Monica Explodica

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fergs1

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Joined 2005
#1
greetings all. I am in need of help. I bought one of diyparadise monica 2 dacs and promptly fried it by hooking it up to 12vac instead of dc. It fried the resistoor across the 317 regulator (smokin') and so I replaced it with another 22ohm resistor but its still not working. Now money is tight and so it will be a while before I can commit to another one and so I'm wondering if it is fixable and If anyone has had experience with these could the help me to track down the fault and so I can replace damaged components.The really crap thing about this is that it was a gift and I never had the chance to enjoy it.Hope to hear from you electro hounds soon yours hopefully
cheers fergs
 
#2
Well you have almost for sure burned the 317-regulator. My first recommendation to you is to replace that.

If you are lucky nothing has passed thru the regulater and you dont need to replace anything else, but there is no easy way to check that without replaceing the regulator.

Start there, and good luck!

Best regard's Carl-Johan (I burn electrics for a living 😀 ]
 
#5
Well i know what we do at work when a regulator is burned, we replace all other circuits connected to it...

Most IC's work at 3,3-5V DC, and that 12V AC must have fried them, or atleast some of them. As raikkonen said, do you have a schematic?
 
#6
I'm afraid there is no schematic as it is a commercial product but here are two pictures of the board, top and bottom showing the ic's. it looks nerve wracking all those tiny little pins. If I replace them I think I'll have to use lead out wires to a plug, unless of course these ic's are only surface mount? Let us know what you think Thankyou for taking an interest in a 'challanged' diyer. cheers fergs
http://diyparadise.com/dackit/monica2_detailed2.jpg
http://diyparadise.com/dackit/cs8414_reclocker.jpg
 
#10
thanks for all your kind replies, I think getting an unstuffed board is a good idea,, trying to clean up all those tiny solder holes is simply going to take years off my life, and frying the dac has already taken care of that. I'm about to go on anual leave so when I get back I let you know how I go. so thanks again cheers fergs
 
#11
fergs1,

Theese things happens sometime. Experience growing.

I was looking for a diagram. The monica2 diagram is not available, but there was an other one similar to monica except it does not have the reclocking section.
It was on DIYParadise, but I can not find it any more.
There was also a diagram for a reclocker, I am sure this is the one built in the monica2. All gone!!
I looked in my files, just in case I had some informations, but nothing.
I have to look again, I may have printed this information sometime ago. That could be quite usefull then.

This is a good step to change the LM317 as you did, but there are 4 regulators on this board. The other 3 are 78L05.
I would check first if you have any voltage in and out of these regulators.
On the TDA1545, you should read: 2.4V on pin1, 5V on pin5, 2.9V on 6, 0.7V on 7 and 2.9V on 8.
Let's start there and see what happens. If all voltages are normal, and the red led does not comme on when the S/PDIF connection is made to the drive, there is a good chance the CS8414 receiver is dead. This is a very sensitive chip.

Jean-Charles
 
#12
fergs1,

I found it. It still is on the DIYParadise site.
Here is the one very similar to monica here, an earlier version: http://diyparadise.com/dacs.html

The receiver will be a CS8414 and not a CS8412. Two more regulators are used with monica, surely one for the clock. You will have to dig this out a bit.

You will find the reclocker here: http://diyparadise.com/asynchreclocker.html

At least, we have a start.

Jean-Charles
 
#14
Hi,

Try to change the 78L05 regulators.
At work I have done that a lot of times. The common fault is that folks use a 9vac adaptor instead of dc. Even that the protection diode is blown away so it is no longer in the circuit the damage is almost always limited in the powersupply. You will see that the 7805 will only put out a few millivolt.
In equiptment that has this fault has often been very sophisticated equiptment with a lot of digital circuits. Any way, I don't understand that so few DIY kit don't have protection diode. I use it on my private design becouse I know I might use a wrong adaptor in half sleep.

Best regards,

Magnus K.
 
#19
After I had measure the voltages on c3, c4, c8 and c10.
This is the reponse from yeo.

".... this means ALL the regulators onboard are dead.
you could try repairing her. 2 stages to try.
1st stage, replace all the regulators. u3, u5, u6 and u4.
then measure all those caps. they should read 5v. if monica sings now, everything's fine. otherwise, there's no point going for stage 2.

stage 2 replaces the 28 pin surface mounted digital receiver, flip flop chip and tda1545.

usually if stage 1 doesn't work, i scrap the board"
http://diyparadise.com/yabb/YaBB.pl?num=1191707022


Tigrine
 
#20
Hi fergs1,

I have monica too and it sings very sweet, of course with dc. Yeo suggest to use 12 VDC to monica and 15 VDC if you use gain stage.

Did you make a repair as Yeo recommended it to you by tigrine?
How about the result stage 1?

Boy
 
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