HP7475A - power transformer secondary voltage ?

P

Peter_purple

Guest
Hi chaps,

I'm trying to revitalise an older HP7475A (Hewlett Packard)
desktop A3 plotter and found the power supply input transformer primary
has gone kafffuuuff,

I'm wondering if anyone out there knows what the secondary push-pull
voltage should be so I can insert a substitute, unfortunately there are
no markings on the transformer and the only clue on the main circuit
board is the power supply filtering cap which has a max voltage rating
of 25V,
so I'm wondering if the secondary is 12v or 24v push-pull and the rating

looks like maybe 2 Amps,

Anyone have any ideas ?

Regards

purple engine from perth packed pickled peppers
 
No load: 10.65VAC - 0 - 10.65VAC
Load (plotter on, not plotting): 10.48VAC - 0 - 10.48VAC

There's a heatshrink-covered quick-disconnect-terminated jumper
between two terminals on the transformer. I wonder if it's a fusible
link?

On Tue, 16 Sep 2003 21:41:11 +0000, Peter_purple <purple@iinet.net.au>
wrote:

Hi chaps,

I'm trying to revitalise an older HP7475A (Hewlett Packard)
desktop A3 plotter and found the power supply input transformer primary
has gone kafffuuuff,

I'm wondering if anyone out there knows what the secondary push-pull
voltage should be so I can insert a substitute, unfortunately there are
no markings on the transformer and the only clue on the main circuit
board is the power supply filtering cap which has a max voltage rating
of 25V,
so I'm wondering if the secondary is 12v or 24v push-pull and the rating

looks like maybe 2 Amps,

Anyone have any ideas ?

Regards

purple engine from perth packed pickled peppers
Click to expand...
Steve J. Noll | Ventura California |
| The Used High-Tech Equipment Dealer Directory
| http://www.big-list.com
| The Peltier Device Information Site:
| http://www.peltier-info.com
 
Thanks for the feedback Steve,

As luck would have it, I opened up the insulation and found that those two
lugs
number 6 and 7 are just spares - somewhere to put the wires, theres no wire
from them, no thermal fuse - they are just dummy spades.

Though after taking it all apart and putting it on an AC source analyser the
transformer sprung to life - really wierd because I couldnt get anything
from the meter setting and the plotter wouldnt work - not with a hasty
connection I have life in the LEDs and next thing is for me to lubricate
all the squeeky bearings and remove spider web floss from the optical
encoders on X and Y drive motors...

Could be running soon !

Thanks for the feedback, just checked the voltages and they are spot on with
your post :)

rgds

peter purple from perth positioned in Western Australia




"Steve J. Noll" wrote:

No load: 10.65VAC - 0 - 10.65VAC
Load (plotter on, not plotting): 10.48VAC - 0 - 10.48VAC

There's a heatshrink-covered quick-disconnect-terminated jumper
between two terminals on the transformer. I wonder if it's a fusible
link?

On Tue, 16 Sep 2003 21:41:11 +0000, Peter_purple <purple@iinet.net.au
wrote:

Hi chaps,

I'm trying to revitalise an older HP7475A (Hewlett Packard)
desktop A3 plotter and found the power supply input transformer primary
has gone kafffuuuff,

I'm wondering if anyone out there knows what the secondary push-pull
voltage should be so I can insert a substitute, unfortunately there are
no markings on the transformer and the only clue on the main circuit
board is the power supply filtering cap which has a max voltage rating
of 25V,
so I'm wondering if the secondary is 12v or 24v push-pull and the rating

looks like maybe 2 Amps,

Anyone have any ideas ?

Regards

purple engine from perth packed pickled peppers




Steve J. Noll | Ventura California |
| The Used High-Tech Equipment Dealer Directory
| http://www.big-list.com
| The Peltier Device Information Site:
| http://www.peltier-info.com
Click to expand...
 
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