Author Topic: Roland w-30 5.2 volt rail to ground  (Read 2509 times)

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Offline PINKBOY1006

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Roland w-30 5.2 volt rail to ground
« on: April 15, 2015, 02:10:46 pm »
Hello, I am trying to repair my dads old Roland w-30 and one of the things we had to do is take the floppy connector off the board to try to get it working again. well |O we ended up pulling traces right off the board  :palm: , and we soldered the wires to the things we could, then we had to microsurgery and solder directly to traces :scared: . Now comes the problem, I have 28.6 Ohms across 5.2 volts and ground, and I thought I would ask you guys before I let the all to well known MAGIC SMOKE out. And me and my dad have looked the soldering and the traces for 1 week, and we see nothing so here is the schematic: http://www.deepsonic.ch/deep/manuals/roland_w-30_service_manual.pdf look for the main board, and some pics : http://www.mediafire.com/convkey/7748/x33od6v11g0i3ulzg.jpg http://www.mediafire.com/convkey/c325/q9ca2fyefy9hkb2zg.jpg Is this bad or not?
« Last Edit: April 15, 2015, 02:39:49 pm by PINKBOY1006 »
A wire without ohms is a short, but a wire with ohms is a resister.
 

Offline ElektronikLabor

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Re: Roland w-30 5.2 volt rail to ground
« Reply #1 on: April 15, 2015, 04:33:06 pm »
Hello pinkboy,
I would try it out; 29ohm would theoretically cause about 200mA of current.
Did you measured the resistance in both directions?
 

Offline PINKBOY1006

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Re: Roland w-30 5.2 volt rail to ground
« Reply #2 on: April 15, 2015, 04:46:18 pm »
If you mean that I checked in diode and ohms mode both ways, then yes and it was the same, but before I bite the bullet ill get some more opinions.
A wire without ohms is a short, but a wire with ohms is a resister.
 

Offline bookaboo

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Re: Roland w-30 5.2 volt rail to ground
« Reply #3 on: April 15, 2015, 05:19:24 pm »
I'd agree with medvedev, visually double check everything then go for it. 200mA on the 5V rail wouldn't be all that high for such an item. Besides it's a semiconductor circuit so won't behave in a linear V=IxR fashion.

If you have a meter with mA range you could put it in series to monitor the current on that line.
 

Offline PINKBOY1006

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Re: Roland w-30 5.2 volt rail to ground
« Reply #4 on: April 16, 2015, 03:13:20 am »
So what you are saying is that it is normal to have continuity between the positive and ground in this type of circuit?
A wire without ohms is a short, but a wire with ohms is a resister.
 

Offline bookaboo

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Re: Roland w-30 5.2 volt rail to ground
« Reply #5 on: April 16, 2015, 11:24:33 am »
You can't say for sure unless you had another unit side by side to compare with.  29Ohm doesn't stand out as a fault flag to me.
On the flip side a high resistance reading on a power line doesn't necessarily indicate everything is OK either.
 

Offline PINKBOY1006

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Re: Roland w-30 5.2 volt rail to ground
« Reply #6 on: April 18, 2015, 03:27:13 pm »
Well after much debate and inspection we plugged it and it worked.  Booted up without having to make any changes.  This was an ugly hack but at least it worked.  Thank for the help. 
A wire without ohms is a short, but a wire with ohms is a resister.
 


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