Resistors for 33120A

[Justincase1979]

Hello everyone, first post...

I am trying to fix a burnt out output attenuator in an Agilent 33120A. The resistors I need to replace are 69 ohm, 0.1%, 1206's, and these seem almost impossible to get a hold of in small quantities. Anyone have any good ideas as to where I could get hold of just a couple of these??

[KJDS]

Have you tried some calculations of the affect of using a readily available resistor?

[Justincase1979]

As far as I understand it would directly affect the accuracy of the output amplitude from the function generator, 1Vpp on the display would no longer equal 1Vpp output. But I haven't done any calculations as to the degree of change with other values, just wanted to see if it is at all possible to get a hold of the correct values first...

[tautech]

Why not stack 3 x 210 Ohm 1206 ?
Get say 10 x and select for value to get a spot on combination.

[brillopad]

These any good ?
From Amazon
http://www.amazon.co.uk/s/ref=sr_nr_seeall_2?rh=k%3A69+ohm+resistor%2Ci%3Aelectronics&keywords=69+ohm+resistor&ie=UTF8&qid=1416347282

[lowimpedance]

Stacking is the best way to get what value you need, but be mindful of the temp co. as well.

[Justincase1979]

Ok, so I have decided to stack one 69.8 and one 6.04k, should give 69.003 total and both of these values are pretty easy to get hold of. My plan was getting .1%, 25ppm resistors, those specs should match the manufactureres parts acording to the manual.

One thing, is thin film the best option since we are dealing with freq up to 15MHz??

[Justincase1979]

OK, new resistor in place and it works great, didn't even have to recalibrate it.

I also replaced the U205 SRAM to fix a 604 error, and that kind of worked. The 604 error disappeared, but now I get a 606 and 607 error. (They were probably there all along, just the self test that stopped at the 604 error.) Anyone have any idea where to start troubleshooting this??