Engineering stimulates the mind. Kids get bored easily. They have got to get out and get their hands dirty: make things, dismantle things, and fix things. When the schools can offer that, you’ll have an engineer for life. — Bruce Dickinson
It’s very satisfying to bring something back from the dead and make it work and look new again. I learned this feeling early on in my life thanks to my dad. When I was 8 or 9 years old, he caught me taking his lawn mower engine apart. Instead of beating my ass, he bought me an old lawn mower from a garage sale for $5 to tinker with and fix. His goal was primarily to keep me away from his machine, but he also wanted a safe outlet for my interests and worked with me when possible.
Thanks dad, you and Bruce were right, I’m now both an engineer and Maiden Fan for life.
Part 1: Background
What is a Hi-Fi?
A Hi-Fi is a 1950-60’s marketing term for a High Fidelity audio system. They began appearing in the early 1950’s in the US, Europe, and the rest of the world. It is basically what we would call a stereo system in the 1970-90’s. The major difference between a Hi-Fi and a stereo system is mostly one of aesthetics and partially sophistication. The Hi-Fi was typically an electronics package mounted into furniture in the style of the era. In the 50’s and early 60’s, this meant a mid-century modern look with simple lines and/or modern space-age like themes. In the later 60’s and 70’s, the Hi-Fi look became a more traditional Spanish or colonial furniture style. In comparison, a rack or bookshelf mounted stereo system of the 60’s-90’s were intended for the audiophile that wanted more audio power, fidelity, or customization. The appearance of the rack system was generally utilitarian with separate components and speakers.
Why would I or anyone want to restore a vintage (old) Hi-Fi?
The appeal of a vintage Hi-Fi over a rack system, or modern solutions such as MP3 speakers, is the style of the system. From a fidelity or sound quality perspective, the vintage Hi-Fi is likely inferior to a component rack or sophisticated surround sound system; however, it can be superior to many modern MP3 speakers and PC systems for certain types of music. Fidelity is not always a critical feature these days compared to storage, portability, or other factors. My own impression is that an older Hi-Fi in good working order can be superior to that of standalone MP3 speakers made by suppliers such as Bose or most PC cheap speaker systems.
The Hi-Fi to me is a beautiful piece of furniture that can be the center of the entertaining area of your house. It is a throwback to a time when couples would have drinks and listen to a new record together. It can be in the background playing the sound track for the party or fill the house with sound while you are working. The final and most important factor for me was having a project that allowed me to tinker with electronic and mechanical systems, as well as apply some basic furniture refinishing with little financial risk.
My Hi-Fi: Webcore Ravinia 1958
I had passively been looking for a vintage Hi-Fi for a while on Craigslist. My criteria were the following:
- 1950’s -1970 time frame due to the styling of that era and the likelihood of finding cheap offerings.
- The wood furniture must be solid, in relatively good condition, and free of water damage or serious contamination from pets or the environment.
- The electronics don’t have to be in working order as I plan on repairing or, if necessary, replacing the guts of the system.
- The Hi-Fi must be cheap enough that I won’t mind putting it on the tree lawn for the gypsies to take away if I completely muck it up.
I found what I was looking for after a few fits and starts of searching. I saw a Webcore Ravinia for sale for $40 locally. I made an appointment with the seller to meet and inspect it. The gentleman selling it inherited it from his grandmother and wanted to get the bulky thing out of this garage so he could fill it with used Firebird parts and meth fixins. It had a lot of dust and grime on it, but the wood was in relatively good shape for refinishing. Finally, the look and size of the system was close to what I was looking for.
The seller was adamant to demonstrate that the Hi-Fi worked, so he showed me that it could play Overkill’s Eliminate using his IPod through the Aux and remote control port. The electronics were functional enough to turn on without letting the smoke out of any components. The phonograph was barely able to turn and had no sound coming from it. I decided to take it that day. So I left my fledgling meth maker with $40 and brought it home and into the house. I proceeded to clean it up a bit, open up the back to ensure there were not pounds of dead mice or animal fur inside, and finally checked out the components and chassis for electrical damage prior to doing a quick test. I dusted the insides and vacuumed the cat fur out of the guts of the system. It looked in relatively good shape so I decided to fire it up to get a baseline assessment.
Assumptions and Constraints
- I assume the electronics and speakers were worth repairing; if not, I will scrap them entirely.
- Do the mechanicals such as the original turntable function, and do I care if they don’t?
- Is the woodwork able to be refinished without expensive tools I don’t have and without taking the entire unit apart?
- During the execution of this plan, the default is to scrap it if things go bad and cost me significant money to move forward. I set a budget of ~$100 for all expenses.
- I plan on attacking this project in three parts
- Assess and refurbish the electronics if possible, or scrap them and replace with something more modern if not.
- Refurbish the turntable if possible or scrap/disable if not.
- Refinish the furniture to a reasonable appearance with focus on the top and front of the Hi-Fi.
- Finally, I’m not looking to keep the Hi-Fi system original if it means costing money or lowering the performance significantly. Do not use vintage or refurbished components; new components are your friend.
Ass Covering Disclaimer: This is not a comprehensive how to article but a description of the path I took. Proceed at your own risk.
The baseline performance assessment was as follows
- The system powered up and the tubes all seemed to be functional (they glowed).
- The turntable was activated and rotated without turning it on by the selector knob.
- The turntable would not turn with uniform speed and the needle appeared to be damaged.
- The radio worked on all bands AM and FM with normal amounts of tuning noise.
- The knobs for volume, treble, and bass all generated a great deal of crackle and spit when actuated.
- I was able to play my IPod through the Aux and Remote control port using RCA and Microphone Aux plugs respectively. The thrash metal meth head was right.
- There was a great deal of 60Hz hum present even without an input present that was amplified with increasing volume. Recapping will be needed to clean this up.
- There was a moderate level of high frequency static hiss present that was not modulated by the volume level. Possibly a bad cap on the amplifier or noise generated somewhere and being picked up in the speakers.
- The speakers sounded ok and looked good from the backside. Keep the speakers if possible.
- There was no functional off switch, but there was a location where it used to be. Use a power strip with a fuse and on/of switch.
- The sound output began to change, diminish, and distort after the unit was on for about 30 minutes prompting me to shut the unit off. I suspect there is a power supply issue somewhere based on this behavior.
In summary, the electronics and speakers appear to be worth a refurbish instead of replacement.
Electronics refurbish plan based on the initial assessment.
- Research the system and try to get a schematic to help with the refurbishment
- Clean up the chassis and all of the tube sockets during the refurbishment
- Replace the old leaky electrolytic and paper caps in the power and preamp stages to minimize line and high frequency noise
- Clean and or replace the pots if needed to eliminate the crackle and snap
- Keep the turntable disconnected until it can be refurbished
- Replace the speaker crossover capacitors with modern plastic film units
- Check for and replace any significantly out of tolerance or damaged resistors or ceramic capacitors
- Leave the radio tuner alone if possible as it is functional and not a high priority
To be successful at this the following basic skills and abilities will be important:
- Able read a electrical schematic and know the basics of AC electrical and high voltage safety (vacuum tubes operate at >300V and the electrolytic caps might have to be discharged)
- Knowledge and application of basic wiring, soldering, and electrical testing with a multimeter
- Have or gain some knowledge of basic components such as vacuum tubes, capacitors, resistors, and inductors
I found a great deal of advice on refurbishing vintage audio equipment as well as a site dedicated to providing information on these old systems.
I learned about recapping systems from this site.
I was able to get schematics called a Sam’s manual from this site.
With schematics in hand, I went about removing the power supply chassis from the rest of the system, this involved cutting some wires and unplugging others. At this stage it’s important to take a lot of photos and label each connection you plan on cutting to be sure you remember how to put it all back together again. I used masking tape and a sharpie and a lot of photos.
Once the power chassis is removed, you need to get an appropriate workspace, prepared to desolder, remove, and re-solder your components. I made a lot of paper copies of the schematics for taking notes and for reference during the process.
I began the process by removing and carefully storing the vintage tubes. These tubes were old RCA units made in the 50’s and 60’s but they are likely still in good shape. I flipped the chassis over and began by inspecting and understanding how the schematic related to the components so I could assess what I was dealing with. I planned on removing and replacing the big electrolytic capacitor containing 4 separate cap values in one can and replacing them with separate modern components. I found some work had been done in the past as evidenced by additional components and connections that were not in the schematics. The system likely had some noise that cropped up as the electrolytic caps aged and a tech added a few new caps in parallel as a fix. This appeared to have been done many years ago based on the age of the components. These had to go, and new components had to be retrofitted. I went through the Bill of Materials (BOM) provided by the SAMs manual and purchased new replacements from Parts Express; you could also use any one of several electronic stores or distributors.
Once the old components were removed, I cleaned and deoxidized the tube sockets with contact cleaner, cotton swabs, and pipe cleaners. After a lot of removal, rewiring, and replacement I found I had room to mount the new components in the chassis. I also checked each component for: tolerance, functionality, solder connection, ground isolation, and mechanical integrity. I also checked and rechecked the circuit for any errors on my part, as I had to rewire as well as replace components.
Now that the power chassis is done, I’m ready for the Pre Amp. This required a bit more desoldering from other components of the Hi-Fi, as well as the removal of the pots from the body of the Hi-Fi. Again take a lot of pictures and label your desoldered and cut connections. The paper capacitors all need to go, and another multiple electrolytic cap can needs to be removed and replaced. I’ll replace the paper caps with newer metalized polymer film capacitors and the electrolytic can with new discrete axial leaded components like in the power supply.
Make sure to check your schematic, look for cold solder joints, and test for bad components and connections.
While I had the Amplifier chassis out, I decided to clean instead of replace my pots that control volume, treble and bass. They were very noisy during the baseline testing. I found a contact cleaner and lubricant that is supposed to be a miracle worker for bad pots and sliders. Caig DeoxIT Fader Spray is apparently used by musicians to clean faders and pots. I sprayed a few squirts into the body of the pots and worked them extensively. I repeated this process one more time prior to rejoining the chassis to the Hi-Fi case. I also used this opportunity to clean the chassis and tube sockets.
Now I used my pictures and labels to reassemble the Hi-Fi. I took the opportunity to replace the crossover capacitors with modern units, while resoldering the power supply leads to the speakers.
I took this opportunity to remove and deep clean the control knobs and display as they looked like they had 60 years of metal meth head’s grandma’s skin on them. Hot water and simple green did the trick for the knobs and a little bit of spray cleaner cleaned up the display.
Once I had everything resembled and cleaned up, it was time to test the sound quality and compare it to the baseline.
- The system powered up without any smoke or fire!!
- The system selector worked as expected-> Radio, Aux, and Phono
- The turntable was left unplugged
- The Radio worked on all bands AM and FM with normal amounts of tuning noise
- The knobs for volume, treble, and bass were free from any crackle and spit when actuated
- I was able to play my IPod through the Aux and Remote control port using RCA and Microphone Aux plugs respectively
- There was a no 60Hz hum present until the volume knob was turned to maximum with no input present
- There was a small level of high frequency static hiss present that was not modulated by the volume level; it was present no matter what connected input was used
- The speakers sounded great and had much more power than before
- The sound clarity was much improved
- The sound quality remained constant after 3 hours of use with no distortion or reduction of output
Here is a video of the operation and sound after refurbishment and where it will be located. The performance compared to the baseline was very significant and the sound is now great.
Part two will focus on the turntable
Part three will focus on the repair and refurbish of the cabinet