Use a C= 1530 datasette as tape audio player

How to listen to audio using your Commodore C1530 datasette, and why.

Please read through the whole post, as there are some things in the end, you might want to start with.

If you’ve ever had the doubt whether there was audio or data on a casette tape, and you’ve only had your Commodore computer and a datasette, and of course a computer to work with. This might come in handy for you.

First of all, you’ll need some kind of connector for the equipment you want to use. I’m using a standard 3,5mm minijack connector. Stereo/mono doesn’t matter as there’s only one channel. If you have a stereo connector, make sure you use the left channel then. You can use the cable from a cheap set of earpieces, one item less to solder.

This is not a stand alone solution, you need to supply power to the datasette, this can come from the Commodore computer, or a stable power supply.

Beware, you might have a different version than this. This one I have here use a Goldstar Lm324, it’s a quad-amp chip. The schematic isn’t precisely the same as the model, but it’s close enough.

Basically you just attach the cable to the output of one of the amps. On the shcematic below I’ve marked Pin 1 and “Pin 7” well actually it’s the output going to the Commodore computer, but I call it pin 7 here. I’ve taken Pin 1 instead of Pin 7 as the voltage level is alittle less there. On the output of Pin 7 you get around 3v peak-to-peak, and you get around 2v peak to peak on pin 1. the normal input of a soundcard is around 1v peak to peak. So just make sure that the input volume is way down.

 

Here is an older picture where Ground and Signal line (pin7) is marked. I did a little testing here, and it’s way too much output. But it’s doable if you don’t want to solder on pin 1.

As you can see I’m using a stereo cable/minijack connector, but I’m only using left channel. Here it’s still Pin 7.

 

Sorry for the image quality. I’ve added a small extension cord to the left channel of the audio cable. It’s the green one you can see in the middle of the pcb, soldered to Pin 1 of the goldstar lm324 amp chip.

 

Before you start soldering, you should take the audio cable and stick through the rubber ring.

This is a real easy hack to do, you only need to know how to solder, and have access to a solder of course.

I haven’t tried transfering data from tape to PC into a tap file using this method, but it might be doable. If anyone tries this, I’d love to hear about it.

 

Disclaimer: if this doesn’t work for you, or if you destroy your hardware, don’t blame me.

 

Adding heatsink to the A4000 voltage regulator

I’ll show you how to add a heatsink to the A4000 voltage regulator without soldering.

 

Background

A voltage regulator like the 7905 shown in this guide delivers -5v out even if you have an input of -10v. As with almost all things in the physical world excessive energy will be transformed into heat, so will the excessive voltage from -10 to -5 volt, that means the regulator becomes hot. I haven’t checked the input voltage on the Amiga 4000 but looking at the print beneath the regulator shows it gets really hot.

On some pieces of electronics you can see the PCB will be used as a heatsink around the regulator, this is done by attaching the regulator to the PCB with a screw. This is ok when it doesn’t become too hot and the engineers have done a good job designing it.

You can also attach a heatsink to the regulator, which is what I’ll show in a few.

 

Getting ready

Tools needed:

  • Thermal compound (optional but recommended)
  • Screw and a bolt
  • A screwdriver that fits the screw
  • A pair of tweezers or similar (optional), or a hexagonal top that’ll fit the nut

I couldn’t get a flat bolt, but the triangular headed screw can do the job. I cut the screw to a shorter size with a dremel.

I bought a few heatsinks on the internet, the silver ones were priced around €0.50 each

The dimensions of the medium sized one is 13.3 * 19.1 * 12.7mm

The black one is way too large, the small and medium ones are good choices. I could use the smallest one as the A4000 didn’t come with any at all, but I might as well use the medium one.

 

The mentioned voltage regulator

Ready to work

Add some compound on the heatsink, not much is required. The cut down screw with nut

I gently lifted the regulator to an upright position so it was easier to attach the screw with the screwdriver. The screw is preferably inserted from the bottom, it was a little troublesome to attach the nut when you don’t have a hexagonal top, but I managed.

The screw doesn’t need to be tightened with force, just enough when you feel a resistance and the heatsink is firmly attached.

 

The finished result from 2 angles

The regulator cannot be bent down vertically again, if you want this, you need to do some soldering.

 

Fixing Soldering Pads

Yesterday I started on repairing the motherboard of an old Amiga 1200. For the first test it seemed to work fine. Then I started looking closer at the board.

The initial inspection, everything seems to look fine, a little rust on the tv tuner shielding, a lot of dust

Amiga 1200 motherboard

Looking closer on the blue resistors, those small blue ones in the middle of the picture, the solderings are matte, they should be shiny. This is typical for old computers where the smd capacitors have leaked acid.

Hold on. There seems to be a capacitor missing, just to the left of the white connectors. The solder pads are gone too. This capacitor is used for one of the audio out, if this is missing, no sound will be heard from on of the stereo channels. I checked the other channel, which was missing too, but solderpads were intact.

Amiga 1200 - Corrosion and missing capacitor

Working with lemon juice on a cotton stick to neutralize the acid from the capacitor, I gave it a good cleaning around the area. After that, a trip to the dishwasher. And letting it dry for ½ day. I probably won’t power it on for another week or so, so all the water should be evaporated for that time.

The following pictures were taken from a USB microscope bought for $1 on ebay, quality is not perfect, sorry about that.

I scraped off the protective layer of the rest of the wires, and tinned them afterwards. Time to look for something that can be used as solder pads, as I didn’t dare solder the new capacitor onto the wires directly, they are just too fragile.

Zoom-in on missing solderpads

I found an old PCI board this is a promise SATA150 controller.

Solderpad spares

Using a simple knife, this one isn’t particularly sharp, I managed to remove a couple of connector legs.

Removing pci connector

Doing a quick measure to see if they are allright, looks like it

Solder pads are ready

I used some loc-tite glue to glue the pads to the pcb. I found out later I should probably have used another kind of glue as this one got liquid again when warmed.

Glued solderpads

After a little work I managed to tin the connectors, and get a connection to the wires. It’s not the best solution, but it’s better than the alternative. I also tinned the copper surface to prevent it from oxidizing.

Solder pads, glued and tinned

Soldering the cap onto the newly made solderpads were less of a hazzle, glue seems to be effective again

Fixed the capacitor

Almost finished board, this now has it’s SMD capacitors replaced, a trip to the dishwasher and cleaned some acid infected solderings. Only the 4 non SMD electrolytes are missing from replacement. Only the electrolytes were replaced.

Amiga 1200 refurbished

There are plenty of guides out there how to replace SMD capacitors, I find them the easiest to replace from regular old fashion caps.It’s basically

  1. Spin the house around till it falls off.
  2. Use the solder iron to remove the broken pin from the solderpads.
  3. Clean the solderpads with a desoldering wire.
  4. Apply alittle solder paste to each pad
  5. Attach the cap (remember in the right direction), eventually adjust it so it looks nice too.
  6. Heat the solder paste with your solder iron until it gatheres around the pad and cap leg. Instead of solder paste you can also use a thin solderwire. I use that when it’s easy to access the pads. I use a 0.25mm wire for that. 0.6mm should be good too.

Updated 28/6-11
New status – I’ve tested the amiga board, and everything runs perfectly (floppy, sound, video, harddrive), except for the right mouse button. Activating the right mouse button gives a click in the sound, and it’s not functioning, I’m affraid that I’ll have to replace paula.

Reverse airflow on aquarium air pump

Aquarium airpumpI recently bought an aquarium pump (this one http://bit.ly/mGSbB5) from dealextreme. It’s a 3w airpump with rubber feet, and nice plastic casing. So I hacked it to reverse the airflow so it would suck air rather than blow. This is due to that I need it to suck away fumes/smoke when soldering. It took me little time to figure out how such a thing worked, and so I hacked it. Not a problem when using hot glue.

It reversed the airflow, but not enough. I had to have the soldering iron just beneath the plastic hose before I could see any effects. So I upgraded it, I drilled some larger holes where the air could flow through, also some holes in the casing itself to make sure the air inside could get out. But with no major luck I still needed to put the hose just above the soldering iron. The smoke didn’t even change direction when the hose was 1 cm away.

Ok the hose is around 5 Meters in length. I’ll go to the pet shop tomorrow and get me another hose that I can cut and adjust as I see fit. The hose I’m using now is meant for water cooling in a PC.

Else I think I’ll need something that can move some air. I don’t think the 5W airpump that DX also have will make any difference.