On Wed, 02 Apr 2014 16:50:00 -0500, amdx wrote:
I recently bought an HP8640B that turned out to by not working, I
shipped it back, it cost $43.95 to ship.
You might have shipped it to me as I fix them:
http://802.11junk.com/jeffl/pics/HP8640B/
However, you won't like my rates. I get two types of customers for
such repairs. One is the bargain hunter, who also wants a bargain
repair. I can't afford to give away my time. The other needs the
HP840B because its cavity oscillator has one of the lowest phase noise
specs (for the price) and is willing to pay my exorbitant rates.
http://www.cliftonlaboratories.com/CannedOscNoise.htm
I got my $430 returned on the
Ebay purchase to cover the item and shipping. But I have not been
offered the defective item return shipping costs.
That's why I like to buy items with "free shipping". If there's a
refund, it includes the paid shipping cost. However, you're still
stuck with paying the return shipping.
I even made my offer contingent that the frequency counter work. I
noted in their pictures that the display read zero and the range setting
was 512 Mhz. I pointed out it could be the int/ext switch and to
verify proper operation. When I got it the counter didn't work.
I'll keep arguing my case.
I about 4 hrs trying to fix an HP8640B that has similar symptoms. I
traced signals, changed modules, and swapped boards, with no progress.
I eventually discovered that the INT/EXT time base switch, on the rear
panel has fallen apart and there was no clock. I thought this was an
oddity, but I've seen it on two similar signal generators, and have
exchanged email with another HP8640B owner that has the same problem.
I should get me new working 8640B today, they tried delivery yesterday,
I wasn't home when they came by.
Good luck. At about 50 lbs, I'm sure the delivery person will not be
thrilled with another missed delivery, and will probably throw it
through a window just to get rid of it. I suggest that you plan on
being home.
As for small quantities of caps, I buy those on eBay. However, the
chances of getting garbage is high, so I always buy duplicate parts
from two different vendors. If I find something that's worthwhile, I
then buy a 100x bag of the same brand.
Testing the caps is easy if you have an ESR meter. The problem is
that I'm not sure my method is 100% reliable as I've only done it with
about 10 different types of caps. Therefore, do not assume that this
works quite yet. I place a cap in boiling water and in the oven.
http://802.11junk.com/jeffl/Electrolytic-cap-test/test-setup.jpg
The ESR does *NOT* drop as it should when the cap is hot,
http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-C.jpg
it is likely to fail. Unfortunately, all the caps, good and bad, have
their ESR go up radically when cold, which doesn't help.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558