Hi, I have a question regarding a motherboard with SS capacitors that I'm having trouble with. Every now and again it would give overclock failed at boot even when not overclocking.
Recently more often, and the last few weeks at every single boot. It seems like the typical capacitors needing to warm up, then everything is fine.
Weird thing is the capacitors are all solid state. Do SS capacitors degrade the same way as normal caps? Is it worth trying to recap the board?
I have already replaced the PSU.
The board is a gigabyte x79 ud3....
amelbye
Member
Last Activity: 11-06-2022, 10:38 AM
Joined: 04-14-2011
Location: Oslo
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degradation of solid state capacitors in motherboards?
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Re: is it ok to replace a dual output transformer with two single output transformers
There are 6 wires going from the transformer to the main circuit board:
15-0-15 and 50-0-50. The center of the 50V rail is connected to Ground, and the center of the 15V center is not connected to ground, or at least not the same ground. Perhaps the preamp-board has its own groun reference. I think I'll leave the center taps separate for now and give it a try
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is it ok to replace a dual output transformer with two single output transformers?
Hi, some prestory: I was repairing an amplifier - a "Phil Jones Bass". It had some bad capacitors an a faulty power switch. Easy job. However upon putting it back together I screwed up. The connector from the 15V-0V-15V from the transformer is identical to the audio ouput from the preamp board to the poweramp board. I ended up putting +-15VAC into the preamp outputs frying some traces on the circuit board along with the power transformer
The transformer is shorted. It blows the fuse immediately even with no load on the secondary.
Now that's a challenge - luckily...Last edited by amelbye; 08-21-2020, 08:52 AM. -
Re: C-Audio RA500 troubleshooting
The second unit: I must have been doing something wrong - the transformer is working again!
I like to build a shopping list large enough to get free shipping before ordering parts - I'm not quite there yet. I need to get started on the next project and will probably have enough to place an order next week. When both units are up and running I'll look into what the trimpots do. Any advice on what could be the purpose of the third pot on each channel would be great!Last edited by amelbye; 08-20-2020, 10:49 AM.Leave a comment:
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Re: C-Audio RA500 troubleshooting
Sorry for the delay, here are some pictures. I did one overview of the whole amp, one of where most the stuff is going on (left side of the heatsink is only rectifier and smoothing caps). Then I did three where I point at problem areas: one pointing at the two capacitors that measured fine in circuit but turned out to be faulty, one pointing at the overheated area causing the +15 rail to drop and one pointing at the component in the driver circuit that caused one channel to go silent....Leave a comment:
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Re: C-Audio RA500 troubleshooting
Solved it - by taking 2 working C2910 transistors from the dead unit, voltages stabilized and the dead channel started working again.
There is one more resistor that should be replaced. R202 has been running hot. It seems to be a 2k2 resistor, both units measure the same but I can't tell from the color bands, they are too faded. I'll upgrade it to a 3W part, and add heat sinks to all TO92 parts.
Then I'll have to figure out what the 3 pots pr channel do. Any clue what the 3rd one would be for?
I'll leave...Leave a comment:
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Re: C-Audio RA500 troubleshooting
The transformer shows continuity on the windings, but I have no voltage coming out of it - I'll get back to that unit in time - for now I'll focus on the unit that still is partially working.
I'll post some "unneccessary" info here in case someone with a similar problem comes across this thread in the future:
I pulled all the electrolytes. C207 and C208 were in fact faulty. They mesured fine for ESR in circuit, but there must be something in parallell that throws of the reading. I also replaced all the 14 small 22uF...Leave a comment:
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Re: C-Audio RA500 troubleshooting
A thought that just came to mind: Is it possible for a capaitor to test good for ESR and still leak?
I haven't come across such behaviour before, but it seems that this might be what's going on here...Leave a comment:
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Re: C-Audio RA500 troubleshooting
Thanks, local, I'll check them out!
I put some more time into this yesterday. Of the two amplifiers one has CH1 completely dead, the other has CH2 completely dead - so the thing upsetting this amplifier is probably concentrated to only one of the channels.
On one of the units the power transformer died yesterday, for no apparent reason. Fuse did not break. I guess I'll part that one out and use the chassis for a class D build. I'll still try to revive the second unit.
There are capacitors...Leave a comment:
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Re: C-Audio RA500 troubleshooting
I'm afraid the Alesis RA-500 and the C-Audio RA-500 are not the same unit.
I'll post pictures tomorrow - I have one of the units cracked open at my desk at work
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Re: C-Audio RA500 troubleshooting
The power supply is shared between the channels, each channel has its own protect circuit - possibly operated by the same chipLeave a comment:
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Re: C-Audio RA500 troubleshooting
It does actually come out of protect, but seems pretty sensitive, it some times enters protect just as I touch things with the probe of my multimeter.
I'm guessing the amp is class AB, it's an old design.
I just noticed a high amount of AC on the positive main rail - could be the multimeter misinterpreting but I'm guessing I have a lot of ripple on there - my output caps seem healthy but I'll try swapping in a fresh one and see. Could be the ripple has blown something down the line.Leave a comment:
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C-Audio RA500 troubleshooting
Hi, I'm trying to repair a C-Audio RA500 amplifier (one dead channel). In fact, I have two identical units with the same problem, so I'd really like to figure this one out. I could just throw parts at it, but I'd prefer to understand the design, and that's why I'm asking for help. I'm hoping someone here is familiar with the design - I'm not a pro and have no relevant education, I just enjoy solving problems.
I can't find a schematic for this unit, and apparently it was manufactured by some other company and is not similar to other C-audio designs.
It's a single rack...Last edited by amelbye; 08-11-2020, 08:11 AM. -
Re: Bosch washing machine PSU problem
The board is labeled Siemens, so probably made by Siemens. I know they exist in Miele machines as well. But yeah - soot attracted by hight voltage makes sense, as all the components seem to be in reasonably good shape.
I cleaned up all the soot, and remelted the solder joints on all components going through the circuit board, leaving the SMD components alone. It seems to have fixed the issue.
For future reference (if someone has a similar problem): the 25V capacitor is running at 9V. If all else fails, one might be...Leave a comment:
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Bosch washing machine PSU problem
For future reference: the washing machine is a Boss MAXX 6 - WAE32160NN/01. the power supply board is labeled 5560 005 559, 9000159339, 9000162937, 170706/418 and 5560 004 652.
Recently my washing machine has started smelling like burnt electronics during use. It still works, but after a bit of sniffing around I found that it was most likely the PSU board. It has serveral burnt areas.
Surprisingly I can't seem to find any malfunctioning components. The worst condition (most burnt) part seems to be the switch mode transformer, and it's not a standard part, so I don't see... -
Re: DIY smart TV or replace tv main board with newer model
I've had a similar thought. I have a high end TV, but it's 10 years old. Picture quality is good enough for me, and I have it hooked up to both a chromecast and an ubuntu-machine running kodi, so it does most the stuff modern tvs do, but without the glitches and poor performance that I've seen at my friends houses.
What bothers me is more about aesthetics. First gen LCD screens have huge bezels, and if TVs are anything like computer monitors, that bezel is completely un-neccessary. I'm sure the only reason...Leave a comment:
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Re: Pioneer SX-434 repair thread
after warm-up voltages between point 27 and 24 and ground move to -20mV and -10mV.
I guess these voltages are the center point of the amplifier and should be somewhere around 0 if the output gains are reasonably matched?
In the amps I've done in the past I've adjusted center point by running the amp into clipping with a sine wave input, then adjusted for symmetrical clipping. I guess this is just a simplified way to deal with this?
The bias voltage is 25mV on both channels. Should be more than 5mV it says, doesn't...Leave a comment:
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Re: Pioneer SX-434 repair thread
I put in the MJE15033G and MJE15032G and the amplifier works!
Now, here's the procedure for aligning the power amplifier:
I'm confused by this. point 3: does it mean that I should cut the jumper if my voltmeter gets a positive readout?
same goes for point 4, cut the jumper for any amount of negative readout?
I get -16mV on one channel, and -8mV on the other between pin 24/27 and ground....Leave a comment:
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Re: Pioneer SX-434 repair thread
Thanks R_J!
I didn't realize darlingtons wouldn't work as replacements (because I don't know what darlingtons are), I thought I was being clever
And regarding the heat-sink isolators, I didn't realize exactly what voltages would be present, but this is exactly what I was guessing.
I'll look over all transistors and resistors in this part of the circuit.
The reason I started troubleshooting to begin with was that one channel had no bias voltage. I'll do what you advised and post...Leave a comment:
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Pioneer SX-434 repair thread
Hi, I'm trying to repair an SX-434 for a friend.
As of now all the outputs are blown. Completely my fault. Long story short, they had to be replaced. Original parts were NLA, so I replaced the Sanyo B507D (PNP) and D313D (NPN) with 2N6042 (PNP) and 2N6045 (NPN), by matching up specs. I found parts recommended across the web but they were all expensive, so I decided to match them up myself.
So I soldered them all in, and here's my first question:
All the collectors are connected together at the heat sink. I can't recall if there were isolation pads or not (I...
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