Purchased a S150 and realized that it has the e series upgrade done with balanced inputs and optical biasing. Amp is clean, quiet, and both heat sinks run within 2 degrees of each other, right around 100 degrees after an hour.
Dc offset is 28mv in one channel and 52 in the other.
What can anyone tell me about this amp? Biasing? Schematic, maintenance, upgrades? Amp runs cooler that i believe it should, can keep my hand on the sink forever.
Thanks in advance for any information.
Dc offset is 28mv in one channel and 52 in the other.
What can anyone tell me about this amp? Biasing? Schematic, maintenance, upgrades? Amp runs cooler that i believe it should, can keep my hand on the sink forever.
Thanks in advance for any information.
You are not alone in saying---"too cool " --not the design but the heatsinks here is some info on the S150 not located a schematic --yet.-
Threshold/ What is the Stasis topolgy? | Audiogon Discussion Forum
Threshold/ What is the Stasis topolgy? | Audiogon Discussion Forum
Thanks for the link, purchased the amp from a vintage resale shop that had it repaired. While it worked, the soldering on the xlr input was horrible. Touch the ground and it was cold soldered, came right off. Nuts on the binding posts were loose, barely threaded on. Ring terminal on the + output wire not crimped and soldered. Made the corrections, set the dc offset and biased to 120 degrees on both sinks. Rails running at 67vdc. Ran for two days and the left channel was out when i turned on the amp yesterday. Heat sinks still get to 120 degrees but no sound. Had a blown output fuse. Replaced fuse and still no sound, fuse is not blowing. Checked all of the transistors on input board and they test good. No short to ground on output transistors. Should i take the outputs out to test them? Im just a novice at working on electronics, dont have a scope but have an lcr meter and a dmm. Thanks for any help or guidence.
You don't have to remove the output transistors just unsolder the wiring to them and test with your dmm -
How to test a bipolar transistor – AntiMath
How to Test a Transistor
The base pin should give you a reading on both the collector and emitter
depending on whether its a PNP or a NPN ,the wrong way round you meter leads should not show a reading on one or the other.
How to test a bipolar transistor – AntiMath
How to Test a Transistor
The base pin should give you a reading on both the collector and emitter
depending on whether its a PNP or a NPN ,the wrong way round you meter leads should not show a reading on one or the other.
Just finished checking all of the output transistors, all tested good. Guess ill look at the input board again and retest those transistors. All of the diodes are good on the input board. What about the opamp looking jfet? If the input was shorted would it have taken this out? Amp played fine for 2 days after biasing and sounded excellent. Has to be something im missing. Guess ill order caps and emitter resistors to refresh those parts while im in there.