sa9500II

moermusic2

moermusic2

Active Member
Have isolated / determined a problem. Right channel via ONLY tuner inputs is half volume of left. Have deoxited and cleaned everything. problem follows to left channel when put mode switch to reverse. Thoughts? & I probably dont trust myself to play with it.
 
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moermusic2 said:
Have isolated / determined a problem. Right channel via ONLY tuner inputs is half volume of left. Have deoxited and cleaned everything. problem follows to left channel when put mode switch to reverse. Thoughts? & I probably dont trust myself to play with it.
Click to expand...

There are 47 ohm resistors in series with the tuner and aux inputs. Further when the input is NOT selected, they are grounded to prevent crosstalk. Too much voltage in when not selected would burn them out.

this thread:
http://www.audiokarma.org/forums/showthread.php?t=98733

shows a similar occurrence. Yours should be in the same places as in the pictures I posted - but hopefully not burned.

Got a dmm? find R36 by pins 10-11-12-13 on the equalizer amp awf-024 over the function switch at the upper right of the front panel and check it, compare it to R37, R38 & R39 .

R38 is next to R36 while R35 & R37 should be over the function switch shaft.


Get the manual if you haven't at www.kallhovde.com/pioneer/
 
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will break down unit and look at this weekend. maybe try another blast of cleaner in the mode switch and the rca tuner input
 
do I have to turn awf 204 over? if so, after removing the 2 hold down screws, what else prevents board from flipping over? perhaps the function sw. shaft? dont want to break anything by forcing.
 
Whatever goes through the front panel - although you may have a short "leash".

You can measure at the solder pads on the upper, exposed side - you should have already acquired the manual. (kallhovde.com for pdf's, or an excellent reproduction (complete with foldouts) from Rick at stereomanuals.com)
 
your hunch is good. R35=47.9;R36=nada;R37=47.4;R38=48.2. Just enough gap to see a really black resistor on the underside with a good LED light. cutting one tie cable might lengthen the "leash" somewhat to do a replace. or - a small bent needle nose may reach the resistor from below while the pads are heated up. replace all 4 with same thing at same time now? old age burnout or what might I have done some time ago?
Thanks: ex DJ, moer music
 
Not old age burnout... those circuits don't (aren't supposed to) carry enough energy to do that. Something with more oomph was connected in to do that.

Hunch... unh unh... experience.....

You should be able to get the one replaced without major disassembly, and only a few contortions. The solder joints being exposed are the advantage.

Just replace the one, with the same wattage part, 1/4 watt - they are expected to act like a fuse, so while perhaps not specified, if the option presents itself, get flameproof 1/4 watters....
 
thanks. thats what I meant- *experience [hunch]* !!! dont know what fried it,
as same source has been in for last 8 yrs. never the less, will attempt contorting
to replace it. ( do have access to a radio comms person who can help). will let
all know if successful at the R&R & if channel comes back in full capacity.
just thought of it, could have fried at same time as my celestion MD 500 mid
driver cooked its voice coil. go figure thanks again
 
thanks. thats what I meant- *experience [hunch]* !!! dont know what fried it,
as same source has been in for last 8 yrs. never the less, will attempt contorting
to replace it. ( do have access to a radio comms person who can help). will let
all know if successful at the R&R & if channel comes back in full capacity.
just thought of it, could have fried at same time as my celestion MD 500 mid
driver cooked its voice coil. go figure thanks again
 
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replaced R36 and its neighbor as it was badly scorched. did turn awf 024 over to accomplish this. did have to make a short wire trace as I somehow managed to break the factory trace from one end of one resistor. while she is opened up , thought mightht as well replace power light. Will a 12V 60ma work ok in place of the 8V 50ma? Is this dc or ac,as I found an automotive bulb that fits the rubber socket much better. Test ran the 12v60ma bulb for about 10 mins with no visible bad effects.
 
That lamp is an unusual case, it is being run by 50v ac through a 910 ohm 3 watt resistor, thus the difference between 12v 50ma and 8v 50ma isn't very large. While it's operating, measure the voltage across the bulb, and the voltage across the resistor, and if the resistor needs changing, there'll be enough info to recalculate a value.

Remember, measure the AC voltage.
 
thought I had posted earlier today my results. appears didn't happen. the bulb I have in now shows 7.6 v across bulb. r 52 measures 43.6 v. should be good to go?

the new 47ohm resistor brought the right channel via tuner inputs back to life. (cd player is actual input via tuner) & sometimes sat. TV is the input).
thanks Mark
DM
 
moermusic2 said:
thought I had posted earlier today my results. appears didn't happen. the bulb I have in now shows 7.6 v across bulb. r 52 measures 43.6 v. should be good to go?

the new 47ohm resistor brought the right channel via tuner inputs back to life. (cd player is actual input via tuner) & sometimes sat. TV is the input).
thanks Mark
DM
Click to expand...

If it is bright enough for you, you're good to go, serendipity....

7.6v across a 12v bulb should last quite a while.... :D

edit: calculating 43.6v / 910 ohms = ~ 48 mA
 
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