small resistance problem

[romulux]

i've got an early-run eros that gave me a little trouble with the resistance value of the right input jack after finishing; it would be hard to get a reading on at all, but occasionally it seemed to flicker with the correct number. the amp sounded fine and functioned well, and at the time i couldn't do a better soldering job, so i've been using it like that for months.

i just got much better quality solder and a solder pump and thought i'd redo the connection, but afterward it still gives me no reading. when the connection was unsoldered, i tested the tip of the red wire that goes into the center pin of the jack alone and got the correct value, so whatever's going on here is only happening when the wire contacts the jack.

there's no continuity between the center pin and outer shell of the jack, and i don't really know how to account for the lack of a reading... the 3 other jacks easily test fine. the amp seems to be working well enough, so should i just ignore this or bother putting in a new input jack to be safe?

[Grainger49]

I just took a quick look at the schematic.  The input RCA Jack, measuring from the center conductor to the outer should read 47k ohms.  The schematic, the instructions and the parts list show 47k ohms for those resistors that are between terminals 19 and 20 and between terminals 26 and 27.

The 220 ohm resistor should not enter into the reading you get there.  What do you get if you read resistance between terminals 19 and 20 and between terminals 26 and 27, 2 readings?

If there is resistance between the two pair of terminals above and not between the RCA jack connections the problem is with the wire.

[romulux]

between the two sets of terminals you suggested i get about 47k ohms, so it may be the wire. do you have any suggestions about how to test the wire itself to be sure?

the jack still seems like it may be damaged or defective; the white spacer between the inner conductor and outer body of the jack is sunken in farther than the others and the center pin wiggles around a little bit. still, without continuity between the inner and outer parts i don't know what could be causing a problem. when measuring resistance between the outer part of the jack to the center pin i still get no reading.

[Grainger49]

Testing the wire is easy, unplug and flip the Eros over.

Using the lowest resistance scale you have touch one probe to the center conductor of the RCA jack on the left and the other probe to the lower part of terminal 19.  Be careful not to touch the wire that is connecting between these two points, you want to be certain that the RCA center pin is wired to terminal 19.

Do the same thing for the outer conductor of the left RCA jack and the lower part of terminal 20.

Again, for the right RCA jack center conductor and the lower part of terminal 27.

And finally for the right RCA jack outer conductor and the lower part of terminal 26.

All should be near zero ohms.  If they are all is fine.