Updating A Legacy Stereo Receiver

We have used a SONY Receiver for our main room TV, Radio, Media Player audio needs for many years, and have been satisfied with it.  However, the FM receiver section has recently developed some apparent AGC problems, and no longer maintains an even volume, fluctuating slowly and unpredictably.  Some internal poking, and a look at the maintenance manual I have for it, show that the FM tuner is a sealed unit, purchased by SONY from a third party, so prob. not something I can repair.

Sticker Shock...

A look at the market for upgrades was a shock!  Admittedly, I included some newer features, such as an Internet Radio capability and multi-channel decoding, but seeing prices closing in on, and exceeding $1000 suggested a look at alternate approaches might be good.  We are okay with stereo, and have other features built into our Media Server, so perhaps just an FM tuner replacement might be good enough...

A Suitable Module:

As it happens, the entry level market is chock full of small add-on modules for this purpose and others (Bluetooth reception, SD card and flash drive inputs, aux inputs, and others...).  The technical reviews I looked at suggest the quality of reception is very good.  After browsing the choices, I selected a basic unit to experiment, for a cost of under $7. 

Making it Look Nice...

Of course, it will take some packaging and a small power supply, suitable for locating with the existing SONY unit in the living room.  Over time, I have collected a number of small cast-off devices for re-use in projects, and a nice Phillips Analog cable TV converter looked like it would do nicely.  After some
hacksaw customization to eliminate the un-needed parts of the internal PCB, I was left with a nice metal and plastic case with internal 5V and 12V regulated supplies.  Some dremeling and filing allowed the new FM module to sit nicely on the front of the unit, and some further drilling and filing on the back provided a coax cable connection (for an antenna) and some RCA sockets (salvaged from a cast-off DVD player) for audio out and aux inputs.

Antenna Improvements:

This was also an opportunity to update the old 300 ohm twin-lead folded dipole FM antenna I have been using with the SONY receiver, connected to it's convenient 300 ohm input terminals.  Twin lead can be awkward to route around the shelving, and gets stiff and cracks with age, so it was worth building another.  However, the new FM module has just a solder point for an antenna connection.  A bit of digging suggested this input is likely closer to 50 - 75 ohms, so a balun would also be needed, assuming I still had some 300 ohm twin-lead somewhere is my junk box...  However, some browsing online suggested I should try a folder coax dipole instead.  No balun needed, and I could some of my plentiful supply of RG59 cable hanging around...  And re-use one of those coax cable connectors I've been saving from old cable converter boxes!!

Results:

Overall, this project has turned out well.  A small number of hours invested in a nice improvement and additional functionality for the venerable SONY receiver.  The original receiver is used in essentially the same way for TV and Media box inputs, with new functions available through the Tape input on the SONY.  The Bluetooth input capability is especially nice.

To Do's and Next Times:

Remote Control:  The new FM module comes with it's own IR Remote, a mini remote control with 21 tiny PBs.  It works, but I would have liked to control the new module with the same remote we use with the TV and the SONY (a cast-off COGECO branded universal remote).  Alas, no such luck.  The mini uses 21 NEC commands, that are well documented online, but there is only incomplete fits within the choices available from the universal remote, not enough to be even partially useful.  Not sure what to do about remote control integration. It may be time to buy / build a full function programmable remote...  Same problem exists with the media box remote, but we usually control it with a mouse.

Folder Navigation:  The USB and SD card players, for MP3 and similar music files, have no folder navigation capability, seeing only a flat list of files to play, in order.  Next time, spend a few more dollars on a module that has some basic folder navigation capability!

Multi-Channel Decode, Quad Amplifiers:  Newer versions and other devices offer both of these choices, and appear to be cost effective.  Maybe there will be a Mark II in the near future!