SCS or Sound Code Systems, Anybody ever heard of them?

[VYNULADIKT]

I picked up another 2450 and here is how it arrived. Nearly destroyed the faceplate. Handles are done. Luckily I have found a source for identical replacements and also some that are a little fancier. I have grabbed several of these when they are low priced. Great power and well built. I have several of each 2450 and 2600A.

 

[Pio1980]

I have a Muse One Hundred, there were several versions. Mine has balanced inputs and eight Hitachi mosfets per channel, the simpler driver boards with stingy traces and no ICs.

 

[VYNULADIKT]

I have a Muse One Hundred, there were several versions. Mine has balanced inputs and eight Hitachi mosfets per channel, the simpler driver boards with stingy traces and no ICs.

I really like the SCS units. Picked most up for well under 2 bills shipped. Worth it for sure, even if just for spare parts.
Would you happen to have a schematic on that 100 ? Curious as to how it differs from the old SCS in the driver boards.

 

[Pio1980]

I really like the SCS units. Picked most up for well under 2 bills shipped. Worth it for sure, even if just for spare parts.
Would you happen to have a schematic on that 100 ? Curious as to how it differs from the old SCS in the driver boards.

Ive been trying to locate skiz for them, but no joy and no support.
I'll attempt to post some board photos later.

 

[Pio1980]

 

[Pio1980]

 

[VYNULADIKT]

Nice neat looking layout. I take this is more like the Haflers and others with the heat sinks on the ends rather than a large one in the center. I mistyped above as well, that was a 2350 not a 2450. The 2450 has twice the capacitors and larger transformer.

 

[Pio1980]

 

[VYNULADIKT]

That's a beast of a torroid. Surprised that they didn't maintain the dual mono power supply configuration of the 2450 and 2600 since this is an "audiophile" version.
Space constraints probably.

 

[Blairjm]

I picked up another 2450 and here is how it arrived. Nearly destroyed the faceplate. Handles are done. Luckily I have found a source for identical replacements and also some that are a little fancier. I have grabbed several of these when they are low priced. Great power and well built. I have several of each 2450 and 2600A.

 

[Blairjm]

Hi hoping you are still available on this thread. I have a 2350, tripping the internal breaker on power up (I have variac btw). The schematics on this thread do not sho the PT section. I have measured the tranny secondaries out of circuit and there is 118vac on the blue secondary wires. A bit odd as this indicates a 1/1 winding ratio. But maybe that is all that is called for. No shorts between primary and secondary windings, however the odd thing is the brown wire coming from the tranny to the first smoothing cap. It is open. No DC resistance between it and ground or the windings. I suspect it is a centre tap and broken inside the PT. but without a schem, hard to say. The bridge rectifier is delivering 120VDC. The breaker trips when the caps are connected but not when they are disconnected from the B Rectifier. (B+/B- rails disconnected during this test. The caps seem ok on a rudimentary ear meter. Any thoughts? Cheers

 

[VYNULADIKT]

The 118 seems right as the rails are in the 70 volt DC range IIRC. Could be a loss of the center tap but have to think about why the fuse blows with the caps.

 

[survey_sez]

yes the brown is center tap. nothing will be biased properly if it is open. don't connect the amplifiers until you figure that out. also - the breaker on these units are very prone to failure. try clipping in a 15a fuse and see if it handles the caps.

 

[Blairjm]

yes the brown is center tap. nothing will be biased properly if it is open. don't connect the amplifiers until you figure that out. also - the breaker on these units are very prone to failure. try clipping in a 15a fuse and see if it handles the caps.

Thanks again. My bad, the centre tap is fine. B- -80vdc B + 80vdc. Tested k135'sand J 50's out of circuit and all ok. Took it up to 40v slowly 40 Vdc at speaker terminals. Can I assume that if the mosfets are looking good likely a short driver transistor ? Both sides btw.

 

[Pio1980]

Thanks again. My bad, the centre tap is fine. B- -80vdc B + 80vdc. Tested k135'sand J 50's out of circuit and all ok. Took it up to 40v slowly 40 Vdc at speaker terminals. Can I assume that if the mosfets are looking good likely a short driver transistor ? Both sides btw.

Offset could go all the way back to input diff pair.

 

[survey_sez]

You'll find the driver board schematic in one of my prior posts. My unit had all good transistors, lousy capacitors, and a bad (open) 100K resistor (yup!).

 

[Blairjm]

OK, I know what the weekend will bring lol, diving into the driver boards, and thanks for the tip about the breaker and your invaluable schematic post, appreciated

 

[survey_sez]

Almost forgot - when I said capacitors I meant electrolytes. Don't worry about the others - they'll likely be fine. But a s a matter of practice electrolytic caps this old should be replaced - especially since that are crap brand. All 3 of mine were very high ESR, and way off capacitance value. These amps can oscillate like hell with bad caps. DO check all of the film resistors - even though they look fine (you can do this in-circuit). I wasted many many hours before I found that open 100K bastard..

 

[Blairjm]

Almost forgot - when I said capacitors I meant electrolytes. Don't worry about the others - they'll likely be fine. But a s a matter of practice electrolytic caps this old should be replaced - especially since that are crap brand. All 3 of mine were very high ESR, and way off capacitance value. These amps can oscillate like hell with bad caps. DO check all of the film resistors - even though they look fine (you can do this in-circuit). I wasted many many hours before I found that open 100K bastard..

well I found the issue, B+ rail was connected to the wrong spade lug (#6), that lug goes straight to chassis ground to the driveer board chassis screws, trace blown off the board in it's thinnest spot. + side filter cap and rectifier survived . All the ELec caps on the driver boards are shot. Have not discovered a bad resistor yet, most are real close to spec, but taking your advice and double checking them. Those 8mf 100v poly caps (big yellow ones) are unusual values but test OK on a chinese esr meter (lol). I am not great with solid state but basic tests on the Mosfets look all ok. (charge up the gate and look for continuity across the drain/ and source, discharge and no continuity)

 

[Blairjm]

well I found the issue, B+ rail was connected to the wrong spade lug (#6), that lug goes straight to chassis ground to the driveer board chassis screws, trace blown off the board in it's thinnest spot. + side filter cap and rectifier survived . All the ELec caps on the driver boards are shot. Have not discovered a bad resistor yet, most are real close to spec, but taking your advice and double checking them. Those 8mf 100v poly caps (big yellow ones) are unusual values but test OK on a chinese esr meter (lol). I am not great with solid state but basic tests on the Mosfets look all ok. (charge up the gate and look for continuity across the drain/ and source, discharge and no continuity)

I pulled a few driver board transistors and they test fine so far, It's a pain but can't test them in circuit easily.