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Old 07-04-2020, 06:56 PM   #61
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Default Re: Old Gateway 2000 speakers out of sorts.

Quote:
Originally Posted by nomoresonys View Post
Pin 2: Bootstrap 2 resistance between 2 and 3 is 219 meter set at 2000 ohms
Pin 3: Output 2
Pin 5: Output 1 resistance between 5 and 6 is 546 meter set at 2000 ohms
Pin 6: Bootstrap 1
Something is going on with Bootstrap 1, and may be that is why the Voltage reading is also bad as reported earlier: Pin 6: Bootstrap 1 reported as: 0.46.
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Old 07-04-2020, 07:22 PM   #62
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Default Re: Old Gateway 2000 speakers out of sorts.

So it could be one of those caps? would be nice if I didn't have to get a new TA.
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Old 07-04-2020, 08:07 PM   #63
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Default Re: Old Gateway 2000 speakers out of sorts.

Boot strap caps location.
I do not think it is the cap problem, beside as reported that both channel output pins Voltages are showing only 0.5V instead of around 1/2 of the VCC Voltage, so you have more then one problem.
Are you 100% sure that output pins DC V are 0.5V? Were the trace damaged and repaired as you reported earlier? I just cannot see that BOTH Amplifiers have bad DC Voltage.
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Old 07-05-2020, 06:22 AM   #64
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Default Re: Old Gateway 2000 speakers out of sorts.

Just tested agian, ac adapter is putting out 17.2 volts, checked with my meter, both output pins reading .89 volts, why its up from the .5 volts measured before, I have no idea.

Last edited by nomoresonys; 07-05-2020 at 06:24 AM..
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Old 07-05-2020, 02:24 PM   #65
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Default Re: Old Gateway 2000 speakers out of sorts.

Pad tried to lift a bit on the cap I replaced but I think it's ok, because it acted exactly the same after replacement of cap, the one I repaired was on the karmons of the other thread.
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Old 07-06-2020, 09:01 AM   #66
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Default Re: Old Gateway 2000 speakers out of sorts.

Switched out c26 with one from a junk board, uf was ok, couldn't check esr, no meter, didn't seem to make any difference, was getting OL when testing uf on c25 in circuit so I switched it out too, tested ok out of circuit, replacement still getting OL in circuit but c26 gives me a uf reading in circuit?? I tested pin 3 output 2 and got like 14 volts once, tested again got the same .89 that I was getting, I have 14.6 volts on the main cap, is that kind of low?
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Old 07-06-2020, 12:39 PM   #67
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Default Re: Old Gateway 2000 speakers out of sorts.

The TA can run from 9 ~ 20VDC per spec sheet so 14V is no problem.
"I tested pin 3 output 2 and got like 14 volts once, tested again got the same .89 that I was getting," I wonder if the VCC on pin 8 (which is supplied through the switch on the headphone jack) is intermittent,if Voltage on pin 8 (ON/OFF) is not present, lots of Voltages will be reading low as if the IC is off.

Last edited by budm; 07-06-2020 at 12:43 PM..
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Old 07-06-2020, 02:25 PM   #68
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Default Re: Old Gateway 2000 speakers out of sorts.

Well crap, I was messing with c16 and pulled the pads for sure this time, can I just run a solder bridge to the nearest joint on the trace/path to reinstall the cap?

Last edited by nomoresonys; 07-06-2020 at 03:43 PM..
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Old 07-06-2020, 03:46 PM   #69
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Default Re: Old Gateway 2000 speakers out of sorts.

They put a bunch of glue on the main cap and c16 and had about 4 resistors completely covered in it, removed most of it, wonder if it messed up the resistors?
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Old 07-06-2020, 06:41 PM   #70
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Default Re: Old Gateway 2000 speakers out of sorts.

The glue that is.
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Old 07-08-2020, 08:41 AM   #71
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Default Re: Old Gateway 2000 speakers out of sorts.

So the switch on headphone jack could be bad? any way to test it? Maybe that's why I get sound coming from speaker 2 when it's plugged into headphone jack?

Last edited by nomoresonys; 07-08-2020 at 08:43 AM..
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Old 07-08-2020, 11:19 AM   #72
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Default Re: Old Gateway 2000 speakers out of sorts.

Can't seem to figure it out, never have much luck with audio or printers.
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Old 07-08-2020, 04:44 PM   #73
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Default Re: Old Gateway 2000 speakers out of sorts.

The power switch on the headphone jack assembly is for supplying the Voltage to pin 8 of the IC to run t he TA IC when head phone is not plugged in, the main key point id that if you do have 14VDC at pin 4 and pin 8 of the TA IC, the output of both amplifier pins should then have about 7VDC but you only has 0.5V so that is not normal.

Last edited by budm; 07-08-2020 at 04:48 PM..
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Old 07-08-2020, 05:59 PM   #74
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Default Re: Old Gateway 2000 speakers out of sorts.

Ok, just checked the TA with headphones plugged in and every pin is 0 volts, is that as it should be? I guess I should replace the TA, can't figure out what else would make both output and one bootstrap so low in voltage?

Last edited by nomoresonys; 07-08-2020 at 06:03 PM..
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Old 07-08-2020, 06:13 PM   #75
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Default Re: Old Gateway 2000 speakers out of sorts.

Quote:
Originally Posted by nomoresonys View Post
Ok, just checked the TA with headphones plugged in and every pin is 0 volts, is that as it should be? I guess I should replace the TA, can't figure out what else would make both output and one bootstrap so low in voltage?
See my post #51 showing the Voltage with and without headphone jack plugged in.
When headphone is plugged in then there will be no Voltage feeding pin 8 of TA so most Voltages will be 0V as you can see my list. For both output to have almost 0V it has to be something common to both amplifiers, I.E.missing Voltage on pin 8 (VCC2) of the IC, or on pin 9 (Ripple).

My post #51:
TA8248, TA8229. Notes: (***V) = Voltage with headphone plugged in. When headphone is plugged in the VCC2 from the switched headphone jack is cutoff so there will no VCC2 on pin 8 of the TA chip.
Pin 1: N.C.
Pin 2: Bootstrap 2 =18.20V (0.56V)
Pin 3: Output 2 = 9.42V (0.51V)
Pin 4: VCC1 = 18.47V (18.47V)
Pin 5: Output 1 = 9.03V (1.00V)
Pin 6: Bootstrap 1 = 18.16V (0.52V)
Pin 7: PWR-GND
Pin 8: VCC2 = 18.47 (0.05V)
Pin 9: Ripple filter = 9.63V (0.51V)
Pin 10: NF1 (Negative Feedback 1) = 0.60V (0.95V)
Pin 11: Input 1 = 0.06V (0V)
Pin 12: Input 2 = 0.02V (0V)
Pin 13: NF2 (Negative Feedback 2) = 0.60V (0.56V)
Pin 14: Pre-Gnd 1
Pin 15: Pre-Gnd 2

Last edited by budm; 07-08-2020 at 06:17 PM..
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Old 07-08-2020, 06:28 PM   #76
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Default Re: Old Gateway 2000 speakers out of sorts.

Ok, TA pin 8 is 14.75 v and pin 9 is 7.75 v, that's measured with headphones unplugged so looks like those 2 are alright if i understood correctly.

Last edited by nomoresonys; 07-08-2020 at 06:39 PM..
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Old 07-08-2020, 08:43 PM   #77
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Default Re: Old Gateway 2000 speakers out of sorts.

Quote:
Originally Posted by nomoresonys View Post
Ok, TA pin 8 is 14.75 v and pin 9 is 7.75 v, that's measured with headphones unplugged so looks like those 2 are alright if i understood correctly.
Those readings are OK.
So the only thing left is bad TA chip.
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Old 07-09-2020, 02:24 AM   #78
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Default Re: Old Gateway 2000 speakers out of sorts.

Ok, Thanks Bud.
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