Tuesday, June 7, 2016

Loose thoughts by Bjorn Landfeldt

Hughes & Kettner Tubemeister 36 repair


A couple of weeks ago I got a new 2x12 inch Celestial Vintage 30 cabinet which I was eager to plug in and test with my H&K Tubemeister 36. After some 10 minutes of playing on the clean channel, the amp started to distort notably and then there was a flash and sizzling sound before the amp went silent. At the back, all four TSC lights were on indicating no output current.

The manual states that this is most likely due to a blown anode fuse which can happen when the amp is turned on with a faulty tube and the TSC does not have time to shut things down.

After searching far and wide on the web I found little information that could help me with this problem, as it happened after ten minutes of playing it didn't sound like the TSC would not have had the time to shut tubes off.

Anyway, the problem was indeed a blown anode fuse and perhaps also a faulty tube causing this, which as far as I can tell would be very unusual as I have played the amp perhaps 100 hours and have the anniversary edition with military grade tubes which should last a LONG time. The amp has not been carted around but stayed on top of my speaker at home so there should be very little risk of mechanical damage done to the tubes. In any case I would imagine that the TSC should have shut the tubes off before the anode fuse fried, but perhaps this circuitry is faulty (amp one month out of warranty of course).

I thought, I'd just post a couple of photos showing where the fuse is located for others who might experience a similar problem, it is really easy to get access to but the amp has to be opened up from the bottom. Just turn it upside down and unscrew all the screws at the bottom and remove the plate. The fuses are located on the circuit board lower down near the power supply connector. You have to remove the red and green wires to get to them and make sure to remember which color sits on which pin when you install them back.

There are two fuses, 400 mA and 800 mA. In my case it was the 400 mA fuse that blew. I would recommend to use a wooden or plastic tool to help loosen the fuse as there are some fairly sizable capacitors in there which may hold residual charge. As there is no circuit diagram available as far as I can tell, it is difficult to know where there may be voltage left on the circuit board.

It is easy to check if the fuses are OK. Test with a multimeter if the resistance is close to zero or infinite. If infinite, the fuse is blown (if you are holding the probes with your fingers you may get some MOhm reading since  a little current goes through the body at this point but the fuse should be close to zero if it is OK).




Closeup of fuses and were they are located.

Sunday, September 13, 2015

Loose thoughts by Bjorn Landfeldt

MAC OS X kernel out of memory problem


Over the past few months i have experienced that my MACBook pro running out of memory and suspending all applications for me to fix the issue. The problem has increased in frequency and recently i had enough and actually started looking into the issue. As of now, I have not isolated the exact problem in the code and let's face it I most probably won't have the time to do so given my work load, but I have managed to get around the problem so the system is now not running out of memory. i am running a 2015 model machine with 16 Gbyte of RAM so it is not an issue of actually having too little memory for the tasks I carry out (email, web, powerpoint, programming, MATLAB, LaTex etc.)

In my case, the symptoms were:

From Activity Monitor

  • kernel_task 11-12 Gbyte RAM 200 % CPU
  • nsurlstoraged Lots of RAM 100-200% CPU


This was the case even without any applications running in some cases, in other cases closing Mail or Safari could solve the problem.

Digging around the web a bit to try to figure out if others have had the same problem, I can see I am not alone but so far I have not found any solid advice on what is going on and how to solve the issue. My own experiments are pointing towards nsurlstoraged as being the culprit, running amok and for some reason causing the kernel to grow in size very rapidly.

I found some advice about deleting the SAFARI cache directory and tried that, but the problem remained. I then started looking more closely at nsurlstoraged and noticed that this process seems to trawl through a whole series of files from various applications. Especially I noticed that it started writing copious amounts of data to disk and even though it accesses a large set of files in the file system it spends a lot of time writing data to:

/Library/Containers/com.apple.mail/Data/Library/Caches/com.apple.mail/fsCachedData


and spending much time in other caches as well.

I reacted by doing two things, first I used Onyx (free tool) http://www.titanium.free.fr to clean out caches. Second, I cleaned the Mail idea database by opening the Terminal and typing in the following command:  sqlite3 ~/Library/Mail/V2/MailData/Envelope\ Index vacuum;

The problem has disappeared since then and I don't know if it will reappear but for now I have no issues with exploding kernel memory.

Also, nsurlstoraged is back to 0.0% CPU usage where it should be. I suspect that there is a bug in the code so that this process starts misbehaving when there is too much data to index and keep track of.

Monday, August 1, 2011

Is DIDO a Dido?

Loose thoughts by Bjorn Landfeldt

Over the weekend, there was much noise in media about a new revolutionary technology dubbed distributed input distributed output or DIDO for short. In Australian media the technology was dubbed an NBN killer.

Of course I was intrigued since the article in the SMH I read claimed that DIDO would prove the Shannon capacity wrong --no little claim even if it came from a tech reporter who had never heard of information theory in their lives.

So, what is this all about? Well, there was a white paper released that was supposed to detail the new revolutionary thinking and of course I read it on my iPhone while waiting to get my new tyres fitted on the car. The paper is very poorly written. In fact, the writing style as well as the inaccurate reference to the Shannon capacity and other subtleties makes the piece very unconvincing (unless you have a pocket full of money and are looking to invest). There is no explanation of the system that any researcher can make use of to understand exactly what DIDO is supposed to do, but media has bought it outright.

However, it is complete unfeasible what is being proposed? I would say no. The paper alludes to some sort of network coding using superposition of radio transmissions that given a specific coding could very well yield a constructive result at given spatial points. However, I seriously doubt that a small group of people would build such a system on their own in a short time. If they have succeeded, the best thing ever in communications.

However, given the white paper that was released and complete lack of information, I would say it is a hoax or hot air at best. Perhaps the definition of DIDO in the dictionary gives a hint. Miriam Webster lists:

Definition of DIDO: A Mischievous or Capricious act. Synonyms: Prank, frolic.

For now, I will still be using Shannon when I work.

Tuesday, July 5, 2011

Why you should avoid to use the US cloud

Loose thoughts by Bjorn Landfeldt

I just read this interesting blog entry from ZDNet.

Microsoft has now openly admitted that US authorities has the power to force any US company to hand over private and public data stored on ANY server in the world AND to force the company in question not to disclose this to the owner of the data. Now, call me overly cautious, but I really don't like the idea of this for my future cloud services. Already, this blog, my Gmail data, flickr images, youtube videos, Google calendar, documents, facebook account, twitter and linkedIn data is readily at hand for these authorities. Couple this with Google keeping a history of all my web searches, Apple keeping my movement history from my iPhone and you guessed it, US authorities know more about me than my wife does already.

In my line of work, I am dealing with filtering of child pornography, web pages with threats to national security Internet vulnerabilities etc. I have publicly commented that the Obama kill-switch is ridiculous etc. Am I an interesting object to investigate? Not unlikely.

Let's play with the thought that some homeland security desk clerk gets an alarm from the data mining stream filter tool that there is an individual who has searched for some irregular things and also publicly commented that the US administration is giving itself powers they should not have. Hmmm, that's interesting perhaps this Australian professor is hiding something... With a mindset of finding incriminating evidence and irregular behaviour it is not far fetched that I would be subject to an investigation and if I had all mu data and all my information stored on servers that are owned by US based companies, I bet there would be lots of very personal information about me in circulation among US authorities. Would I mind? Probably not if I was kept unaware of this situation, but what if someone saw some incriminating pattern by chance and they actually acted on it?

I guess there is a real business case for non US owned cloud services. Greece?

Wednesday, June 15, 2011

Loose thoughts by Bjorn Landfeldt

We had the pleasure of hosting Kevin Brown, the CHRO and Manager corporate services for the Australian NBN Co in School of IT at SYdney Uni last week. He was going through the reason behind the NBN roll out, the state of affairs and projections for the future. In all, the talk didn't contain any news apart from what has been covered in the media already but one thing he did state that I thought surprising was that the reason for their existence was that Telstra has failed the market and something needs to be done to break up their near monopoly. I have suspected this for some time now, that the motive behind the NBN is not to provide broadband services as such, but to correct the horrible mistakes done when Telstra was privatised. In fact, I remember telling Quentin McDermott from 4-corners about my suspicions a couple of years back when his team came to interview me about the mandatory Internet filtering.

I was reflecting on this statement for sometime after the talk and it dawned on me that this can in fact be one of the most expensive stuff ups by any Australian government in terms of cost to rectify the situation. If the point of the NBN is to create a functioning telecom market, isn't $42bn a pretty hefty bill compared to the cost of breaking up Telstra in a retail and a wholesale company from the beginning and then float one or both? True that tax payers bill is only estimated to be $27bn, the rest coming from private investments.

Since I am generally speaking a bit interested in what is happening in the telecom market around the world, and I still have pretty strong ties with Sweden I couldn't help myself but to investigate the state of affairs in that country just to compare. Sweden is an interesting country to compare with because it is just like Australia a country with high concentration of the population in few cities with much rural regions in-between. It is true that Australia is vastly larger, but the majority of Australia will be covered by satellite which in effect renders the vastness pretty unimportant. In Sweden, rural areas will be covered by LTE just as the case in Australia (Ericsson just got a large order from the NBN Co). Also, Swedes and Australians are fairly much at the same level of computer usage, literacy etc. and the envisaged applications for the NBN is the same as the applications envisaged for the broadband network in Sweden in general.

So, how do things stack up? Well, in Australia the vision for the NBN is to provide 100 mbps broadband to just over 90 % of the population with the remaining part receiving 12 Mbps. Currently, it is far from certain that one can get more than a couple of Mbps even in Sydney because the distance to exchanges can be quite long and mobile broadband deployment is pretty patchy. Of course, there is no doubt that the NBN will deliver a completely new infrastructure and service to Australians but how much ahead of the rest will AUstralia be after paying all this money?

The Swedish equivalence of ACMA, the PTS, released a report on the state of broadband in May, detailing how it sees the compliance in the country with the Swedish government's broadband policy. The policy is in many ways similar to that of the current Labour Government, including target broadband penetration, minimum rates, competition in the market etc. The difference is that in Sweden, the Government has not had to roll out anything, the market is taking care of this on its own with the aid of spectrum release and other policies.

The Swedish state of affairs is as follows; currently, 44% of the population (residential and businesses) had access to at least 100 Mbps in 2010. The Government's goal is that 90% of the population will have access to at least 100 Mbps in 2020 and PTS sees this goal as being likely to be met (nothing of concern at present). Currently, there are 1100 households that do not have access to at least 1 Mbps broadband in the country and the average broadband downstream speed is ~18Mbps.

So, it is clear that Sweden is miles ahead of Australia in this regard and it is also clear that in 2020, the two countries will have similar levels of service. It must be noted that the Australian NBN will have a larger fibre base, the Swedish rollout will incorporate a larger portion of wireless broadband through LTE2 technologies so it is most likely easier to upgrade the NBN beyond 100 Mbps when there is a need for that. However, the investment level in Sweden in broadband technologies is in the order of $1 bn per year by the market, a far cry from the NBN figures. Tax payers do not pay for the roll out and monthly broadband subscription costs are lower than they are in Australia currently.

Where there is a significant difference between Government policies is also on the focus of what to do with the beast! THe Swedish government has concerns about inclusion in the digital ecosystem, how many people feel integrated in the broadband world and do not feel excluded, alienated and disadvantaged. There is a similar goal of 90$ of the population feeling part of the digital ecosystem by 2020. Also, the Swedes are clever in that they actually discuss how to make good use of the infrastructure, how to grow industry and maximise benefits since this is the driver for the development. Sadly, in Australia we are breaking up a monopoly.

SO

Friday, September 10, 2010

Suits in Sweden

Loose thoughts by Bjorn Landfeldt

Since I am visiting the country of the Polar Bear, I thought I'd have a look at cold water diving equipment and pricing compared with Sydney. So far, it is looking good.

I am considering buying a new wet suit or dry suit since 1) My old crap Mares trilastic completely fell apart the last dive I did before leaving to go to Europe and 2) My Pinnacle Dry suit Cordura is just far too stiff and captures a lot of air so I need far too much led to break the surface. There are quite a few dive shops in Stockholm but similar to Sydney, the vast majority do not disclose any prices on their web sites. There are some different options available of course, but where I can see some interesting alternatives are basically in two different shops.

First, we have Alpin & Dyksport in Stockholm. The sell the Northern Diver Vortex dry suit for kr 7500, about AUD 1136 and the Waterproof W1 wet suit for kr 2600 (AUD 400). Then we have Dykmagasinet in Karlstad that stocks a wider range of options:

  • Waterproof W1 kr 3000 (AUD 455)
  • Waterproof Taurus Semidry kr 4500 (AUD 682)
  • Waterproof Sedna Drysuit kr 8900 (AUD 1350)
  • Waterproof Drako Drysuit kr 9500 (AUD 1439) and
  • Ursuk Heavy Light Drysuit kr 7800 (AUD 1180)

All prizes include 25% sales tax.

The Waterproof suits are really top of the line quality with lots of features and an aura of quality. There is a funky looking Australian Waterproof web site that lists some retailers, but the websites have all but no information / little visibility and no pricing. I found one company in Victoria that retails the Taurus for AUD 1000.

The Diveoz forum has had some threads on these suits but there is little information available apart from everyone complaining about the pricing.

I am going to Karlstad next weekend to have a look at the suits and hopefully to try them on. Right now, I am leaning towards the W1 and Ursuk suits, but a Taurus would be a very good alternative in Sydney too.

The W1 has some nice features, extra strength around shoulders, elbows, knees and bottom. Ankle and wrist seals and zips, the shape of the suit looks much better thought through than the competition, neck comfort seal, front zipper (not dry) with flap inside, warm lining etc. (7 mm). The Ursuk seems in description very similar to the DUI TLS350 with an added hood with latex front. I would be very interested in a drysuit made of soft Nylon material with unrestricted movement and little trapped air. Sydney does not get cold enough to warrant really heavy undergarments and this suit can give similar buoyancy characteristics as a thicker wet suit.

I'll also have a look at the neoprene drysuits, it seems they are a much snugger fit on the body than trilam and a thin undergarment would be enough in Sydney. I might enjoy diving with this all year round, who knows.

Wednesday, June 9, 2010

Renting in Sydney

So we sold our house in Western Sydney and moved to the Sutherland Shire to be in an area where the schools are bette and we are closer to the water. BIG mistake. The Shire is full of people who were born without morals. I mean completely without morals. Not just shifty, I MEAN COMPLETELY WITHOUT MORALS.

First we moved to Grays Point. We rented a house from Raine & Horne Miranda. The owners were traveling the world and even though the property was a bit expensive ($600 / week) we were in an area with a good school and it looked peaceful so we went for it.

After 4 months, the owners declared that they were moving back home and we had to find another house to rent. We had plans to go to Sweden for a sabbatical at this stage so we asked if we could stay a couple more months before we were going. The owners suggested that they would move in with us, we would pay full rent and they would use our stuff. Naturally, we were a bit hesitant and while we were discussing this, I got a phone call from the real estate agent siply stating " the owners are moving in with you tomorrow, is this OK?" I was a bit bewildered at this and told the real estate agent that we had made no such agreement. The agent was fairly abusive asking me what the owners were supposed to do now that they had already rented a truck. The next day we had the owners coming to our house to "have a chat with us".To cut a long story short, the real estate agent tried to rip us of by stealing our bond money but when we filed a counter claim with the tenancy board, there was a very quick shift in atitute and we got our bond back. We then moved to Gymea Bay and rented a house from Ray White Gymea. It became evident quite quickly that the house was in a very bad condition and needed some urgent repairs. The bottom floor had a rising dampness problem which caused mould to grow everywhere, on all our clothes, furniture, books, you name it. My wife even got respiratory problems and has started using asthma medicine as a consequence. The real estate agent never did anything about the problem as it unfolded. It was not until after we had called mould experts ourselves they reacted and offered to 'clean the carpet'. At this stage, we had all out belongings off shelves and out of drawers on the floor to stop the mould destroying everything.

The landlord came past and cut three holes 20x 10 cm in the walls in the bedroom plus installed a fan to circulate air and get rid of some of the moisture. If you have lived in Sydney during winter, you know that you don't want three such holes in the bedroom wall since the indoor temperature quickly falls to 5-8 degrees. We had no option but to request to move again, 3 months after we moved in. At this stage, Ray White Gymea started to become really abusive. The correspondence we have had with them is unbelievable. They have had my wife in tears, done everything they can to make our lives Hell even though we have started to get ill from living in the premises and we have two young children who may be affected for life. Very interesting people those Ray White people. Now, we have the outgoing inspection tomorrow and we notified the Ray White Ofifce so we could do the inspection together. We were tole that they were going to do the inspection alone and we were not allowed to be there, go figure.

I was told by the residential tenancy board to notify the agent that we would do an inspection so they can be present if they choose to. We should have witnesses and take many photos. When I wrote an email to RayWhite Gymea about this, the owner, Bill Anastasiadis wrote me an email saying that the tenancy board was ill informed and going on about him being the principal of Ray White Gymea.

I can't wait for the final inspection. Obviously these people are following their own moral standards, not what the tenancy board thinks is the norm for Australian renting agreements.

The question is, is this a Sutherland Shire decease or is this just Raine & Horne Miranda and Ray White Gymea business operations and moral standards?

One thing is for sure, renting properties in Sydney in this climate sucks. It is not enough paying rent on time and looking after the property. You also have to be prepared to take abuse from real estate agents and bow down to the people who own property, after all, they must be better than you since they own a house to let and you don't have that much money.

Loose thoughts by Bjorn Landfeldt


UPDATE!!

The principal left the following comment on this post

"Bjorn,

It is amazing how you have posted only parts of the true facts.

When we where alerted to the mould issue it was my office that paid for a steam cleaner and mould expert to attend the property not you.

It was my office that also had someone attend to rectify the problem.

You also fail to mention that my office also negotiated and had the Landlord release you from the Lease and also had the Landlord pay for your removalist costs and compensate you.

I advise that you have the true facts mentioned on this blog of yours otherwise it will be construed as defamation."


Anyone who may have thought I was exaggerating.......

It is true that Ray White wanted to steam clean the carpet, but it was not until we ourselves had an expert inspecting the property they got some cleaners in to clean the mould off the walls and outside the furniture. All clothes, books, inside book cases etc. were left covered in mould and also left for us to clean.

It is true that the landlords agreed to end the lease and pay for our move, after all we were starting to develop serious respiratory problems and with a pregnant woman.......

We are out of the house and there were no surprises towards the end apart from the removalists not moving everything so we had to do much of it ourselves, but still...