Very nice... I agree. @catch22. Also having some clippers/side cutters/flush cutters for cutting the lead legs is very valuable to have in the toolkit. They usually cost about less than $10 for decent ones like a Weller brand name version. But if you already have side cutters that are sharp and effective then use those.
Unfortunately, registration is closed to new members.
Oh. Wowow. Well I have the service manual downloaded and can email it to whomever wants it.
Private me and give me your email address and I'll sent it.YepOh very cool.
II managed to find one store that has a physical collection point, and ordered collection in 2 days. For those in Ireland - RS. When I get the cap and replace, we'll see further. Thanks!
If I find, I will replace. If not, will try cleaning and tinning/wiping this one, hope will be ok for this cap.
Just ordered today a bit earlier 1.5mm desolder braid from the same RS shop together with the cap. Will 1.5mm work, or 3mm is way more convenient? It is just 3-4 euro for 1.6m length, so no problem to buy another one
These mentioned resistors discharge those 2 huge caps? thats cool
Just wondering it this the main purpose of these resistors, to help the technician? Or a helpful side effect? Oops "Sorry, but registration is currently closed to new members."
Oh good to know for the future as well! So if I ever purchase another Yamaha, it's good 1st to check whether or not the adjustment is part of the design, and if not, check the DC offset before purchasing?
If you have a smaller gauge solder wick that will work too. If you have lotsa solder to removed just double up on the solder wick and voila... bigger wick..LoL.
They are called Bleeder Resisters and they are solely there for discharging the power supply for safety reasons so that you don't get a discharge to your body from the large caps. I was very busy one day @ work and was working on a large amplifier. I was powering ON and OFF and unplugging often and I made a error in process and I took the fully charged power supply caps across my forearm on the bottom soft skin near the elbow area. My arm muscles deflected from the electrical energy, my arm swung up so fast I never even saw it happen, smacked myself in the face very hard, broke my prescription glasses, had a red welt on my face and felt very stupid. I could have broken a bone or been seriously electrocuted. So yes, those bleeders are a good feature to have...LoL.These mentioned resistors discharge those 2 huge caps? thats cool
well yeah
stupid me
With the way things have been going manufacturers are skimping on stuff and not providing stuff that at one time was considered essential stuff. To check the offset before buying opens a can of worms as you might need to purchase it and then measure and return it. But if that works for you then that's OK. The reasons the offset imbalance exists is due to variations in the tolerances of resisters and transistors that are operating in the amplifier circuitry. Also I have seen bad solder as a culprit. Almost invisible cracks caused by thermal expansion and contraction repeating many times causes donut ring cracks in the round solder joint that still conduct electrons although the joint becomes very slightly resistive and that changes the circuit design operation causing offset or worse. Electronics components and circuitry is very very sensitive stuff can be incredibly accurate but with amplifier circuitry being what it is and the nature of it offset is something that cannot be eliminated without a calibration adjustment in circuit or some sort of very difficult to design auto calibration circuit if it even exists. Yamaha has chosen the fixed parameters circuitry method and it works but it's not as nice and cool as having the adjustments in the circuit to manually calibrate to ZERO the offset and also calibrate the BIAS exactly too.Oh good to know for the future as well! So if I ever purchase another Yamaha, it's good 1st to check whether or not the adjustment is part of the design, and if not, check the DC offset before purchasing?
What are the reasons of the disbalance? Some caps losing the original capacity? You will know from the schematics who are the problematic components?
Not everything is rosin fluxed including solder. For differing operations sometimes one needs non-fluxed or fluxed. There are several soldering systems/methods and all require different consumables and they all have advantages specific to the differing operations. The system you use is basic solder with rosin core and thru hole PCBs stuff. The easiest stuff to work with. Purchase fluxed because for anything you do fluxed is the one to get. The desoldering pump is a nice tool for removing large quantities of liquid solder @ the PCB. It's overall less expensive to operate in comparison to solder braid because solder braid gets expensive when a technician is removing lotsa solder all day long everyday. I was buying solder braid in large spools of hundreds of meters each and that lasted me ~4 or ~5 months and then back buying another spool and it was expensive after years and years of buying it. BUT there is no getting around using solder braid. It is a consumable that is worth it's weight in gold per say when servicing PCBs. So get the braid but the manual pump solder sucker is a add-ON that comes after you have the solder wick braid. To get really technical a solder sucker if not a good one from a proper brand name has a mechanical action to the spring loaded suction assembly. The spring when moving the suction diaphragm causes a mechanical kickback that can actually damage the PCB copper trace. I used a solder sucker a lot for really big gobs of liquid solder and I owned a pretty expensive electric solder sucker that looks like a handgun and that was the preferred tool combined with solder wick.Since this thread is becoming a tutorial for beginners
1. Desoldering braid - clear (if such thing exists or they are all fluxed?)
vs
2. Desoldering braid - with rosin - example 4 euro (3mm 1.6m fluxed) https://ie.rs-online.com/web/p/solder-wicks/1047690
vs
3. Desoldering pump? - example 25 euro https://www.amazon.co.uk/Weller-7874B-ESD-Safe-Desoldering-Aluminum/dp/B00DKYNKPK/
Very cool. Thanks. Every bit of contributing assistance and technical know how is a major big advantage. Are you good at figuring out where and how to MOD the Yamaha amp circuitry to include a BIAS and a OFFSET calibration trim pot for each adjustment? I'm not a electronics engineer as I mentioned before in a comment and from that I decided some time ago to stay in my proper lane when it comes to MODing circuitry unless a MOD method is provided to me by a manufacturer.
Ooh, ooh, I have some stories! I had a electronics bench in high school, full of discarded vacuum tube equipment I fixed up. Once I discharged the full plate voltage from an old CRT oscilloscope through my pinky. A loud crack, smell of burning skin, and I jumped about a foot. I think it was about 2000V in a big metal can cap. Taught me some respect.
Sure, send me the schematic (I sent you an IM) and I'll sketch some ideas.
All very WoW moments for sure. I have never ever ever everrr (LoL) serviced a microwave oven. I decided to go straight to mechatronics and avoid all that dusty yucky TV and microwave oven stuff in consumer/domestic electronics repair and so that's what I did. Anyway my workmate was working on a big size powerful model of Panasonic microwave oven and he took the powered ON magnetron on his body somewhere. He yelped pretty much exactly like a dog does when in fear and major pain. After his eyeballs where huge and he was a mental mess. Could not talk properly and was muddling his words and was generally amazed that it happened and took the remainder of the day off work because he was not fit to be at the shop. We where very concerned at the time because that was a near death experience. Another account was my father a industrial firefighter paramedic in a fully equipped fire department overseeing the safety and security of about 7500 workers at that location. He and the crew attended a call and they found a male electrocution victim crispy all over and alive. He was administering mouth to mouth because that was still the method at that time and the victim convulsed and ejected the contents of his stomach out the mouth into my fathers mouth. It took days before he could look at food and eat it. He was a mess for weeks and really was having a difficult time of life. The electrocution victim lived for awhile as they manually kept his heart and lungs operating but he died at the location of the electrocution. I really respect my father for that. It made him seem like can-do type of person that didn't give up no matter the circumstances.
Far out!
Oh man! I read some anecdotes online that large capacitors can hit more painful than the grid... I myself was hit by 230V a couple of times, nothing pleasant either...
Must be a bit milder in North America?
Yes, in North America/Canada we mostly have 120VAC for the residential mains although for clothes dryers they use 240VAC. I have sustained hundreds of 120VAC shocks and it's not a big thing for me now but 240VAC is not pleasant and I avoid that like the plague. 240VAC is danger zone de jour to me.Oh man! I read some anecdotes online that large capacitors can hit more painful than the grid... I myself was hit by 230V a couple of times, nothing pleasant either...
