1960A Cab mono/stereo switch bypass help

[ceeingred2]

Okay, got a typical marshall 1960A cab w/ 75 watt celestions and the mono/stereo switch has failed. Cant wait for a replacement. I want to wire it for 16 ohms cause I dont really need the other options. Oh, and Im using my JVM 210H with it. All wiring is stock and nothing changed. So, tell me please do I combine the two pos leads(from board/switch) and solder to the replacement 1/4 mono jack pos and combine two neg leads and solder to 1/4 jack neg?

 

[mickeydg5]

Do you have a new or different jack?
How are you rewiring?
Pictures can help.

 

[Dogs of Doom]

Seems like every other day, someone wants to fix their unbroken cabinet input jack plate...

 

[mickeydg5]

You are right. This comes up a lot.

Ceeingred2
Did you try cleaning jack contacts?
Are the contacts of the slide switch accessible for cleaning?

 

[Dogs of Doom]

Maybe one of the guys who want to rip out their perfectly good one could donate it to him?



Best bet, is just remove the PC board & wire series/parallel <> parallel/series.

What do you mean by failed?

 

[ceeingred2]

Im only wanting to attatch a new 1/4 mono jack in place of the stereo dual jack that has malfunctioned. All the wiring is unchanged inside the cab. Thanks...

 

[mickeydg5]

That is what I am trying to understand. It seems that you have another jack plate and want to mount that to the cabinet connecting the speakers to its jack.
Is that correct? If so each speaker pair, using 16 ohm speakers, should be paralleled and the two pairs then wired in series with the new jack for 16 ohm operation.

What Dogs and I are asking is what exactly malfunctioned on the Marshall jack plate? Did something burn, melt or actually break? Did you try cleaning it or fixing it?

 

[ceeingred2]

I have a common, single 1/4 mono jack that I want to put in place of the stock jack plate. the speaker wiring has not been altered and is the same as the date of manufacture. Nothing has burned or melted. The cab is 13 yrs old and from a pawn shop and the switch/jack plate has worn out. Isnt that a common issue with these components? Ive read alot of posts that confirm it. I do thank you for your time.

 

[mickeydg5]

I have read of others doing the same.
Just wire it as I described iof doing so.

I have also mentioned this in other threads to which some may or may not agree.
The jack being used should have at least an electrical contact rating of 5 Amps in general especially when used in conjunction with a 100 watt or greater amplifier.

 

[ceeingred2]

Yes I was just reading that thread. Kinda cleared up some things I was unaware of so i decided to wait for the replacement mono/stereo jack plate. I thankyou for your time regarding this issue.

 

[ceeingred2]

Oh one other thing, would you suggest soldering the wires to the speaker terminals instead of the stock slip on type connectors? Thanks

 

[mickeydg5]

I use both methods but it depends on the situation.
Some like the permanent idea of soldering, especially with swinging wires in things that get moved a lot.
I put a pliers to my electrical quick connect receptacles (female), crimp it some to make it tight as possible.

 

[chuckharmonjr]

All 4 of my cabs are soldered.

 

[Adwex]

Soldering is not necessary, like mickey said, just squeeze the lug with a pliers to make a tight fit. It'll never come out.

 

[Obi Plexi-nobi]

Reviving this old thread, because I had the same problem on a JCM-series 4x12 I'm changing the speakers out in. I tried (3) different Marshall switchplates, and none of them worked right. I know the speakers are all good.

I ended up getting the original switchplate to work again by re-crimping all push-on connectors, re-heating all switchplate solder connections, & spray-cleaning the switching jack contacts, as well as dripping the CDC (unlubricated) contact-cleaner into the switch and flipping it back & forth many times. I actually re-connected it several times to test it, only to go back and re-spray everything again. Did this several times.

Also, I lifted the switching-jack contacts using a 1/4" plug like you use for FX pedals, then cleaned the contacts with a Q-Tip dipped in contact cleaner, and did a bit of 'sanding' contacts with an emery board.

In short, it was a pain-in-the-arse, but it finally worked, & I didn't have to spend $50 for a replacement...

 

[Obi Plexi-nobi]

Besides re-heating the solder beads & cleaning the switch, my guess is those damn CLIFF switching jacks are the culprit. I don't have any problem with CLIFF jacks- only the switching ones.

I used to run a Mesa/Boogie Studio Preamp into the FX Return of my Marshall 4203 Artist combo, back in 1990 (when everybody wanted high-gain). It sounded great, but after I disconnected the cables, I experienced my Marshall intermittently cutting out, and was worried that I had damaged it somehow, running it this way.

I ended up selling & re-owning several 4203 Marshall combos (and the head versions too) over the years (they sound great at low-mid volumes), and they ALL had the 'cutting out' problem. After learning a bit about electronics, I traced it to the switching-jack that makes/breaks the preamp circuit when you engage/disengage the cable in the FX return port. I was able to solder a jumper wire past the switching jack so it was always 'closed'. I never used the 4203 FX loop anyway- It sucked IMO..

But that fixed the problem. I spoke to the U.S. CLIFF Rep about this problem. He sent me some replacements & warned me as well, that China-made CLIFF counterfeits are making their way into the market. They even say 'Cliff' on them. Unrelated to my problem, but builders, keep an eye out. He told me how to identify the REAL ones, but that was years ago & memory fades... lol

 

[Obi Plexi-nobi]

Personally, after the fiasco with the 4x12 switchplate, I definitely will be HARDWIRING all my speaker cabinets, either mono 16-ohms or stereo 8-per-side from now on, like the pros have their techs do. Not going to risk an expensive output transformer on a cheesy switch!

 

[Dogs of Doom]

Ha! funny thread... This was way before I was a mod. I was snarky that day...

On my 1960 cab, the guy I bought it from toured the Vans tour w/ it & he had replaced the nut that holds the jack on w/ a big metal one. From what he told me, that all the guys on tour did the same & it solved their problem. I guess that they failed, then when replaced, they added the heavy duty nut & noone had any problems after that.

I haven't had an issue - I bought the cab off him 4+ years ago.

That said, the cliff jack, was also a problem on the JCM2000 heads, where the speaker out switch would fail & then cause a ground problem. Maybe the same kind of failure?

I guess the board could also be a problem (which the blame is usually laid upon), but the switchjack makes a lot of sense...

 

[NOGE]

....my guess is those damn CLIFF switching jacks are the culprit...

I had this problem too. Replacement jacks fixed it. They were corroded. The switch itself was fine...

 

[Dogs of Doom]

here's an article I just found, when looking to see what the jacks actually are/do...

http://laluna.co.uk/2015/01/marshall-cab-jack-socket-fault-fixed/

This is what I meant by switch & I believe what Obi meant...