Author Topic: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value  (Read 15806 times)

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Offline Adal

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #50 on: March 24, 2015, 07:32:19 am »
Bad news.
I made the same test than
Andrew and noting appears. Additionally I lost the tracking generator option because I check the backup battery and the machine doesn't remember the installed options  |O
Maybe is time to call Instek México distributors for help
Instrument behavior: Instrument does not turn on
Instructions: The main board is probably defective. Replace it.
 

Offline G4JMO

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #51 on: March 24, 2015, 06:08:39 pm »
Oh no! Sorry to hear of your problems.That is unfortunate. I was lucky I suppose that I have no options fitted otherwise I would have shared the same fate!
I guess you have no other option but to contact the service centre.   
Best regards
Andrew
 

Online Fraser

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #52 on: March 24, 2015, 06:42:10 pm »
I truly hate designs that use a volatile memory to hold calibration data or option keys.

I have several pieces of quality equipment that contain lithium memory batteries with a predicted life of 10 Years. the service manuals just specify a p.d check. One manual provides details of placing a temporary supply across the lithium battery contacts while the cell is removed and a new one fitted. Anyone owning older test equipment should really check that such does not have a battery backed memory containing essential data. If so, check the battery every year and fit a new one if the p.d drops significantly from its stated output. I change 3.6V lithium batteries when the reach 3.0V. Some volatile memory suffers corruption issues at voltages less than 2.6V. Remember to apply a 'holding' voltage across the lithium battery terminals though. From memory you need two AA alkaline cells (approx 3.2V p.d) supplying the memory via a 10K resistor.

There is little excuse for volatile memory being used for mission critical data inside modern equipment. Blimey, eeproms have been around for so long now, why would anyone want to have a flippin battery backed memory except maybe for an RTC module.

Rant over, but I really feel for Adal. He is in a situation that now makes OEM support essential and that could be costly and inconvenient.

Aurora
 

Offline G4JMO

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #53 on: March 24, 2015, 09:32:26 pm »
I completely agree. It's a poor way to design. I've just faced a similar issue with my  Gigatronics 6100 sig gen. It must be at least 20 to 30 years old. Whilst fixing it recently, I got hold of the service manual and discovered that a Dallas NV Ram held critical calibration data that if lost would render the machine useless. Gigatronics refused to even discuss the unit because of its age so they wouldn't have been any help if the worst had happened. Fortunately I could still read out the contents using my EPROM programmer so it's all safely backed up now and I've also replaced the Dallas device. In a way, I'm lucky the unit needed fixing, otherwise I'd have never discovered this Achilles Heel until it was too late.
 

Offline Adal

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #54 on: March 25, 2015, 03:44:19 pm »
Dear all, thanks for your help and comments.  Yes, I have bad luck with my GSP-827 due the design of the configuration info. I attach some pictures  of the inners for your info.
Best regards
Instrument behavior: Instrument does not turn on
Instructions: The main board is probably defective. Replace it.
 

Offline Adal

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #55 on: March 25, 2015, 03:52:01 pm »
Now I have the demodulation option. ??? Lesson earned, don't acquire "high performance" used test equipment without support or technical information. Maybe Agilent/HP
Best regards
Instrument behavior: Instrument does not turn on
Instructions: The main board is probably defective. Replace it.
 

Offline Adal

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #56 on: May 29, 2015, 06:37:34 pm »
Hi.
Some news.
Recently I found the service manual for my machine:
http://www.melchioni.it/moduli/assistenza/ricercaRiservatoDownload/1/?&page=2
For calibration or activate the options, I need a "service password" only available by Instek.  :--
So I inquiry for that an Instek Mexican distributor, I´m still waiting for a quote.  :-//
Best regards.
 
Instrument behavior: Instrument does not turn on
Instructions: The main board is probably defective. Replace it.
 

Offline G0HZU

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #57 on: May 30, 2015, 11:12:10 pm »
Quote
The signal then gets +16dB gain from U18, an NBB400 MMIC. Looking at this components solder seems to suggest it has been the subject of some attention before!. I plan to isolate it, power it and feed a signal into it and check how much gain it is giving.

Looking at the various images of the RF front end I'd guess that the first RF amplifier U18 (marked N4) is an old Stanford Microdevices  GaAs HBT part. The logo looks right for the NGA-486 but it's many years since I did any design work with these devices as they went obsolete a long time ago.

RFMD did take over Sirenza a few years ago so the NBB400/NLB400 may be descended from the same technology. The NGA-486 was quite a fragile part and required careful attention to thermal management and also they can be easily damaged from minor overload and transients. I've seen a lot of dead NGA-486 parts in my time :)
« Last Edit: May 30, 2015, 11:55:21 pm by G0HZU »
 

Offline xmicron

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Re: INSTEK spectrum analyzer GSP-827 -6 dBm down than the real value
« Reply #58 on: June 25, 2015, 08:34:34 pm »
Hi Andrew,

Have you managed to solve this issue?
It looks like I am having the same problem!

Regards,
Frank
 


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