Posted on 2017/12/10 13:13.
Tagged as: diy.
Here are some photos and tips of the rebuild process of a Nikko RC 6V battery pack.
Beware! Do not try to do this if you don't know what you're doing. Batteries are not a joke. Wrong polarity mistakes and short circuits can lead to a fire or an explosion. Take the following information at your own risk.
I've opened the sealed battery case with the help of a Dremel multitool and a cutting disc. It is necessary to be very careful not to damage the battery cells when cutting the sides of the sealed battery case. Inside whe can found five 1.2V AA NiMh regular batteries tied together in series to get the required 6V.Read more...
Using strong tape and 5 brand new Amazon's 1.2V AA NiMh 2500mAh rechargeable batteries, I've set up the new battery pack (carefully taking account of original cell's polarity).
To make the cell links, I've used copper braid. Before welding the new links, I've prepared the surface of the poles by gently sanding and tinning them.
Protect the cell links with tape and weld the battery pads from the original pack. Be careful to not make shorts with other cell poles. Remount all in the original battery pack case. I've used more tape to secure all.
Ready to roll and recharge... ;)
Posted on 2017/08/03 22:44.
Here are some photos of two modifications I've made to improve the amplifier.
I've replaced the old and rusty speaker terminals with some new golden plated banana plug terminals:
This amplifier do not have an AC input EMI filter, so I've installed one to reduce power-line interference problems.
Posted on 2017/06/25 20:10.
Previously, I've removed the top cover and the aluminium front panel and knobs to access the inners of the amplifier. Over the many years of use, control knobs and front panel tend to accumulate a lot of grime and grease. To make the aluminium parts shine again, nothing better than wash the surfaces gently with hot water and neutral soap. Carefully wipe with a wet microfiber cloth, to avoid damaging the front panel lettering.
... and testing.
After recapping, the sound stage has improved considerably. This little amplifier sounds really, really good.
Posted on 2017/04/26 19:35.
This new blog entry gathers some information about recapping, or the dark art of replacing the capacitors in vintage audio gear. As I stated on my previous blog entry, the electrolytic capacitors tend to decrease its perfomance through the years, and it's a common practice to replace all of them in audio equipment with more than 20 years old. Nowadays, good quality capacitors have better electric characteristics and smaller footprint, and can be easily found on online shops.
To make the task of replacing the caps easier, it's a good idea to grab a copy of the unit's service manual. Some small capacitor's values can be tricky to decode and a look to the schematic can help us a lot. Below you can find the complete Pioneer SA-5300 schematic that I've restored in one single image from various parts obtained browsing the net.
Once all capacitor values were identified, I ordered new parts using Panasonic low ESR references (FM and FC series) when available on RS Online, my shop of reference when searching for electronic components. The result: a lot of little plastic bags filled with shiny new caps ready to be installed.
One by one, all old capacitors were removed from the PCB and replaced with its new Panasonic equivalents. This task is not complicated, given the simplicity of the amplifier's board PCB layout. All the capacitors are easily reached without removing the PCB from the chassis. Once all elements are replaced, the difference in size between components is easily visible.
On the table, a bunch of old electrolytic capacitors, some of them with signs of leaking badly.
Bonus: The power indicator bulb was blown. At first I thought of replacing the bulb with a led connected to the amplifier's DC section, but fortunately I found a store in Madrid where these small bulbs were available. I desoldered the blown bulb from the AC supply wires and reconnected to the new bulb, insulated the joints and reattached to the holder using hot glue.
Next stop: cleaning and testing.