Hitachi SR-903 Restoration

only thing left now is to clean knobs and faceplate
and replace six dial bulbs, cant find any specs on those in the SM but i assume im dealing with 8V bulbs, the kind about 20mm long with one long leg sticking out on each side, for through hole mounting, i dont know what theyr called.

and lastly i have the issue with the tuning knob. havnt decided yet how to go about that.
 
Pg 35 in the manual lists some 8V 30ma bulbs (just above PL13), but doesn't mark what they're for - could be the ones.
 
the dial bulbs are PL1-6

30ma smells like its the selector indication bulbs?

not shure what pl13 is but pl11-12 is stereo and AFC

edit: found it PL13 is the protection LED
 
also some selector indicator lamps are dead,
and my stock of 8V buls have been drained with my receiver thread fun:)
i think i´ll go LED on the indicators on this unit. easy since they run on DC, from what i can tell.
still need to solve the dialbulbs i dont want to solder "fuse style" bulbs in there.
 
i have replaced all the indicator bulbs (six) with LEDs
pretty easy mod since it was powered by 12VDC i used 680Ohm resistors.

004.JPG

008.JPG


now to my dilemma! i dont have the dialbulbs and i dont even know what spec they should be. probably 8V 300ma.

but i think i´ll try out a LED mod for the dial lamps. this would require DC voltage. currently they are powered with AC.
im thinking something like this..

Untitled.jpg

Haha LOL i should be working with designing schematics:)
 
the Dial lamp assy is finished.

it looked like this, very brittle and broken
012.JPG

the new LED´s
013.JPG

mounted with R680

016.JPG


Initial testing!
019.JPG

11,9VDC is what i got when meashuring at the points where i will hook them up in the receiver.
022.JPG

Finally some good old gluing! :)

023.JPG
 
Looks good - a nice example of what long term heat ageing does to some plastics.... should survive much longer with the cooler running LED's.
 
tnx goldie.
here is how i ended up doing

the lamp assy is powered with 2 cables, one yellow and one blue.
so we need to move them to a position after the rectifying diodes.

Untitled.jpg

in reality it looks like this.
024.JPG

Like this
026.JPG


be aware! there are two blue cables solderd to the post here. only the one leading to the dial lamp assy is removed
025.JPG

Like this

027.JPG

and we get DC!!! and lights! yey!

028.JPG
 
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now i just need to find a tuning knob

oh and my camera doesnt like LEDs,
this is NOT what it looks like in reality, it looks very good.
in the pic it looks as if its way too bright, but it isnt.
and it looks somewhat green in the pic. wich it isnt.
031.JPG
 
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tonight its gonna go down! the sx980 vs SR903 duell! test speakers will be JBL L65 Jubal
i think i already know the winner:)
 
while waiting for the winner of the "tonites receiver shootout" i´ll supply the voting list for the next project.
I´ll expand it beyond receivers:)

so here are the contenders for the next AK thread.

1: Sony STR-3800L, struck by lightning and missing 28transistors :)
2: Kenwood KR-5600, working but broken lights and many bent pot shafts.
3: Sansui AU-3900, looks ok not tested
4: Kenwood KA-5002, looks ok not tested
5: Yamaha C-50, no sound
6: Philips CD202, 99,9% distortion
 
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that STR-3800L could be interesting! even has TO-220 outputs! i like my TO-220's :p
i vote the STR-3800L, KR-5600 or AU-3900. should start a poll!
 
hmm i dont know how start a poll :(

ok one vote for the sony, fyi it has no outputs:) theyr missing, pretty much a wreck, but exterior is good.
 
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I had the one right below it,the SR-803.It was the second receiver I ever bought as a teenager.I really missed it for a long time.I know you will bring it back to its former glory.
 
well it turns out i had to change the plans. all of a sudden we had some ppl over for dinner so i didnt want to be totally antisocial:)
i´ll get on it. results of test is coming soon!
 
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