{"id":2016,"date":"2024-10-21T21:38:44","date_gmt":"2024-10-21T21:38:44","guid":{"rendered":"https:\/\/storycase.co.uk\/radio\/?p=2016"},"modified":"2024-12-19T17:21:57","modified_gmt":"2024-12-19T17:21:57","slug":"jvc-r-s5-stereo-receiver-faults-and-fixes","status":"publish","type":"post","link":"https:\/\/storycase.co.uk\/radio\/common-faults\/jvc-r-s5-stereo-receiver-faults-and-fixes\/","title":{"rendered":"JVC R-S5 Stereo Receiver Faults and Fixes"},"content":{"rendered":"\n

Do you have a JVC R-S5 or JVC R-S7 receiver fault that is too quiet on FM radio or the sound level generally is poor? This post runs through some possible repairs to fix and restore your receiver to its former glory.<\/p>\n\n\n\n

JVC produced the R-S5 series in the late 1970s and after fifty years some of its components may have failed causing poor performance or have stopped working completely. But JVC, like most manufacturers of this period designed for repair and service in mind as you will find. So don’t throw your receiver out – try to give it a new lease of life.<\/p>\n\n\n\n

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As with any mains powered equipment always switch off and remove power cables before opening or operating the unit with the case removed. Dangerous voltages are exposed and shock or serious injury can result if you ignore the warnings!<\/p>\n<\/blockquote>\n\n\n\n

Many hifi amplifiers and receivers of this era provided phono input as standard and this JVC is no exception. With the revival of vinyl you can plug a turntable directly in to the R-S5 and enjoy those vintage LPs. The R-S5 is also excellent when driven from a good CD source via the Aux input. And for those wanting to replay analogue tape there’s also a handy tape monitor input and output.<\/p>\n\n\n\n

The receiver faults<\/h2>\n\n\n\n

This JVC R-S5 receiver was sold in ‘working’ condition but after an initial inspection several faults were found which I’ve listed below.<\/p>\n\n\n\n

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  1. Electrolytic capacitor leakage on amplifier circuit board<\/li>\n\n\n\n
  2. Tuning meter lamp blown<\/li>\n\n\n\n
  3. Low audio level on FM radio<\/li>\n\n\n\n
  4. Control knob caps loose – volume and source input<\/li>\n<\/ol>\n\n\n\n

    Cosmetically the JVC’s case was a little worn with some rust discolouration to the paintwork and silk screen lettering worn around the front panel power switch. Overall, for a fifty year old receiver, it was in good shape!<\/p>\n\n\n\n

    I’ll now run through the faults and how to fix them.<\/p>\n\n\n\n

    1. Electrolytic capacitor leakage<\/h3>\n\n\n\n

    Both large electrolytic capacitors had leaked around the amplifier circuit board. You can see this more clearly when the 6800uF 35v capacitors are removed in the photo below. While the receiver still worked, the sound lacked bass depth and a slight hum was audible. These symptoms are common with a failure of the power supply smoothing or reservoir capacitors, so I was not surprised to find the leakage although this is not always present.<\/p>\n\n\n\n

    Notice JVC have used wire wrap connections between circuit boards rather than solder. You would need a wire wrap tool to undo and redo these connections so if you see an odd wire soldered it’s probably an indication someone has attempted a repair without suitable tools \u2014 so beware.<\/p>\n\n\n\n

    \"JVC\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button>
    JVC R-5S Reservoir capacitor leakage goo<\/figcaption><\/figure>\n\n\n\n

    There was evidence of heat marks on the top of the casing inside. The main area was directly above the capacitors suggesting over heating may have caused the electrolytic to leak. Electrolytic capacitors can overheat as they fail and their ESR increases due to ripple current.<\/p>\n\n\n\n

    \"Inside\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button>
    Heat spots inside case<\/figcaption><\/figure>\n\n\n\n

    It’s fairly simple to remove and replace the caps with a soldering iron and solder sucker or copper braid to help unsolder the connections.<\/p>\n\n\n\n

    To unsolder the capacitors you need access the underside of the circuit board. Fortunately JVC’s good service design allows access with a simple removal of the plate beneath. Luckily the electrolyte has not damaged the copper circuit board tracks below. Similar electrolyte leakage on double sided PCBs, used by more modern equipment with surface mounted components, needs more repair work.<\/p>\n\n\n\n

    \"JVC
    JVC R-5S service access plate<\/figcaption><\/figure>\n\n\n\n

    I replaced the 6800uF 35v capacitors with 63v versions with the same size – 25 x 50mm. The replacements can be found for less than \u00a310 and typically have only two connections rather than the original’s three. The third was just used for mounting and is electrically isolated, so is not required, but ensures correct polarity – see warning below. I drilled an additional hole, in line, as the replacement had a narrower 10mm tag spacing rather than 12mm. This ensured the capacitor sits flush with the circuit board for better mechanical stability.<\/p>\n\n\n\n

    \n

    Observe the negative terminal of each capacitor before removal and check your replacement is the same way around. Failure to do so will damage the electrolytics and associated components.<\/p>\n<\/blockquote>\n\n\n\n

    \"\"
    Original and replacement electrolytic capacitors showing the negative terminal banding<\/figcaption><\/figure>\n\n\n\n

    After replacing the capacitors I measured the power supply voltages as +31.3v and – 31.3v now both equal rather than the previous values which differed by 0.5v. The poor bass and hum issues were also improved – see Listening Tests<\/a> below.<\/p>\n\n\n\n

    Increasing capacitor values<\/h3>\n\n\n\n

    It’s tempting to choose higher value electrolytic capacitors, such as 10,000\u00b5F or higher, as modern replacements are often smaller for the same capacity. JVC chose 8200\u00b5F for their uprated 50w R-S7. While increasing the capacitance can improve sound quality, ripple current will increase along with peak current and strain on the bridge rectifiers. So for the modest demands from the R-S5’s 25W output I decided to keep to the original 6800. These were only rated at 50v so increasing this to 63v is worthwhile as it allows a better margin.<\/p>\n\n\n\n

    2. Tuning signal lamp blown<\/h3>\n\n\n\n

    Both tuning dial lamps were working but a third bulb at the back of the tuning meter dial had failed. As the bulb was wired in \u2014 see the blue and black wires below \u2014 rather than via a holder I had to cut the wires to change the bulb. Not a very good design but I guess JVC thought the bulb would last longer than the next upgrade!<\/p>\n\n\n\n

    The tuning lamp supply measured 6.3v ac and the circuit diagram specified a 6v 150mA filament so the bulb had likely just reached the end of its life. I found a small wire ended 6v bulb and soldered the wires back in place. There are many LED alternatives but note the supply voltage is AC which can flicker if the LED is only designed for DC.<\/p>\n\n\n\n

    \"Tuning\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button>
    JVC R-5S Tuning lamp wiring<\/figcaption><\/figure>\n\n\n\n

    The bulb is a push fit in a flexible blue plastic housing which had stuck with age. Take care not to damage the plastic as it acts as a filter producing the soft blue hue for the meter dial. Also note the tuning dial cord runs close to the wiring, so ensure you don’t catch or damage it.<\/p>\n\n\n\n

    3. Low audio level on FM – Radio Fault<\/h3>\n\n\n\n

    During initial testing I found the FM radio volume was much quieter than AM or a CD player connected to Aux input. From the service manual \u2014 see links<\/a> at the end of the post \u2014 I checked several preset pots in case their contacts had oxidised over the years. It made no difference. Next I checked the muting circuit and found the level did not change when tuning or FM auto \/ mute was selected. <\/p>\n\n\n\n

    I traced the fault to transistor X301 – 2SC458D which caused the mute circuit to operate continuously. The 2SC458 device is on the suspect list of troublesome Japanese transistors – see links<\/a>.<\/p>\n\n\n\n

    \"JVC\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button>
    JVC R-5S Faulty 2SC458D<\/figcaption><\/figure>\n\n\n\n


    I had to remove another plate to access radio circuit board to desolder the transistor. Notice some of the tracks are obscured by the chassis so the whole board would need removing along with the drive cord assembly, but fortunately I could just reach the connections to X301.<\/p>\n\n\n\n

    \"JVC
    JVC R-5S Access to radio circuit board<\/figcaption><\/figure>\n\n\n\n

    I replaced the 2SC458D with an BC184L that has the same ECB pinout and similar characteristics. This restored the FM volume level and fixed the Auto \/ Muting when selected via the source switch.
    Listening to the FM radio at normal volume sounded good although I could hear some sibilance on certain voice programmes similar to how the Pioneer SX-850 had sounded \u2014 see     Pioneer SX-850 Common Faults and Fixes<\/a> for more details. I suspect my aerial may be to blame as the signal strength indicates rather low.<\/p>\n\n\n\n

    4. Control knobs loose<\/h3>\n\n\n\n

    Although the JVC appears to have solid aluminium controls the rotary knobs are in fact plastic with an aluminium sleeve. These are glued on and over time the adhesive deteriorates allowing the sleeve to rotate around the plastic or worse still, fall off! A simple application of glue will fix the problem as long as you have the sleeve. If not, replacement knobs for these receivers are available on auction sites and push into place. Be sure to align the splines and centre correctly.<\/p>\n\n\n\n

    Compared to the Pioneer SX receivers, the JVC is not fitted with a heavy flywheel, so the large tuning control does not spin through the dial as quickly. However, all controls are smooth and firm and legends are easy to read. And worth noting, these JVC receivers can be purchased for around a tenth of the price of the Pioneer SX range.<\/p>\n\n\n\n

    \"\"\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n\n\n\n
    \"\"\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n\n\n\n

    Listening Tests<\/h2>\n\n\n\n

    I connected a pair of Q-Acoustics 2020i speakers and my original Rega Planar 3 turntable. JVC chose good old fashioned terminal connectors for the two pairs of loudspeaker outputs rather than the less reliable spring loaded types fitted to Pioneers and others of the era.<\/p>\n\n\n\n

    At 25w per channel the R-S5 was never going to sound very loud but I was surprised how good it does sound. The distortion figures at 0.03% THD are low and with a damping factor of 45 drive the 6 ohm Q-Acoustics without issue. Spinning up Music Man from the Doobie Brothers album Stampede the sound stage had the right depth and I could follow the lead guitar panning from left to right. The vocal harmonies, percussion and guitars strings on I Cheat the Hangman kept me involved with a dynamic range lost in MP3 streams – such as waste.<\/p>\n\n\n\n

    Only the bass drums seemed still a little weak probably reflecting the 2020i’s low frequency response which drops off below 70Hz. Bass depth had improved from initial testing before replacing the power supply capacitors. I noticed an edge to some vocals that is probably the pressing – it’s had a hard life since I bought the copy in the seventies. The sound improved adding a little more weight to the Rega’s arm – I’m using my Shure V15 III with a VN35HE that seems to need around 1.5g.<\/p>\n\n\n\n

    Ultravox’s title track from their album Vienna was next up to compare. I find most of my 80s vinyl a cleaner sound and a contrast to the Doobie’s classic rock sound. Immediately the rich synth drum beat and leads filled the sound stage and Midge’s vocals followed through. Transported back in time. Even my wife was captivated – recalling Lee Mack’s truth about his daughter crying even time Vienna was played. We had to laugh.<\/p>\n\n\n\n

    FM radio pulled in the usual dozen or so stations from the house dipole. Stereo separation and quality were excellent on most broadcasts with a little background noise from the weaker ‘local’ stations. Accurate tuning is simple using the meter for maximum strength in combination with the red stereo indicator. The source selector offers FM auto to tune in weaker stations without muting.<\/p>\n\n\n\n

    Overall the JVC R-S5 is a competent performer and a bargain if you can find one before other vinyl hunters discover their merits and tire of the crazy prices being asked for similar vintage Pioneer kit.<\/p>\n\n\n\n

    Links<\/h2>\n\n\n\n

    All the R-S5 service manuals I could find were low resolution which made it difficult to identify component values. As the R-S7 has the same radio circuitry I’ve included a link which has a higher resolution copy. <\/p>\n\n\n\n