Philips 388 Amp Help Please...

[incredibleh]

Hi Everyone,

I have a Philips 388 Integrated Amp that I'm going to be recapping. I was putting my cap list together and found that my large caps are in series.... Or at least I think they are. It has two 10000uf 56v caps separate from the PC board, wired together, then they head out to their spots on the board.

I've attached a picture of the wiring and I'm hoping someone could double check what I'm looking at before I move forward. These are in series right? Why is it wired this way? And what should I replace them with? I really like this amp and don't want to mess it up.

Thanks for the help,

Adam

PS: It's hard to see in the pic, but the black wiring that looks T shaped is connected to the neg on the right cap and the pos on the left cap. Red on right attached to pos, blue on left attached to neg.

 

[redk9258]

Looks like the black wire is common, red for positive power rail, blue for negative power rail.

 

[elnaldo]

They are in series, as you describe. Negative from your rectifier bridge, to the negative of one cap, that's the "-V". Positive of that capacitor to ground, and to the negative of the other cap. Positive of this 2nd capacitor connected to red wire and to the positive of your rectifier bridge. That's the "+V" rail.

You should replace them with 2 capacitors of same capacitance, same or higher voltage rating. If they are exposed to heat, 105º capacitors are preferred over 85º caps.

Please, read all the suggestions you can find before start to desolder.

My 2 cents: I always MARK all the capacitors with a dot or a line pointing to the front of the unit, so I can remember how they were connected after removed.

IT'S VERY EASY TO INSTALL THEM BACKWARDS when you are working from one side and the other of the PCB.

Also, it´s VERY EASY to forget how the cap was installed, or where a wire was connected. I never remove more than 1 or 2 capacitors at a time. Take one out, put it apart beside the unit, far from the other capacitors you already removed, double check value and position, replace it, bend a bit the leads so it won't drop off the board.

Take a good picture at high resolution of every board, and from details and corners not visible from the top. In case something goes wrong, you have a reference.

Also, it's a good practice (but not always possible), to replace just a few caps from one section, and try the unit to check everything is fine. In case something doesn't work, you only search on that recent work done. If you finish the full recap, without periodic checks, and something doesn't work, you need to trace back the 100% of your work.

Don't be lazy, disconnect everything, specially the plug from the wall. Connect everything and assemble all the parts needed to test the amp. Even if it involves to install 5 or 10 screws and take them out 5 minutes later. If you try the unit in a crowded table, wires and chassis parts hanging around, the chances of a problem increase a lot.

 

[incredibleh]

Thanks for your comments guys, I really appreciate it. I will order the caps and report back once I'm done.

 

[incredibleh]

I have one more question about the caps. Do they need to be audio grade or can they be any matching cap of decent quality? I would like to use 10000uf 105c caps with the same post configuration and size as the originals, it makes it so much easier to just swap them, but I can't find a matching audio grade caps....

 

[elnaldo]

No need for "audio grade" caps. This is the power supply filtering, no audio signal there, you need hi quality tough caps in that application.

"Snap in" type will have that kind of pins.

 

[incredibleh]

Awesome. Thanks for the info.

Adam

 

[ZOOM]

Don't overspend. You will literally be throwing your money away. Pay $2-3 per capacitor, tops. Paying more will not do you any good. 10 mF / 63 V caps are cheap.

 

[incredibleh]

I just wanted to follow up with this thread.

After delaying the recap on my Philips 388 for almost a year due to having a busy life, I took it to a local repair guy that I like for a recap and a cleaning, etc.

WOW! I'm really impressed, this amp sounds fantastic. My current main system is a Marantz 2275 and a set of Mirage 750's, both have been recently recapped/refurbed. I need to spend more time with the Philips, but I'm pretty sure it sounds better than my Marantz. The overall clarity and the finer details seem to be better to my ear.

I was hoping for something close to the Marantz, so I'm very pleased that it may even be better sounding. I still need to spend more time with it, and haven't tried the phono section yet. I will report back in a bit once I get familiar with this amp.

Cheers

 

[Ray Gianelli]

They are in series, as you describe. Negative from your rectifier bridge, to the negative of one cap, that's the "-V". Positive of that capacitor to ground, and to the negative of the other cap. Positive of this 2nd capacitor connected to red wire and to the positive of your rectifier bridge. That's the "+V" rail.

You should replace them with 2 capacitors of same capacitance, same or higher voltage rating. If they are exposed to heat, 105º capacitors are preferred over 85º caps.

Please, read all the suggestions you can find before start to desolder.

My 2 cents: I always MARK all the capacitors with a dot or a line pointing to the front of the unit, so I can remember how they were connected after removed.

IT'S VERY EASY TO INSTALL THEM BACKWARDS when you are working from one side and the other of the PCB.

Also, it´s VERY EASY to forget how the cap was installed, or where a wire was connected. I never remove more than 1 or 2 capacitors at a time. Take one out, put it apart beside the unit, far from the other capacitors you already removed, double check value and position, replace it, bend a bit the leads so it won't drop off the board.

Take a good picture at high resolution of every board, and from details and corners not visible from the top. In case something goes wrong, you have a reference.

Also, it's a good practice (but not always possible), to replace just a few caps from one section, and try the unit to check everything is fine. In case something doesn't work, you only search on that recent work done. If you finish the full recap, without periodic checks, and something doesn't work, you need to trace back the 100% of your work.

Don't be lazy, disconnect everything, specially the plug from the wall. Connect everything and assemble all the parts needed to test the amp. Even if it involves to install 5 or 10 screws and take them out 5 minutes later. If you try the unit in a crowded table, wires and chassis parts hanging around, the chances of a problem increase a lot.

Well said, Elnaldo. Words to live by!