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Showing posts with label Hardware. Show all posts
Showing posts with label Hardware. Show all posts

Wednesday, July 27, 2011

How do Energizer Lithium AA cells work?

How do Energizer Lithium AA cells work?

Non-rechargeable lithium cells are 3 volts right?

But if they're AA cells, then people will expect a notional 1.5 volts at the terminals right?

So ... what gives? Do they have an internal DC-to-DC converter or what?

The answer is that there are many battery formulations which use lithium, and cells made using them can all be described as "lithium cells".

As far as I can tell, Energizer Lithium AA cells are Lithium Iron Disulfide cells. According to Wikipedia this formulation results in a cell voltage of about 1.4 to 1.6 volts, which should make them broadly compatible with scenarios expecting 1.5 volt cells.

Search strings:

  • How do Energizer Lithium AA batteries work?
  • How do Energizer Ultimate Lithium AA batteries work?

Monday, July 4, 2011

Lexmark X543 beeping five times

Lexmark X543 decided it didn't want to start up. The power was coming on and the display was lighting up, but nothing was being displayed, and it was giving me a five beep cycle.

The Lexmark website said that this five beep indication would be given if the main board could not see the control panel.

So I wondered if it was as simple as a loose connector on the cable connecting the main board and the control panel.

So took off the back panel which covers the main board and had a look. Had a poke around to see if there were any loose connectors. Nothing really in evidence.

Switched it back on. Still not working. Gave each cable a poke and a wiggle. When I poked the membrane cable in the top centre, the display changed and started to show the sequence of dots for the printer startup. The printer then came up and was able to print. Cool.

Later on I tried printing but the printer had frozen again. Switched off the printer and switched it on. Not working. Held the cable slightly up. The printer then started up and I was able to print a page.

Decided it must be this membrane cable causing a problem and wondered if it was just the connection to the main board which might be the problem. Wondered if it could be unplugged from the main board so, with the machine switched off again, gave it a progressive tug.

The membrane cable came out of the recepticle on the main board. Then wondered if it would go back in again, so carefully lined it up and carefully eased it back into the recepticle.

Switched printer on, and it booted up without assistance. A few minutes later it proceeded to print the entire backlog of unprinted jobs on the Windows 7 machines on the network. Ah well, at least it's printing again.

If it carries on working, I may decide to risk putting the back cover on again.

If this posting helped get your Lexmark X543 printer working again, please consider donating 5 U.S. dollars or 5 Euro.

Keywords: Lexmark X543, not printing, not starting, beeping 5 times, beeping five times, five beeps, 5 beeps

Tuesday, March 1, 2011

Humax Foxsat-HDR won't record two channels at once — FIXED

A few years ago, I installed a Sky free-to-view system for a relative. This involved installing a Sky minidish on the outside of the house with a single LNB and a single cable coming down to a Sky digibox. This was just a straight standard definition receiver box — I think it even pre-dated Sky HD services in any case. There was no record facility so it, so only one cable was required. The Sky digibox was acquired second-hand via eBay. I think I originally set it up with one of those viewing cards which was no charge per month and let you watch just the basic channels.

This all worked fine. After a while the situation meant that the relative wanted to have a basic package from Sky, which they got, and were paying fees monthly to Sky. After another while, they decided they didn't want to pay Sky anything, so changed their package again down to a no-charge-per-month package.

This was fine for a while. Then the digibox started playing up. It would work for a while, then go downhill with the picture breaking up. If switched off overnight, it would then work for a few hours the next day before going downhill again.

I was called in to fix it — a 100-mile trek. I reasoned that as it worked for a while after powering up, it must be the digibox, perhaps something like it was overheating. So I swapped in another digibox, the same make and model, which I had lying around after having had my own installation upgraded to Sky Plus.

With the other digibox swapped in, everything looked fine. 100 miles back home. But then it started doing the same problem as the first one had. So I wondered if perhaps it was something else.

In the initial installation, I didn't really know what I was doing, and had bought the dish and cable as a kit. There was 20m of cable (aluminium foil screened I believe) in the kit, which wasn't really long enough to reach, so I had routed the cable in a way which left it a bit exposed to the elements and not thoroughly clipped down. So I wondered if the cable had deteriorated. So, after another 100 mile trek back to site, I tried putting in a short temporary cable (using proper copper-foil-screened foam dielectric cable) from the dish to the box, and I also tried a third digibox (my Sky Plus box from home).

Neither of the Sky digiboxes would work on any cable, but the Sky Plus box worked on all cables. So I reasoned that my second "test" digibox was broken in the same way as the first digibox.

So this would require changing the box. I advised my relative that they might want to take this opportunity to upgrade to a recording Freesat system and to get a Humax Foxsat-HDR.

Now, at the time they only had one cable coming down from the dish, and of course a Foxsat-HDR, to work fully, would need two cables.

So the plan was for them to get a Humax Foxsat-HDR, install it themselves on a single cable, and then I would come back another time to arrange a second cable. 100 mile trek back home again. As it was, the original cable was not long enough and was not routed optimally, so I decided to put in two new cables.

So eventually I found the time to put in two new cables from the dish to the Foxsat-HDR. 100 mile trek back to site again. This time I used proper copper-foil screened, foam dielectric cable, with brown outer insulation to match the colour of the house, clipped on with matching brown clips. The cable was also routed properly so as to be out of the elements, no tight corners, and clipped all the way. Much better.

Connected it up to the Foxsat-HDR. The box said that it could see good signal on both inputs. "So", I thought "Job Done". 100 mile trek back home again.

I spoke to my relative in the meantime to help get them into being able to record programmes, which eventually I was able to do. After a while they discovered that they were not able to record two high definition programmes at once. I was puzzled by this, but put it down to the data rate on high definition programming being too high to cope with another stream at the same time.

After another long while, it transpired that they could not even record two standard definition channels at the same time. Very puzzling. After all, I had checked the box and made sure that both inputs were showing a good signal.

After a while it was time to visit again. I had a play with the box. Sure enough there was still a really good signal on each receiver channel (something like strength 90%, quality 100%). But if I told it to record a programme, then I went to watch something else, I would find that many of the channels were "greyed out" and unable to be selected. Puzzling.

I had a sniff round on the web and found that this problem could happen because of the box only using one receiver input. But … but … I checked, and the box was showing two good signals, so surely it couldn't be that.

Then eventually I found a suggestion that the box only "decided" how many cables it was going to use at initial set-up time, i.e. the thing which it usually only does once when you first set the box up. So, for example, it would not do it on a soft power-up time, or even on a hard power-up. Only when the box is initially set up. As I had not thought I would need to do this when I had first put the two-cable feed in place, the box would then only be using one of the inputs.

The solution suggested was to do a "factory reset" on the box. I was concerned that this would erase all stored programmes, something which people would not normally want to do. But I thought I'd go and have a look.

I went into the "factory reset" option on the box, and thankfully it presented a clear message on-screen to say to the effect that recorded programmes would not be removed.

So I went through factory reset, and the box went through its initial set-up, and I had to re-enter the postcode etc.. Crucially, at one point it put up a message to the effect of "Detected cables: two". This then told me that it was detecting the number of cables connected.

After that, I could tell the box to record a programme, then go and watch another programme, and all channels were available, i.e. none were "greyed-out" as before. I could also record two programmes at once.

So it looks like the engineers at Humax have decided that the number of cables is pretty much fixed, and they haven't really catered for the case of someone starting with one cable and later upgrading to two cables.

I am surprised that the box does not re-detect the number of cables more easily. It even shows the signal strength and quality on both cables, so it knows that the signal is there. Also there seems to be no option anywhere in the menus to re-detect the number of cables. The only way is to do factory reset and go through initial set-up.

Update 2011-03-14: It turns out you can change the number of cables without having to do a factory reset. The cable configuration can be changed through a hidden menu.

So it is both (a) hard to even tell that it hasn't detected the second cable, and (b) even when you do figure this out, it's a bit hard to discover how to fix it.

Once you know, it's easy. But the knowledge is "magic" and not easily discoverable.

Hopefully by posting this article, it may save some people some trouble.

If you found this article helpful, please consider donating 0.25 U.S. Dollars or 0.25 Euro.

Phrases to help people find this page:

  • Humax Foxsat HDR some channels are grey
  • Humax Foxsat HDR won't record two channels at once
  • Humax Foxsat HDR won't use second cable
  • Humax Foxsat HDR won't use second receiver
  • Humax Foxsat HDR won't let me record one channel and watch another
  • Humax Foxsat HDR problems

Tuesday, November 2, 2010

Netgear DGN2200: Don't buy

Netgear DGN2200 review: Don't buy. Zero stars out of Five.

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I bought a Netgear DGN2200 (from Amazon) to replace the DG834Gv4 which appeared to have failed (all lights coming on).

As I'm talking about two devices here with gobbledegook codenames, I'll highlight them differently in different colours. So the new (bad) one is the DGN2200, and the old (good) one is the DG834Gv4.

(As it turned out later, the DG834Gv4 hadn't failed; only the power supply had expired. By pinching the power supply from my previous-previous router (DG834Gv2), which was also 12V 1A with the same pinout, I was able to get the DG834Gv4 going again.)

Back to the DGN2200, it is a case of: Nice hardware, shame about the firmware. The DGN2200, as offered in its current form, is a load of rubbish. In a couple of years, assuming the firmware gets fixed, it could be a good little router. But today, don't touch it with a bargepole

The DGN2200 seems to incorporate a perfectly decent DSL modem. On my somewhat lengthy telephone line, I get a DSL synch rate which is in the same ball park as the best I have seen.

Also the DGN2200 seems to incorporate perfectly decent wireless hardware. As far as I could tell, all my kit seemed to connect up to it easily and maintained a reliable connection.

The problem, and it's a biggy, is the network software:

If I try to access an HTTPS website on a non-standard TCP port number, then I find that it takes 5 or 6 attempts to connect. Now, this might look like simple packet loss, or perhaps the MTU is too large. Well, sorry, no, for several reasons:

  1. If I do swap test with the old DG834Gv4 router, the DGN2200 fails on this point whereas the DG834Gv4 doesn't. The DG834Gv4 connects first time, every time.

  2. I can run a simultaneous ping which shows 0 out of 100 packet loss. Also I can run a simultaneous SSH session which is consistently snappy and responsive. So why do ping and other services work reliably but HTTPS (on a non-standard port number) doesn't?

  3. I can take the MTU down to 1400 or 1350 and there is no difference. In any case, why does the DG834Gv4 work fine when the DGN2200 fails miserably?

I tried monitoring the HTTPS packets on the server side using tcpdump. When the problem is manifesting, the server does not see any initial packet arriving. So the server has no cause to respond. The packet is simply not arriving, and everything points to the packet being lost by the DGN2200.

More problems: If I try to set up an OpenVPN connection to a server listening on UDP port 1195, it takes 5 or 6 attempts before it connects. Packet loss or MTU? Nope, for the same reasons as the first problem. Again, the DG834Gv4 connects first time, every time.

I tried raising support requests through Netgear, but we were moving at a snail's pace, and besides I now have the old router working again.

So I have raised an RMA through Amazon and the DGN2200 is going back. Update 2010-11-04: Amazon have now issued a full refund for the unit.

In addition, I have advised Netgear that I would be more than happy to consider assisting them on a consultative basis.

If you found this posting useful, please consider donating 0.25 U.S. dollar or 0.25 Euro.

Thursday, June 10, 2010

LG 37LH5000 red button prompt dismissal

When you're watching a programme on the LG 37LH5000 via the integrated Freeview receiver, you sometimes get an overlay at the top right of the screen telling you that you could press the red button.

On Sky Digital, you get similar prompts and you can dismiss this prompt by pressing the 'back' button.

But this does not work on the LG 37LH5000.

So can you do the same thing another way, and if so, how?

Yes, press the green button.

Friday, February 20, 2009

Dead Amstrad DRX400 Sky Box — fixed

Presented with mother-in-law's Amstrad DRX400 Sky Box, not working. Fault reported as "power button does not work".

Upon powering up, the power light came on red, and also the remote command light was on red continuously. Pressing the power button did indeed not make the power light go green, even after allowing a long time for boot-up. The remote command light being on continuously was not a good sign — it should only light up when an infra-red command is coming in from the remote control.

Sniffed around on the web, initially searching for "factory reset". This showed up some common problems with the DRX400:

  • Doing up the connector on the dish input too tight can result in the innards of tuner module breaking
  • A 2200μF capacitor can fail in the PSU module
  • A 3300μF capacitor can fail in the PSU module

Showing an invalid light combination seemed to tie in with a PSU problem.

Popped the lid and looked for burst capacitors on the PSU module, but could not see any.

The legends on the main PCB indicated what voltages should be coming from the PSU. Guessing that the end pin (number 14) was 0V, measured the potentials on the other pins using a DMM. Found various voltages, plausible for the indicated potentials but with significant errors (see table below).

Upon pointing out various parts of the innards to my wife, she commented that one of the capacitors on the PSU looked a bit funny, with a slightly bulging top.

The bulging capacitor was a 2200μF 6.3V 105°C radial electrolytic (branded "Licon") on the PSU PCB. This matched one of the common problems.

Maplin was showing a plausible substitute for under a pound, so I thought it was worth a shot. Procured a 2200μF 16V 85°C radial electrolytic from Maplin, a little larger diameter, but would still fit. Temperature rating 85°C rather than 105°C though if it gets over 85°C inside the box, I think we have other problems.

Replaced the capacitor on the PSU.

Upon powering it up, the power light came on red, and the remote command light did not come on. Pressing the power button made the power light go green.

Measuring the voltages again, they were much closer to the indicated potentials (see table below). Also I found that what I thought was the 3.3V rail was actually the 5V rail and vice versa!

Put lid back on. Connecting it up to TV and dish feed showed it was all working.


PinBeforeAfterDesired potential
PotentialErrorPotentialError
131.3 V+4.3%31.1 V+3.7%30 V
229.8 V+49%24.9 V+25%20 V
38.11 V+21%6.42 V-4.2%6.7 V
43.59 V-28%5.08 V+1.6%5.0 V
53.59 V-28%5.08 V+1.6%5.0 V
64.32 V+31%3.39 V+2.7%3.3 V
74.32 V+31%3.39 V+2.7%3.3 V
84.32 V+31%3.39 V+2.7%3.3 V
9-5.12 V+2.4%-5.02 V+0.4%-5.0 V
100 V0%0 V0%0 V
110 V0%0 V0%0 V
120 V0%0 V0%0 V
130 V0%0 V0%0 V
140 V0%0 V0%0 V

Tuesday, November 21, 2006

ZyXEL wireless ADSL router: rubbish

I had the misfortune to buy a ZyXEL wireless ADSL router.

It was atrocious.

Comparing the ZyXEL to the Netgear DG834G is like comparing wee to Pinot Grigio.

My advice would be to steer well clear of ZyXEL.

Tuesday, November 14, 2006

Toshiba Satellite Pro A30 hard disk drive HDD removal

This will involve the removal of several tiny cross head screws. Use the right tool or you will likely mash up the screw heads and make things really unpleasant for the next guy. A set of miniature screwdrivers can be bought for £5 or so, so don't go whining about not having them.

Remember to keep a note of which screw goes where so that you can put them back in the right places.

With the machine upside-down, the hard disk is buried 'underneath' the optical drive.

So you need to get the optical drive out first. This can be done by removing the "F5" screw which is near the inboard-most edge of the optical drive, and sliding the drive out outboard-wards.

You should then be able to see the hard drive.

To get the hard drive out, remove the four screws at the four corners, then slide the hard drive in its cradle outboard-wards to unplug the connector.

The hard drive is in a cradle, so if you are selling the hard drive or some such, detach the cradle and keep it together with the screws which hold the hard drive to the cradle.

Installation is pretty much the reverse of removal, subject to application of reasonable amounts of common sense. Be sure to put all the screws back.

Keywords: remove extract Toshiba Satellite Pro A30 hard disk drive HDD removal extraction