For good measure you should check the rectifying diodes. If one has failed it could cause this hum. Make also sure that all ground leads are tight and free of corrosion 😉
I learned how to do all this in the Navy... and they paid me to learn did 25 years. went to formal schools on discreet electronic repair, knowledge, and soldering. the Navy's 2M repair is amazing and because they have to fly aerospace the standards are very specific. Thanks for your videos I enjoy watching them very much and the specific knowledge you share is great!
Aidan a wonderful exploration on whether we are relevant with the advancement of technology. Keep in mind how many times AI referred you to an expert. You have a wealth of knowledge to share with us and your admittance of mistakes makes you realistic and humble. Both more reasons for me to watch you. Thanks for this video of transparency.
I suppose if one suspects the filter caps, one could use alligator clip leads to parallel a good cap to each while still in circuit to test to see if it makes any difference in the buzzing. It could save time.
You are absolutely correct. I repaired audio gear for 30+ years and time is money when you do this for a living. Personally, I would just take a look with an oscilloscope looking at dc voltage plus ac ripple at supply rails and regulated supplies for bad filter caps, but for a quick test of electrolytic caps used in the lower regulated voltages or to couple one stage to another, bridging across with a similar (or higher value) cap can quickly find a bad cap. One exception on the filter caps is when they go bad they can become resistive, draw lots of current, and decrease the dc voltage. With these class A amps from the 70's you are always going to have your main supply rails at identical positive and negative voltages so any difference in the two will generally be a filter cap.
CHATGPT may be good and finding generic answers to questions, but I’d like to see “it” actually work on the equipment! You’re not obsolete Aiden! From what I understand hum is usually caused by bad caps, and hiss by bad transistors. My tech friend has proven this to me a number of times! Looking forward to you finding the culprit.
Another great video. I'm always impressed with your knowledge and your communication skills related to clearly explaining the diagnosis and possible solutions.
Another great video, Aiden. I tried ChatGPT and compared it to Google's Bard. Google Bard is far superior. I asked it about an issue I have with my SX-1010 (Left channel gets very noise after the receiver warms up) It identified two transistors 2sa725 and 2sc1451 that may be causing the problem. I then asked where they are located. This is the response. 2sa725: Power supply board: Look for two 2sa725 transistors located near the large transformer on the power supply board. They will usually be mounted on a heatsink. Tone control board: You might find one or two 2sa725 transistors on the tone control board, usually near the volume control potentiometer. 2sc1451: Power amplifier board: These are the most commonly replaced transistors in the SX-1010. You'll find four 2sc1451 transistors on each power amplifier board, located near the output transistors and mounted on a heatsink. Tone control board: You might find one 2sc1451 transistor on the tone control board, near the phono input section. Pretty cool and again, much better the ChatGPT, or so I think.
Hmmm I would be curious how you got those results because when I tried on Bard it never lists out any transistors. What was the complete phrase you used to get that?
@@plyzo This is the conversation The left channel on my pioneer sx-1010 starts to make noise after playing it for a while. What can cause this? Left channel noise in your Pioneer SX-1010 after playing for a while can have several potential causes. Here are some possibilities: Dirty potentiometers: Over time, dust and grime can build up inside the receiver's volume and tone control potentiometers, causing them to crackle or pop. Cleaning them with a specialized electronics cleaner can often solve this issue. Failing transistors: The SX-1010 is known for certain transistors (2sa725, 2sc1451) being prone to failure, which can manifest as noise, distortion, or complete channel loss. Replacing these with modern equivalents is a common repair. Capacitor issues: Aging capacitors can lose their capacitance or develop leaks, leading to hum, hiss, or other forms of noise. Replacing the problematic capacitors with high-quality replacements is usually necessary. Thermal issues: As the receiver heats up after extended use, components can expand and contract, potentially causing intermittent connections or noise. This can be due to dry solder joints, loose connections, or faulty cooling mechanisms. Other possibilities: Faulty speaker cables, input jacks, or internal wiring can also contribute to channel noise. My follow up question: Where on the sx-1010 are the 2sa725 and 2sc1451 transistors located. The locations of the 2sa725 and 2sc1451 transistors in your Pioneer SX-1010 can vary depending on the specific production run of your receiver. However, here are some general guidelines to help you find them: 2sa725: Power supply board: Look for two 2sa725 transistors located near the large transformer on the power supply board. They will usually be mounted on a heatsink. Tone control board: You might find one or two 2sa725 transistors on the tone control board, usually near the volume control potentiometer. 2sc1451: Power amplifier board: These are the most commonly replaced transistors in the SX-1010. You'll find four 2sc1451 transistors on each power amplifier board, located near the output transistors and mounted on a heatsink. Tone control board: You might find one 2sc1451 transistor on the tone control board, near the phono input section. Here are some additional tips for finding the transistors: Consult the service manual for your specific SX-1010 model. The manual will have a schematic diagram that shows the location of all components, including the transistors. Look for transistors marked with the codes "2SA725" and "2SC1451" directly on their bodies. If you're unsure about the location or identification of any component, it's best to consult a qualified electronics technician. Important safety note: Always unplug your receiver from the power outlet before attempting any repairs or maintenance. Working with electrical components can be dangerous, and it's important to take proper precautions to avoid injury. I hope this information helps you locate the 2sa725 and 2sc1451 transistors in your Pioneer SX-1010. Good luck with your repair!
Great job! It's very entertaining to watch human vs robot diagnostics. Still curious why the corroded cap is good! That thing should be leaking (electrically) all over the place.
How often are bulk filter caps the issue on receivers? I rarely see them failed, at least enough to cause issues. Seems like it's usually the smaller filters in the low voltage supplies and bypass circuits.
Even in switchmode power supplies that have 170+ volts on the main filter caps (rectified mains), you hardly ever find failed filter caps. The caps that fail are always the bulk capacitors on the low voltage DC side - usually on output rails of 3 - 30 V, and the caps are somewhere from 100uF to 4700uF, low ESR / high ripple caps designed for switchmode output filtering. Those are the ones that always go bad. Sometimes it's the small one on the primary side that provides the DC rail that runs the switching controller / oscillator, or some other issue in the startup circuit.
I'm going to say before you find the issue, there must be a Common Ground to the Power supply and possibly in the Relay , as far as how to trace this down not my area !!! But I do suggest looking for Corrosion from the Power Wash!!! Now after watching. I believe I would go through any where corrosion could collect on all the systems until everything has been checked! Again I definitely am no expert at all!
I've been at this a long time, and I could have told you the main filters weren't your problem, although with the corrosion you were still right to replace them. I've seen MANY main filters which had vented and still function. Your actual problem is in the regulated power supply area.
It is an advantage to have some education about the simple AF & RF circuitry used here. To know the limits of AC- & DC coupled amps and its limitations. Allthough the build quality is very good, the circuit solutions are very much standard of the time and with modern components can easily be improved upon with minimal modifications to a more modern std.
Hi Aidan, thank you so much for another great video! I have a Forte Model 3 and I'm thinking about replacing the filter capacitors. The unit is more than 30 years old and there's a slight hum on both speakers. I think it's time to do it and, assuming it fits, I might go a bit higher in capacitance. Questions: - Besides not touching the pins unless I want to get fried, is there any other stuff I need to watch out for? - Do I need to rebias the unit afterwards? Is it ok to not touch the bias pots before replacing and see how it behaves afterwards? Thank you!
I have a Sherwood receiver that had a hum. I recapped it one board at a time. The hum went away after recapping the tone control board. You never know.
My guess is it's probably the 14 volt supply or the regulated = & - 35 volt supply and it may still be a small cap or a bad pass transistor in one of those sub supplies. You'll find it ! I have no fears...
Hello, I have a 2330B model, yesterday the back fuse blew out. I have replace it and it blows again. What suggestion can you give me begin an repair it? Thank you for your feedback.
Hey AH! Maybe you could help me. I just finished a restoration of a Sansui 5050 and I think I may have damaged the new filter caps by connecting things wrong a couple times and powering it up. On start up there is a period of time when the lights flicker and there is a sizzling type sound from the filter caps. It usually continues until after the relay click and then stops and the lights come on fully. The unit works great after that and sounds good. Any thoughts? I think I’ll just swap them out and see if it fixes it. I don’t have an ESR meter.
They have a wire wrapping tool that you can buy. Most seasoned technicians will always tell you never break that connection. If you have to they usually say to unsolder it from the board and keep the wire wrapped.@@brianhajder5013
You could have proved they were bad by paralleling some bypass caps in before you went to the trouble of tearing the board out. If the hum went away then you would have known it was the filters.
I thought the AI was going to have some revelations. Without a half dozen or so, good pieces of equipment, trying to fix any piece of equipment is futile. That's my problem. Do I lay out the money for the equipment, or just bring it somewhere to have it fixed.
Get a trade job. AI can't change brakes, aircraft engines, HVAC repairs, climb power poles but damn sure it can write news articles, and take your drive thru orders. And it's good money!! You don't need college. Go into the Trades!
Hahaha, who would of thought we still need humans to fix things... Well Aidan, you'll just have to fix it yourself. I know right, what kind of BS is that. Oh well, good for you and good for us. Thanks for the look ahead.
