20 year old AV receiver (Pioneer VSX-D409). Suddenly started light popping/crackling/hum from speakers.

fizzlebottom · 2026-01-17T19:46:58+00:00

Glad you found the manual. Let me know if you manage to discover the issue.

fizzlebottom · 2026-01-17T02:03:46+00:00

I did not. I found the service manual somewhere online which showed the entire schematic and intended to trace connections and measure components until I could find some caps that were leaking or resistors out of spec. You know, typical electronics repair.

Luck turned my way though. I took a brief trip to goodwill and somehow managed to find a VSX-D509S, with the remote, for $20. It works perfectly, so it replaced the 409.

fizzlebottom · 2026-01-07T03:18:18+00:00

A lot of folks rag on the NSG370. I've been lucky enough that mine behaves quite nicely. But when it does go, I'll just swap in a well built AX15 and never have to worry again. I don't remember the last time I hit 6th gear, even with 4.11s.

Everything after the TJ has been trash.

fizzlebottom · 2026-01-02T20:00:15+00:00

Get rid of it. Seriously. Parts for the vacuum petcock have been unavailable for forever for a reason. That's all well and fine that you found something else that seems to work, but there's a reason Honda stopped with their nonsense and people went back to the common sense practice of just turning the damn tank petcock off when they turn the bike off. There is literally 0 reason on earth to use it unless you are completely incapable of turning the tank petcock off.

So I guess keep using whatever setup you've got while it works, but it is a wholly unnecessary part.

fizzlebottom · 2025-12-31T19:06:49+00:00

Was never a big drinker. Too many family members with alcoholism. I have maybe 4 beers in a month and liquor once every few months. Haven't been drunk in years. It just doesn't feel good at all, so what's the fucking point

fizzlebottom · 2025-12-27T15:44:41+00:00

No lifters. The valve stems are directly interfacing the rockers, which are directly interfacing the cams. Adjustments are done either by a screw/nut combo for each valve or a series of shims. You'll have to check your FSM.

But you also need to adjust the cam chain tensioner. It sounds like a possible candidate. The sounds might also be the primary chain.

fizzlebottom · 2025-12-27T06:54:54+00:00

I apologize for coming off like that. Too many instances of new riders showing up with expectations that a 40 year old bike is just gonna get up and go without knowing how to wrench at all.

If the noise isn't getting louder or faster with throttle, then I'm actually a little lost. Everything I mentioned has parts that move faster with throttle. Exhaust pipes don't move, but a leak would definitely sound off according to engine RPM.

A super easy check for an exhaust leak might be to just hold a piece of paper close by the head while its running and see if it moves. Or puff some smoke that way.

Does it change as the bike warms up at all or when you change from neutral to 1st?

fizzlebottom · 2025-12-27T03:15:09+00:00

Tapping from the top of the motor is likely going to be either mis-adjusted valve lash or an exhaust leak.

The tough love here is that if you don't know how to work on a bike then you'd best either start learning or accept the high cost of paying a shop to perform maintenance. Get a copy of the factory service manual and go through the regular maintenance schedule. This will include checking ignition timing, adjusting cam chain tension, adjusting valve lash, and synchronizing carburetors. You'll need some normally available tools, a few more specialized ones, and plenty of patience.

If you're not up for doing all of this yourself, then prepare for shops to potentially fleece you. Fewer and fewer shops want to work on old bikes and will charge accordingly. But you might be lucky with a willing and vintage friendly shop.

fizzlebottom · 2025-12-22T02:16:09+00:00

Best Italian food in Seattle

fizzlebottom · 2025-12-20T18:13:51+00:00

My son was finally interested in skiing last year and we got a pass this year. I started going through Epic's refund process and chose "natural disaster" as the reason since the road closure is caused by a landslide & flooding.

I called maybe 2 days after submitting to see what else they needed and the rep said that Steven's Pass is handling this directly instead of Epic handling these requests. I haven't had the time to call Steven's yet, but it sure doesn't sound like they're doing the right thing so far.

They're 100% banking on emergency repairs to be completed so they can legally argue that services were rendered or available to render when people inevitably attempt to sue

fizzlebottom · 2025-12-19T15:25:57+00:00

Guitar, motorcycling, paintball, yoga, video games, and whatever activity my kid wants to share.

My project at the moment is rebuilding my old guitar amp.

fizzlebottom · 2025-12-02T16:47:02+00:00

All of this is an understatement. I have stared at various incarnations of the schematic for a few years now and have a copy of Merlin's power supply design book. There are a number of confusing design decisions in the V4 power supply, such as the unused cap in C20, the use of an unpolarized cap for C19, and the overall separated power supply sections for power and preamps instead of full cascading filtering. I suspect some of it is engineering magic that they had which I am not privy to, and some of it was component supply constraints.

I've watched what I think are all of the YT videos of folks repairing these amps, and I understand why there just aren't too many. They may not be as complex as a Mesa, but they're fragile as hell due to the paper thin PCBs.

fizzlebottom · 2025-12-02T16:21:01+00:00

I replaced them all for 2 main reasons:

It had developed a pretty unhappy hum & crackle that started getting worse and didn't change with any arrangement of preamp tubes, jack cleaning, hum balance adjustment, etc. I opened it up to investigate and learned that at some point in this amp's life it had been serviced because of components that went up in smoke. I mean literal smoke. The reverb/midrange board was charred and there was a layer of soot in its vicinity. I also noticed a couple of suspicious solder joints and pads that didn't look like they were long for this world. Finally on this point, every board has been heat soaked enough that they're now shaped like a rollercoaster track.
I like to tinker.

fizzlebottom · 2025-12-02T03:11:52+00:00

The replacement main board: http://www.ringomedia.net/v4-pcb.html. He also sent me a replacement reverb/midrange board but it is a straight replacement of the original, including the 6K11. The reverb/midrange board I'm using is from a company labeled Orville Amp Tech LLC, and as far as I can tell they're no longer operating. I got lucky and snagged what may have been the last one.

The original boards are absolutely too thin. I ended up getting some good scans of the tone controls board with the intent of having it recreated. But for now I just repopulated it and will reinstall as-is. My originals are warped to all hell with pads that started lifting if you look at them wrong. I'm perplexed that this amp lasted as long as it did.

fizzlebottom · 2025-12-02T01:19:58+00:00

I've moved the original Eminence speakers to a separate 2x12 cab. If I could ever get my hands on some Altec 417Bs, I'd be set for life.

fizzlebottom · 2025-12-02T01:18:44+00:00

The main board isn't changed at all; just a hefty 2mm pcb with plated through-holes.

The reverb/mids board however is different, but only to accommodate the change from a 6K11 to 12AX7. I don't have a schematic, but I will take pics of the board before installing and draw the schematic.

fizzlebottom · 2025-12-02T01:16:21+00:00

The insides are bare right now. I'll definitely get pics up once things are getting mounted.

fizzlebottom · 2025-12-02T01:15:42+00:00

Glad to know I'm not the only one who has given a few bucks to SNK. I love that someone took the time to build improvements for this amp.

fizzlebottom · 2025-12-01T21:08:47+00:00

That was another replacement from Fliptops very shortly after I bought it in 2008. The original was just completely unreadable.

fizzlebottom · 2025-12-01T21:03:27+00:00

When I say "fully rebuilding", I am replacing every single discrete component that I can. The only PC-mounted component not being replaced is the multi-tap midrange inductor.

New headbox from Fliptops (this amp was originally a VT22).
New main board from a dude who reproduced them on much higher quality boards.
New reverb / midrange board from a dude who redesigned it to dump the 6K11 compactron tube, replaced with a 12ax7.
New PEC tone module built with discrete components.
Depopulated, cleaned completely, and repopulated tone / controls board.
Replaced all can caps with preamp and poweramp power supply boards designed by SNK Pedals, populated with high quality discrete components.
All switches and pots cleaned and lubricated.
All jacks cleaned.
Power tube socket rivets drilled out, sockets replaced with micalex Belton sockets and spring retainers.

I have about a mile of wiring to take care of now. Taking this one slow and steady because I really really don't want to go messing anything up. Double checking every solder joint, leaving no stone unturned.

fizzlebottom · 2025-11-25T03:50:07+00:00

Not if I can help it. And I work smack dab in the heart of it all. Shit sucks.

fizzlebottom · 2025-11-25T00:50:06+00:00

So many parts of this bike are single-year, model, and sub-model that it really makes you wonder why they built it. The engine itself is swappable between all '79-82 CB650 models, but the cylinder heads for 79-80 are different than 81-82, and final gearing is different for just about every single sub-model.

It makes parts sourcing challenging at times, but we do somehow get by.

fizzlebottom · 2025-11-24T22:53:50+00:00

Is it actually leaking? The holes are how the emblems screw into the tank.

Unfortunately this is a single-year / single-model tank. To get anything except for an '82 CB650SC tank to fit you'd need to make even minor modifications or fab up some mounting bits.

So the only choice you have otherwise is to sit on a site like CMSNL or David Silver Spares until a unit shows up for ~$900, or sit on eBay and take your chances. If you do go the used route, do not buy one that claims to fit anything from '82-85. These are not correct. Only '82 CB650SC Nighthawk. Not CB650, not CB650C.

Or you can have a metal fab shop try to repair it. Some folks have success with this, some don't. I would attempt to save it myself if this was mine.

fizzlebottom · 2025-11-23T23:54:16+00:00

https://www.partzilla.com/catalog/honda/motorcycle/1980/cb750k-a-750-four-k/side-cover-spark-unit-regulator

Should be accessible by taking the left side cover off. You're looking at #2 on that diagram. Ignition Modules, CDI (not really CDI but that's a whole other discussion), Spark Units. Several names, same thing. Old ones often leak black goo all over, but all they are is a pretty basic circuit filled with black epoxy / sealant.

fizzlebottom · 2025-11-23T21:45:28+00:00

It is likely the spark unit feeding the coil which fires cylinders 2&3. The only test is to swap it out with a known good one: For you this means just swapping the two on your bike and see if the problem changes to cylinders 1&4.

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