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JVC RC-M70 boombox review, specs, historical details, and service manual.

JVC RC-M70

JVC RC-M70 Boombox


The JVC RC-M70 boombox sits just under the JVC RC-M90 model rung within JVC's boombox lineup. It is quite possibly the single best medium sized boombox ever in terms of the whole package deal. No other boombox offers the size, power, features, performance, looks, and availability as this particular model offers. It's ubiquitous quality means you never have to look far to find this in any internet search. Although HiFi enthusiasts would likely never mention the JVC name when discussing the best home audio gear manufacturers, it is a different world when discussing the portable stereo line. JVC's quality is clearly up there amongst the other top vendors. This particular model is a perfect example of what one seeking a quality boombox would ask for. Great looks, great performance, portability, auxillary inputs and outputs for flexibility, power to spare for external speakers, sensitive tuner, very reliable tape mechanism, and sturdy construction.

JVC RC-M70 Boombox JVC RC-M70 Boombox JVC RC-M70 Boombox JVC RC-M70 Boombox


Victor RC-M70 (Japanese domestic):

The JW suffixed model features a 6-band radio tuner. The japanese model however is a 2-band model and branded as Victor.

Tuner of the Victor branded M70:

Victor RC-M70 Boombox


The Victor branded M70 also features pitch controls below the cassette deck. The example below was modified by the owner changing the 76-90 Japanese FM tuner to an international spec'd 6-band tuner:

Victor RC-M70 Boombox


Label and top panels showing japanese writing:

Image Image Image

Issues:

The RC-M70 line has turned out to be a robust and reliable design. After 30+ years, there are however a few idiosyncratic issues that are known to afflict this model:

  • Worn slide controls. JVC employed Alps branded sliders for the slide controls and over time, the internal feelers break off and/or the internal resistor board has fractures on the traces. These controls are now obsolete but enthusiasts have found ways to repair these.
  • Power Switch. The power switch is a brass leaf design that sometimes fail. Filing, bending the contacts or leafs are sometimes the only way to repair them. These parts are obsolete.
  • Muting Circuit. A failed muting circuit can sometimes result in extremely attentuated output at the speakers.
  • Failed voltage regulator: The M70 employs several internal voltage regulators and failure will affect only the circuits powered by that particular regulator. The most common regulator to fail is the X505 regulator which also powers the tuner dial lamp and parts of the cassette deck.

Variants:

Along with the JVC RC-M70 model (and the various suffixed variants), there are several similar variants.

  • JVC RC-M70
  • Victor RC-M70 (2-band tuner, 100V, front mounted pitch controls)
  • JVC RC-M71 (Goldish tint and different trim)
  • JVC RC-M75 (Looks like M71 with front mounted pitch controls)
  • M70 (GX)? This appears to be a gold tinged unit.

Aside from the first 2 models above which are common, the others are rare models that command higher prices. No model however is considered cheap, regardless of its rarity level. Their popularity and reputation ensures that demand for this iconic model remains high and accordingly, their value.

Modifications:

This model just may be the most modded boombox model.

  • LED tuner mod:
    • Several years ago, an enthusiast performed an LED upgrade of the tuner dial. This mod was so well received that the mod was packaged and offered as a kit. Since then, scores of LED tuner'd M70's began pasting the internet. And no wonder, the difference is night and day compared to the original design. Additionally, the mod that was offered included modifying the switching circuit so that the lamp could remain on. The original design required depressing the switch to illuminate the lamp and releasing the switch also extinguished the lamps. This remains an extremely popular mod today.
  • Refinishing the cabinet:
    • In 2009, member Superduper of Boomboxery.com(external link) refinished an M70C in a maroon color. That same boombox is part of Wikiboombox and Boomboxery member Superduper's avatar here. Since then, M70's have been repainted in many many colors. One enthusiast in California has a collection of several M70's, all painted a different color and another CA (socal) collector painted his and called it the Van Halen edition . This just may be the most repainted boombox model we know of.


A Victor RC-M70 with blue LED dial lamps:

Victor RC-M70 boombox LED mod


Superduper's Maroon RC-M70:

Maroon JVC RC-M70


Community Member (Lasonic TRC-920)'s 'Van Halen' edition

Van Halen edition JVC RC-M70 boombox

Specifications:

  • According to official JVC literature, the M70's BTL amp provides a minimum of 7 watts per channel between 100 and 15,000 Hz (@ 8 Ohms and no more than 10% THD). Its "maximum" output is described as 30 watts (2x15).
  • Wow & flutter is 0.065%.
  • It has 6.5" (16cm) woofers and 2" (5cm) tweeters.

Optional accessories included the JVC MU-103E electret condenser microphones (impedance 1 kOhm +/-30%) which require two to get stereo, or the M-201/T/U, a 600 ohm microphone that only needs one for stereo.

Service Manual

A service manual for this model (along with LED tuner modification kit) can be purchased here: AnalogAlley.com(external link)


Created by Reli. Last Modification: Thursday 28 of September, 2017 15:37:55 GMT by Reli.
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