MarkBassChat

That correct. Modern cables have additional conductive layer on inner wire. You have to remove it. Otherwise, you will short the output signal of the bass. There should be no measurable resistance between the tip and the ring of the jack. Mark

Three contacts don't mean stereo effect. Usually third contact is used to switch on/off the battery. In active bass guitars you have a stereo output jack but this does not mean that the bass is stereo. The battery is connected by this pin to the ground. Mark

[quote name='dincz' timestamp='1340300975' post='1702619'] Vy jste čech? Mluvím trochu česky - ale špatně! [/quote]No, I'm not but it's not difficult to understand it without knowing the language. Let me guess; Is it: "are you Czech? I speak a little bit czech but not very good." ? I'm glad you know how to solve the problem. Mark

So you are an Englishman in Czech Republic and you don't speak local language. What about local guys who could help you? Have you tried contacting either AKG technical support, or locally this guy: [url="http://www.akg.com/site/distributoren/powerslave,id,74,nodeid,28,_language,EN.html"]http://www.akg.com/s...anguage,EN.html[/url] ? I don't think that he does not speak English. You could send him an e-mail with a photo, or even call him. You can also browse through service manuals on akg.com and look for similar microphones (service manual for D 190 is missing there). EDIT: contact details: [url="http://www.audiomaster.cz/kontakty.php?cid=553"]http://www.audiomaster.cz/kontakty.php?cid=553[/url] Mark

Would manual for D200 be of any help: [url="http://www.akg.com/mediendatenbank2/psfile/datei/52/D2004190be0d1a3aa.pdf"]http://www.akg.com/mediendatenbank2/psfile/datei/52/D2004190be0d1a3aa.pdf[/url] Mark

In RH450 the preamp is digital (processing is performed by a DSP chip) and they use electronic volume control. If this is the same in you version, the problem may be as simple as non-contacting potentiometer, or as complex as incorrect program that is used in the amp. I think that you have no choice other than contacting TC Electronic. Unless you accept the way it works (which seems to be incorrect). If you manage to solve the problem, let us know what was it exactly. This may be very useful information for other users. Mark

Have you tried contacting TC Electronic directly? This may be an issue with the amp and they know how to fix it. I would also compare settings used on demo videos, here: [url="http://www.tcelectronic.com/classic450.asp"]http://www.tcelectronic.com/classic450.asp[/url] or on youtube. I don't think that you can easily replace the pot in the amp. It is very advanced amp and even in order to dissassemble it, you need special tools (I know because I was fixing RH450). Mark

For a moment I thought that this amp does not have a Standby switch, but it does - I looked at the amp manual. The problem is that most probably it does not work as in valve amps. When the switch is in "off" position in valve amp the power supply voltage for the power amp (valves) is disconnected. But this is not the case in SMX 12 . It has only one valve in the preamp section so most probably the standby switch turns off only the valve - the rest of the amp still works. It means that you shouldn't worry for the switch but rather give the amp to a tech to fix it. Or, maybe try to replace the valve first. EDIT: it can be also a problem wit a power amp - depending on what you mean by "loud buzz". Can you record the sound and post it somewhere (and post a link to it here)? You can still investigate the problem a little bit by pluging a cable directly into the Power Amp Input and not into the Preamp Input. Do you still get a buzz in this case? Mark

I'm sure that fixing it will be much cheaper that buying a new one. If you want a new one, have you tried contacting the manufacturer directly? Mark

You can contact the guys here: [url="http://www.fender.com/community/forums/viewtopic.php?f=9&t=54074"]http://www.fender.com/community/forums/viewtopic.php?f=9&t=54074[/url] - they have it. Also a photo could help. Usually it is possible to guess which wire goes where (especially if this is a wire from battery). Mark

This is very funny - few years ago I was fixing HA3500, which had exactly the same problem; a screw (also not belonging to the amp) shorted a transistor from the power amp to chassis. I had to replace several transistors. Mark

Have you checked directly below the power supply cord? The fuse is integrated with the power supply socket. You don't need to open the amp to check the fuse. Mark

You can easily test a battery with a multimeter. I usually make sure that there is some load - e.g. I connect a preamp that draws 2-5 mA, and I measure the voltage. If it it is above 8.5V, the battery is still good. If it is less, I buy a new one. We are talking here about batteries for preamps, which usually draw current between 1 and 4 mA. If the battery is OK, the problem is with the preamp (or connections). We are not talking about laptop batteries, right? Mark

A photo could help. Have you tried it with another battery? What about checking what it is the battery voltage - do you have any meter? Mark

[quote name='geoffbyrne' timestamp='1324725892' post='1477326'] errrrrrrrrr........ how would this do for those of us who use 18V - or would it? G. [/quote]This is difficult since such professional circuits are built using micro-power comparators and they usually work only up to 12V. There are two workarounds: 1. monitor only one battery and assume that the voltage or the other one is simmilar. This is very good assumption since the current drawn from the second battery is the same as from the first one. 2. buy 2 circuits and monitor each battery separately. I plan to build such a circuit next month. If I get good results, I will present it here. Mark

[quote name='barneyg42' timestamp='1334396011' post='1615545'] I took it to a tech who couldn't find what was going on, he then wired the fan to be on permanently and it was ok, needless to say it was a bit noisy and I've moved on from it now. It's just sitting in my storage as a spare. I suppose there was some sort of overheating issue although the problem started from straight after switching on so not a lot of chance to get hot. It appears the speaker wasn't the problem as the tech was running it into his diagnostic equipment. Seemed a good versatile sound when working properly, had to be cranked a bit to get the volume though! I found the Hartke 3500 a far better unit with great tone shaping and fantastic headroom. I've gone down the pre amp/power amp route now though. [/quote]I'd say that this is a very simple problem to be found and fixed. It looks like it is related to overheating. Most probably the bias is not set up correctly. There is a mini pot for this on the power amp board. But don't touch it if you don't how to use it. Take the amp to a tech that knows what means "set up a bias in an amp". It may be also a problem w thermistors (heat sensors) in the amp. In any case this is a problem that can be easily diagnosed. Of course the amp is not that strong as Hartke 3500 so you cannot expect the same power. Mark

[quote name='Ghost_Bass' timestamp='1330425959' post='1557100']Tell me, i would you lower the input stage gain? [/quote]You have to find out the schematic and read it. I already mentioned that one of possibilities is to decrease R23 resistor - from 68k to e.g. 22k and use input #2. Another option would be to decrease R16 resistor from 33k to 22k. [quote name='Ghost_Bass' timestamp='1330425959' post='1557100']In regard to the resistor on the cab i think that he would probably get a 8Ohm cab instead and sell his. [/quote]You have to understand that it will not be the same as adding a resistor in series. With 8 Ohms cab 100% of the output voltage will be still delivered to the cab (only the power will be lower). With a resistor in series only a fraction of the output voltage will be delivered to the cab. I don't even mention that buying a resistor costs less than a new cab. Mark

What is special about Le Paul is that it has a very strong signal, which easily overdrives the input stage of an amp. So any modification to the guitar will change it's sound. Les Paul is a perfect match with e.g. 50W Marshall so using 250W amp is questionable. What about listeners or owners of the pubs you play? Do they accept the sound level your colleague can produce? I wouldn't modify the guitar, I would rather decrease the gain of the input stage of the amp and add a resistor in series with the cab. Mark

Marco, You have several options but I must say that you forgot to mention few most important facts: - that your coleague plays Les Paul (this guitar has very strong signal), - that he uses 2 Ohms cab (with amp that is 250W), - that he likes the amp and you accept it even though 250W for a guitarist is not acceptable. The guitar that he has would sound well and be already very loud with e.g. 50W Marshall, or Rivera or any valve amp (even Fender Bandmaster - 40W). I would sell the amp and buy any of the amps mentioned here. If he insists to keep the amp, you have roughly three options: - decrease the sensitivity of the amp (by changing just 1 resistor in the input stage - R23 and using input #2), - add a high power resistor in series with the cab (e.g. 8 Ohms 50W - with a heatsink), - change the speaker from 2 Ohms to 8 Ohms (or change whole cab). But being frankly 250W power is rather suitable for a bass guitar and having such an amp for a guitar does not makes much sense (unless you are playing concerts like Woodstock) - I would get rid of it. Mark

First you have to tell what exactly is the type of the amp; I haven't heard of Jazzman - is it maybe Jazzmaster Ultralight? That's true that Fender is known of using incorrect pots but it all depends how a pot is used in the circuit. In case of Jazzmaster, the pot (VOLUME CLEAN) is in negative feedback loop with the middle lead grounded. I think that this is the reason why they used unusual type of the pot (antilog) and this is not a mistake. Most probably changing the pot to log type will make it even worse. Have you tried the input #2? It is less sensitive (50% compared to input #1). In any case I would recommend to give the amp to someone who know electronics and can measure the signal and understands why it is to high (and he knows how to correct the problem). Mark

What do you mean by "had some EMG PJ pups"? Do you have one of models listed in the diagram? Which diagram are you using, #2? In this diagram the pickusp are shorted to the ground when pots are turned down. So probably you have pots not connected to the ground. Can you make a photo and post it here? Mark

[quote name='Bobby K' timestamp='1327921864' post='1518665'] Ok got one of those. What would I do then...?[/quote]If you connect a battery to the pickup, it will form a magnetic coil. Depending on the direction of the voltage applied you should get different directions of magnetic field. I think that comparing it with the other pickup (using a compass or any other magnetic device) you should be able to verify whether both pickups are wound in the same direction, or not. Let me know if it worked. Mark

It can be anything that has two magnetic poles, even Smartphone [url="http://en.wikipedia.org/wiki/Compass"]http://en.wikipedia.org/wiki/Compass[/url]

I think you don't need a DVM for this. How about a 9V battery and an old fasioned magnetic compass? This is assuming that you have another pickup to compare with :-). Mark

[quote name='andyonbass' timestamp='1327129955' post='1506718'] I have changed the strings, but this hasn't improved it at all really.[/quote]Andy, It's a pitty that you haven't check what's inside. When you take the strings off you have a possibility to take the saddle off and see what happened. I fixed several guitars with this problem and sometimes it was caused by slightly moved piezo transducer, sometimes by uneven surface beneeth it, and quite often by failed transducer (it's very delicate). [quote name='andyonbass' timestamp='1327129955' post='1506718']I'm reluctant to have it apart myself, having no experience of this type of bridge and I dont want to make it worse.[/quote]As I said, you already had an opportunity to check it. You have to fix it anyway so I wouldn't worry about making it worse. [quote name='andyonbass' timestamp='1327129955' post='1506718'] What I'd like to know is whether it is a job that can be trusted to my local guitar shop or if a specialist would be required,[/quote]You need a person called luthier and I assume that at your local guitar shop they have, or at least they know such a person. It's a simple task for a luthier. PS: I don't live in your neighbourhood . Mark