Paul Williams

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@davidnewton2805 Ай бұрын

As you've been looking inside it, maybe you can help ? I bought one brand new when they were discontinued. Played it for only a few hours before all my gear had to go into very long-term storage due to lengthy house repairs, then disruptions of lockdowns. Amp was kept clean and dry at normal room temperature... It was stored idle for several years because of family circumstances beyond my control. No one touched or moved it in all that time. When I finally got it back out and switched it on again, the light came on but absolutely silent. No sound with or without a guitar plugged in either input socket. Despite this serious problem the amp still looks mint condition. Please can you advise. Do you have any ideas or suspicions what might have gone wrong while it was unused ? Some blokes who don't know much more than I do about electronics, share a low opinion of Fender quality control. They suggested it could be dodgy solder joints failing, cheap components expiring even though unused, or the shock of being powered back on again after such a long lay off. It makes me very nervous about switching on any of my other valve amps that were stored with it for all that time. Cheers...

@paulwilliams4984 Ай бұрын

@davidnewton2805 Sorry David, I can't really offer any real advice without having the unit here.

@davidnewton2805 Ай бұрын

Thanks, I didn't know you took in repairs. This is the first time I've found your channel. I was just asking on the off chance for any suggestions, or your informal opinion on fender build quality inside this amp. Does it look to you if their factory used cheapest unreliable components, or not soldering properly ? Cheers again.

@paulwilliams4984 Ай бұрын

@@davidnewton2805 Hi David, I don't take in repairs, it's just that I'd be loath to suggest anything when I'm not a tech. As for build quality, it seems much on a par for other Chinese kit I've looked at over the years & a bad solder joint would 'usually' manifest as noisy/crackly output rather than total silence. Obvious things to check (as the pilot light is glowing) are speaker connections (before switch on) and are the valves glowing. Sorry I can't be more help.

@steveburrows101 Ай бұрын

Lovely sounding amp, but a friend asked me to look at one of the same model that was misbehaving, and while I have it partially fixed so it's "working" it's not "right", so a couple of months ago I enquired of Laney about a replacement VC15 Pre-amp board 9416-6 and got the response "Sorry but those PCB's are now obsolete and no longer available". So when it dies it's dead.

@paulwilliams4984 Ай бұрын

@steveburrows101 This is the unfortunate fact about loads of amps, although in many instances, it will be possible to do repairs to the board (if you can find someone to do it) but the cost is often prohibitive. I've recently sold mine, although it is a fabulous amp.

@biomed2560 Ай бұрын

This video generates more queries than it answers. (Actually it doesn't answer any.) A matched pair may or may not be matched according to the accuracy of matching that you're looking for. Perhaps an approximate match is OK - after all most amps with push-pull output stages have masses of negative feedback which irons out a lot of irregularities. Is the test circuitry on the two versions of the tester different? If so, what are the differences? If not, is the calibration different or are there faults in the machine? Heater current differences are no big deal. As long as there is sufficient emission then it's OK (within limits). Not quite sure about thermal runaway, never come across this in decades of work with valves. Perhaps it's another word for interelectrode shorts. We don't know about the capabilities of the tester. Is one able to plot the characteristic curves of the valve under test? What about the valve bases? I saw an Octal one (presumably not a Mazda Octal) a B9a or noval holder and I suppose the third on was a B7G. Is there a way to cobble together other bases with flying leads, (side contact, British 4 and 5 pin bases and so on? Does the company provide a booklet with thousands of different valve data sets (like the Wireless World data books of years ago)? Finally - for the time being - are the internal circuitry and the method of working fully explained? When reviewing a piece of equipment it is essential to review the accompanying documentation.

@paulwilliams4984 Ай бұрын

@biomed2560 In my previous video, I mention there is no technical documentation to explain what the tester is doing or parameters being measured. The user manual is available online, but is very minimal. Yes, I had lots of questions about the tester, but at least the first tester mimicked what I expected from real in amp usage, whereas the second tester didn't. In the end, I don't feel an overideing loss that I won't have this as a long-term tester.

@jamesbowskill2067 3 ай бұрын

Ive recently bought this amp and got it serviced. Not a tech myself but the clean channel sounds very stiff and cold to me - no compression or warmth. Would altering the bias help with this?

@paulwilliams4984 3 ай бұрын

@jamesbowskill2067 Yes, I feel setting the bias hotter would give it more aggression. But I feel that the drive channel can be set to give a clean but aggressive sound with no change in bias.

@aalperuzun 3 ай бұрын

I have the same amp, early version with spring reverb and Jensen C10Q speaker, made in UK. I'm an total abuser, using it fully cranked (vol max, mid max) for hours at gigs about 2-3 times a week. Never had a problem. I love it.

@ClaburP 3 ай бұрын

Hi Paul! Thank you very much for this and your previous VC15-videos, very informative 👍 I have the second version of the VC15, still made in the UK. A question about discharging the filter caps. How to you discharge the caps when the leads are on the underside of the board and also the traces to the caps? I read on some Marshall forums that you can connect an insulated alligator clip on a wire from pin 1 on preamp valve V1 to another clip to ground and that will discharge the caps after a while. Is that how you do it or do you have another preferable method on the VC15? Thank you :-)

@paulwilliams4984 3 ай бұрын

To be honest, I've never in the years I've worked on valve amps had to ever discharge any caps! Of course I do check for residual voltage before I delve into an amplifier, but I've no 'go to' method of discharge as I've never once needed to do so. Basically when looking a something I'm unfamiliar with, I'll first check the there is continuity between the chassis, negative side of the amp and the earth pin of the mains plug, then usually plug the amp into a mains socket, but switched off. Most reasonable well designed amplifiers 'should' self discharge when switched off with a route to earth via resistors. I would then check the HT side for residual voltage - in the case of the VC15, using the solder pads on the top of the board, though the leads from the 450v smoothing caps are also visible on the top of the board, so wouldn't be an issue to rig-up a discharge resistor. But modern standards require capacitors to be able to self discharge and the VC15 takes about 30 seconds to get down to a few volts after switch off. The issue is of course very different with some vintage amps and self builds. As always, check before you delve inside, but it's never been an issue for me so far.

@ClaburP 3 ай бұрын

@@paulwilliams4984 Thank you Paul! I see 👍Excellent explanation of the situation and what to check for/do in this case. Much appreciated 🙏

@tymanngruter1808 3 ай бұрын

Its a hot amp! Thanx for posting! ♨️

@nstrug 5 ай бұрын

Mk1 has a parallel fx loop whereas later versions have a series fx loop which is more useful for most people. It’s a stretch to say it’s similar to an AC15, the preamp is Marshall-like with a cold clipper stage. It’s got a LOT of gain on the drive channel.

@neilmeansneil 6 ай бұрын

It's interesting that you appear to be doing product testing for the design, I wonder if they layout diagram has been updated after all your issues?

@paulwilliams4984 6 ай бұрын

@neilmeansneil I don't know how many of the ROX-15 kits have been sold, but Modulus say they've not had this issue flagged by anyone else. Though, to be honest, as far as I'm concerned the only real issue is the Boost Switch. As for the DC at the master volume, this wouldn't have been a problem if I'd used JJ valves! As stated, the matched pair I'd bought some years ago turned out to be wildly 'unmatched' so couldn't be used in the application.

@skeeterbuck1355 6 ай бұрын

Thanks Paul for the follow up video and posting the voltage chart. I think this additional information will be very helpful for anyone interested in building this amp. I am considering building one after my current amp build is finished. (Fender Blonde Bassman)

@WalterWiseman 6 ай бұрын

These amp build videos have been absolutely great. Invaluable to those of us who are interested in starting such a project but are a little intimidated. Really appreciate you taking the time to document the process and the troubleshooting involved. Nice tone too! (Also very interested in a kit amp sound round-up video!)

@paulwilliams4984 6 ай бұрын

Thanks for the comments, I never really wanted to create any videos, but there was nothing available for the two Modulus amps I was interested in building, so did these.

@skeeterbuck1355 7 ай бұрын

Just play some chords and dial in some different tones with and without using the master to give us an idea of what the amp is capable of.

@neilmeansneil 7 ай бұрын

Another potential buyer of this kit here, thanks for making this video series, they've been very useful. Still can't decide between the Rox 15 or a TubeTown kit. I don't need 15w's to noodle in the spare bedroom.

@paulwilliams4984 7 ай бұрын

I can't offer an opinion on Tube Town, though I used to buy valves from them in the past, but Modulus have provided great support very promptly to any issues I've had.

@skeeterbuck1355 7 ай бұрын

Good troubleshooting job Paul. Those generic silver mica caps (just marked "SM") can definitely cause issues. I have been considering building this kit and those would all be replaced with CDE silver mica or Vishey ceramic disc caps. How about some more playing videos so we can hear what she sounds like. 😎

@paulwilliams4984 7 ай бұрын

Thanks for the kind words - as for playing videos, I really am a very bad guitarist, I just like making things, but I will try and put something together when I do my final thoughts on the kit.

@steveguitar7 8 ай бұрын

Hi Paul, well done in completing the build. I have followed your journey on the amp from the beginning and found it very informative. Where you were testing the amp towards the end, do the instructions for voltage measurements come comllete with the amp, or is this aspect due to your expertise in working on valve amps in general? If the latter, would you be able to post the measurement details to enable myself and perhaps other people might find it helpful, if they are going to build this particular amp from modulus. Thanks again for highlighting the whole amp build process.