Bought this for my folks as a Christmas present what felt like recently but it's actually been 6 years already!
The audio quality has successively become worse to the point that even my mom said it was unusable now, and I had to agree!
I have had it open before to add a secondary coax to optical converter for an unrelated issue with audio dropouts when hooked up to a Dreambox that it had since it was new.
Back then I noticed the craptastic choice of capacitors, and I was not really keen on replacing them all if it would not fix the issue, which I was doubting would be capacitor related.
So I desoldered all the caps around the audio out connectors looking for a bad one but they all measured fine on my ESR meter.
However I did find two bad bipolar electrolytic caps, they have the text: ZHN® (M)105°C CD71H 3.3uF 50v NP
They are at positions C133 & C134 and are part of the audio crossover circuit. I think Nantung might be the manufacturer.
Member DjKrish actually posted the service manual for it in his thread here.
I cropped out the relevant section of the schematic as a picture below.
I didn't think I had any bipolar caps but looking through my bins I actually found a couple WIMA MKS2 polyester film capacitors in an old Elfa bag with article number: 65-227-67
They should be much more appropriate for the job except they where a bit small.
Well not in size as you can judge from the photos but in capacitance: only 0.47uF.
But since I had nothing to loose I put them in after some careful leg-bending wizardry and tried it out: to my surprise the set seemed to sound just fine again!
Of course I can't remember fully well how it used to sound so it's not an apples to apples comparison.
But maybe someone with experience on audio crossover circuits can chime in on how the loss of capacitance might effect the audio?
P.S: I also replaced CE9 & CE3 as they measured a little high in ESR too, but nothing like C133 & C134.
The audio quality has successively become worse to the point that even my mom said it was unusable now, and I had to agree!
I have had it open before to add a secondary coax to optical converter for an unrelated issue with audio dropouts when hooked up to a Dreambox that it had since it was new.
Back then I noticed the craptastic choice of capacitors, and I was not really keen on replacing them all if it would not fix the issue, which I was doubting would be capacitor related.
So I desoldered all the caps around the audio out connectors looking for a bad one but they all measured fine on my ESR meter.
However I did find two bad bipolar electrolytic caps, they have the text: ZHN® (M)105°C CD71H 3.3uF 50v NP
They are at positions C133 & C134 and are part of the audio crossover circuit. I think Nantung might be the manufacturer.
Member DjKrish actually posted the service manual for it in his thread here.
I cropped out the relevant section of the schematic as a picture below.
I didn't think I had any bipolar caps but looking through my bins I actually found a couple WIMA MKS2 polyester film capacitors in an old Elfa bag with article number: 65-227-67
They should be much more appropriate for the job except they where a bit small.
Well not in size as you can judge from the photos but in capacitance: only 0.47uF.
But since I had nothing to loose I put them in after some careful leg-bending wizardry and tried it out: to my surprise the set seemed to sound just fine again!
Of course I can't remember fully well how it used to sound so it's not an apples to apples comparison.
But maybe someone with experience on audio crossover circuits can chime in on how the loss of capacitance might effect the audio?
P.S: I also replaced CE9 & CE3 as they measured a little high in ESR too, but nothing like C133 & C134.
Attached Files
Bought mine off of Craigslist cheap.
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