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HP 5335A Timer / Counter - Anything i should know?

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orin:

--- Quote from: Dr. Frank on May 26, 2014, 10:09:16 pm ---
--- Quote from: Orange on May 26, 2014, 09:48:00 pm ---My unit also has a Papst DC fan, its rated for 18 Volts, but it runs from 24 Volts !

Strange that official diagrams do not include this change. For sure it was build by HP like this.

I could change it for a Sunon Maglev, that should kill the noise  :)

--- End quote ---

This change from 110V to 24V is described in words, but I'm lacking the schematics.
So it was an official change, definitely.

The fan operates from 18 to 28V.

--- End quote ---


Replying to an out of date post, but since I just replaced my fan and fixed another problem:

The change was described in a service note (attached).

I strongly recommend replacing the relay socket and implementing the wiring change in the service note or one day, you'll turn it on, the fan will run, but you will get no display.  The relay socket is part #27E213, PB806-ND from Digi-Key.  The socket contacts fatigue from running too hot/heat cycling and eventually, when cool, the contacts for the 5V supply don't make contact any more.  In my case, I got strange behavior for while before it finally wouldn't turn on.

I have put an 8414NGM in my unit too, but be aware that it cannot handle the same static pressure that the 8124G can.  Compare the charts:

http://elcodis.com/parts/452608/8124G.html#datasheet
http://img.ebmpapst.com/products/datasheets/DC-axial-fan-8414NGM-ENG.pdf

I have no idea what is required in terms of static pressure vs. air flow for the 5335A.  All I know is that the original parts list specified 32CFM air flow for the 120V fan.

1980s_john:

--- Quote from: Wim13 on May 22, 2014, 04:44:31 pm ---I got mine 5335a very cheap, because it was totally dead, but cosmetic very good condition

After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.
--- End quote ---

Thanks for the tip, my 5335A is similarly dead (well the fan comes on and that's it), all the main PSU outputs read close to 0V with the regulator inputs are at +/- 12V and +/- 24V. I am used to shorted tants in IBM PCs, where due to the high current available the results are a little more spectacular  ;)

Regards,
John

orin:

--- Quote from: 1980s_john on March 04, 2015, 02:10:59 pm ---
--- Quote from: Wim13 on May 22, 2014, 04:44:31 pm ---I got mine 5335a very cheap, because it was totally dead, but cosmetic very good condition

After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.
--- End quote ---

Thanks for the tip, my 5335A is similarly dead (well the fan comes on and that's it), all the main PSU outputs read close to 0V with the regulator inputs are at +/- 12V and +/- 24V. I am used to shorted tants in IBM PCs, where due to the high current available the results are a little more spectacular  ;)

Regards,
John

--- End quote ---


If you have the DC fan, it's likely that the contacts on the relay socket have opened up.  See the service note in my post above.  The relay socket is a 27E213, Digikey part number PB806-ND.  If it is the relay socket and you do the modification in the service note, you probably don't need a new relay; I'm still using my original relay.  Anyone with a 5335A should make sure that this modification is done and switch to a DC fan.  The 5V supply relay socket contacts get hot, fatigue and eventually, when they cool down, don't make contact with the relay any more.

You can check if it's the relay socket by following the input for the 5V supply from the fuse and across the relay.  If the 5V supply is down, the other supplies don't come up either.  You might try reseating the relay (carefully, the top tends to come off the relay).  That worked for me for a while.

The relay itself is pretty much unobtainium - it's a 6PST NO with 5A rated contacts.  It should easily carry the 2A or so that I measured on the 5V supply, but the socket contacts don't.  The modification uses the contacts that were originally used for the AC fan in parallel with the original contacts for the 5V supply so the DC fan modification is absolutely required.

There is a similar relay available with 2A contacts.  I have one but haven't tried it yet.  I'm sticking with the original relay while it's working.

Orin.

1980s_john:

--- Quote from: 1980s_john on March 04, 2015, 02:10:59 pm ---
--- Quote from: Wim13 on May 22, 2014, 04:44:31 pm ---After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.
--- End quote ---

Thanks for the tip, my 5335A is similarly dead (well the fan comes on and that's it), all the main PSU outputs read close to 0V with the regulator inputs are at +/- 12V and +/- 24V.

--- End quote ---

I finally got around to working on my 5335A, the service manual is a must have. The input board is the 'A3 Amplifier Buffer assembly (05335-60003)', I replaced the big blue tant caps (22uF) with new 35V parts. It now powers up and the front panel / processor / display appear to work, but it is not working as the PSU voltages are still not right. I get:

-15V output = +0.7V
+5V = 5.07V
+10V=10.0V
+15V=15.7V
-5.2V=+0.6V
+3V=3.0V

So problems with the -15V and -5.2V rails, which appear to be independent. Any tips please?

Regards,
John

1980s_john:

--- Quote from: orin on March 04, 2015, 06:03:16 pm ---If you have the DC fan, it's likely that the contacts on the relay socket have opened up.  See the service note in my post above.  The relay socket is a 27E213, Digikey part number PB806-ND.  If it is the relay socket and you do the modification in the service note, you probably don't need a new relay; I'm still using my original relay.  Anyone with a 5335A should make sure that this modification is done and switch to a DC fan.  The 5V supply relay socket contacts get hot, fatigue and eventually, when they cool down, don't make contact with the relay any more.
--- End quote ---

Thanks, my relay seems to be OK. However removing it shows a black heat mark on the socket, presumably where the 5V passes through. Thanks for the service note, I must give it a go.

The HP part for the relay is 0490-1172. Printed on the side is the code R10A-E1-X6-V430, and a date code 7923. ebay shows loads of R10-E1-X6-V430, is the R10 2A relay and the R10A 5A then?

Regards,
John

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