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    New Production CE Quad Cap Reliability (?)

    PeterCapo
    PeterCapo

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    Post by PeterCapo on Wed Apr 29, 2020 1:00 pm

    Does anyone know if the GZ37 is directly or indirectly heated? Any documentation?
    danmartinic
    danmartinic

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    Post by danmartinic on Wed Apr 29, 2020 1:44 pm

    I see. It (thermistor) seems such an odd tiny thing to install in series with one side of a power cord... but then again, so is a fuse lol
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    shermanaudio

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    Post by shermanaudio on Wed Apr 29, 2020 1:54 pm

    PeterCapo wrote:Does anyone know if the GZ37 is directly or indirectly heated?  Any documentation?  

    http://www.r-type.org/exhib/aaa1092.htm

    Indirectly Heated.
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    shermanaudio

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    Post by shermanaudio on Wed Apr 29, 2020 4:02 pm

    PeterCapo wrote:Well, I can't deny the possibility of manufacturing defects.  But, I think it would be appropriate to at least rule out the amplifier as a source of the problem.

    You bet!

    The Amp pictured has been modified, so it is a good thing to look for the instructions that came with the nice new Board to validate the wiring.

    Also, as previously mentioned by me, something tells me by looking at the C354 Choke, it looks extra crispy.

    If that part got shorted, the voltage drop across that Choke will be absent, although it likely is around 10-12 Volts DC (approximate) more on the first section of the mutli-cap.

    I would sure like to listen to that Amp with the board modification, gotta be nice to enjoy.
    PeterCapo
    PeterCapo

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    Post by PeterCapo on Wed Apr 29, 2020 4:32 pm

    Forgive me for pointing this out, but the images show the original brown, phenolic Dynaco 7199 driver board, not a different replacement circuit of some kind (if that's what you meant).  Seems like an appropriate enough time to point out that a thorough restoration to the original Dynaco circuit design, including a fresh copy of the original 7199 driver board if the original PC board is damaged, results in a mighty fine sounding amplifier that competes with the various "mods" as well as other new amplifiers in the price range and beyond.  Which circuit someone prefers would boil down to personal taste.

    For the choke, they all have wax dripping out of them, and this gives them a haggard look.  Out-of-circuit it should measure about 62 ohms, in which case it would be fine.
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    shermanaudio

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    Post by shermanaudio on Wed Apr 29, 2020 8:48 pm

    PeterCapo wrote:Forgive me for pointing this out, but the images show the original brown, phenolic Dynaco 7199 driver board, not a different replacement circuit of some kind (if that's what you meant).  Seems like an appropriate enough time to point out that a thorough restoration to the original Dynaco circuit design, including a fresh copy of the original 7199 driver board if the original PC board is damaged, results in a mighty fine sounding amplifier that competes with the various "mods" as well as other new amplifiers in the price range and beyond.  Which circuit someone prefers would boil down to personal taste.

    For the choke, they all have wax dripping out of them, and this gives them a haggard look.  Out-of-circuit it should measure about 62 ohms, in which case it would be fine.

    Correct, I confused posts. Thank You
    danmartinic
    danmartinic

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    Post by danmartinic on Sun May 03, 2020 11:17 am

    Ok.. job done. I have the following measurements:

    tube pin mine (manual)

    EL34
    one 1.56 (1.56)
    two 6.7 (6.4)
    three 395 (410)
    four 399 (415)

    GZ37
    two 414 (435)
    four 375 (360)
    six 375 (360)
    eight 413 (435)

    7199
    four 6.3 (6.4)
    five 6.3 (6.4)

    Selenium rectifier
    Top -65 (-65)
    Did not measure bottom

    Cap
    square 268 (305)
    triangle 343 (375)
    blank 400 (415)
    half-moon 30uf 413 (435)

    PCB eyelets three & eighteen 340 (370)




    New Production CE Quad Cap Reliability (?) - Page 2 Dbd06f10
    danmartinic
    danmartinic

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    Post by danmartinic on Sun May 03, 2020 11:23 am

    Sounds amazing!
    New Production CE Quad Cap Reliability (?) - Page 2 Image10
    PeterCapo
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    Post by PeterCapo on Sun May 03, 2020 11:31 am

    High voltage secondary feeding the GZ37 is a bit high.  Voltages downstream of the GZ37 are lower than the spec for 5AR4/GZ34, which is expected assuming the GZ37 has a greater voltage drop than 5AR4/GZ34.  Therefore, the amplifier will not quite meet its originally specified maximum power output.

    Again, there is no reference data for using a GZ37 in this amplifier, therefore there really isn't a way to get a good sense for what these readings might really mean.  All we're doing is guessing.  At the same time, if the amplifier is working to your satisfaction, then that's the most important thing.


    Last edited by PeterCapo on Sun May 03, 2020 3:18 pm; edited 2 times in total (Reason for editing : clarification)
    danmartinic
    danmartinic

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    Post by danmartinic on Sun May 03, 2020 11:40 am

    The sound is super! Big and deep. I guess compared to the leaky / open cap, it's an eye-opener lol

    I'll keep an eye on the bias and any funny noises. Thanks for all the info and responses!

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