Re: Useful inspections (capacitors a. o. things) before using a QL?
Posted: Fri Feb 23, 2018 12:01 pm
The difference between the environment for electrolytic capacitors in a QL and a ZX Spectrum is what makes the difference.
In a QL, they are in a case that is cooler inside compared to a rubber key ZX Spectrum 16k/48k. The ZX Spectrum+ is not as bad but still rather warm.
The electrolytic capacitors in the DC/DC converter section of the ZX Spectrum are worked hard and operate in a hot environment. The loss of the -5V supply generated by this DC/DC converter means that the 4116 DRAM chips loose their bias supply. They don't like this, and can die as a result... Hence it's best to replace them before failure
In a QL, with it's design of power supply, the electrolytic capacitors get an easier life (they therefore last longer). Plus, it's safe to run the machine until failure.
Most electrolytic capacitors are rated for 1000 to 2000 hours at 85 degrees C. So if run at 25 degrees C, especially if use is time limited, they can last for many, many years.
With regards to the electrolytic capacitors that were available after the 1980s, a lot of that problem was the drive to reduce size and cost while improving performance, and an alleged stolen but defective "new" electrolyte formula... With far too many companies jumping on the bandwagon...
Now that the manufacturers know about the problem, current production and recently made electrolytic capacitors should be fine
Mark
In a QL, they are in a case that is cooler inside compared to a rubber key ZX Spectrum 16k/48k. The ZX Spectrum+ is not as bad but still rather warm.
The electrolytic capacitors in the DC/DC converter section of the ZX Spectrum are worked hard and operate in a hot environment. The loss of the -5V supply generated by this DC/DC converter means that the 4116 DRAM chips loose their bias supply. They don't like this, and can die as a result... Hence it's best to replace them before failure
In a QL, with it's design of power supply, the electrolytic capacitors get an easier life (they therefore last longer). Plus, it's safe to run the machine until failure.
Most electrolytic capacitors are rated for 1000 to 2000 hours at 85 degrees C. So if run at 25 degrees C, especially if use is time limited, they can last for many, many years.
With regards to the electrolytic capacitors that were available after the 1980s, a lot of that problem was the drive to reduce size and cost while improving performance, and an alleged stolen but defective "new" electrolyte formula... With far too many companies jumping on the bandwagon...
Now that the manufacturers know about the problem, current production and recently made electrolytic capacitors should be fine
Mark