GPO 746 Rotary Dial Phone – Remember these?

UK GPO 746 Rotary Dial Telephone

When I was small I have memories of my grandma and my parents owning one of these phones, not that they had much choice of course since it wasn’t until the early 80s that other companies were allowed to make phones in the UK; before that it was the good old GPO’s job to rent one out to you. I took mine to bits to fix the dial, it kept sticking, and while taking it apart I took some photos which are attached to links throughout this post. Read on, this is more than a bunch of photos…
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Attempting to repair my FAL Phase 44 amplifier

FAL Phase 44 Amplifier
FAL Phase 44 Amplifier

Sometime last year my old Kenwood hifi amp stopped working due to the speaker cutout relays not working. The speakers would never switch on, making for a fairly useless amplifier.

While my cousin was sorting out his mess before moving to the US he found this old “FAL” brand amplifier. A spot of Googling reveals this was made by a company called “Futuristic Audio Limited” who also seem to make guitar amps. He didn’t want it, I needed an amp, so it came home with me.

Due to its age I noticed quite a lot of noise when trying to adjust the volume so decided today to take it apart and attempt to clean the insides out. I also bought some switch cleaner to spray in the potentiometers.

The insides were very simple. Here is a photo of the main circuitboard which contains nothing but through-hole mounted resistors and capacitors. The most complex electronic components in this are the four transistors bolted to a piece of metal. There are also some large looking capacitors, and an interesting looking network of diodes.

Unfortunately I think cleaning the contacts on the potentiometers and switches might have messed the electrical characteristics of the amp up. Since this isn’t an IC based amp, I have a feeling there’s a fine balance between the components that makes the thing work, and squirting a load of switch cleaner into things has altered this. When I power the amp up, only the left channel works and the volume goes really loud then distorts – all by itself, without me moving the volume knob. I’ll leave it for a few hours to see if the cleaner evaporates off. It’s no great loss if it is broken, the reason I took it apart was because the sound wasn’t correct and the volume kept wandering between left and right speakers, so maybe it’s finally packed in.

Looking at the electronics inside, part of me wonders if it’s repairable.

Ubuntu 9.10 – Tedious Timewaste

I’m attempting to install Ubuntu 9.10 server edition on my server. To say it’s not going smoothly would be as big an understatement as saying “That Hitler bloke, he was a bit naughty, wasn’t he?”. The damn thing just won’t boot up! It gets as far as saying ‘Grub Loading.’ and then gets no further.

At first I thought it might be the weird combination of IDE controllers and disks I have. I have a 1TB SATA drive, plus two PATA drives. The machine is supposed to boot from one of the PATA drives, and use the SATA as a data drive. This used to work. It even used to work with some crazy extra IDE card in the machine. The motherboard has some half-baked combination of IDE, IDE-RAID and SATA, giving me a total of ten possible disks in the machine. Whoever designed this motherboard was going for a bit of everything, the machine even takes DDR and DDR2 RAM.

Thinking that maybe all this crap was confusing things I switched it all off and pulled out every drive except the drive I wanted to boot from and reinstalled Ubuntu on that. GRUB was installed, it all went well… then the machine rebooted and sat there looking like an oversized doorstop.

I know the BIOS can find the correct disk because I see the ‘GRUB Loading.’ message, but then it seems GRUB fails to find the rest of itself and stops working.

My next plan is to install onto a spare SATA disk I have to see what happens. If that fails I’ll install a previous version of Ubuntu to see if they broke something in this version. It seems they’ve switched to something called Grub2, which has lots of new cool features. Is “booting my system” one of these new features?

Blogs and websites I like to read

I use Google Reader to follow quite a lot of websites, blogs and anything else interesting that squirts out an RSS feed. For the curious, here is a list of my favourites. I’m leaving out the well known things like XKCD, Dilbert, Hack-a-day and so on.

I often find these kinds of sites while browsing around the comment fields of popular websites. It’s fun to click the random links in people’s signatures…

What are your favourite websites to visit? I’m always interested in new things to read.

ZX Spectrum +3 with DivIDE CF board and RGB cable

A month or so ago I ordered a DivIDE board from Papaya Labs. The DivIDE board is an ATA interface for the ZX Spectrum, allowing IDE devices such as hard disks, CDROM drives and Compact Flash cards to be plugged into the Spectrum, which, through a special loader built into the board, allows .Z80, .TAP and .SNA images to be loaded into the Spectrum and run. The .Z80 and .SNA images are simply pushed into the Spectrum and it runs them with no need to reboot. The .TAP files are presented to the Spectrum as real tapes, and after typing ‘LOAD “”‘ they load in exactly as a tape would – only in a few seconds, rather than a few minutes.

This is a long post, with lots of information in, more after the break… Press it, you can watch a YouTube video at the end. More photos of the setup available on my photos website.

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Macro Electronics Photography

A cluster of SMD resistors that look like a small town
A cluster of SMD resistors that look like a small town

While building my MAME cabinet and sorting out the various motherboards in my posession, I got a bit bored and started taking random photos. Electronics are interesting close up, this image shows some surface mount resistors on the back of a motherboard, their positioning looking like a small town.

I took other pictures and they are on my photos website, so have a look at an iBook Logic Board and iBook 3GB Hard Disk fromwhen I upgraded a tangerine first generation iBook’s hard disk (which takes a mere 30 steps).

There are also images of an Intel Celeron CPU before adding heat paste and after adding heat paste (yes, I put on more than that, don’t worry… I know how to apply heat paste to CPUs). And some very dusty power regulation electronics on a PC motherboard plus a nice abstract shot of the underside of three PCI expansion slots.

Linux on your oven – or why fans are good in computers

Intel Celeron CPU with not enough CPU paste
Intel Celeron CPU with not enough CPU paste

So, my MAME cabinet was having stability problems all day. Either it was locking up, the network kept dropping or bits of it stopped working (like the sound). By a process of elimination I managed to make it consistently crash running Memtest86 after about ten seconds. No errors were printed about the RAM, and it did it with both sticks of RAM in the machine.

The BIOS reported the CPU at a toasty 70c which is kind of high, but then my P4 based server upstairs runs at 60, and seems quite fine with that. All the same I went to Maplin, bought some heat transfer goop and gave the CPU and heatsink a good clean. Not that the CPU needed much cleaning, since there was barely any heat paste on it. There was a large chunk of crusty, dry paste on the back of the heatsink too. Lm-sensors now reports the machine running at 40c while under heavy load.

Don’t buy cheap hole saws and expect them to last for more than one use. Also watch out, MDF is really easy to start smouldering. Make sure all the clumps of burning MDF dust are removed and the holes aren’t smoking either.

Today has been a slow, frustrating day. I “lost” four hours earlier just faffing with the machine trying to make it work. I still don’t know why the PC says the BIOS checksum is incorrect every time the power is removed, the motherboard battery is good so all I can think is the flash in the BIOS chip is starting to fail. It wouldn’t surprise me, I did get this motherboard free inside a junk PC case on Freecycle.

Mame Cabinet – With added electroshock therapy

danger-electric-shock-risk-signAs part of my ongoing “learning by my near fatal mistakes” attitude to life I’ve discovered some interesting problems with my MAME cab. While undergoing the torture known as “getting MAME to work” I found the PC kept crashing, or being just plain weird. Having to reset the BIOS every time it was powered up was getting tedious too.

So, deciding the motherboard was probably to blame I reached my hand in and went to switch it off. While doing this I noticed that whenever I touched the PSU and rubbed my finger over it I felt a strange ‘fuzzy’ bumpy sensation, exactly like the weird vibration aluminium macbook owners sometimes experience. It also caused something to emit a familiar 50Hz humming sound.

After I’d finished playing with this amusement (really, if I’d discovered radioactivity, I’d be dead by now… oooh look at the glowing warm rocks!) I set about finding the source of the faulty ground connection. It didn’t take long, the 4-way power strip I was using had faulty connections where sometimes the earth pin of the plugs going into it didn’t make a good contact with anything.

That’s all fixed now, but the PC keeps crashing so I have no idea what’s wrong. I’ll try removing the wireless ethernet card now, maybe that’s at fault.