Re: Resistors on schematics
Now that I see the circuit you're building (sorry, missed the URL), 1/4 or 1/2 watts would be fine, and 5% tolerance would be fine as well. You probably already have a PCB with these parts on it, so you won't need to buy them. I mean, if you're building an ESR meter, I bet you have some old boards in your junk box....right?...
romansroad
Senior Member
Last Activity: 08-07-2012, 07:33 PM
Joined: 02-25-2010
Location: Dallas, TX
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Re: Resistors on schematics
Ohm's law is always best, but if you're working on a piece of gear and are replacing a resistor, you can estimate the wattage by comparing sizes on the board. If you're scratch building, then you're back with ohm's law.Leave a comment:
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Re: Dynaudio Bm5a
Nice pics! A little hard for me to see the ID on the caps, but the vent design should clue us in. As to the bridge rectifier, I'm not sure you would see any advantage with changing....just my 2 cents.Leave a comment:
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Re: Sony STR-DE725
Since the left channel is a mirror of the right, compare the collector to emitter resistance of Q757 to Q707. If the transistor is shorted, you should see nearly zero ohms on Q757.Leave a comment:
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Re: Sony STR-DE725
Check the output transistor, Q757 on page 21 of the schematic, for a dead short (zero ohms) with your multimeter. You can check it incircuit if you have a DMM, or remove it to be sure. This appears to be the output section for the rear (surround) portion of the audio amp. It appears that the protection relay circuit protects both left and right with the same DPDT relay, so if you hear sound from the left, its probably not the protection circuit.Leave a comment:
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Re: Sony STR-DE725
With Plain Bill's service manual schematic in hand, start with the defective side's speaker terminal, and work your way back. I didn't check the PDF, but some units do have output fuses (rare these days) so be on the lookout for that. If there are discrete (transistor/MOSFET) output devices, you can check them for shorts (collector to emitter). Also look for signs of overheating near the big heatsink...even if the insulating washers are distorted, or the board under the device is browned you may have found the problemLeave a comment:
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Re: Cap suggestion please help!
I was wondering what happened to initiate the rebuild? ADS's are great, with robust crossovers and rubber surrounds, so was there an issue with overdriving them?...Leave a comment:
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Re: Yamaha A-760...no one under 30 needs to read this!
Thanks!
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Re: Samsung 731N menu keeps popping up
I measured the voltage at the panel board end, i.e. not at the logic board to avoid opening it up again. On my unit, CN901 is the connector on the panel board. With the board plugged in, pin 2, 3, 4 all read 1.3v. With the panel board disconnected (at the panel end of the ribbon cable) pins 2 and 3 read0.03 vLeave a comment:
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Re: Yamaha A-760...no one under 30 needs to read this!
I was planning a full restoration, and the zener may be fine as I haven't had a chance to test it yet. I'll look on Diyaudio for that thread. Thanks!
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Re: Lights go out on Westinghouse LCM-19v7
Seriously, perhaps you improved a connection on the ccfls....it may be temporary....let it cool overnight (or put it outside for 20 seconds!) and try again. You know from all your prior fixes the expansion coefficient of metals and the contraction of them when cold.Leave a comment:
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Re: Lights go out on Westinghouse LCM-19v7
Just like my Samsung on another thread.....the electronics are learning to fear the full weight of the BadCaps forum !
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Re: Samsung 731N menu keeps popping up
I noted the board itself wasn't on the schematic and saw the pull down resistors. You're right, as I didn't suspect the board, and remain suspicious of the cable/connectors. I'll check that voltage and report back. I considered squentially removing the switches, and testing the board, but lately the defect has been more sporadic (I hate intermittant defects). Thanks to all, and I look forward to finding the source.Leave a comment:
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Re: Yamaha A-760...no one under 30 needs to read this!
if you're looking at the A-760, the zener I'm worried about is directly under a larger blob of text! Just like the bug that splats on your windshield is always directly in front of the driver's face.....
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Re: Samsung 731N menu keeps popping up
Which point to use the reference while measuring pins 2 and 3?
Now, it won't dance at all....I think it fears the combined forces of Badcaps veterans!...Leave a comment:
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Re: Samsung 731N menu keeps popping up
Ah, I concluded the same thing, yet was really implying that some interaction between the card and the logic board was more the source. I had talked myself out of the only logical conclusion since the button board (front panel card) seemed too straightforward in its construction (three tested normal resistors, 6 PC mount dimple switches which seem to function normally and a normally functioning LED). I suppose I'm a bit jaded by my prior experiences with logic boards!
Thanks for pulling the manual...I had looked,...Leave a comment:
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Re: LG LV880 VCR issues
Definitely a liquid cleaner, and I bet all will be well. You could pop the cover and use 95% isopropyl alcohol with a soft (chamois) swab as well.Leave a comment:
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Re: Samsung 731N menu keeps popping up
Al, you are so right!.
Very interesting. When I disconnect the button board, all is well. The monitor powers up (backlights) when the computer boots, and the display is crisp. When shutting down, the monitor turns off after the computer shuts down, and the backlights switch off. All I lose is panel adjustments.
Would still like to figure this out, though, if there are any ideas on how to repair it completely. I could build a new cable....but somehow I wonder if the problem is at the logic board end.Leave a comment:
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Re: Yamaha A-760...no one under 30 needs to read this!
You're so right. I would have been ticked off if I had spent money on these copies as they were so poor. Looks like someone just slapped an old manual on a scanner and hit the button....UGH.Leave a comment:
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Re: Dead Agilent u1732a
I have a contact with their group here in Texas, and I'll ask around if they can spring a schematic.Leave a comment:
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