Replacement Power Transformers for Urei 1178

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hageir

hageir

Well-known member
Joined
Jul 29, 2008
Messages
55
Location
Reykjavík, Iceland
Me and my buddy are working on a Urei 1178 which has an after-market power transformer that is currently rigged to 15V (should be 18V)
we were just wondering if you guys know of any replacement power transformers that would work for the 1178?

Thanks a ton in advance,
one love

-Geir Helgi
 
Originally it uses a 2x18V supply, regulated by the 7818/7918 regulators.

if you have +/-18V DC in the circuit (and you probably have, even with a 2x15V transformer), there's no need to change anything

If DC voltages are less than +/-18V, you may want to put in a 2x18VAC transformer. In this case, get a toroid rated 15VA or more, that will fit inside the box.

Another option is to change regulators to 7815/7915 and live with 1dB or so reduced headroom..

Jakob E.

 
gyraf said:
Originally it uses a 2x18V supply, regulated by the 7818/7918 regulators.

if you have +/-18V DC in the circuit (and you probably have, even with a 2x15V transformer), there's no need to change anything

If DC voltages are less than +/-18V, you may want to put in a 2x18VAC transformer. In this case, get a toroid rated 15VA or more, that will fit inside the box.

Another option is to change regulators to 7815/7915 and live with 1dB or so reduced headroom..

Jakob E.
Click to expand...

Yo Jakob, the master himself! :)
Thanks for the swift reply.

Ok, it's been modified;
it's got 15V regulators so we're getting +/-15V DC instead of the 18V it should be…
(currently it's 2x16V AC)
So maybe the first step would be to change the regulators?

ps. any tips for a replacement power transformer? (other equivalents would be fine)
 
hageir said:
gyraf said:
Originally it uses a 2x18V supply, regulated by the 7818/7918 regulators.

if you have +/-18V DC in the circuit (and you probably have, even with a 2x15V transformer), there's no need to change anything

If DC voltages are less than +/-18V, you may want to put in a 2x18VAC transformer. In this case, get a toroid rated 15VA or more, that will fit inside the box.

Another option is to change regulators to 7815/7915 and live with 1dB or so reduced headroom..

Jakob E.
Click to expand...

Yo Jakob, the master himself! :)
Thanks for the swift reply.

Ok, it's been modified;
it's got 15V regulators so we're getting +/-15V DC instead of the 18V it should be…
(currently it's 2x16V AC)
So maybe the first step would be to change the regulators?

ps. any tips for a replacement power transformer? (other equivalents would be fine)
Click to expand...

If you're saying your unit is working, but you want it to run 18V, read Jakob's post again.

Running it at 15V will only mean a reduction of about 1dB in headroom.

If you want it to run at 18V, you will have to change the regulators to 7818/7918.  If you transformer is putting out 16VAC, it should be just enough to supply 18VDC.

Gustav
 

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