sc20h power

[fer1991]

Then you can proceed to proceed to measure the voltages on the secondary pairs of the transformer. Ideally, you should be able to put the positive lead on the fuse and get a positive reading. If you get a netgative reading (of the correct voltage, or close to it) it's been reversed and would need to be corrected.

I didin't get it, how should I set the multimeter and exactly where should I put the positive's and negative's tips/wires to measure??

 

[PelliX]

I didin't get it, how should I set the multimeter and exactly where should I put the positive's and negative's tips/wires to measure??

Sorry, missed that message and went to bed eventually (different time zone, few beers involved). Upon re-reading one of my previous posts, I believe I may have expressed the concept a bit poorly. Assuming that the polarity is correct entering the device (receptacle on the back of the amp) - the mains fuse will function correctly and "kill" the live connection to the device (which is its main purpose, together with protecting against an overload which is when the amp attempts to draw too much current). That's fine, you checked that.

Next, observe this section of the schematic:



Here the fuses are *between* the secondary outputs/windings and the rectifier (the collection of 1N4007 diodes you see above). The fuses marked as "F" will function regardless of their positioning, as they will break the circuit in case of an overload/short. Presuming the "pairs" are correct (which they appear to be in your case as the amp is functioning correctly), this is fine. Any fuses *after* the rectifier will always be correct as the rectifier determines the (DC) polarity.

Here's some decent reading on meter usage and so on, just the basics:

Safe Meter Use

 

[fer1991]

Here's some decent reading on meter usage and so on, just the basics:

Sir, you have been patient and teachfull to me, really, thank you very much. I hope they were a couple of beers, you truly deserve them. Around the week I'll seek for better clipping or alligator cables to take the measurements. If I understood well I think it should be taken with the positive cable from the multimeter attached to the brown wire from the transformer, and negative one from the multimeter to the red one. And repeat with the white - blue team. without disconnecting anything. If that's correct, I'll do the test since I need the new multimeter cables anyway.

I can't point out how much less stressed I feel about this now, knowing that the amplifier it's still protected by the fuses. I'm curious about doing this last test to be free of worries about the amp beeing properly feeded.

 

[PelliX]

Sir, you have been patient and teachfull to me, really, thank you very much.

You're welcome, mate. When I was learning a lot of this stuff, I didn't have Internet forums to ask people on. I knew a couple of guys who I would bother as little as possible and there was a library. Now we have these means, let us make use of them, right.

I hope they were a couple of beers, you truly deserve them.

Uh, a couple and then some, hehe.

Around the week I'll seek for better clipping or alligator cables to take the measurements.

Clips certainly make life easy (and a little safer). Alligator clips and the 'hook type' are really handy to have.

If I understood well I think it should be taken with the positive cable from the multimeter attached to the brown wire from the transformer, and negative one from the multimeter to the red one. And repeat with the white - blue team. without disconnecting anything. If that's correct, I'll do the test since I need the new multimeter cables anyway.

Well yes, but the polarity in this setup with that transformer is "indiscriminate", so it doesn't matter which way around they are. The transformer itself will (in simple terms) "put voltage on all wires".

I can't point out how much less stressed I feel about this now, knowing that the amplifier it's still protected by the fuses. I'm curious about doing this last test to be free of worries about the amp beeing properly feeded.

I take this stuff fairly seriously, but I don't really worry if I accidentally reverse a plug from time to time. Doctors make the worst patients, as they say ... Glad you're happy, though - and you learned a little bit on the way. To take a risk (like I do from time to time) you should be able to understand the implications. Some risks I'll take, others not - but understanding *what* is at risk is key when making that decision, right.

 

[fer1991]

I take this stuff fairly seriously, but I don't really worry if I accidentally reverse a plug from time to time. Doctors make the worst patients, as they say

That's exactly right, doctors make the worst patients! We do have forums nowadays, but the more connected we are, the more "figure that out for yourself " we end up finding sometimes, so, you've made some guy happy on the other side of the globe, I can now play just knowing that everything it's properly connected. I'll let you know once I tested the teamed wires, thanks!!

 

[Pete Farrington]

Clips certainly make life easy (and a little safer). Alligator clips and the 'hook type' are really handy to have.

Absolutely, but I'd much prefer to see shrouded 4mm banana plugs at the meter end of things, especially for an inexperienced user.

 

[PelliX]

Absolutely, but I'd much prefer to see shrouded 4mm banana plugs at the meter end of things, especially for an uinexperienced user.

Yup, agree - I carelessly snagged a stock photo from google focussing on the hook/clip ends. @fer1991 - Pete makes a good point here. ^

 

[fer1991]

@PelliX Sorry for the delay, I have some personal things going on and I didn't have the time to do the test. I went looking for the multimeter's cables and they didn't have them in stock, so I guess I'm leaving it as things came from the factory, since now I feel everything should be correct. Pellix, would you know if the "upgrade" or "fix" from the fx loop had become a standard in newer units? I freaked out at that time and I would like to try it again further down the road, it always intrigued me that they changed the R103 that's a resistor close to the treble pot, that moves it's value when turning the bass pot.

 

[PelliX]

Hey there, no worries! I'm fairly sure this is not applied in production as the "perceived problem" is not really an issue for most people, myself included.

 

[fer1991]

Hey there, no worries! I'm fairly sure this is not applied in production as the "perceived problem" is not really an issue for most

Thanks again! I got intrigued by the resistor changed in the eq section. I also think that the volume drop isn't an issue, but if the R103 changes the eq shape that would intrigue me again.