U2000 D706 Shorted need replacement.

Spunky1562

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I'm working on a Wells U2000 that went into shutdown and was clicking at power on. I located a shorted D706 which is listed as DFH10TR in the schematic.

What is everyone using as a current substitute?

I have GI1-1600GP and DGP15 but I believe both of these are too slow when trying to compare the data sheets.

Any help is appreciated.
 
BY228.

Does it test shorted out of circuit? Because if it's in circuit there are other parts in parallel that might be shorted instead. Q704 (collector to emitter short), C718.
 
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from my experience, I'm leaning towards that being a red herring. if the chassis hasn't been recapped and properly solder serviced, you should do that first. if so, Q703 didn't come with a heatsink and should have one, if that transistor fails it'll pop the HOT. Q708 and R760 and potentially also R765 should be tested out of circuit too. if Q708 shorts it'll kill R760 and will likewise pop the HOT.

and if you haven't done so, test the HOT Q704 out of circuit with red probe on the left leg and touch black probe to the middle and then right legs (these should be junction drops; if reading 0.00 or low, it's shorted)

it's been awhile since I've mucked with these, that information kind of fell out of my head since then. lol
 
Thank you. The monitor was capped and reflowed last year and suddenly began clicking at start up this year. The hot showed 18ohms across it so I removed it and it tested fine out of circuit. I removed the poly cap next to the heat sink (covering d706) as it tested as 18 ohms in circuit. Then found that d706 tests 18ohms both directions out of circuit. Removed it and installed new hot and it's testing as expected in circuit.

I'll check the other transistors and resistors you mentioned as well.
 
C718 is the poly cap I removed to get to D706 and it isn't shorted.
Q704, the hot, tests good. I upgraded to J6920 anyway.
Q703 and Q708 test good.
R765 should be 33k but mine is testing 44k
R760 should be 470ohm 1watt according to the schematic but my 760 is a 100 and looks like a 1/2w. This looked factory.

Should I order a 33k and 470ohm or are those ok?
 
Looks like somewhere along the line wg started using the 100 so that is ok, but I think I'll order a new 33k.
 
Just to close this out:

Replaced R765
Replaced D706; had to enlarge pcb holes slightly.
Replaced B+ pot
And monitor fired back up.

Found missing blue which was an intermittent issue that was present at clients location previously reported. Replaced blue transistor on neck board and all seems good!

Thanks for the help everyone!
 
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