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Old 4th June 2009, 12:59 PM   #351
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Quote:
Originally posted by Calamaro
panda, just bypass the electrolitic with the 100nF film cap: solder its legs on electrolitic legs. The film cap (100nF) is non polarized so you don't have to pay attention to + and - legs.
If you prefer you can solder the little film cap under the board

Hi Cal,

I just finished the modification by passing the opamp. Except input cap. (I can't good quality 470uf cap at this moment. ) The sound quality is better than before. But the sound level is lower. Before mod, I turn to 12 oclock position is enough. After mod, I need to turn to 1 o'clock position.

Anyway, I am happy with this amp.

Thank you.
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Old 4th June 2009, 01:17 PM   #352
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Quote:
Originally posted by col
just removed the zener and put a 2k resistor with led on the No18 pin. drilled a hole in the front between the tone controls to mount. So I now have a fault led

col.
Nice work.

Some people at the 41Hz forum suggest shorting the speaker outs is a good way to test if the fault LED works, but I'm not sure if I'm that brave to do it to my Lepai!

I'm making a perpex faceplate for mine, I've found that the pot I want to use is a little large so I've had to improvise...
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Old 4th June 2009, 01:38 PM   #353
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The led comes on then gradually goes out if I pull the power cable out (under voltage fault). Thats about as much testing I'm going to do. It's the same behavior as other Tripath amps I have.

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Old 4th June 2009, 02:00 PM   #354
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Quote:
Originally posted by col
The led comes on then gradually goes out if I pull the power cable out (under voltage fault). Thats about as much testing I'm going to do. It's the same behavior as other Tripath amps I have.

col.
I didn't know that, I think as I'm making a new faceplate I'll leave a hole for a fault LED, it's a good and simple addition IMO.
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Old 4th June 2009, 05:16 PM   #355
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Quote:
Originally posted by panda360
the sound level is lower.
Did you replace input resistors?
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Old 5th June 2009, 03:43 PM   #356
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Quote:
Originally posted by Calamaro


Did you replace input resistors?

Hi Calamaro,

Yes-replace input resistors with 20/22k
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Old 8th June 2009, 11:11 AM   #357
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Hey guys, another Lepai arrived today, and it appears to be a little different, I guess this could be Mark 3?

Here's a pic, new (mk3) on the right and my old (modded mk2) on the left:
Click the image to open in full size.

As you can see the mk3 has notches for mounting bolts, and I've also found that the switch now turns the LED on and off, but there is a big turn on thump... I guess the switch must switch the power and mute is now disabled?

I haven't opened it up yet, but when I do I'll post some more pics.
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Old 8th June 2009, 04:08 PM   #358
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I have that one (the new). I think it has the same pcb.
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Old 8th June 2009, 05:45 PM   #359
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I think I've finished tinkering with mine for today:
Click the image to open in full size.

The red LED on the bottom left is the fault LED, the orange wire has a 2k2R resistor from pin18 for the fault LED. The big cap on the left is exactly like Calamaro's power mod. I've also wired 4 x white LED in series so when I'm powering this amp from my Li-ion battery pack I can see when the voltage goes below 9v when the LED's go dim.

I've replaced the volume pot with a 50k A&B pot which is a little large so I've had to have it floating and have the front panel hold it in place.

I've made a new front panel from 4mm perpex, and because the front panel is now removable, I can now mount decent quality RCA connectors on the rear panel. I've gone for a 4pin molex connector for the speaker connectors so I can quickly disconnect and reconnect this in the car...

View from front:
Click the image to open in full size.

I need to buy a knob for the volume pot, right now I'm just using 6mm washers taped together! I'm used a drilled 2p coin as a washer for the volume pot.

Once the new op-amps arrive I think I'll try swapping out the JRC4558, and I have still yet to try tone control bypass and I still need to wire in a mute switch.... Right now it's just shorted so it's unmuted the whole time.
Quote:
Originally posted by Calamaro
I have that one (the new). I think it has the same pcb.
Yep, I just taken it apart and it is the same PCB... Pic:
Click the image to open in full size.

I guess this could be a the early version after all? Did that one have the LED switch on and off with the switch on the front?
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Old 8th June 2009, 06:43 PM   #360
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Quote:
I guess this could be a the early version after all? Did that one have the LED switch on and off with the switch on the front?
Please check both boards under the switch: just a different wiring.
Congratulations for your hard work!
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