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Thank you for posting this Ray. I own 2 of these amps in a bi-amp system and I have no desire what so ever to change them out with anything. I enjoyed your content fella.

I have 5 of these Tek 485s, two working, two with PS issues like yours, and one parts donor. Indeed the tantalums on the various rails are the main failing points. Your clean, methodical approach of following the shorts on one or another of the rails, and smartly utilizing the power distribution chart in the schematic is much more expedient than what I've been doing in the past. I very much appreciate you having illuminated this approach to me. It gives me renewed enthusiasm to get my other two 485s back on the bench. These are great scopes. Top of their class in the day.

Funny I didn't think I'd find a video with the exact problem I'm having. Never done audio repair though and this feels too far out my wheelhouse so will likely send this to the repairmen I eventually send my unit to lol. Unless you live in NYC! Lmk ;)

I have a Marantz 2265, just move from Chile to Canada, and the volts in Chile is 220v and in canada 110V. I've bought a Setup converter and started the maratnz, I can see the lights but the click noise, that would normaly does which of course is the relay of the protection is not sounding at all. Could it be that the voltage converter is the problem? Im using an UMI 2000W converter. Greate Video by the way!

There are a lot of facets to this issue, and it often comes down to a combination of knowledge, experience, wisdom and luck. I see far too many people on RUclips just getting the cheapest crappiest no-name Chinese "capacitor tester" that has no manual, and the users don't even know if it can test caps in-circuit, and if so, under what conditions; and they don't know how to interpret the results either. They don't know when and how to test for DCR, and leave badly leaky caps in just because their poor capacitor testing method gave an OK based only on ESR. They also don't know anything about the various TYPES of capacitors and their respective issues, e.g. a MICA cap or a ceramic capacitor is almost always still good, while paper caps are almost always at least iffy on older equipment. Mr. Carlson give a nice primer on this topic. Many people who go into repairs and/or restorations just plug equipment in and power it on, possibly blowing up lots of stuff because the power supply electrolytics are badly leaky. Personally, I mostly work on full restorations of equipment (mostly test equipment) from the 60s, and I won't even power that stuff up until I have replaced the POWER SUPPLY electrolytics. Then I replace all paper capacitors. After that, I start to follow symptoms, and replace other caps only as needed. On the other hand, if I was only doing a repair rather than a restoration, I might stop with the power supply elecs and replace only when proven bad.

Thank you Ray for doing these videos. I know it takes lot of time out of your schedule to publish the videos. Cannot thank you enough for the details you go thru using the schematic and explaining every little details. I learn a lot from your videos. One thing I really admire of you is, you are never afraid to admit your mistakes and correct them as you learn. Very few are blessed with that, you are one of those people. Thank you again. Keep up the good work. I wish I lived closer to your place. I would have volunteered to help with anything you needed in the electronics repairs. By trade I am a internet networking and software engineer. I just have the passion and interest to learn vintage electronics gear repairs.

We used to call this practice "parts cannon". Nothing wrong with replacing caps, and other parts if it's needed. But replacing _all_ the parts because you have no diagnostic skills is lame. And if anyone uses the word "audiophile" RUN LIKE HELL!!!

Nothing beats knowing what you're doing.

Gave me an idea, blood-infused gold oil silver foil copper-legged green tea wrapped capacitors. 🙏

Is this module okay to use on amps that where the negative speaker terminals show continuity on the amp it's okay that they are common on the module? Therefore it would have a DC ground to sense any High DC to turn off the speakers?

Tried to make a repair on my 30 year old car by installing part myself and saving pro mechanic markup cost and $110 hr labor. My amateur misdiagnosis wound up costing me twice that of what it would have cost me if I had only taken it to a good mechanic to begin with.

Huuummm .........A crown amplifier with no protection circuit. I wonder what the rational was for that?

What happened to part 2? was looking forward to that part. I got a repair project of 2245 flicking like this and then a Trigger A fail. So was hoping to get some good ideas from here. But like the stuff you post.

do you have any suggestion for replacing the toshiba "2SC1095A" and "2SA2565A" because i have a nikko alpha 440 that have MELTED/DISINTEGRATED 2 resistors an it might be the output transistor that has died and also might have taken 2 drivers with them

Its pretty good that those Black Flags lasted 40+ yrs. I removed them in my AU-719 replaced with Mica caps.

Excellent explanation. But my Marantz SR4000 receiver uses STK3062 and STK0050 integrated amplifiers, and does not incorporate adjustable resistors for the Offset and Bias. One of the channels has an offset of -0.360V, and produces a clicking noise every time I turn the equipment on or off. I´m thinking of adding an IDLING circuit, or an adjustable resistor in the feedback of the Pre-amp. Do you have any experience with these?

Do you include tantalum in the group Electrolytics. They seem to also pop quite often and are electrolytics.

Thanks for actually giving an idea how much DC is too much. I'll watch your other videos about this. Really nice to see 3 schematics. I've got one receiver stuck on protection. I'm trying to learn enough to attempt to fix it. I have another one that may or may not have problems but I've got to buy some throw away speakers for testing. Excellent video, Thanks.

I'll go one step further - if you can't diagnose the problem correctly then you shouldn't be recapping at all, even with a working unit. And I agree that some units just need a wholesale recapping due to age or manufacturing, and that sometimes you actually DO have to begin with recapping if you don't want the power supply to smoke. But these are things you learn over time. Focus on diagnosis first then try your hand at restoration.

Excellent advice.

How do you remove the top front cover to access the tubes. I've removed the screws and there seems to be a clip somewhere on the plastic. It's loose but won't pull forward in the middle. Thanks Ray

If you have vintage audio thats what 30-40 years old, those caps are likely expired, leaking, out of spec or gonna explode and you better hope its not one of those big ones that will smoke your other components. You're an amateur

That was a really great "basic" series of videos. I'm rather new at this and I learned a whole lot of new things, including how to use the Ti-30xa! I appreciate your videos Ray!

Thanks Ray! I have a Parasound amp that does the same thing.

I know this is 2 years old but might be helpful. I use pudding cups for screws & such & stack them on top of one another.

I got a (Akai GXC-709D cassettedeck) where all the caps where way out of spec's, it got recapped and some modifications and it sounds way better and good with new caps.

I heard you mention NAD. When I was repairing Hi-Fi, NAD was known as "Not Another Defect." However, FWIW, I totally agree with "fix it first" before going on a cap replacement expedition. That said, should you run across an electrolytic with the top open and cotton-like material coming out, that cap is a "go-to" in the repair process.

Really appreciate you making these videos, Ray. I find your content to be informative and motivating. John in Pretoria, South Africa.

Give us a clue were your moving to. Just clues. Stay away from Alabama lol

Well why did the offset get out of spec. Something must have changed? Be interesting to know what that was?

People seem to forget a most fundamental law: If it ain't broke, don't fix it.

Hello. I have a boombox with an analog tuner. It does not play any FM station with no static noise. Stereo light comes on. It have a new antenna. FM stations’ signals are good because my other tuners have no problem. Inside the boombox is very clean. Antenna cables are connected. I cleaned all the switches with contact spray. I played with the tuner pot screws but it did not get any better so I put them back to the initial position. What can be the issue?

So glad to hear you mention confirmation bias. It's probably the most dominant human factor in all of audio.

What exactly is the job of capacitors in relation to where they are in circuit and how can you tell what function it is performing? Can identify components and replace them and make repairs but have little understanding of how everything works as a system.

I recapped my crossovers in my JBL S38 speakers. There was a terrible buzz on the right speaker. I didn't have the capability to test them, so I just replaced all of them in both speakers. They sound great now. So like everything, it depends.

Service life, not shelf life. Just to be correct. But great point.

Those green caps are notorious. I used to work at a shop that was a warranty repair service center for many name brands, including Sony, Sansui, Kenwood, Marantz, and more. Those green caps were often the cause of trouble because they would become intermittent.

Merry Christmas Ray !

Hi Ray, thanks for the videos! Very Helpful. I'm looking for an 8904A myself. Would one with only Option 01 and not Option 02 (2nd synthesizer giving 4 BNC's) above serial 2948A be sufficient for MPX alignment? I would be feeding the 8904A into my 8657A? I've seen another RUclipsr mention you need both Options 01 and 02 for FM alignments.

I think your title is right on. I recently sold a 35 yr old amp to a guy who couldn't wait to get it home and recap it. The amp was in perfect condition and absolutely no noise.

What a great and simple explanation of how you narrow down the problem. Even me, an overfed, long haired, leaping gnome type of guy can understand it. Thanks for posting this!

But will it protect when an out put device fails? In other words, the +- 80 volt rails will be sent directly to your speakers. That’s 80/8ohms. That’s 10 amps of current straight to the beautiful speakers. 10 amps at 80 volts! Yikes!

I rebuilt my driver board a couple of years ago and when I was doing the bias adjustment, just like you warned, I shorted between two fuses. So +50v to -50v and blew out my left channel. I tried for so long to try fix the board, it should have been easy because the two sides are exact mirrors of each other but I had no luck. I know it's the driver board because I can plug it in backwards and problem goes to the opposite channel. Eventually I found a board on eBay but I'm going to take another shot at getting my original one working. BTW, I did make a couple of those blown fuse leads for next time, it's very dangerous poking probes down in that area.

manufacturing places have hillbillies they mess up stuff on purpose to spite everything good because there actually garbage, I'm not scared of them because smart people are better then them and know how to fix the stuff silly hillbilly tried to make difficult for us, America is ungrateful for that reason all the countries help them by offering there products and they just cant understand a good thing and screw it up just to bite there thumb at people who actually did a nice good thing for them there, especially manufacturing in Mississippi and Alabama, like rewiring something to be a power surge on purpose geez hillbilly people really i think you owe those nice people an apology for messing up there things hmm ya know noticing that sorta thing perhaps investigations need to happen on a noticing people not having a brain sorta thing, hmmm yeah pretty much everyone getting attacked by dumb butts nowadays is like as i as if they even told my cat she wasn't going to get to have finger nails or something and i was like get away from us ew! garbage these people treat em as garbage and laugh of them dumb

Just what I needed! Thank you!

Can you do a point to point diagram how you have all your equipment hooked together?

Its the new surgery. You need to understand why you are doing what you are doing. If you think you understand but really dont and fail the surgery it will explode

I have to agree with your statement about having to repair the problem before recapping, if recapping is needed, in most cases. I have been an avionics tech since 1984 and have seen aircraft communication, navigation, radar and autopilot electronics failures from many reasons, with equipment built from the 1940s to today. And the electrolytic caps were not always to blame! Even when repairing Amateur radio equipment of many eras, the only equipment that needed recapping was the equipment that showed the need for replacing the caps. What started the craze was the old tube equipment that had the old paper caps that were suspected to be shorting out due to age, followed by the mica caps with the silver migration problem were the typical recapping jobs, and only in the recent years, the electrolytic caps became the number one suspects. But even so,the equipment needs to be working before any caps get changed, as it makes it much harder to troubleshoot afterwards. Sadly we have to reeducate many people before we turn on our soldering stations and begin repairing their equipment and bring it back to working condition before we can even think of any caps getting replaced. And like you said, the caps that are in the unit are sometimes better than the replacements available today, especially if it is tube gear with the high voltage requirements of that equipment!

Thanks for a very imformative video!

Ray- thank you so much for this video. I am new to electronic repair as a hobby and stereo enthusiast.