Electronics > Repair
BK Precision 2120 trace issues
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vexatag:

--- Quote from: bdunham7 on July 14, 2020, 12:51:26 am ---Do you have a 9 volt battery or some other low voltage source handy?  Try setting your meter on 2V DC and giving it 9 volts (it won't hurt it) just to see if that '1' does indicate overrange. 

--- End quote ---

The 1 indicates overrange, I'm getting 274 volts from TP+140v to either side of R504.


--- Quote from: bdunham7 on July 14, 2020, 12:51:26 am ---And does your meter should indicate zero when there's no voltage, so when you measured from TP+140V to both sides of D502, you said it was 102V on one side and 'nothing' on the other.  If that 'nothing' was a zero reading that's  lot different than an overrange reading.

--- End quote ---

My meter indicates 0.0 when there's no voltage, TP+140V to D502 resulted in 102V on one side and 0.0V on the other. I will be more precise in the future, my apologies.

As for the ohms I'll get it figured out,
vexatag:
Update, I've figured out the ohms, none of the resistors were open after all.

R503: 4.68k Ohm
R504: 99 Ohm
R505: 500 Ohm
R506: 48k Ohm
R507: 180k Ohm
R508: 1.68 mega Ohm
97.5k Ohm
bdunham7:
If those readings are accurate, R507 and R508 are both bad and that might be the whole problem. They are the voltage divider that sets the output of the supply. It looks like they are a different type than the others?  They seem to be specifying 1/4 watt metal film 1% tolerance, which are readily available in 100K and 115K values.  I wouldn't do any more testing until you have replaced those.
vexatag:
I'll round up a source for them (annoying that Mouser and Digikey shipping costs can easily exceed the cost of parts in situations like this), it'll be a bit before I'm able to replace them as something in my soldering setup is super janked, all my joints are cold.

1/2 watt metal film resistors are probably also fine, right?
bdunham7:
!/2 watt are OK if they fit OK, but unnecessary.  Try eBay for very small orders, for something like resistors they'll be fine.  You might want to just get a big set of resistors if you plan on making stuff in the future.  You will have to buy the 115K separately, or else use a 113K or 120K, depending on the set you get.

https://www.ebay.com/itm/US-1460Pcs-1-4W-Metal-Film-Resistor-Kit-Assortment-Set-Labelled-1-Precision-Set/133464890909?hash=item1f13209e1d:g:B1MAAOSwDO9fDSDI

And yes, figure out your soldering before you start any repair work. 
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