...snip...
- Components : on the underside, see close up, there are a couple yellow axial components, that are leaky. Not even sure at this point if they are caps or.. maybe batteries/cells (for the voltage reference maybe... will need to look that up in the schematics).
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1455697;image)
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1456432;image)
Those crusty axial components look to be wire-wound resistors for the reference circuit, it uses a 6.2V Zener as the reference.
David
A resistor that leaks green stuff ?!
![Shocked :o](https://www.eevblog.com/forum/Smileys/default/shocked.gif)
But... resistors they are indeed !
Looking at the schematic, and the wiring on the board... it adds up. They correspond to the two low tempco resistors.
I pulled one leg on each, to measure them... schematic says they must be 3k and 2.1k ... I measured 1.25k and.. open circuit. That green stuff must have been bad...
Then one one of them, the lead I had slightly lifted... broke off, flush with yellow buddy. So it was definitely the end for it.
I sacrificed it in the name of science. Indeed it's a wire wound resistor in there. The green stuff looks like it's corrosion of the metal caps at each end, not the resistor per se.
I guess the meter must have gathered too much moisture for too long sitting on its arse on the ground of a damp garage... moisture got inside the resistor, yellow rubber not air tight, and then it was the end for poor little resistor.
So I must replace them. Tempco wise, should not be a problem, as schematic reads 1,050 ppm... which is... atrociously crap ?!
![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
1,000ppm when any cheap metal film is 50ppm ? I guess in th '60s 1,000ppm was good, and the Allen Bradley carbon composition were even worse ?...
So the real problem is... to know the value of these resistors because.... I can't trust the schematic 100% seeing as my board has 2 extra resistors that aren't depicted in the schematic. So... who knows if those yellow resistors in my instrument still have the same value that the schematic pretends hmmmm....
![Undecided :-\](https://www.eevblog.com/forum/Smileys/default/undecided.gif)
I will compare with the other meter.
Other problem : looks like the service manual is based on the 'B' suffix model, not the 'D' suffix I have to fix here !
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/facepalm.gif)
Pfff..... that doesn't help. The first 4 nixie boards are the same I am sure, as is the power supply too I would guess but... what about the other board and wiring....
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
This repair is looking like it's gonna be a lot of fun...
EDIT : I measured the Zener in circuit, powered up. Reads 6.34V. That's 2.2% off. Good enough I guess, the calibration trimmers should have enough range to adjust for that.
Good night....
![Indifferent :=\](https://www.eevblog.com/forum/Smileys/default/indifferent0023.gif)
![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1456471;image)