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1979 sanyo receiver blowing fuses

Zenbrewer

Nov 9, 2014
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higher voltage isn't an issue :)
What do you think about changing the tolerance?
Radio shack has the same ones but at +- 10% but the originals are 0 to 100%
Seems to me like thy might work but perhaps be more prone to failure?
 

davenn

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Sep 5, 2009
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I have never seen something written with a 0 - 100% tolerance
it doesn't really make sense .... think about it ... if it has 100% tolerance, then it cant have anything less than that ;)

did you misread ?, were did you see that figure ?
 

Zenbrewer

Nov 9, 2014
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I have never seen something written with a 0 - 100% tolerance
it doesn't really make sense .... think about it ... if it has 100% tolerance, then it cant have anything less than that ;)

did you misread ?, were did you see that figure ?
Here is the manual page that lists the caps.
#C901, C902
Do you figure a +/- 10% would work?
image.jpg
 

duke37

Jan 9, 2011
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C901 is 0.01μF +100 -0%. In other words can be up to 0.02μF but not less than 0.01μF.

Minus and to can often be confused.

+/- 10% would almost certainly work. The value does not appear to be critical.
 
Last edited:

davenn

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Note you wrote it differently than what was written in the parts list ;)
gives it a totally different meaning :)

hence why I asked the Q's I did

as Duke37 said tolerance shouldn't be too critical ... particularly in that circuit

cheers
Dave
 

Zenbrewer

Nov 9, 2014
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So its been a long time but i finally got back to this repair.
replaced capacitors C910 and C911 "smoothing caps"

original
12,000 uf
63V
tolerance unknown

replacements
12,000 uf
80V
± 20%

april 003.JPG

I also replaced the ceramic caps around the bridge rectifier
C-901,902,903,904

originals
.01μf
+100% - 0%
500V

replacements
-20%, +80%
.01uf
1KV radial


april 014.JPG


1. powered up with both hot leads disconnected from the power amp
fuse held
2. reconnected left side hot lead to amp with Left IC (Audio power output stage module) disconnected
fuse held
3. reconnected right side hot lead to amp with Right IC disconnected
fuse held
4. reconnected Right IC
fuse held
5. reconnected Left IC
FUSE BLEW

to further verify the left IC or something further down the line from it is the issue i removed the right IC only and fuse blew. removed the left IC again and fuse held, finally replaced the right IC and fuse holds.

april 015.JPG


in this this state i assumed that the right side of the receiver should work but with a speaker hooked up it does not. the channel power indicator lights also do not move.

4 questions

1. how do i determine if the issue is the left IC (Audio power output stage modules / darrington power pack) and not something further down the line?

2. how do i test the test the power packs?

3. in this state why is the right side of the amp not functioning? does the circuit require both power packs in and operational to work?

4. do the specs on my replacement parts seem OK? they are not identical to originals.
 
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