Phase700b
AK Lurker & Kinsman
I just acquired a three piece Hitachi combo. An FT-440 Tuner, HCA-7500 Control Pre-Amp, and the matching HMA-7500 MOSFET Power Amp. I've been wanting the Control Pre-Amp for the two phono inputs it has with the selectable load switches. It just happened to be with the rest of the gear.
The caveat was that all 3 pieces were in storage and very dirty complete with dust laden cobwebs. However, I love a challenge and also the chance to keep some vintage audio gear out of the scrap heap.
The equipment was beyond just some gentle dusting off. I first used a soft brush and low pressure air hose. Then, disassembly of each piece. The tuner and control pre-amp were not too bad inside as there are no louver/vents to allow much dirt inside. But even so, there was the often found filmy dust on bits inside. So, careful work with a soft, static free carbon bristle brush and some judicious use of Deoxit got things in order. The tuner will need some dial and meter lamp bulbs. But after the initial clean up.. . these two pieces are looking and sounding very good.
The HMA-7500 was a different story. Because it has open vents on all sides it was just layered with dust. Also, the front anodized panel either had a poor finish to begin with or had something happen to it. It has a faded, almost transparent, purple-like look to it with a copper looking finish coming through. I think it was a poor finish when new , because this is also present inside the back of the front panel. The other two pieces have beautiful dark satin black finish inside and out of their front panels. Also, both meter lights are out and the right meter is good checking it with a meter, but does not move with signal applied.
I completely removed the heat sink with the output MOSFETs on it. It has two wiring harnesses with amp type connectors to the drive circuits. So I used a Flitz type polish on Q-tips to polish the pins that the plugs mate to. They appear silver plated and are now clean and shinny. I then used Deoxit on with one of those very small dental brushes and cleaned out the socket end of the connectors. The amp seems to work fine, except for the meter and the appearance factor. I still have it on the bench wondering what I can do about some kind of restoration to the front panel and still retain the lettering and logos? Any suggestions?
I'll be setting the trio up here in awhile and post some pictures.
Does anyone have any idea how I might mask off the lettering and dye or paint the faded anodized Power Amp panel? I read where paint doesn't always adhere to anodized surfaces very well. There is a product used for craft metal work called "Swellegant" that is a ploy type metal dye that also has a finish sealer. Anyone every try this product for metal work?
The caveat was that all 3 pieces were in storage and very dirty complete with dust laden cobwebs. However, I love a challenge and also the chance to keep some vintage audio gear out of the scrap heap.
The equipment was beyond just some gentle dusting off. I first used a soft brush and low pressure air hose. Then, disassembly of each piece. The tuner and control pre-amp were not too bad inside as there are no louver/vents to allow much dirt inside. But even so, there was the often found filmy dust on bits inside. So, careful work with a soft, static free carbon bristle brush and some judicious use of Deoxit got things in order. The tuner will need some dial and meter lamp bulbs. But after the initial clean up.. . these two pieces are looking and sounding very good.
The HMA-7500 was a different story. Because it has open vents on all sides it was just layered with dust. Also, the front anodized panel either had a poor finish to begin with or had something happen to it. It has a faded, almost transparent, purple-like look to it with a copper looking finish coming through. I think it was a poor finish when new , because this is also present inside the back of the front panel. The other two pieces have beautiful dark satin black finish inside and out of their front panels. Also, both meter lights are out and the right meter is good checking it with a meter, but does not move with signal applied.
I completely removed the heat sink with the output MOSFETs on it. It has two wiring harnesses with amp type connectors to the drive circuits. So I used a Flitz type polish on Q-tips to polish the pins that the plugs mate to. They appear silver plated and are now clean and shinny. I then used Deoxit on with one of those very small dental brushes and cleaned out the socket end of the connectors. The amp seems to work fine, except for the meter and the appearance factor. I still have it on the bench wondering what I can do about some kind of restoration to the front panel and still retain the lettering and logos? Any suggestions?
I'll be setting the trio up here in awhile and post some pictures.
Does anyone have any idea how I might mask off the lettering and dye or paint the faded anodized Power Amp panel? I read where paint doesn't always adhere to anodized surfaces very well. There is a product used for craft metal work called "Swellegant" that is a ploy type metal dye that also has a finish sealer. Anyone every try this product for metal work?
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