I'm not sure what is going on, I remeasured this time and they were all different than last measurement. Also noticed that I put red lead on pin I'm measuring, then turn on power and voltage slowly raises over a minute or two and its hard to get a precise measurement.
1. 5.5
2. 0
3. 0
4. -6.8
5. 0
6. .08
7. 6.8
8. 5.10
I have been afraid to keep the amp powered on more than a couple of minutes at a time while testing because I cant secure board to heatsink very well while working on it because the legs are getting weak from bending back and forth taking board in and out of heatsink. None have got hot as of yet but those two resistors are now starting to discolor the longer I have it on.
Do you see only ±6.8v on the power supply pins of the other op-amps?
Do you read 0 ohms between the speaker terminal you have the black probe on and the secondary center tap of the power transformers?
Do you read 0 ohms between the speaker terminal you have the black probe on and the RCA shields?
Do you read 0 ohms between the speaker terminal you have the black probe on and the secondary center tap of the power transformers?
Do you read 0 ohms between the speaker terminal you have the black probe on and the RCA shields?
Yes, I see +5.2 on all pin#4's and -6.7 on all pin#11's of the 4-quad amp op's.
Yes, actually 0.1 ohm's to secondary center tap and 0.3 on rca shield's. Not sure if it's because of my meter sensitivity or actual resistance to shield's?
With the black probe on the non-bridging terminal again, what is the DC voltage (down to the millivolt) on pins 2 and 3 of the opa134 and also on the bridging terminal for that channel?
Perry, the voltage is jumping all over the place under 1 volt after turning the amp on, but after 20-30 seconds it is around .04 volts on both pins.
To the positive right channel it started around 1 volt then when the amp delay kicks off it jumped to -11 volts for just a second then went down to about.04 volts.
To the positive right channel it started around 1 volt then when the amp delay kicks off it jumped to -11 volts for just a second then went down to about.04 volts.
0.04v DC isn't anything to worry about.
If you connect a speaker does it pop loudly (as you'd expect with 11v on the speaker terminals)?
If you connect a speaker does it pop loudly (as you'd expect with 11v on the speaker terminals)?
The other boards you have worked on like mine that had the 180 ohm resistors, did they have the single channel opa134p's or opa2134's? Just wondering if maybe they revised some of the components between board's or someone did just pop in the wrong resistors?
I've only seen a few of these amps.
I have photos of this model and the extreme 1200, which uses the same board. One 1200 has 68 ohm and one has 180 ohm. Of the two photos showing the same resistors in the photos of the 275r, one has 68 ohm and one has 180 ohm.
I don't see 2134s in any of the photos.
The 180s look stock in the photos. The 68 ohm resistors do not look like something that Orion would install (sloppy).
I have photos of this model and the extreme 1200, which uses the same board. One 1200 has 68 ohm and one has 180 ohm. Of the two photos showing the same resistors in the photos of the 275r, one has 68 ohm and one has 180 ohm.
I don't see 2134s in any of the photos.
The 180s look stock in the photos. The 68 ohm resistors do not look like something that Orion would install (sloppy).
Ok, I thought I had something close to 180 ohm, But looks like the closest thing I have is some 100 ohm 5 watt. So you think I should just put it back together and see what happens?
The pulse would be only about 1/10th of the one on the speaker terminals.
Do you get the pop on that channel every time the amp is powered up?
Do you get the pop on that channel every time the amp is powered up?
Ok, I checked it again and pin 3 did get a pulse of about 3 volts at the same time the speaker popped.
Yes, everytime
Yes, everytime
You need to try all switch options to see which ones make the amp pop and which ones eliminate the pop (if any).
Also check for excessive DC on the output pins of all op-amps for that channel.
Also check for excessive DC on the output pins of all op-amps for that channel.
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