jwjarch
New Member
Let me start by telling everyone, this will not be a multi-day or multi-week restoration. Not exactly sure how much time it will take because I will be going over every part and piece to restore this amp back to as close to or better than factory condition as possible. I don't see a ton of info on the A-7 floating around. I hope this thread comes in handy for future A-7 owners out there.
A few notes before I start in on this project. When I saw the old Onkyo's I fell in love with the silver faces with well laid out knobs and a general sense of weight to everything. I couldn't wait to dive in and find one for myself. This particular integrated came to me via Ebay, from Honolulu of all places. I don't see that this amp has ever been serviced before. Surprisingly, it is in pretty good in it's age, circa 1978-1979. There are a few small issues but nothing to stop me from hearing what it sounds like pre restoration. On the AUX and TUNER inputs there is a slight noise that comes equally through both channels. It is audible from about 6 feet from the speakers and is not affected by the volume knob. The PHONO inputs both have a significant noise in the left channel. Most likely the SA726's in the PHONO stage getting old and noisy, These will certainly get replaced. The volume knob and balance have a little scratchiness to them. Every pot and switch will receive a good DeOxit. The amp has been on and playing music for the better part of 8 hours today and warmth is barely detectable. I like that!
I'm auditioning it with a pair of Betsy driver on 18"x18" open baffles using my laptop (Microsoft Surface) and a Sabre ES9018k2m DAC. A few things for my personal notes. Hoping for some improvement in all of these areas after the restore. The sound stage is OK but not very expansive or deep. Imaging is decent, not pinpoint. Separation of instruments is OK but does muddy in complex orchestral type music. Decay of instruments is not great. I don't have that issue with these speakers and my ACA Class A amp. Overall a very neutral sounding amp though. Just enough warmth. Just enough detail. Very easy to listen too for long periods of time. I think this one is worth saving.
So peering into the guts (see attached photos) this is a very well constructed amp. It's clear that Onkyo spent some coin on their development as well as their manufacturing back in the late 70's. All wires are attached with beautiful wire wrap at all of the pins. All of boards look pretty accessible so far. This will be a huge benefit, as I plan to replace all of the electrolytics throughout and will also have a good look at any signal path components, such as film caps, carbon comp resistors, and any "problem" transistors such as the infamous SA726's. The main supply caps are 25,000uF 55V Nichicon CEW. These things are huge! I'll see what tests I can preform to check their health. In general there is a lot of surface rust throughout. I plan to disassemble completely and get of rid of any traces of dirt and rust, refinishing and even re-painting as needed. I may also replace the speaker binding posts as the stock posts don't give a very positive attachment of even 14 gauge speaker wire. Most of the knobs also have issues with the clear cote over the aluminum, as you can see in the photo of the volume knob. If anyone has any suggestions to help restore these, let me know.
Should be a fun journey. Stay tuned!!!
A few notes before I start in on this project. When I saw the old Onkyo's I fell in love with the silver faces with well laid out knobs and a general sense of weight to everything. I couldn't wait to dive in and find one for myself. This particular integrated came to me via Ebay, from Honolulu of all places. I don't see that this amp has ever been serviced before. Surprisingly, it is in pretty good in it's age, circa 1978-1979. There are a few small issues but nothing to stop me from hearing what it sounds like pre restoration. On the AUX and TUNER inputs there is a slight noise that comes equally through both channels. It is audible from about 6 feet from the speakers and is not affected by the volume knob. The PHONO inputs both have a significant noise in the left channel. Most likely the SA726's in the PHONO stage getting old and noisy, These will certainly get replaced. The volume knob and balance have a little scratchiness to them. Every pot and switch will receive a good DeOxit. The amp has been on and playing music for the better part of 8 hours today and warmth is barely detectable. I like that!
I'm auditioning it with a pair of Betsy driver on 18"x18" open baffles using my laptop (Microsoft Surface) and a Sabre ES9018k2m DAC. A few things for my personal notes. Hoping for some improvement in all of these areas after the restore. The sound stage is OK but not very expansive or deep. Imaging is decent, not pinpoint. Separation of instruments is OK but does muddy in complex orchestral type music. Decay of instruments is not great. I don't have that issue with these speakers and my ACA Class A amp. Overall a very neutral sounding amp though. Just enough warmth. Just enough detail. Very easy to listen too for long periods of time. I think this one is worth saving.
So peering into the guts (see attached photos) this is a very well constructed amp. It's clear that Onkyo spent some coin on their development as well as their manufacturing back in the late 70's. All wires are attached with beautiful wire wrap at all of the pins. All of boards look pretty accessible so far. This will be a huge benefit, as I plan to replace all of the electrolytics throughout and will also have a good look at any signal path components, such as film caps, carbon comp resistors, and any "problem" transistors such as the infamous SA726's. The main supply caps are 25,000uF 55V Nichicon CEW. These things are huge! I'll see what tests I can preform to check their health. In general there is a lot of surface rust throughout. I plan to disassemble completely and get of rid of any traces of dirt and rust, refinishing and even re-painting as needed. I may also replace the speaker binding posts as the stock posts don't give a very positive attachment of even 14 gauge speaker wire. Most of the knobs also have issues with the clear cote over the aluminum, as you can see in the photo of the volume knob. If anyone has any suggestions to help restore these, let me know.
Should be a fun journey. Stay tuned!!!
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. Anyone can tell me if there is a replacement potentiometer that would match this amp by the chance? Thanks in advance