Katana 100 head, internal speaker dead?

BeardyAndy

just bought this on eBay, works fine with headphones and cab but I get nothing from the 5” internal. I’ve read the manual to see if i’m missing something, opened it up to check the leads are attached and am now at a loss!
I messaged the seller and he’s offered a no quibble refund or partial refund, maybe a sign of guilt or just a genuine honest seller and i’m prepared to give him benefit of the doubt.

any suggestions?

Edit* I’m going to get a cable and see if a firmware update helps over the weekend.

midlifecrisis

have you tried a factory reset?

BeardyAndy

midlifecrisis said:

have you tried a factory reset?

Yeah, did that this morning. Still nothing, it's a real head scratcher!

Borrowed a USB printer cable this morning so i'll plug it into the pc tonight and see what that throws up. I read about someone that had an issue with the switch that activates when there's no plug in the cab socket but it's board mounted and buried deep, I don't really want to start pulling things apart while i'm still able to return if needed. I am however aware it would be a cheap head if i can get another £50 off!

ICBM

I'd be interested to know the outcome of this for future reference...

As far as I can see there are three possibilities:

1 - the speaker is blown
2 - the switch in the jack is faulty
3 - something in the power reduction circuit has failed (there are several ways it could be done)

If you can get at the speaker and disconnect it, you can test it with a 9V battery very briefly touched to the terminals.

BeardyAndy

@ICBM I can get to the speaker so i'll try that, thanks. 

JayGee

ICBM said:

I'd be interested to know the outcome of this for future reference...

As far as I can see there are three possibilities:

1 - the speaker is blown
2 - the switch in the jack is faulty
3 - something in the power reduction circuit has failed (there are several ways it could be done)

If you can get at the speaker and disconnect it, you can test it with a 9V battery very briefly touched to the terminals.

I have a vague recollection from somewhere that the Katana head actually has a second dinky little power amp dedicated to the internal speaker - if so that’s another candidate, and if it’s on some sort of daughter board it might be possible to work out the connector pinout and replace it with a generic small audio power amp board/module/whatever...

BeardyAndy

JayGee said:

ICBM said:

I'd be interested to know the outcome of this for future reference...

As far as I can see there are three possibilities:

1 - the speaker is blown
2 - the switch in the jack is faulty
3 - something in the power reduction circuit has failed (there are several ways it could be done)

If you can get at the speaker and disconnect it, you can test it with a 9V battery very briefly touched to the terminals.

I have a vague recollection from somewhere that the Katana head actually has a second dinky little power amp dedicated to the internal speaker - if so that’s another candidate, and if it’s on some sort of daughter board it might be possible to work out the connector pinout and replace it with a generic small audio power amp board/module/whatever...

I've found the problem..


This little fella (ext speaker jack) wasn't making contact, i slipped some silver foil in there and it works perfectly.

Cant see a way of bending it because of the way its fitted so I guess i'll need a new one fitted, as good as I may be getting with a hot iron I don't fancy muffing up my board so I think i'll pay someone to do it.

ICBM

There are ways of bending it, although it’s tricky to get it right without making it worse - but given that you still have to replace the jack otherwise, it’s always worth a go first.

There are two ways, both which need a similar tool, like a small screwdriver with a bent end - you can make one, but you’ll probably have to soften the metal first and then re-harden it. A small Allen key can sometimes work. In either case you need to fit it through the slot in the middle of the jack and under the metal contacts.

1. Bend the switch contact - the small strip underneath, at the top in your pic - up slightly, so it makes better contact with the underside of the plug tip contact strip.

2. More difficult - get the tool under the right-angle bend of the plug tip contact, at the bottom in your pic, use it to support that, and then bend the far end of it down using a second tool, a plain screwdriver is ideal.

If you’ve never done one before it can be frustrating to get it just right, but even if it takes a bit of fiddling it’s still much easier than changing the jack.

I normally do 1 if there’s only a tiny gap, and 2 only if the plug contact is very obviously bent upwards a long way - that happens if the cable gets tugged hard, usually.

BeardyAndy

@ICBM Thanks, I can see what you mean.

On a plus side, with a partial refund for my trouble I ended up getting the amp for £120 so if I can sort it myself it will be the deal of the year!

ICBM

BeardyAndy said:

On a plus side, with a partial refund for my trouble I ended up getting the amp for £120 so if I can sort it myself it will be the deal of the year!

Until you hear it working, anyway .

For what it's worth, looking at it on a bigger screen it does look like the plug was tugged hard - the contact is bent sideways as well as slightly upwards. The usual cause of that is forgetting to unplug the speaker cable before lifting the head off the cab and walking away with it... so try not to do that!

BeardyAndy

*Thread update...

I've fixed it. Ordered the jack socket as per @ICBM recommended and last night I (brutally) removed the offending part and fitted the new one, one heart in mouth moment when I managed to push the copper circuit off the PCB when I pushed one of the new legs through but it didn't break and is now glued in place with lashings of fresh solder!

sev112

I love a happy ending
great forum value

ICBM

BeardyAndy said:

*Thread update...

I've fixed it. Ordered the jack socket as per @ICBM recommended and last night I (brutally) removed the offending part and fitted the new one, one heart in mouth moment when I managed to push the copper circuit off the PCB when I pushed one of the new legs through but it didn't break and is now glued in place with lashings of fresh solder!

Well done. That's a hazard when doing things like this even when you're quite experienced at it. You can put a drop of superglue on so it will wick under the loose trace and secure it, once it's all cooled and tested. Just be careful if you ever need to solder to it again, the fumes are nasty.