afterthisnap
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Posts posted by afterthisnap
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New fancy autorange multimeter says:
Middle Setting
1-3: 9.6 kOhms
1-2: 12.4 kOhms
2-3: 12.53 kOhms
Clockwise setting:
1-3: 9.6 kOhms
1-2: 9.61 kOhms
2-3: 9.3 Ohms (no kilo)
Counterclockwise:
9.6 kOhms
7.6 Ohms
9.62 kOhms
All these were taken with the pot on the board. I'm about to take it off now.
4-6: 10.2 kOhm
4-5: 13.6 kOhm
5-6: 13.6 KOhm
7-9 had identical values
Thanks.
Edit:
Desoldering pumps are cool!
Off the board I get:
Middle setting:
1-3: 39.7 kOhm
1-2: 19.9 kOhm
2-3: 20.0 kOhm
Clockwise:
1-3: 39.7 kOhms
1-2: 39.7 kOhms
2-3: 10.4 Ohms
Conterclockwise:
1-3: 39.7 kOhms
1-2: 7.7 Ohms
2-3: 39.7 kOhms
I'm wondering if the heating from desoldering did anything to normalize the middle setting. Regardless, I'm still into the idea of doing the bypass. It looks like the pot+/- resistance for 1-3, 4-6, and 7-9 are all about 40 kOhms.
Will six 20 KOhm resistors do the trick?
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Here are some more pics if it helps clarify anything:
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Also, the #2 connection does not have continuity with the steel case of the radio, which I assume would also act as ground.
I should have a better multimeter available to me tomorrow. I'll post up some better readings.
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Thanks, guys.
Cleaning the pots didn't help, and I'm pretty sure the innards of the pots are mangled based on how crunchy they now feel.
I'll get some more pics up tonight.
I should have mentioned that connections 1 through 9 are connected to the balance/fade pot. You pull the knob out (up in the pic) to adjust balance, push in (down) to adjust fade.
10-15 are connected to the treble/bass pot.
Nathan-
I've only really used multimeters to test car parts and batteries. It's entirely likely that I'm using it wrong to test circuit boards.
The volume control knob is on a separate board but is connected to the one it the photos via a 4 wire connection. The volume wires connect via the 4 vertical connections at the bottom of the first pic.
Replacement pots have been impossible to find (unless I order 800 or more).
Thanks!
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Apparently I don't know how to use a multimeter...
All these values were taken at a 10x setting. At 1000x I get different values but they are relatively the same.
Also, I get different values if I test the same connections but switch the black/red probe of the multimeter.
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The left side sound cut out on the oem 1990 tape/aux head unit. Jiggling the fader control worked for a while to restore full sound, but now the left side is totally dead.
The front/back fade setting works fine.
Treble/Bass seems to be functional.
I've read that you can bypass the fader/potentiometer by replacing it with resistors rated at half resistance of the fader/potentiometer.
I opened up the unit and the fader connections are a bit more complex than I anticipated. Here are the pics:
I think the FUBAR condition is in the 1,2,3 connections.
Checking resistance with all settings in the middle, I get
1-3: 45 ohms
1-2: infinite
2-3: 70 ohms
With the left/right fader turned all the way clockwise, I get
1-3: 45 ohms
1-2: 60 ohms
2-3: 5 ohms
With the left/right fader turned all the way counterclockwise I get
1-3: 45 ohms
1-2: 7 ohms
2-3: 55 ohms
I'm not entirely sure what to make of this, as when the fader is turned full counterclockwise (right volume cutout), I don't get any sound from the left speakers. I don't get any sound from the left speakers in any setting anymore.
I know it's easy enough to put in an aftermarket unit, but this is a quest of curiosity to see if I can rig a fix.
I don't need fade/balance, so I thought perhaps a 20 ohm resistor from 2-1 and 2-3 would bypass the fader and give me full left/right sound again. Please let me know if I'm missing something as circuitry is not exactly my forte.
Thanks!
OEM headunit fader bypass- electrical gurus needed!
in 1990 to Present Legacy, Impreza, Outback, Forester, Baja, WRX&WrxSTI, SVX
Posted
Update:
DID NOT WORK.
I had half sound for a few seconds before everything went dead. Luckily, I found a replacement unit online and now everything sounds great!