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Fisher RS-2010 Darlington pack STK-0080 or 0105?

Discussion in 'Fisher' started by alexrw3, Apr 18, 2005.

  1. alexrw3

    alexrw3 Guest

    The unit I am repairing has STK-0080 packs installed. They appear to be originals. However, the service manual shows STK-0105. Does anyone know if the two are equivalent, or if Fisher might have substituted somewhere along the way?
     

     

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  2. Bill

    Bill Active Member

    Messages:
    275
    Location:
    Indianapolis, IN
    I have repaired at least 4 or 5 Fisher RS-2010's over the last few years and they all had STK-0080's. I don't know about the STK-0105. Maybe they were in a early production run. Don't know. The STK-0080 is very reliable power pack as long as you dont drive them at near clipping levels into low speaker impedances of 4 ohms or less. If you do they are toast.

    Bill from Indy
     
  3. yrly

    yrly Breaking records is good?

    Messages:
    2,556
    Location:
    Buffalo NY
  4. alexrw3

    alexrw3 Guest

    I have the STK-0080s in hand. Ordered them last Friday from Matelectronics and they arrived on Monday. Great service (I guess it also helps that we are both in PA). I should have ordered more since I also have a Fisher CA-880 to repair. They were only $10.50 each. Fortunately I remembered to order the heatsink compound too.
     
  5. alexrw3

    alexrw3 Guest

    I installed the STK-0080s (figured I might as well replace both while I had the hood up). Works like a champ. My first reaction is that the tuner is as clean sounding as any I have ever heard. The amp section seems to be working just fine. Thanks to all who helped, especially Bill and Yrly. This was an easy fix. The biggest problem was getting the old 0080s out. Looks like one had previously been replaced and the pins were a little crooked. Had to be careful not to crack the board. Bill - I will PM regarding the slider board.
     
  6. Tony75

    Tony75 Well-Known Member

    Messages:
    551
    Location:
    Newcastle, Australia
    My magic book on STK chips does not have the 0080s listed oddly enough, but it does have to 0105. That chip is a 100W module with 50Vcc rail.
    The table has the STK0060 at 60W and the STK0070 at 70W. with 40v and 43v respectively. I gues you could conclude that the 0080 is an 80W chip.
    I guess they were cheaper to fit than the 0105 and maybe gave fewer problems if say, they gave out more heat.
    But you seem to have solved your problem anyway :)
    Cheers
    Tony
     

     

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  7. RocknRoll

    RocknRoll Super Member

    Messages:
    1,086
    Location:
    Great Lakes
    That is part of the reason they blow so easy they are an 80 watt chip.
     
  8. cbottorff

    cbottorff Member

    Messages:
    83
    Location:
    Utica, New York, America
    Several years ago, I read this thread and ever since that time, I've had this thread in the back of my mind. As I have recently acquired relevant new material it is time to update this thread.

    Here are pictures of the specific receiver in question, in this case a pristine condition Fisher RS-2010.

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    This unit is in mint condition.

    So... What's under the hood?
     
  9. cbottorff

    cbottorff Member

    Messages:
    83
    Location:
    Utica, New York, America
    As previously discussed in this thread and at least half a dozen other Fisher threads here on AK, Fisher model RS-2010 receivers are commonly equipped from the factory with Sanyo STK-0080 power pack modules. STK-0080 power pack modules are rectangular with perfectly square corners. There is another slightly different Sanyo case style topology that slants in at the bottom on each side at about 20 degrees, and is more hollow on the sides where the fasteners mount, which is common to the STK-0040, STK-0050, but this particular version of square case style outline isn't one of them.

    Here are what STK-0080 modules look like in a Fisher RS-2010 receiver. I elected not to clean the dust out of the unit at the the time because cleaning this much dust out may cause even further problems unless done properly, with the right equipment and under the best conditions. So it is safer to for me to leave this small amount of light dust as it isn't causing any heat buildup problem.

    [​IMG]

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    But is the STK-0080 what is under the hood of the unit in question?...
     
    Last edited: Mar 19, 2010
  10. cbottorff

    cbottorff Member

    Messages:
    83
    Location:
    Utica, New York, America
    And... The answer is... Nope.

    The pristine condition Fisher RS-2010 receiver we have here is a factory original that has come through equipped with the originally specified STK-0105 power packs. STK-0105s are substantially larger than STK-0080s being both wider and taller than STK-0080s. Also, STK-0105s are gently rounded on their entire sides where the screw fasteners pass through.

    At first glance in these low resolution, low contrast pictures the difference is not clear or evident at all. The presence of STK-0105s in this particular Fisher RS-2010 escaped even my casual observation, and I'm specifically looking for them in every RS-2010 internal picture and physical unit I see. It was only after viewing the entire set several times and then zooming in on second picture in particular that I discovered that the STK power packs in this Fisher RS-2010 are in fact STK-0105s.

    And, before someone might say that these were replaced by someone (which is what I am in fact very inclined to do), consider the fact that while STK-0080 and STK-0105 are specifically designed as electrical equivalents and they may, with proper engineering discretion, be interchanged with each other, STK-0080 and STK-0105 power packs are obviously not mechanical equivalents.

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    But, do the differences end here?
     
  11. EchoWars

    EchoWars Hiding in Honduras

    Messages:
    28,399
    Location:
    Kansas City
    The STK-0080 has a full complementary output stage and is designed for 80W output and a maximum of +/-65V rails (power rated using +/-46V rails), The STK-0105 is a quasi-complementary part, designed for 100W output and a maximum of +/-75V rails (power rated using +/-50V rails). They DO have the same pinout, and you can change one for the other, as long as the maximum recommended voltages are not exceeded.
     
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  12. cbottorff

    cbottorff Member

    Messages:
    83
    Location:
    Utica, New York, America
    In post #13 EchoWars says:

    > The STK-0080 has a full complementary output stage and is designed for 80W output and a maximum
    > of +/-65V rails (power rated using +/-46V rails), The STK-0105 is a quasi-complementary part,
    > designed for 100W output and a maximum of +/-75V rails (power rated using +/-50V rails).
    > They DO have the same pinout, and you can change one for the other, as long as the maximum
    > recommended voltages are not exceeded.

    This is correct for the maximum voltage ratings...

    As more clearly described and documented by the applicable Sanyo datasheets:

    [​IMG]

    This particular data sheet cites power output / voltage data as:

    STK-0080 (power rated as 100 watts RMS using +/-42V rails)

    STK-0105 (power rated as 120 watts RMS using +/-45V rails)

    with a speaker load of 4 ohms rather than 8 ohms.

    It's too bad Sanyo didn't design these power packs with a higher thermal power dissipation as they clearly appear to be designed to drive 4 ohm loads.
     
    Last edited: Mar 19, 2010
  13. PacificStereo

    PacificStereo Super Member

    Messages:
    1,725
    What a beautiful piece! For those that aren't aware, it is a Sanyo through and through, it doesn't just have Sanyo output devices.
     
  14. kcollins4

    kcollins4 Rocking somewhere

    Messages:
    5,731
    Location:
    Katy, TX
    What "special equipment and conditions" do you need to get the dust out?
    Nice pics.
     
  15. cbottorff

    cbottorff Member

    Messages:
    83
    Location:
    Utica, New York, America
    Another different Sanyo datasheet reflects echowars' aforsaid cites for the STK-0080 and STK-0105 specification for 8 ohm loads.

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    My interest continues with the physical and electrical design of the STK-0105 as distinguished from the STK-0080. A further closer examination of the Sanyo datasheets reveals why the STK-0105 is quite a bit physically larger than the STK-0080:

    [​IMG]

    In detail, the specific electrical and mechanical differences between STK-0080 and the STK-0105 are as follows:

    The physical outline for the STK-0080 is 64 millimeters wide and 39.5 millimeters tall with a fastener distance of 55.6 millimeters center to center:

    [​IMG]

    The physical outline for the STK-0105 is 78 millimeters wide and 44 millimeters tall with a fastener distance of 70 millimeters center to center:

    [​IMG]

    The internal electrical schematic for the STK-0080 is a pure complementary circuit of 5 transistors in a darlington configuration with 2 emitter follower outputs:

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    The internal electrical schematic for the STK-0105 is a quasi complementary circuit of 8 transistors with 4 emitter follower outputs. Thus, in short, the answer why the STK-0105 is substantially larger than the STK-0080 is because the STK-0105 is physically housing twice as many high current emitter follower power output devices than all of it's other STK siblings:

    [​IMG]

    Therefore, the STK-0105 is clearly capable of better power output performance than it's STK-0080 "little brother" which has only half the emitter follower final output devices.

    In the future, I am definitely going to remove the lesser capable STK-0080 devices and use the original specified STK-0105 devices in any Fisher RS-2010 repair and/or restoration project. The difference in cost is only just a few bux, if you know where to look for them. The power output of the STK-0105 should be greater and long term reliabillity should also be substantially better.
     
  16. cbottorff

    cbottorff Member

    Messages:
    83
    Location:
    Utica, New York, America
    In post #14 kcollins4 (Kevin) says:

    > What "special equipment and conditions" do you need to get the dust out?

    Lots of clean dry air under fairly high pressure. I'm just too cheap and I can't bring myself to buy air in can. (Isn't air free?) Many air compressors commonly have a lot of moisture - fine water droplets and oil droplets as well in their air, especially when the air is delivered at the higher volume an air chuck allows.

    I don't want high pressure oil and water driven inside the intermediate transformers and moreover, the most delicate area, the tuning capacitor, which on my unit, needs to be cleaned very badly. So I'm waiting until I can get access to clean dry air before I clean it out.

    > Nice pics.

    Those pics are nothing, mine are size reduced by a ratio of 3:1 from 4000x3000 pixel originals and then cropped even further down from the 1333x1000 pixel size reduced versions to 900x900 pixel "cardiac friendly" versions you see posted herein.

    Personally, I hate low resolution pics. More than 20 years ago we were limited to 800x600 and 1024x768 super VGA resolutions. Eh, it's not 1989 anymore. Our computers have gotten a lot better in the last 20 years and so have and should our pictures as well.

    So, at your prompting, I've updated my three dusty pics making them hot clickable to the original "heart attack" high res 4000x3000 pixel original pics.i
     

     

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  17. tarior

    tarior Dirty pool, old man? Subscriber

    Messages:
    6,523
    Location:
    Kelso, Washington
    If it's not broke, why are you going to "fix" it? With the voltage rails in a 2010 (around 62V, IIRC on the last one I fixed), you won't gain any power output and run a real risk of installing counterfeit parts in your receiver. The STK 0080 is a tried and proven device, leave it be. IMO.
     
  18. montecarlossfan

    montecarlossfan Active Member

    Messages:
    477
    Location:
    Canton,CT
    Not to open an old thread but.....I replaced my stk080s with 105s Nos models though no fakes here is what it had before and after notice one fake stk80 that blew [​IMG]
    [​IMG]
     
  19. we_doyle

    we_doyle Member

    Messages:
    76
    Darlington Power Pack stk-0080

    Which one is the fake one?

    I may need to replace one or both of these. Where can I order it? How can I know I am getting the right part?
     
  20. jrj90620

    jrj90620 New Member

    Messages:
    6
    Here we are in 2018 and there are a lot of junk STK0080's being sold on Ebay by Chinese sellers and I guess,some U.S. sellers.I got a refund after the ones I got from a Chinese seller ran way under biased.Tons of crossover distortion,when driven sine wave into load.There are no adjustments for bias or offset in Fisher CA-880.Got some used pulls from U.S. seller and work like originals,probably because they are Sanyo originals,not the junk imitations being sold as new.
     

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