Marantz 1150 Main Filter Cap

[ZeroG]

In my project pile is a Marantz 1150 to be recapped in the semi-near future. The main filter is a single cylinder but a dual filter cap. I've seen pics on recap threads that show it being replaced with two caps, but so far no description of how that is done. Looks like two new clamps get screwed down, but how are the new caps wired, and by how much can the 13,000uf cap be upsized to?

Thanks! for any assistance.

 

[OverLoad]

Don't get caught up in the main filter extra capacitance hype as in a vast majority of cases it's really unnecessary. I would tend to focus on extra quality versus quantity. A small increase without worrying about rectifiers, power switches, transformers and inrush current etc. will normally be just fine. The 13,000uF is not a standard value so in this case I would use some 15,000uF.

As far as how they get wired, just think of the single can dual capacitor in your Marantz as two seperate caps that share a terminal between them thus there is only three terminals. Obviously two physically separate electrolytic caps each have their own negative and positive terminals. Where there is OFTEN confusion for people having zero to just enough knowledge to be dangerous is they assume the negative terminals mean ground when wiring polar electrolytics. The amp has both postive AND negative supplies. This means the capacitor for the positive supply has it's negative terminal connected to ground and the negative supply capacitor has it's positive terminal connected to ground.

Personally when I restore units I try not to drill, cut or alter the chassis or anything else for that matter in any way. In some cases it's unavoidable and other's the customer dictates. In the case of the Marantz 1150 and 170DC for examples, I choose to custom make and etch boards for solder terminal or snap-in style capacitors. You can take advantage of the 3 chassis mounting holes for the old single clamp to mount the PCB. IMO it's a nice and clean "factory like" look in the end. If you didn't want to get involved with etching you could also use perf board; not near as elegant but it get's the job done.

 

[ZeroG]

OK, so in simple connect the dots step by step language for us electronically challenged, one would be using

1. Two caps that add up to something around/just over 13 - 15,000? OR -
Two 15,000s? (Does a dual core 13,000uF produce 13K or 26K uF?)

2. Three terminals then would be created from the 4 (two pos + two neg) that two caps would total by: Tie one pos and one neg together to form the center terminal? That would yield one pos, one neg, and one in the center as a blend of the two?

3. Add two clamps installed in either perf board or custom made PCB to anchor the new caps/

Muchos Thankyou-ousnesses for your clarifications!

 

[OverLoad]

OK, so in simple connect the dots step by step language for us electronically challenged, one would be using

1. Two caps that add up to something around/just over 13 - 15,000? OR -
Two 15,000s? (Does a dual core 13,000uF produce 13K or 26K uF?)

Remember, the dual cap as I mentioned is essentially TWO SEPERATE capacitors with a capacitance of 13,000uF each. You need two 15,000uF capacitors; one is for the positive supply and one for the negative supply. They DON'T add together. You need to start thinking in terms of completely seperate and doing their own duty. The only thing in common between the two is the fact that a terminal of each one happens to connect to ground.

2. Three terminals then would be created from the 4 (two pos + two neg) that two caps would total by: Tie one pos and one neg together to form the center terminal? That would yield one pos, one neg, and one in the center as a blend of the two?

Yes the dual capacitor shared terminal in this case equates to having the negative terminal of one seperate capacitor connected to the positive of another seperate capacitor. That "shared" terminal gets tied to ground. The left over positive terminal of the one cap gets all the positive supply connections tied to it and the left over negative terminal gets the negative supply connections.

3. Add two clamps installed in either perf board or custom made PCB to anchor the new caps/

If you go the etched PCB route then you don't require clamps. You would simply design the appropriate style of solder pads and spacing during your layout process to accept the capacitor and terminals whether they be a solder lug or snap-in style. The caps sit on the PCB and the terminals act as the anchoring. Some will even have extra "dummy" terminals to assist in anchoring.

As the saying goes, there's more than one way to skin a cat. The etched PCB using solder lug or snap-in style caps is the way I do it in this particular amp. It's not something you can just cobble together and might not be for the inexperienced. Some skills along with thought and planning are certainly required.

 

[ZeroG]

I understand that you wouldn't want to devalue the unit with a sloppy mod. But for only one circuit board it seems excessive to buy all the chemicals and materials needed, if one doesn't have further use for it.

Looks like there is little room to do other than to install a plate and a few spacers. I'll probably use your perfboard suggestion. I'd also think a clamping device near the top would also be a good idea, maybe even just some ABS pipe trim rings cut from an adapter or some 2" pipe, if it fits.

These 15K caps are from a project that was never done, so they're perfect for the job, though there might be ones with a smaller diameter available.

 

[OverLoad]

If you're going perf board route then you would want the clamps to be secured to it or whatever else you choose to mount the caps on much like the exsisting one is to the chassis. Those caps are snap-ins and are perfect for PCB mounting and no clamps required. Extra securement and clamping certainly is never a bad thing though They do look a little big to try and shoehorn in there but hey, it's your project

You get the idea now anyways it seems so you're on the way.

 

[ZeroG]

These 50 mm caps are a little big but if they'll fit then it'll save about $35 for new caps. Seems like even the 40 mm caps would need to be mounted on a board with some spacers (~.5 inch), right?

OK, just for grins - what kind of costs for pcb fabrication are we talking about here? And do all the pos and neg terminals of these caps get tied together, or does any one pos and one neg terminal suffice?

 

[OverLoad]

Some Ferric Chloride and a piece of copper clad board will run you maybe $15-20

Go back, read and try to absorb what I said about how the caps would get wired in place of the single dual cap. Until you fully understand that part then there is no point.

 

[OverLoad]

All you need to do is figure out what each of the three terminals on the dual cap are. They are labelled but you can figure out what terminal is which in seconds by measuring the DC voltage on them. One of the 3 terminals will have approx +46V, one will have -46V and of course the last is the common/gnd. Take pictures of the wiring before hand and mark everything and there should really be no Fup's.

OK, so in simple connect the dots step by step language for us electronically challenged....

I can't "connect the dots" any simpiler than this

 

[ZeroG]

I was referring to the new CDE 5-pin caps, each with two pos, two neg leads, and one dummy lead for support. The question was whether each of the leads needed to be wired in, or just one pos and one neg.

The conversion from 1 dual cap to two single caps was already handled in the beginning of the thread and since then has not been an issue. But thanks fer the purdy pitchas!

Never having had the pleasure of fabricating my own PCB, I appreciate your estimate. Thanks!