| Products > Test Equipment |
| Looking for the serive manual of an HP 70951 optical spectrum analyzer |
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| _Wim_:
I know it is a long shot, but does someone here has a service manual for the HP 70950/51 optical spectrum analyzer? Together with the 70004 display module, this combination is also called HP 71450/51. I already have the "installation & verification manual", "quick start guide", "user guide", "reference manual" , "programming manual" and "quick reference guide". According to the reference guide (see attached screenshot) a service manual has existed. I already looked on the usual places and googled quite a bit, but so far no luck. If the manual is somewhere for sale, that would also be an option for me. My unit has the following error I am trying to fix: "Cal Failed (2C) ERR 7055". If any-one knows more detail about the "2C" hex code, that would also already be very helpful! Thanks for looking, Wim |
| zrq:
Although very unlikely with the service manual, we have a similar HP OSA at work, so I hope I can answer some questions. Does it scan normally? These grating based OSAs have moving parts, so inherently have limited lifetime. The oldest Yokogawas we have at work makes screaming noise when scanning and from time to time aborts with monochromator errors. Good luck. |
| _Wim_:
I have been doing various tests this evening, and the monochromator part seems fine I think (my unit has the monochromator out option, so I can use it as an optical "preselector", and this works fine for the optical signals I could test with). There is at least an issue with the transimpedance amplifier, as the signal comes and goes depending on the sensitivity setting, so probably some gains do not work any longer (could be a faulty COTO relay, will try to check tomorrow). Attached some pictures on the transimpedance section. If not the COTO relays, the DG441 cmos switches would be my next guess... |
| _Wim_:
Forgot to mention, I also replaced 2 opamps on the X-Y control board (U401 and U402) because they were running quite hot (>100°C). After the replacement, U401 dropped to about 85°C, and U402 to 60°C. I did however not have any TL072 on hand, so I replaced them with AD712 as a temporary solution, so this might also explain the temperature difference. Still, this board remains suspect also, but I first want to concentrate on the transimpedance section, because debugging is much easier when a signal is present. |
| _Wim_:
This morning I checked both the COTO relays via their driver (74ACT244), and they were fine. The two analog switches (U400 and U402) however both had their port 4 damaged (other ports are working fine). As I do not have any ADG441 cmos-switches in stock, I will have to wait on the parts to continue the repair. |
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