SCOTT STEREO MASTER DRIVER
SCOTT STEREO MASTER FULL

It’s tough to track down the specific issue with the feedback loop involved, so I disconnected the feedback. I spot-checked and replaced a couple of components which seemed questionable, but overall the DC voltages were correct for both channels, and those turned out not to be the root cause.

SCOTT STEREO MASTER DRIVER

With the oscilloscope, it showed that the driver stage of V3/V103 wasn’t properly amplifying the yellow trace demonstrated the good channel while the blue the channel lacking output power. While one channel plays well, the other caps out at about 1W of power and won’t go any higher. Total power output is very, very uneven though. Much better, now both channels get an equal signal at the inputs to their driver stage: The larger were replaced with CDE film caps, and the smaller with CDE mica capacitors which are nearly perfectly stable over a range of temperatures and bias voltages. One couldn’t be saved, though, during the operation and was also replaced. For good measure, I replaced both channel’s 0.02 uF capacitors, both ceramic 47 pF capacitors in the compensation network, and tested the resistors which were in-spec. The failure traced to one of the 0.02 uF ceramic coupling capacitors was fading, going low in value. Working backwards, though, the signal was fine – with the only item in between being the compensation network on the volume control. Shown here at the input to the driver/phase inverter tube for each channel with the good channel in yellow and the weaker channel in blue, with a 1 KHz test signal. Immediately at low volumes, there was a bit of a channel imbalance. There was enough room for the 100 uF 75V caps used for filtering the bias voltage the original early bias rectifier diodes were also replace with 1N4007s. The second can cap had a bit more wiring.

SCOTT STEREO MASTER FULL

There’s not enough room under the chassis for a full set of terminal strips for the electrolytic capacitors, so I fitted this amplifier with CE Manufacturing new manufacture twist-lock capacitors. Underneath it was all original, with Ceracap sealed paper capacitors, and a handful of electrolytic and ceramic caps.Ĭhecking all the iron, everything seemed in order, so it was on to a component replacement. Unfortunately, though, the electronics weren’t in such great shape after sitting for so many years and this amp’s owner reported it would start to smoke when powered on. This example was wonderfully well preserved, coming out of a storage unit looking like it had just left the showroom floor. 'Sold' listings from that auction site always feature the older tube units near the top, followed by the later higher end models from the later 1970's which were built in Korea or Japan.I was lucky enough to get to work on a very nice Scott 233 stereo integrated amplifier. Solid state Scott values from Maynard (US) are difficult to peg. On the other hand, Scott also started announcing amazing 'vaporware' models, such as the top of the list 525 receiver, which only existed on paper, or the RD1000, which never made it into production. Note: The 433 tuner later became the T-33S. Here's another photo from a site that has information on many of the later solid state offerings. Before the sale, Scott also dumped a ton of money into creating a digital tuner found in this ad from 1971. They were facing an onslaught of new competition from Japan who were producing 'quality' stereo equipment. A German consortium bought them around 1973, and later Scott was sold to Emerson.īefore the 1973 sale, Scott was scrambling in different directions. On the other hand, in the early 1970's H.H. As with many manufacturers, equipment made during the early 'awkward years' of solid state is often a mixed bag. Scott solid state gear is undervalued, and it's complicated. Word of caution: DO NOT try to clean the interior of the dial glass with anything liquid as the graphics on the dial scale will literally disintegrate before your eyes.

Scott stereo master