Any reason not to use these...

[I'm a beginner!]

Hi folks! I hope everybody's projects are running nicely!

If the photo has been added succesfully you should see an image of a JCM800 chassis. It's not mine, but the one I have looks very similar, a few more dents.

The amp itself has many faults that need correcting, too many for a single thread (or two, or three, or four...) but...

If you look in the picture, those big blue capacitors. They have died (one has changed shape).

Because I'm not blessed with golden ears, and I'm not bothered how a chassis looks or whether all the parts are original or NOS or whatever, I just want the amp to make nice noise... I was wondering if there is there any reason not to use some of these EEUEE2W470S - PANASONIC - CAP, ALU ELEC, 47UF, 450V, RAD | Farnell UK to do their job? Since I already have some and those big blue ones are really hard to get around here it would be a bonus if I'm good to go with the panasonics!

[Enzo]

First: changed shape. Did the black end of the cap bulge up? That is just a plastic disc covering the end of the can. SLit the blue wrapper, and free the disc. Is the aluminum can bulged under there? Those discs can warp over time. If the can is not warped, the cap may be OK.

What does the amp do wrong at this point?

As to your sub, aren;t the big blue ones 500v caps? Your 450v subs might not be very happy trying to handle 480 B+.

[nickb]

^^^ What he said ^^^^

This thread is relevant too http://music-electronics-forum.com/t36909/

[I'm a beginner!]

Oops! My bad, I posted the wrong link!!

I would like to use these - EEUEE2E101S - PANASONIC - CAP, ALU ELEC, 100UF, 250V, RAD | Farnell UK

I was going to use pairs in series for 50uF with resistors to balance the voltage. Make a little board and put them where the big blue ones went.

Thanks nickb for the link to the other thread - it's nice to know others have faced the same dilemma! I was going to have my little board on show, but I suppose I could always keep the big blues so I can drop them back in if I ever get rid of the amp (unlikely while there's a breath in my body! etc)

It's an expense thing. I can buy the radials easily through work, but can I find a supplier of the big blue ones? Well yes, but I'm getting nailed for shipping... factor in the shipping costs and the caps would cost me about £25 each (I think that's about $38 US) so if I can rig something from what I have I'd be happier.

Thanks guys!!

[oc disorder]

The photo from "Beginner" is a 50 watt Marshall. Correct me if I'm wrong but isn't the HT in those less than 450v ?
If it is surely the Nat Pan caps would be ok with 2 in parallel either side of the choke to approximate 100uF.
I gather LCR no longer make caps so F&T would be a good choice although rather expensive for a beginner.

[I'm a beginner!]

It is a fifty watter - good spot!
There's loads of faults need correcting, but the caps seemed like an easy place to start.
And expense is a big consideration!!

[nickb]

Have you looked here FTCap Dual-section 100x100uF 500V LFAZ10150035066

[I'm a beginner!]

They are yummy looking things but I can buy 17 or so of the Panasonics for the same money... before adding the shipping.
Looking on the datasheet the lifetime is rated at 4000h. I'm sure the Panasonics are rated better than that, so it looks like I'm better going with the ones that are easy to hand. Thanks for introducing me to that site though! I'll be exploring that as I do more projects I'm sure!!

I'll still examine the big blues more closely as Enzo suggested, but not until the weekend, too much on at work!!

Enzo asked what the amp does wrong... that's a long list!

But a few of the more annoying faults are:

Gigantic background hiss regardless of volume levels, channel or guitar.

Imagine you're playing, and an annoying person grabs the volume or master volume control and starts widdling it at random while you're playing. It does that. Regardless of channel.

Imagine you're playing, and an annoying person grabs the gain control and starts widdling it at random while you're playing. It does that too.

It changes channel as and when it feels like it, without warning. Whether or not the footswitch is connected.

See, there's plenty to be getting on with...

[oc disorder]

Well they are cheaper there than here!
11 English pounds 99 pence = $21.68 Australian Dollars
In this local link to me they are $45.38 Aust $. Thats double !! I better check with the ACCC !
FT100X100, F&T DUAL VALUE RADIAL CAPACITOR, F &T CAPACITORS | Wagner Electronics, wagneronline.com.au

I'm curious did the "blue" caps get damaged mechanically (ie whack to the chassis?) or was it caused electricially ?
Sounds to me like you have multiple dry joints and perhaps there are some other areas you could start on before replacing the main caps.
Just a thought as too often, caps are replaced unnecessarily.
I didn't realise JCM 800's had a footswitch !

[I'm a beginner!]

Mine's a 1 x 12 combo. There's a "footswitch" jack on the back and it came with a footswitch but it's not a fancy one like you get on Mesas with multiple buttons and coloured lights - one switch, that's your lot!

Does Aus slap a big import tax on them or something? Or maybe it's down to the shipping them around the world price? It does seem harsh!

[dai h.]

some 50-50uF/500Vs (the typical dual cap in many Marshalls) here:

https://www.watfordvalves.com/products.asp?ID=3

[g1]

Sounds like some of your faults could be as simple as dirty/oxidized pots and jacks. Have you cleaned them?
What is the exact model number of this JCM800?

[Enzo]

Most places that sell vacuum tubes to us will also sell the caps we use. So I googled "vacuum tubes australia" and got many. I of course know none of the companies, so I picked one at random - Evatco

Evatco | Electronic Valve & Tube Co.

In their product listing I see caps, and in that section they seem to carry both JJ and F&T, including the 50-50/500v ones. I didn't go any further, so their competitors might have different prices or selection.

[52 Bill]

I'm with g-one, what you have described so far does not make me think filter caps. That doesn't mean that you don't need them, but the problems don't point in that direction.

Please tell us the model number of your amp, and seeing that shipping costs are a concern, exactly where you are located. Some part of the UK?

[I'm a beginner!]

The exact model number is not something I can get to before the weekend because I'm not going to be back with the amp until then.
I do suspect that the amp has more than one component at fault. I figured I'd ask the question about the caps before anything else because I thought there was a visible problem without even taking the chassis out of the cabinet. Although I will make the inspection of the cap as Enzo suggested. I don't know the history of the amp and have not had it very long so I don't know how much physical injury it has sustained (or inflicted) in it's life. Caps don't last forever though so for my own reference it is probably worth me knowing what can and can't be used as replacements.

I'm in the UK, and thanks to the suggestions here and google I have now found suppliers that will post stuff to me at reasonable (ish) rates - although £6.95 (ex VAT) still seems steep for carriage on something that small and light.

Looking at the data sheets on the caps and the price of the cans versus buying the Panasonics from work I still think that the 'sonics would be the way to go if I do have to recap, unless there's something in favour of the cans that I've missed....

I like the thought of dirty pots!! That's an easy fix, will get them cleaned with pot cleaner at the weekend. The jacks are definitely clean though because that did occur to me and I did make a point of cleaning them, and trying different leads / guitars.

I have only had a little experience with forums, so I still find it a little bit odd the way help and advice arrives in little batches as different parts of the world are awake! It's like wow - somebody in Australia or the USA or China or wherever has just read my post and taken time to reply and try and help to find a solution! If we can do this for amplifier problems....