Any reason not to use these...

[Enzo]

Sorry, something made me think you were in Australia.

[g1]

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 mentioned the jacks thinking not so much about the inputs, but FX loop jacks if it has them, and footswitch jack.
These jacks have switches in them that must connect when not in use. Dirty FX loop jacks (or preamp out, power amp in) can cause volume fluctuation. Dirty footswitch jacks can cause unwanted channel switching.

[oc disorder]

Enzo I'm the Australian possibly causing confusion Was trying to illustrate that I thought the UK price was a fair deal.
Well yes , it pays to shop around, Evatco have quite a lot of useful imports and at a reasonable price.
Think they are looking for a potential buyer for the business too.
They don't however have the 100uF 500 F&T in a can and I initially was mistaken in thinking "Beginners" Marshall used
100uF's for filtering whereas I now know 50uF is also used.
Wagner actually have a wholesale arm WES Components but why let the truth get in the way of a good story ?

I think it is a JCM800 4210 combo based on the 2205 head.
There seem to be 2 versions of the 2205 head.
One with a CA3046 IC for switching and the other using 5 BC 184's.
The CA 3046 is a general purpose NPN transistor array.

Link to 2205 pre with IC
http://www.drtube.com/schematics/marshall/2205prem.gif

Link to 4210 combo complete with 5 x BC184
http://www.drtube.com/schematics/marshall/4210.gif

Here's a picture of what I think it is ...................look familiar "Beginner" ?



And from the 800 handbook

[I'm a beginner!]

Yes! That looks familiar!! More dents in mine though...

Yikes! I don't really have any experience of working with ICs. Never soldered one, never connected one, never installed one, never removed one.
Hope they are not the cause of the symptoms! I'll give the rear jacks a good clean when I get back, along with the pots to be sure!!

[km6xz]

When using the term "cleaning" most techs mean "de-oxidize" which will probably clean up more of those symptoms than not. In UK you have CRC and Cramolin, in the US/Canada, mostly De-Oxit from Caig Labs. Cramolin was the first really good chemical for de-oxidation. In the studio with 10s of thousands of jacks,plugs, patchbay cables etc and any of of them could stop a session. So we lived and breathed Cramolin R-5. Oxidation causes far more intermittent or distorted signals than cracked solder joints.
Wet each pot resist element, every switching jack, every tube socket( do not use much, if you can see it, it is too much. With tube sockets, use a wooden tooth pick dipped in Cramolin Contakt and brush the pick lightly over the socket contacts the connect to the tube pins. Don't spray it or any liquid into the socket because any dirt in solution will create an arcing path. Exercise every pot, switch and jack right after applying the de-oxidizer. Do all this once a year and never have intermittent signal again. If a lot of tubes have been inserted and removed over the years, it is a sure bet the spring tension of the contacts mating with the tube pins, need to be reformed(fancy word for "bent") so they grip the tube pins better.
Does the amp have strong 100 hz hum in the speakers? No? Don't waste your money on caps it does not need. Attack the real, repeatable problems and get the amp repaired. Only after it works normally, then consider restoring it. Restoring only comes after it is fully repair. Restoration is not needed but if you have more money than desire to play it, restore is, otherwise, just repair what is actually wrong.
Restoring while repairing will introduce more variables, more doubt and triple the cost and time before you get to play it again.

When anyone recommends resoldering everything or doing a cap job as the first step in diagnosis and repair they are just admitting they have no clue what the problem really is. Repair is a fun detective game, collect evidence and come up with a hypothesis that fits ALL the symptoms and you have great odds of repairing it quickly, while the restorer-before-repair guy is still trying to reproduce the symptoms that might be changed by working on it randomly, but still exist waiting to bite them just as they thinking it is road worthy. There are two types of amp hobbyists, amp hobbyists and players, often they are not compatible with each other. You sound like a player. Fix it then go play.
Good luck

[Tom Phillips]

I just want to emphasis the following bits of wisdom

...Attack the real, repeatable problems and get the amp repaired. Only after it works normally, then consider restoring it...

...When anyone recommends re-soldering everything or doing a cap job as the first step in diagnosis and repair they are just admitting they have no clue what the problem really is...

Excellent advice.

I just repaired an amp that had a single mis-installed part that was a factory mistake. That was easy to remedy. However, there was extensive damage done by previous people who were obviously doing shotgun parts replacement and using guessing as their main troubleshooting tool. Repairing that damage to make the amp reliable again was a big deal.

Perform the cleaning / deoxidizing first then take your time to carefully troubleshoot any remaining problems. I recommend that you resist the urge to replace parts until you have reasonable evidence that they are defective.

Good Luck,
Tom

[I'm a beginner!]

I would like to thank everybody for the sound advice (no pun intended)!
The frustrating thing is that getting the advice makes me want to start the process... and I won't even be back with the amp until Saturday!!
On the plus side my new speaker (different project) arrives tomorrow so it looks like I'll have plenty to keep me occupied over the weekend!!
The trick is to find some Cramolin or CRC before Saturday... I wonder if there's any kicking around at work...

[I'm a beginner!]

Hmmm... can't find Cramolin... Farnell do some 3M contact cleaner but wont deliver before the weekend...
Maybe this would be suitable?
www.toolbank.com | WD-40 Specialist Contact Cleaner Aerosol 400ml
or even this
HEAVY DUTY CLEANER DEGREASER 3 In One Oil

The new speaker arrived!!! It is good!!!

[Tom Phillips]

...www.toolbank.com | WD-40 Specialist Contact Cleaner Aerosol 400ml
or even this. HEAVY DUTY CLEANER DEGREASER 3 In One Oil...

NO and NO! Do not use those products on your pots & switches. Use only products that specifically list the electronics uses in the manufacturer's application literature. "De-greasing is not the same as "de-oxidizing." Also, the products we previously recommended leave a protective and lubrication coating behind after the de-oxidizing is done. If you completely degrease your pots using the products you listed, the shafts will eventually seize up. They could also cause other problems such as damaging plastic parts. Take the time to obtain the correct chemicals.

[nickb]

Hmmm... can't find Cramolin...

Cramolin 1011611 CONTACLEAN 400 ml from Conrad Electronic UK they offer 24 hr shipment but it'll cost ya.

[dai h.]

some more bits of good info:

Caig Deoxit Usage on Soundcraft Desk - Gearslutz.com

re: (in reference to what Tom says above about degreasing) yes, you definitely don't want to use anything that removes all the grease or the pot will freeze up (I've done this with a can of alcohol-based cleaner). The grease (which is around the pot shaft) is called "damping grease" used to damp mechanical movement in pots, switches, cameras and whatever else that needs smoothing and damping of mechanical movement. Although something like Deoxit does seem to contain a lubricant, I don't think this is the same stuff (it may be something thinner--see thread above), so to me it seems a good idea to be very judicious with the amount you spray inside the pot (I would use only a "spritz" and defnitely don't "flood" the pot expecting that "more is better"). When I've used larger amounts of Deoxit and (sister product Faderlube meant to be used after), the movement (to me) didn't quite feel the same (which is why it seems a bad idea to wash the original damping grease away). If someone encounters a pot (or ends up washing the damping grease away for whatever reason) one possible (I haven't confirmed) source for damping grease is vendors who supply maintainance supplies for cameras. They seem to sell damping grease in different viscosities in small amounts (didn't seem particularly cheap, unfortunately). Also, a "Nye Lubricants" was a supplier (IIRC) and googling might get a source (to buy a small quantity). I've also searched for damping grease (here in Japan), and (besides the camera supplies vendors) there didn't seem to be anyone selling in small quantities (it seems to come in huge drums or something, presumably for manufacturers). Anyway, I think it's quite evident it's much easier to take care to not wash the lubricant away(you don't have to buy a replacement, pay for shipping, (disassemble the pot?), apply it(method?), etc.).

[I'm a beginner!]

Thanks for the information. Now I'm more confused though, as we want a chemical that will clean but won't leave a residue... unless it's the right type of residue. The WD40 one said "contact cleaner", and claimed it was good for electronics so I thought I had found a winner.

Does anybody know if any of these products are good for the purpose?

1625 - 3M - CLEANER, CONTACT, ELEC, 400ML | Farnell UK

6130001500 - AMBERSIL - CONTACT CLEANER, AMBERTRON, 400ML | Farnell UK

6150009510 - AMBERSIL - CLEANER, ELECTRICAL CONTACT FG | Farnell UK

ES1605E - CHEMTRONICS - CONTACT CLEANER, 400ML | Farnell UK

Because I can get hold of them much more easily than the Cramolin.

If they aren't any good then I'll get the Cramolin and give that a go. When there's so many products all claiming to be "contact cleaner" it gets confusing!

[Tom Phillips]

...I can get hold of them much more easily than the Cramolin. If they aren't any good then I'll get the Cramolin and give that a go. When there's so many products all claiming to be "contact cleaner" it gets confusing!

Yes there are many products that are made for use in electronics but, if you want the one that experienced people have found to work best for the pots & switches in audio equipment, then I'd recommend the Cramolin over the other choices you have listed. Otherwise it would appear that you would be sacrificing good performance in favor of fast availability.

[km6xz]

The products listed have two things in common with Cramolin ContaClean, they are in metal cans and say they "clean contacts". All similarity ends there. There are no laws about what name products as to being accurate descriptions of what they do.
The way to find out is look at their Safety Data Sheet(EU) or MSDS(USA) to see what they really have in them. All the chemicals listed in the prior post are strong quick drying solvents which are good for cleaning crude and dirt out of gear, one being more of a Power Wash for flushing out dirt(ChemTronics: Power Wash, contact cleaner and Tuner Wash are all the same chemicals). Those Safety Data Sheets would tell you they would be bad for pots, switches, connector etc because they are too "dry" as solvents are and evaporate very fast. They would leave contacts devoid of any protective coatings(like residue de-oxidizer), would accelerate corrosion and oxidation, remove any lube in switches and pots. 2 of them are not safe with polystyrene which is used as the case of some jacks and switches, causing them to shatter after light use.
None claim de-oxidation feature. The fact is that you do not want perfectly clean connectors, jacks, switches or pots. A protective layer of film is helpful in preventing excess oxidation. Oxidation is a natural result of metal surfaces being bathed in atmospheric oxygen. Many metals are intentionally oxidized in production to protect the outer most layer (which becomes an oxide of the base metal, which prevent further corrosion deeper into the metal) such as aluminum. When people say "aluminum color" they are referring to the grey oxide covered aluminum, not state of pure aluminum which is shiny bright as a mirror. The surface oxide prevents oxygen from penetrating deeper, the oxide is preventing more oxidation. Why does this matter? An oxide of a metal is a very good insulator. That character of metal-oxide makes modern electronics possible, electrolytic caps to be smaller than your car, and every logic junction in your computer to function. A pot gets "scratchy" when the oxide layer gets a little too thick, more than 6-10 molecules say, so the close proximety of the wiper to the resist element is not quite close enough for electrons to migrate though it consistently. De-oxidizer does the job of being more attractive to oxygen than the base metal so strips it from the oxide. It would immediately oxidize again if left open to oxygen so the trick is to leave a protective barrier that prevents direct contact with oxygen and never really dries. That is why all those other cleaners would make the problem worse, by stripping protective film but also not removing the oxide chemical bond.
So it REALLY matters what you use. Please wait for the Cramolin. One small can will last a couple years if keeping your jacks, guitar cable plug, your stereo jacks controls and pots free from noise etc.

[g1]

A better generic term for what we often (wrongly) call "contact cleaner" would be "control cleaner".

For certain electrical contacts, lack of residue is required (relay contacts etc.). That is what contact cleaner is for.
I use contact cleaner and brake cleaner interchangeably. For pots and jacks, I use control cleaner.