Products > Test Equipment
HP 5335A Timer / Counter - Anything i should know?
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Vgkid:
Good luck with your 5335. I will be bringing my old one back online in a few weeks. Everything not t&m related seemed to die.
Cubdriver:
LOVE the opening photo - nicely done!   :-+  Unfortunately, it's way past my bedtime, I'm over tired, and I can't resist being a smartarse >:D

<Cue Crocodile Dundee voice> That's not a classic counter. 

 

^^THAT'S^^ a classic counter! <End C. Dundee voice>

;D

(This of course will likely prompt someone to post a picture of their 521C - I haven't managed to get my paws on one of those yet.   :(  )

-Pat
1980s_john:
Hi,

Summary
I previously worked on my 5335A back in March 2015 (on the input board 'A3 Amplifier Buffer assembly (05335-60003)', I replaced the big blue tant caps (22uF) with new 35V parts), the unit then switched on but -15V and 5.2V volts were missing.


--- Quote from: Wim13 on March 29, 2015, 01:14:01 pm ---Replace the -15V regulator by a 7915, the -5 volts is depended on the -15V.
because of the op-amp that is in line with the -5 V.
--- End quote ---

This month I finally pulled it off the shelf and replaced the 7915 (U7 on A1 PSU), and removed the 110V fan and used the spare relay contact to parallel up the 5V relay. Once reassembled it all powers up fine and displays '0' on power up, so I now need to run some tests and learn how to use it!

Detail
I tested the PSU by making up a test lead with a power switch and connected it to J1, and connected up a dummy load of switchable 100/68/47/33 ohm 10W resistors. I found that sometimes the -15V would come up from power on, and sometimes not. When 25 ohm load (ie 0.6A @ 15V) was attached it would never power up.

I found I had to remove most of the boards to access the A1 power supply board, and only when I unscrewed this did I realise the transformer and Q1 wires could simply be unplugged from pins in the board.

A small piece of metal dropped out (see attached) - it seems to work fine without it, but any ideas where it fits?

Thanks for the recommendation to follow the service note to change the fan from 110V to 24V. I unsoldered the two black 110V fan wires and two white wires leading to the mains input module (line input). This left the A1 board free of all wires so much easier to work on. The white wires could then be unplugged from the mains input module, I put some heat shrink over the exposed terminals for peace of mind.

I added jumpers to parallel up the 5V feed, and attached a pair of wires across diode CR7 ready to connect to a 24V fan which is now fitted. The relay and socket don't look damaged (the black marks wiped off) so I left these.

Finally I replaced the 7915 regulator. After checking I refitted the A1 PSU board and it came up fine, the -15V output could drive 25 ohm @ 0.6A, and the -5.2V supply was fine with a 33 ohm load. I checked voltages for +15V, -15V, +10V, +5V and -5.2V and all were good. (Somehow I forgot to check 3V.)

I re-connected the boards one by one and all above voltages stayed fine. My unit has option 010 (HP 10544A OCXO), 020 DVM and 030 C channel (old type).

On power up it initially displays HPIB address, then displays 0. I have yet to try out any of the functions with a signal or even try the DVM, but it is looking good at long last.

Regards,
John
edpalmer42:
That piece of metal looks like it could be from one of the buttons.  Check here http://www.rbarrios.com/projects/HPSWITCH/ for details.  See if one (or more) of them has no spring return.

Ed
Dr. Frank:
Yeah, that looks like a metal bar spring out of one of the switches.
Maybe, one of them is 'hanging', when pressed.

Anyhow, these switches always have problems, due to relaxed springs.

Frank
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