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Well, I didn’t expect this type of reaction. I thought people here shared my passion for repairing things. It’s not like I know nothing about electronics, and PSUs in particular, this is just the first time I’m trying to repair one myself. Obviously I made some mistakes at the beginning, but...

I successfully created an adapter for the ATX power supply and it works very well! Now, the original PSU also has output AC. Inside the PSU there is a relay which is operated by the 12V rail, which turns on the AC output. I also ordered a similar relay to possibly keep the functionality. If...

That seems indeed the connector! Thanks! I'll try to see if I can get aftermarket ones. I'm going to try to crimp them using a pair of pliers, otherwise I'll have to get a crimping tool.

The contacts inside the internal speaker of my Quadra 840AV connector are broken. Does anyone know what replacements I need? Also, do I need to buy a crimp tool? Also, does it matter which speaker cable goes in which hole of the header?

Just an update, but I decided to take two approaches. Try to repair the PSU and use an ATX PSU. Fortunately, I swapped connectors with the apple and ATX PSU and was able to get the Quadra 840AV running again! This was a first test and after I confirmed, I quickly ordered PCBs (for the first...

Unfortunately, the PSU I ordered, didn’t have the advertised amperage, so that one is going back. I immediately ordered an alternative one, but soon after I found out that my PC also has a PSU with a quite high 5V rail of 28A, so I can always use that one 😊

Thanks for sharing! This will certainly help. Did you go for splicing or did you use the staple method to transfer the pins to the Mac’s connector? I will order the ATX PSU, and see if I can at least get signs of life from the 840AV. Hopefully it was just the power supply!

I’ve got nothing crazy and I don’t intend to. Also have bluescsi instead of a hard drive. It’s good to know that I can also probably use a better quality PSU with perhaps 20A on the 5V rail.

Problem is, I cannot find any ATX power supply with 30A on the 5V rail from any reputable brands. I assume the Inter-tech I mentioned above is on the look low end.

The reason I asked if I should go with revealing an old one or converting an ATX one, is due to This article. Apparently, the newer cheap ATX psus are not as good as the old ones.

You think so? Everything else looks fine. I’m now wondering if just the MOV short-circuited. I read that this can happen, and indeed catch fire. I can’t find any obvious shorts anywhere. So I’m now wondering if I should risk it and replace the MOV and some of the caps and try again. BTW, I...

Indeed, doesn’t sound very intelligent of me when I read your post! 😅

Bad news, I removed the daughter board successfully, and then went ahead and removed the capacitor with the hanging base. I then went ahead and plugged the psu without the board in, but started hearing burning sound again, I sprinkled some alcohol to try to locate the problem, but it resulted in...

I dusted the psu off this morning, and discovered what seems like a probable blown capacitor — the bottom black plastic is hanging, and on the other side of the board it looks darkened. There is also corrosion on some pins on the same daughter board, and I think at least one more capacitor is...

I had my quadra 840AV (which I recapped and had working) plugged in for some time without using it and randomly decided to turn it on today. Unfortunately it did not turn on. After checking the PSU, I found out I was not getting anything from 12V, only from the 5V rail. After a few minutes, I...

I would like to connect my Quadra 840AV to a PC that has Munt running, emulating the Roland MT32. I was wondering if I can put together a cable that connects the Mac's serial port to USB. Would I need some kind of TTL adapter like this one? Has anyone tried doing this?

Visually, although difficult to see, one of the two lips inside the connector is not extended as much toward the center. Then, when I push the inserted headphone jack sideways towards one side, the internal speaker cuts off, while the connected headphones keep getting sound. The headphones...

I am in the process of restoring a Quadra 840AV and one of the problem it has is that the 3.5mm headphone connector is loose, which causes the connector's internal switch to not trigger, making both internal speaker and plugged in headphones be audible at the same time. I'm wondering if you...

@landoGriffin I recently got a Quadra 840AV, and although the PSU works fine, I want to be proactive in case it dies on me. Do you have any more pictures of how you assembled the PSU, and what ATX PSU do you recommend? Also, did you use the original fan or did you replace that too?

I finally received an stlink I had ordered and I updated the BlueSCSI with the latest firmware and that fixed the problem.