Vintage Pioneer SX-1500T Stereo Receiver Upgraded Tested

Description: Offered is a vintage Pioneer SX1500-T receiver fully serviced and in excellent working and, generally, in very good cosmetic condition. I always document my work. This model, released in 1969, is said to be a slightly newer version of the first solid-state fully solid state receivers offered by Pioneer (starting in 1968). As received the receiver was not operational because of problems with the power supply and the driver board. This is the third receiver of this series I've rebuilt in the last two years. Both these boards required updating over and above what is done in a typical recap. For the supply board, many higher rated diodes, transistors and capacitors were installed. Some of the dc supply filter caps were undervalued (allowing for weak but audible hum) and so their capacitance was increased. For the driver board, all transistors were replaced and, additionally, the four output power transistors were upgraded (originally rated at up to 7 amps to ones rated for up to 16 amps) as well as a few out of spec resistors. Once back in service then more typical problems were observed such as burnt out lamps and the tuners had drifted. Thereafter all other boards received a standard recap (i.e., electrolytic, including those in the tuner sections and the two main coupling caps) and transistors known to age badly (e.g., the 2SC458s) were replaced (replacement parts sourced from Mouser, Digikey, Newark and/or Arrow Electronics). The main filter caps were upgraded from 1000uF, 100 V to 2200uF, 100 V. Typically Nichicon audio grade caps (Fine Gold, KW, KT, KL) or power caps (series PW, HE and/or PS) were typically used but Panasonic (FM or polypropylene film) or Kemet caps may have been substituted. At present everything now operates well within stated specifications. Also included are a pair of speaker plugs (plus, if needed, fork crimp terminals). Cosmetics: The presentation is generally very good but the faux wood top has a number of small scratches at the very back on the right side. The side trim pieces are of a real wood veneer and these are in very nice condition with some minor wear, typically at the corners. They have been cleaned and then refreshed with a wood wax. The front face and knobs are generally in very good shape but there are some detractions. The top surface of the anodized aluminum rail has some light scratches (which the camera's flash really enhance) and the lettering does show evidence of improper cleaning (please refer to the photos). IMPORTANT: Pioneer receiver lettering from this era cannot ever be cleaned with ammonia containing cleaners because they will partially dissolve the black lettering. Use only mild neutral detergents. Lighting (see item 10 below): To better match the original color scheme, diffusing optical gel filters have been inserted where needed. Service items (in addition to those stated previously): 1 FM tuner aligned and stereo separation reset . NOTE: The 4-gang FM tuner sensitivity and selectivity are excellent; this is one function in which this receiver really excels. 2. Full AM tuner alignment. There is a 3-gang AM tuner. 3. Light cleaning of the interior and exterior. 4. Front potentiometers contacts cleaned with DeoxIT and lubricated with synthetic oil. 5. Outputs from the amplifier channels tested at 1kHz. With a single channel driven, clipping occurs at about 20 V_rms and so the amplifier can actually deliver up to 50 watts per channel (1 kHz sine wave into an 8 ohm load) at this frequency. As is intrinsic to this model, with both channels driven there is a bit of sag to 40 watts per channel. It is nominally rated at 55wpc (power ratings became more standardized later on). 6. The front face was removed and cleaned. 7. The dial glass was removed and the area behind the glass was cleaned. 8. Harmonic distortion measured (including that of the FM tuner). After the upgrade both are within stated specifications. 9. Offset and driver bias adjusted. This receiver has a single sided dc power supply and so, for best operation, the offset must be adjusted at maximum power. 10. All lamps, six BA9S bulbs in total, were replaced with warm white LEDs. Because the STEREO beacon LED uses much less power than an incandescent bulb it will turn off somewhat more slowly when tuned out of a stereo broadcast. 11. Unit tested for an extended period (many weeks). At idle, the receiver uses under 20 watts.12. New AC power cord Quirks: 1. At very low volume, starting from zero, one channel will engage just before the other (this is intrinsic to the volume pot and is also a common occurrence). 2. The amplifier output is capacitor coupled and so there will be a bit of speaker thump at turn on and, to a lesser extent, at turn off (especially with headphones). 3.The treble and bass knobs specify "Front" and "Rear" (as opposed to LEFT and RIGHT). It is my understanding that, at this time, stereo was coming in vogue but many users had mono set ups with a front and a back speaker. This item comes with a 30 day return; buyer pays return shipping. Thanks for looking.

Price: 339 USD

Location: Madison, Wisconsin

End Time: 2025-01-05T16:06:34.000Z

Shipping Cost: 8 USD