hitachi hma-8300

rshadley

Active Member
Picked up a Hitachi HMA-8300, Hitachi HCA-8300 and Hitachi FT-440 tuner today. Amp has equal output on left and right channel but has alot of distortion. Have isolated the problem to be the amp. Since both channels are working, is it an issue with some electolytic caps?
 

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Picked up a Hitachi HMA-8300, Hitachi HCA-8300 and Hitachi FT-440 tuner today. Amp has equal output on left and right channel but has alot of distortion. Have isolated the problem to be the amp. Since both channels are working, is it an issue with some electolytic caps?

Have you tried cleaning the subsonic filter switch and the input attenuator controls with Deoxit first?
 
If distortion is in both channels - replacing caps in the power supply might help. Personally I'd fix the issue before a wholesale cap swap.
 
That's some seriously nice looking stuff there. Good luck on getting it cleaned up and playing.
 
cleaned the attenuator controls but not the subsonic. Will try later. appears that both channels are strong and equal. Would be nice if it was the subsonic filter.
 
cleaned the attenuator controls but not the subsonic. Will try later. appears that both channels are strong and equal. Would be nice if it was the subsonic filter.
If the distorted sound is equal as well.It stands to reason to be something common between both channels. The subsonic switch or the power supply.
or the IC chip for the subsonic filter. A missing or abby-normal power supply voltage would definitely cause issues.
 
Well its been nearly 4 months now and my service tech finally said he can't find the probelm. The sign wave is fine on the bottom but is severely clipping on the top. It is the same in both channels. Any other thoughts before I take it to my old service tech that competely rebuilt my Sansui AU-717 and Kenwood KR-9600 to great satisfaction.
 
I don't know what the problem is, or what it could be, but that is some serious looking vintage Hitachi gear you have that I've never seen before this. Hope you get it fixed!
 
that is nice gear you should get Hitachi D-900 tape deck and post a pic off them stacked up .
 
Hitachi System Back In The House and sounding great. Let that be a lesson to us all! Never cheat on a good service tech it's much worse than cheating on your wife. Amp and tuner sound great! Still not sure if the preamp is up to the same level. Phono section is a little weak. I would have posted pics but the wife is out with her boyfriend and has the camera!!!
 
A couple bad solder joints and about 1/2 dozen resistors out of spec. Kinda what I was originally thinking as I told the first guy to check the resistors on the driver board as this amp is known to run very hot.
 
I know the thread is old, but just wanna say congratulation. What a wonderfull set! I hope I will get my HMA/HCA...

Greetings
 
Now with genuine screws for the windows and new front plate of the poweramp. The old one had some burns on it. Now it is perfekt in any way a 36year old Hifi can be.


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Brilliant mosfet monster. I have one selling in my local ads (just the power amp) but its too pricey, otherwise I would grab it in a sec.

I read somewhere that these Lo-D/Hitachi mosfets started the trend that killed off the Sony vfets.
 
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