Thank you Sir.
Do you mean I have to keep the value as 0.15uF but can increase the voltage?
As for the other two, these are PS but maybe PP will improve the sound as per material nature. How is your experience?
Keep capacitance values the same. Remember to check that the pin spacings on the caps you are interested in, are compatible with the PCB.
If its PS as in polystyrene, then changing to polypropylene is probably not worth the expense in time or money. You'd probably need to go to teflon but I don't think it will be a significant audible difference. In the end it's your judgement call.
Changing from a 10uF polyester input cap to a polypropylene input cap could be beneficial, but, the polypropylene one will likely be much larger and not easily fit.
Replacing old electrolytics with new ones in an old amp makes far more sense than debating over polystyrene vs polypropylene.
Tantalum caps are certainly prone to failure and should be replaced.
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Thank you for the clear advice.
I will give a chase to Russian military grade Teflon FT3 to tray against orange drop 0.1uF. But FT3 is BIG but the place is convinient to fit.
For the input MKT I already see the fitment issue against PP, looks like fiol has not chance to fit, but maybe metalized one...
PWR CAPS already replaced, gave a huge difference, now I am waiting for the IYXS bridge to arrive.
I will give a chase to Russian military grade Teflon FT3 to tray against orange drop 0.1uF. But FT3 is BIG but the place is convinient to fit.
For the input MKT I already see the fitment issue against PP, looks like fiol has not chance to fit, but maybe metalized one...
PWR CAPS already replaced, gave a huge difference, now I am waiting for the IYXS bridge to arrive.
DC offset is measured at the speaker terminals (provided the amp works OK) and should be near to zero although values of -/+100mv are no real problem in practice.
A high DC offset should cause any speaker protection to trip. In a non working amp you must measure before any such protection (relay).
Bias normally refers to a preset quiescent current that is flowing in the output stage and must be measured correctly, normally calculating the current with reference to some volt drop across a resistor in the output stage.
Small temperature differences mean little as the ventilation will not equal on each side of the amp.
A high DC offset should cause any speaker protection to trip. In a non working amp you must measure before any such protection (relay).
Bias normally refers to a preset quiescent current that is flowing in the output stage and must be measured correctly, normally calculating the current with reference to some volt drop across a resistor in the output stage.
Small temperature differences mean little as the ventilation will not equal on each side of the amp.
The bias is about -.13 so guessing bias is not the issue. Left channel is running about 145 F to 155 Fat top center of heatsink, It has one generic part which is the optical coupler NTE 3041, I have not been able to locate an original but the channel has very clean signal at 1000 hz / 1.2 volt with 8 0hm load resistors. It is as though running in class A mode compared to the right channel . The gain of each channel is equal but right channel is somewhat cooler by about 30 degrees F. Any Idea's of where to look for an issue would be much appreciated. Everything test very close to equal in respect to other driver boards values. I do not want to return it to a friend until sure it will be stable. The turn on thump is negligible. My Plinius can bake potatoes in class A but have read the S series should not be that hot to the touch.
After a years with Threshold s300, and s300II I finally mange to get nice Optical Bias model which I was catching for a long time, I got S200, with one of the channel showing DC offset 99 mV which is not good.
I still see Tantalum 0.15uF caps in place, which need to be relapsed, but I have only 0.1 uF film at home and to order a 0.15 is a long story (thanx to the COVID).
My question if I can replace 0.15 with 0.1 with no issue?
What are the other places to look in to fix the 99mV DC offset?
I also found 5 different types of well known small transistors: 2N5566, MPSA42, MPSA92, MPSU10, MPSU60, and one type unknown transistor on both channels.
Please, advice what could it be?
I still see Tantalum 0.15uF caps in place, which need to be relapsed, but I have only 0.1 uF film at home and to order a 0.15 is a long story (thanx to the COVID).
My question if I can replace 0.15 with 0.1 with no issue?
What are the other places to look in to fix the 99mV DC offset?
I also found 5 different types of well known small transistors: 2N5566, MPSA42, MPSA92, MPSU10, MPSU60, and one type unknown transistor on both channels.
Please, advice what could it be?
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Deeply appreciate your advice!
But I have just a pair, another pair 100n I have at home is ceramic. Would be nice combination, right?
Got your idea on soldering points, I will pass through all of them.
Any thoughts on unknown transistor on the board aside the regular set?
Zen Mod, checked all the s200 related topics, but no schematics for s200 other than thresholdadjustment file posted by you, but I found very useful topic with your advice on adjustment..., and here I have not enough English:
@besides that , first thing I can think of - if there are NTCs , check cold resistance of each , desoldering one leg from pcb
if there is 10% difference to written value , replace@
What is NTC?
I also got confused with info about two s200 modifications, one with two trimpots for bias and dc offset, but mine with just one for bias...
@besides that , first thing I can think of - if there are NTCs , check cold resistance of each , desoldering one leg from pcb
if there is 10% difference to written value , replace@
What is NTC?
I also got confused with info about two s200 modifications, one with two trimpots for bias and dc offset, but mine with just one for bias...
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