD86 board. Pin one of the XLR goes to pin one of J2. Pin 2 to pin 2. Etc. Follow attached schematic for single-ended connections. This is described in more detail in the design documentation for the MOD86.
~Tom
The wires coming out of the Power-86 board go directly to the MOD86 boards.
The speaker connectors connect directly to the output terminals of the MOD86 boards. The input connectors connect directly to the input terminals on the MOD86 board. Pin one of the XLR goes to pin one of J2. Pin 2 to pin 2. Etc. Follow attached schematic for single-ended connections. This is described in more detail in the design documentation for the MOD86.
~Tom
Attachments
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No that is wrong, Dominique. That is the most important connection of all, for safety. That connection allows the circuit breaker to feel if any voltage ever touches the chassis, so it can shut off the power to prevent electrocution.
Right now you have the ground wire on the output of the Power86 going to chassis, then continuing on to the ground input of Mod86. You want to replace those two pieces of wire with one single wire that does not stop in the middle at the chassis.
Then use one of the removed wires to connect the Power86 Ground connection to the chassis, at the same location as the IEC earth's chassis bolt.
So the chassis is only connected to the Power86 Ground on the AC input side and to the IEC earth, both sharing the same chassis terminal.
The audio ground connection to Chassis does not need to be taken all the way to the PE connection bolt.
The PE connection to Chassis should be fairly short and close to the mains power input location.
The audio ground connection to Chassis should also be short and should be where the audio ground is located. It should not be a long wire traversing across the other components inside the Chassis.
In an anodized chassis, I'd rather return the "audio ground" to the chassis grounding bolt. If you are 100 % certain that all metal parts of the chassis are connected electrically, you can use a short wire from the "audio ground" (GND terminal on Power-86) to the chassis.
~Tom
That is a two fold requirement.
Safety requires all the panels of a metal chassis to be electrically connected.
Even if it means adding direct wire connection between panels.
Secondly, the enclosing chassis only works as a screen if ALL the panels are electrically connected. And the gaps at the (panel to panel) connections reduce the effectiveness of the screening, if they are long.
Hi Tom,
In this case, signal passes through the shield, for me it's not a good way..
I prefer connect shield at only one point (amp board), or use only two twisted wires (xlr pin 2 and xlr pin3). I observe a better sounding without schield, more clear and details..
But I have not schematic of M86, can you explain : "grd" "in+" "in-" R3 and R8 ?
Thank's.
Phil.
In this case, signal passes through the shield, for me it's not a good way..
I prefer connect shield at only one point (amp board), or use only two twisted wires (xlr pin 2 and xlr pin3). I observe a better sounding without schield, more clear and details..
But I have not schematic of M86, can you explain : "grd" "in+" "in-" R3 and R8 ?
Thank's.
Phil.
I have rewired the earth and grounds in accordance with Tom instructions.
No difference that I can notice, but I feel more comfortable...
I plan to paint the wood enclosure in black next week-end.
I am happy with the results. My wife decided very quickly that this amp was sounding better than our ML-29.
Very neutral, subtil with the details, and no problem to supply power when needed. Bass are tight like I like them, very clean and powerful.
Tom, this is a great amplifier! I will receive soon a Kaneda 224. A new challenge for the small Modulus-86...
Cheers,
Dominique
No difference that I can notice, but I feel more comfortable...
I plan to paint the wood enclosure in black next week-end.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I am happy with the results. My wife decided very quickly that this amp was sounding better than our ML-29.
Very neutral, subtil with the details, and no problem to supply power when needed. Bass are tight like I like them, very clean and powerful.
Tom, this is a great amplifier! I will receive soon a Kaneda 224. A new challenge for the small Modulus-86...
Cheers,
Dominique