eccerr0r
Solder Sloth
Last Activity: Today, 07:24 PM
Joined: 11-08-2012
Location: CO
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Yeah the cells you have for this topic is 726Wh total, so the box is $137/kWh. $40/kWh sounds a bit nicer but at least these cells are new. -
My electric rates have gone up, but not really that much. Just that I want to f**k with the so called "peak demand" hours where they charge 3-4x nominal rate because they want people to reduce consumption during that time. With the batteries I want to do some arbitrage...but more importantly it would be nice if I could save some of the excess power my solar panels are generating and dump it during the peak demand hours.
Unfortunately even as fun as it sounds, it's not worth it TBH. The battery cost simply doesn't make sense or at least the payback time is immense. If I buy...Leave a comment:
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I just want to f**k with the electric company just for fun
Or also power my electric lawnmower when its battery goes flat (it currently uses a lead acid 24v 10Ah pack.)
I've been recharging my cordless mouse's alkaline AA battery because I'm cheap. Really need to find some cheap NiMH that hold some energy. Since BH is selling cheap alkaline AA's too, I don't know what I should really do. 200 alkaline AA's for $10 will buy at most 4 NiMH AA's? (my mouse uses 1AA so not much space to work with...)Leave a comment:
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dang...about ready to push the button on a few of the used packs from BH... should I beware?
thinking about seeing if I can save a kilowatt hour and dumping it back onto the grid when the electrical rate is high, but unsure how my GTI will handle it, not to mention still need to figure out how to charge these batteries.Leave a comment:
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Looks normal to me, looks like red-green-blue-green repeated which is fairly common?
If there is no blue the screen would be yellowish. If it's white it's fine...
actually i'm not sure what i'm seeing, pixels are not perfectly focused. hmmLast edited by eccerr0r; 02-01-2025, 01:52 AM.Leave a comment:
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Actually now reading the other forum, that's what he did with the scopemeter though it wasn't clear since the wording wasn't in the same post as the photos... Still not clear whether they are probed the same way (which probe is on B and which is on E) - by the looks of it, all 8 transistors are cutoff... minus Q41b which seems to be have noise on it.
Ideally measure B-E with red on B, black on E with DVM. A properly biased transistor will have around .7V when you measure a NPN and -.7V when you measure a PNP.
Also unclear if you got the formerly working channel working...Leave a comment:
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Don't worry about the scope now. Not helpful because the biasing on Q41a/b is wrong, really wrong - if you measured the voltages properly. Besides, I'm not sure how you hooked up the probes and the waveforms mean nothing without that point of reference.Leave a comment:
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Correct, but I would assume that 145 should be somehow tied to the positive rail in order for Q41a/b emitter to be at a higher potential allowing the transistor to function in common emitter mode and allow for gain. As mentioned the B-E junction of these transistors are in deep cutoff or reverse breakdown which shouldn't be affected by the downstream Q44a/b. Perhaps something with Q42a/b could cause a problem with Q41A/b... don't know...Leave a comment:
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Well actually the problem was showing with the DMM only and no oscope was needed because we measured Q41a/b were deep cutoff/reverse breakdown and this needs to be fixed. As far as I can tell, again, I don't understand node 145. and how it's pulled up to the high side, and this is necessary to get proper biasing to work...
Actually do you have a clear track photograph somewhere? Are the two 145's for both channels hooked up together on the board, and what else is it hooked up to, other than R41a R41b R412 R443 R411 and R442? Could the only source of the bias depend on the midpoint...Last edited by eccerr0r; 01-08-2025, 06:55 PM.Leave a comment:
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something wrong with emitter voltage but the schematic's too confusing for me to read. "145" or port 9 (probably the subassembly pin 9)? goes to both but I don't see where it goes, must be something tying this transistor to the positive rail but haven't found it yet... If your measurements are right, the transistor's in deep cutoff and no sound is going through.Leave a comment:
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it appears that power is used solely for biasing the bases of Q41a and Q41b. What are the voltages there?
This is a high impedance power supply so it will be heavily dependent on these loads.Leave a comment:
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Oh it did look like you changed the polyester and ceramic disc caps. Nope, it's on you to figure out what was disturbed....Leave a comment:
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As said, any scope will work as long as you know how to use it.
Did you only disturb electrolytic capacitors or did you also replace ceramic/polyester caps? I don't think any capacitor really needed to be changed but for the "J"/Left channel:
capacitors removed/broken that would cause no sound: C403 C417
The other ones would cause sound quality issues.
If C403 and C417 are intact, then did you check all the voltages against the voltages on the schematic and find a point where the voltages don't mismatch?Leave a comment:
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Reading your other followups in the other forum it looks like you failed to follow an important mantra when working on something you don't understand:
>>> Change one thing at a time.
Your first priority is to fix your previously working channel and you definitely did something to break it. Check all your connections carefully.
Also I disagree with the person who claims low frequency scopes are of limited use -- pretty much any scope, due to the low frequency of audio, is usable. In fact a bandwidth of 100KHz is sufficient for most debug and a 200KSPS...Leave a comment:
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Technically in steady state/quiescent/0V input, the voltage at the input of the capacitor should be about half the rail. and the output should be near 0 V because the speaker is pretty much a short to ground at DC. If it's not 0V there's an open somewhere after the capacitor...
if there's no open after the capacitor and all the voltages prior to the capacitor matches the other channel, then you'll need the oscilloscope to find where the signal is lost. Severe loss in volume is a rare failure mode in circuitry unless it's a bad pot/connectors/loose ground or something like R402 got...Last edited by eccerr0r; 01-02-2025, 12:30 AM.Leave a comment:
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well looks like most of the work is done isn't it?
Did you try swapping C416 and C417 or swapping the suspect bad capacitor with a spare or even a smaller µF if you don't have an exact one?
I think you can ignore R416/R426/C420 and R417/R425/C419 for now, they shoudn't fail in a way that would cause no audio output. They will pull a weak capacitor to 0V as they are a resistor network after all.
So you say the speakers are good, so C416, swap it and see... A dried up, broken C416 will behave the way you seem to observe.Last edited by eccerr0r; 01-01-2025, 07:43 PM.Leave a comment:
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Have not forgotten:
[URL=filedata/fetch?id=3525103&d=1733820400][ATTACH=JSON]{"alt":"Click image for larger version Name:\tpointless.jpg Views:\t0 Size:\t156.0 KB ID:\t3525103","data-align":"none","data-attachmentid":"3525103","data-size":"small"}[/ATTACH][/URL]
Why did I bother... I'm currently using secondhand units from a thrift shop that will never have this problem.Have not forgotten:
[URL=filedata/fetch?id=3525103&d=1733820400][ATTACH=JSON]{"alt":"Click image for larger...Leave a comment:
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Needs an IC to negotiate power so likely you'll need to get the adapter else you'll have to emulate the IC.Leave a comment:
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make sure the output isn't shorted and you're not chasing after something that doesn't exist...Leave a comment:
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woah wtf.
that tap is the input/hot tap, the browned out section is the "boost" section and the right is the 'buck' section?
Usually if you have a short, two adjacent windings are shorted. This looks like you have a whole bunch of windings that are overheating? Means the boost output is shorted against something perhaps?Leave a comment:
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