[n4k33n]

The LEDs on my Monica 2 DAC are some of the faulty ones and I need them replaced. I can't solder at all, so maybe one of you can help me. Here is the link on the data sheet for the dac:

Monica does USB!

Here is a picture of what the leds look like:

I really don't want to have to ship it back to asia to get it fixed, so someone please help

. I can pay a fair price for the led's and whatever someone thinks is a fair price for the work.

Thanks

 

[darkfury18]

What is wrong with them and does it still function properly without those LEDs?

 

[dBel84]

what does the bottom of the board look like - are the leds easy to get at? ..dB

 

[n4k33n]

Yes, it works, but the LEDs are faulty and it leads to a skewed noise to sound ratio. Meaning, I can hear a lot of background fuzz esp when the volume is turned up.

 

[dBel84]

I am assuming that Yeo has posted something to the effect that there has been a problem with leds? It looks like a discrete IV stage and the leds would be critical to the circuit. Yeo mentions on the web link that the underside of the pcb is packed with smd components and desoldering may be more involved than ususal - if this is under Yeo's guarantee, it may be better to send it back..dB

 

[Heady]

The LEDs are not especially difficult to remove and the smd chips are not that near. I am no expert in electronics and so can't explain why the LEDs are critical but they are. I think they are used as diodes to drop voltage at a fixed level. But unfortunately, some LEDs are noisy and need to be replaced.

 

[TzeYang]

1) Find out the voltage drop of the LED.
2) Find out the noise level of the LED.
3) Find the same LED with the same level of voltage drop
4) Replace
5) ???
6) Profit.

EDIT: personally i'd just swap all of it with a set of low noise LEDs/voltage reference chips with the same voltage drop.

 

[n4k33n]

^ I'd love to, unfortunately I can't solder worth a damn.

 

[Pars]

That is rbroer's SS I/V stage (diyaudio). I have a hard time believing the LEDs are noisy, but whatever, I suppose it is possible with particularly crappy ones. These are used to set up CCS, and can be either red or green LEDs with ~1.7-1.8V drop.

Where are you located? I could do it, but am in the Chicago area. I have built and am using Rudolf's TDA1541a I/V stage in my CDP, so I am familiar with his circuits, and I have lots of appropriate LEDs.

Chris

 

[PhaedrusX]

there was a faulty batch of LEDS that made their way onto a few boards. they were the clear ones. after the problem was found, yeo reverted back to the cloudy opaque kind.
there's no need to hunt down your own replacements if you don't want to. yeo is well aware of the problem and will send you a new batch of LEDs free of charge.

 

[n4k33n]

^ That won't work because I can't solder, like I said. I doubt yeo is willing to pay shipping to have the dac sent back to him and then back to me.

 

[PhaedrusX]

Quote:

Originally Posted by n4k33n /img/forum/go_quote.gif ^ That won't work because I can't solder, like I said. I doubt yeo is willing to pay shipping to have the dac sent back to him and then back to me.

well, i was taking into consideration Pars generous offer to change the LEDs for you. get the lights from yeo, send everything off to him.

it probably would help to state your general location, as there might be someone local who can help you out.

as for yeo, if it's just the board i don't see any reason why he shouldn't fit the bill. it's an assembly and parts related defect that he is aware of. however, if it's all cased up, that might be a different matter as shipping cost will be higher. run it by yeo, you've got nothing to lose by asking.

 

[JadeEast]

I got an email from Yeo after I bought a usb dac during the time of a bad batch of leds, not sure why you didn't get it. My dealings with him have been excellent and I'm sure he would take care of you.

Quote:

so if your LED is of the transparent type, i'm bracing myself for your assault! send me a mail and i'll send the batch of correct LEDs to you. if you rather i change them for you, no problem too. just send your monica or usb monica to me, i'll be happy to atone for my mistake.

 

[n4k33n]

Oh, I'm sorry, I didn't see your message there Par. If you want to, I would be much appreciative. I am located in San Francisco, but I would take care of everything. I'll send you a PM. Thanks