Nearly done ... !

The final stages of painting a guitar are fun .. real fun. Having waited impatiently for a few weeks to let the final lacquer coats go hard enough to finish properly, I followed the guides on Manchester Guitar Tech's web site to do the necessary. It involved starting with an all over sanding with 1200 grit sandpaper, using a small block for the flat areas and by hand on the more curvy areas wet and dry. I took great care not to go too far on the radiuses. This left the body with scratches all over. I then went over with 1500 grit wet and dry again, which kind of removes all of the scratches and leaves it with a dull surface, with some faint scratching still visible.

Then I went over again with 2000 grit - again wet and dry, which magically changed the surface to a semi-reflective, burnished kind of finish. You can afford to get a bit more robust as the sandpaper is taking much less material away. There were a few areas where I had to go back to 1200, 1500 and back to 2000 to make it uniformly burnished all over.

The final step involved applying T-Cut and polishing, and the effect was almost magical. I've now put all of the re-polished (Dremel style) hardware on, and this is how it looks now - before re-stringing.

New headstock ...

I am a little proud of the way this turned out ... waterslide decal, layer of varnish over the top .. oh, my ...

HP LaserJet 2100

Replaced my laser printer with a newer one from that auction site. Paid £15 delivered. Scary what you can buy these days for pennies. It even came with a Jetdirect network option I wasn't expecting ..

Time for a bit of guitar painting ..

My favourite guitar from the collection is a Peavey Predator .. it looks a little old, jaded and beaten up around the edges so I have decided it's time for a remodelling. It has a grounding issue as well, so time I took the faceplate off. I have a couple of slightly hotter pickups for the neck and middle as well, so hopefully this will be an improvement.

Tobacco sunburst original (meh)

So we are in the business of respraying body and front of the headstock in a nice traditional surf green, nitrocellulose paint.

I sanded down the body to mostly paint, but some of the sunburst left. It is a proper paint job, not plastic coated so once sanded it makes a good surface to paint on. The first job is to give the body a complete priming - this is three thin coats followed by one last one.

Once the primer has dried overnight, I gave it it a light wet and dry sanding with 1200 grade paper, and then began putting the colour coats on. This is after about six thin coats. It's now hanging in the garage for a week to harden nicely before I give it another wet and dry, probably with grades up to 2000 and then it will be time for about six coats of clear gloss lacquer. Then, it will be a good month of letting it harden properly before final sanding, polishing and re-fitting all of the hardware. I've a little extra thing to do; I have some waterslide decal medium for the inkjet, so I need to make up something to go onto the headstock front, which is Surf Green as well now.

I am looking forward to this a lot - it's difficult to be patient!

Active Crossovers

I thought it was time to assemble the active crossover boards. One is going to be for playing with, and will find itself into the subwoofer amp at some point in the future (have dug the Peerless 850140 out of the loft).

Here's one I prepared earlier.

Liberator, my trusty Z210 had a small failure two days ago. Wouldn't boot up - I have been switching her off during the heat wave when I haven't needed her going all the time. She'd come on for about 2-3 seconds, and then flump.

I felt like my right arm was cut off. I have not been in the new Lab in the garden very long, and things are still finding a place, but even so.

I pulled all of the USB devices, all of internal cards, re-seated the fan connectors and re-did the heat sink and fan assembly. Still broken.

So I did a search on eBay, found a company called ICT Reverse who had one in stock, and they delivered within less than 24 hours.

And today, Liberator is back up and running! I must take those Windows stickers off it, though. This machine proudly runs Linux Mint 19.

Meanwhile I have installed a new CPU board in the 16500A. (an eBay purchase from the far Americas for less than 30 quid - amazing) The new CPU board has twice the memory of the old one, so it 1) takes longer to boot and 2) the 1 gig sa/second two channel analogue board and the 100MHz logic analyser can run at the same time. Result!

I know this is nowhere close to WightFibre, Andy, but ...

I think I have fixed the network ...

Have we fixed the phones ?

The home network has been a journey since we moved in. I have recently joined up the last bits of the network, and I now have a Netgear SRX5308 Prosafe firewall between the three house wired networks, and the outside world.

Well it kind of worked, but still had problems with the phones, which mostly worked but sometimes struggled with DNS, and SIP timeouts, and the service de-registering from its peers.

Struggled for a day with this, doing Wireshark traces and so on, and then eventually found something odd. I couldn't see the activity from UDP packets on the inside showing on the outside.

And then, I found this snippet on a web site somewhere:

I had just installed a new Netgear SRX5308 VPN/Firewall in our network (5 VLANs, about 70 users and around 200 devices total). Everything seemed to be working fine, but — randomly and intermittently — new connections would be slow or time out. So users would experience web pages loading slowly, or failing to load at all, but then working again on a second try, etc.

Netgear support couldn't help much with it, so I did more of my own diagnosis, and eventually found that it was related to DNS lookups slowing down or failing intermittently when going through the firewall; if I was outside the firewall, everything was fine.

I then found the solution myself: to uncheck the "Block UDP flood" on the "Attack Checks" configuration of the firewall settings. Since I deactivated it, everything has been working fine.

I then went back and looked in Netgear's documentation — apparently, the "Block UDP flood" option, which is enabled by default, triggers when it has 20 or more simultaneous UDP connections from a single LAN-side client. And of course, DNS works over UDP port 53, so we were seeing intermittency whenever we got to >20 DNS requests at the same time from a client. (And, in fact, the current manual acknowledges this in a note on p. 136 — which is in the firewall rules section and unfortunately not referenced in the Attack Checks section).

The reason I think this is likely a common problem: 20 simultaneous connections is WAY TOO LOW for modern browsers and network usage; an single average webpage can load material from its own server, 2-4 social networks, various sources for Javascript libraries, fonts, CSS, etc., and CDN servers for images — all of which require DNS lookups. You could easily get to 20 on a single page, even without accounting for stuff the computer is doing in the background that might involve DNS lookups or other uses of UDP.

I have made the change on the firewall now, and since then the https://www.sipgate.co.uk/ service doesn't reregister, or deregister every 20 seconds; DNS lookups are more stable, and things are feeling a lot more snappy.

AND all the phones seem to work now - result! 

.. and we need more space ..

The lab is getting a bit full, so I have had to add some storage space to organise the stuff and get it all connected up. I've bought an extra table so I can have my digital scope out working, and to get some of the audio stuff off the floor and put to good use (and so I can play the piano I repaired a little while ago) I thought I would make a 19 inch rack for the effects, amp and so on.

And now, embedded in the new Studio / Lab / Office ... 

.. and this is the other end (the Office-y bit)

Sony STR DB-830 horrors

So I spent a little time working on the Sony problem with the mute. I used a heat gun to warm up various boards, and I found that when heat was applied to a very localised spot on the digital board, it burst into life; only to retreat into silence again a few seconds after the heat is removed.

The issue seems to be either cold joints or an oscillator. So I've replaced the oscillator crystal, and resoldered the cold joints. There's a small repair to the PCB as well, since the removal of the old piezo took a bit of track with it. (cheap PCB). Fingers crossed ...

Denon 1910 horrors

So I ran the diagnostic on the 1910 .. and it is showing that it is version E2, and the communication between the main processor and the sub uCom is broken ...

Sub Error 01 ... No response from Sub-μcom

So the question is what to do about this? It seems that a bunch of people out there in the Interwebs have had issues with the HDMI board on 1910s, and the solution involves changing said HDMI board. Of course finding a 963189004020D might prove difficult.


So my thoughts are:


1) Find one

2) Warm the existing board up with a heat gun to see if it might be the usual lifting of a leg here or there

3) Give up with the amp.

I have a Sony STR-DB830 around the place somewhere, which has a fault on it, but that fault might be easier to fix. Given my setup in the Lab uses the TV to do the video switching, and then the TV feeds out optical digital to the amp, I don't need the HDMI switching capability of the amp any more.
Actually, I just found it in the loft, and it does seem to function. Ta da.

The Sony suffers from a 'mute' issue, which seems to be temperature related. If I turn it on, and leave it on in a warm room for 15 minutes, it suddenly kicks into life. I have fixed that temporarily before with a heat gun on the digital board, and it might be worth a go. The amp has lived a bit, and is not as cosmetically appealing as the Denon, but we need some sounds quick!

On another related topic, I have used a 3.5mm jack on an Echo Dot (version 3) to feed the analogue input of the Denon, which works well.  (assume I can do the same with the Sony, should the need arise) However, the bass is a bit lacking, so I will need to find a way of changing that. There is talk in the fora about an equaliser app for the Echo Dot? I also need a way of making sure that the Echo Dot audio is always audible, so I might be venturing inside it with a glue stick to see if I can get it to feed out through its own speaker as well as feeding out via the 3.5mm jack. Or maybe I mix the audio in the amp with a couple of resistors. Neither approach being very satisfactory tbh.

There is some advice on T'internet that you can put the 3.5mm jack in, and then, when you need to short out the contacts on the socket when you want the internal speaker to work. So that might be when the amp is not listening to the Echo input, or is muted. Maybe I will do something extra to the amp so if it is on, and not muted I will mix the output from the Echo onto the front two channels. Or maybe the centre speaker. Oh, that sounds right. Watch this space.

Reconing the Missions

And another one for the new Lab; I have removed all of the drivers from the Mission 700s. I think these speakers came from a small shop in Chandler's Ford in about 1981; I had re-coned them with some Audax drivers in the 90s, but they have lived a long, sun-drenched life in the Office on Hayling, and it was time to replace them again.

I had a good experience with the Monacor SP210 drivers in the Kef 104 I have in the lounge. They really do kick out a great, punchy but not overstated bass/midrange, so I bought another pair for the Missions.

Since the Lab is white and light Oak, with touches of chrome, the dark ?walnut of the boxes just had to go. I am not really sure how I feel about painting over veneer, but they were a little battered anyway on the corners. I took the trouble of spraying them with a white primer, and then an eggshell finish white. The new drivers went in after a couple of weeks of the enclosure drying in the garage, and they seem to have come out quite well:

Sounds? Well, having a bit of trouble with the amp at the moment. It doesn't seem to be decoding a digital input. I have the optical output from the TV, and I was hoping that the amp would just pick it up and drive the speakers, but it doesn't. I wonder if the HDMI board has left the planet when the old TV HDMI input went bang.

I did plug the Alexa into the analogue input on the amp, and I listened to Bon Jovi's Wanted Dead or Alive through the speakers. They work, and really very well.

All change for the house network

I gave up trying to get DD-WRT working successfully on the DIR-868L wifi hub. It was working quite well, except all of the Amazon Echo devices would occasionally disconnect, and I had a time getting Android phones working. The wired functionality was all fine, but that's not good enough.

So, I have now moved to buying another server, suitable for running pfSense on. This distro is a simple install of a BSD box that is configured as a firewall, router, VPN, VLAN-aware and capable box. So I have now re-architected the house solution to use that box instead ..