Products > Test Equipment
Anritsu MT8801A/B/C & MT8802A
Howardlong:
Folks
I believe that there is a lot of similarity between these test sets, I have had an MT8802A for about four years now with the spectrum analyser (option 07).
Over the past three years, although the analogue receiver tester has been working perfectly, the analogue transmitter tester and spectrum analyser have been misbehaving intermittently to the extent where I'd stopped using them. Most notably the tx tester worked increasingly intermittently or was terribly deaf, and the spectrum analyser was unstable or otherwise significantly off frequency, and it did not measure levels accurately.
Although the symptoms weren't specifically mentioned here http://www.kolumbus.fi/oh5iy/HW/MT8802A.html I decided to bite the bullet and do an electrolytic transplant over the past day and a half.
The results have been superb, all of those intermittent problems appear to have gone.
I wouldn't recommend doing it unless you have a lot of patience and you can accept having the unit out of action for a couple of days. There are tons of screws to keep track of, and about twenty boards to get through. The power supply and A10 converter seemed to fix most of my problems, and I did those first anyway, but I thought as I'd already started I might as well do the lot.
Removing some of the caps wasn't always easy. I used a Weller DSX80 on a WMD-3: they've been in a box for about four or five years as I only really do SMD on boards these days for projects, it's very rare that I need a through hole on a board. While it worked, much of the time I found that touching up the exposed cap pin stubs on the underside of the board with a bit of full fat solder helped with the heat transfer and suction on the (mostly) multilayer boards.
If you have one of these test sets and are experiencing odd problems, I can recommend the cap replacement procedure, but unfortunately there aren't many short cuts to replacing electrolytic caps.
G0HZU:
--- Quote ---ough the symptoms weren't specifically mentioned here http://www.kolumbus.fi/oh5iy/HW/MT8802A.html, I decided to bite the bullet and do an electrolytic transplant over the past day and a half.
--- End quote ---
Hi Howard
Your link doesn't work because there is a comma at the end
Hope the one below works OK ...
http://www.kolumbus.fi/oh5iy/HW/MT8802A.html
nctnico:
Intermittant problems are often poor contacts. Taking everything apart probably solved the problem.
G0HZU:
Maybe... but the insides of something like this can run quite hot and this can shorten the capacitor life and cause multiple failures after many years' service.
I've had to replace a few dead caps in my old HP8566B analyser and they caused similar symptoms. In my case I used a simple homemade in circuit ESR tester (function gen + sense resistor + 100kHz receiver) and tested all the caps in the suspect areas.
I found several dead caps that had gone high ESR.
I'm not a fan of blindly recapping complete units mainly because of the time and cost and also the risk of causing damage or fitting inferior performing parts. To replace that many caps that is shown by Howard (with new high grade ones) would have cost me more than I paid for my complete HP8568B analyser about 7-10 years ago (£125). I tend to wait for an obvious failure or issue and then try and find the cause. I'm too much of a tightwad I guess :)
Howardlong:
I did also clean up a couple of dozen trimmer pots which could also have had an effect.
Some of those caps had ESRs in excess of 20 ohms, most were between 7 and 10 ohms. They were all past their prime that's for sure.
Had I had a service manual for it, I would have done a rather more analytic approach, but I've been unable to locate one.
In fact, documentation for the analogue rx/tx and spectrum analyser parts online seems lacking. There is documentation available for the GSM/CDMA etc functions for what that is worth. The UI isn't the best I've had the pleasure of using, but I've used worse.
The MT8802A is pretty useful, as as well as a 3GHz spectrum analyser, it has a 3GHz RF signal generator and power and modulation measurement, again to 3GHz, although the modulation capablities are limited to FM, and there is no tracking generator. But light it ain't.
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