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  • PSU query

    From Cursitor Doom@21:1/5 to All on Sun Sep 10 21:29:04 2023
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out
    the polarity. The actual psu is getting 8VDC in from my measurement.
    Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

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  • From piglet@21:1/5 to Cursitor Doom on Mon Sep 11 12:57:59 2023
    On 10/09/2023 9:29 pm, Cursitor Doom wrote:
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out
    the polarity. The actual psu is getting 8VDC in from my measurement.
    Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

    The regulated output on the left of that pic at TP1 is +4.9V the other
    output to the right labelled 6A is the switched battery voltage +5.3 to
    +7.8V

    piglet

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  • From Cursitor Doom@21:1/5 to All on Mon Sep 11 14:59:47 2023
    On Mon, 11 Sep 2023 12:57:59 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 10/09/2023 9:29 pm, Cursitor Doom wrote:
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out
    the polarity. The actual psu is getting 8VDC in from my measurement.
    Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

    The regulated output on the left of that pic at TP1 is +4.9V the other
    output to the right labelled 6A is the switched battery voltage +5.3 to
    +7.8V

    piglet

    Thanks, Erich. This design seems highly unusual to me and it's hard to
    work out what's going on here. I'm seeing minus 8V on the emitter of
    T8 which makes no sense to me. Es gibt keinen sinn! Does negative 8V
    WRT GND seem okay to you??

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From piglet@21:1/5 to Cursitor Doom on Mon Sep 11 15:46:02 2023
    On 11/09/2023 14:59, Cursitor Doom wrote:
    On Mon, 11 Sep 2023 12:57:59 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 10/09/2023 9:29 pm, Cursitor Doom wrote:
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out
    the polarity. The actual psu is getting 8VDC in from my measurement.
    Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

    The regulated output on the left of that pic at TP1 is +4.9V the other
    output to the right labelled 6A is the switched battery voltage +5.3 to
    +7.8V

    piglet

    Thanks, Erich. This design seems highly unusual to me and it's hard to
    work out what's going on here. I'm seeing minus 8V on the emitter of
    T8 which makes no sense to me. Es gibt keinen sinn! Does negative 8V
    WRT GND seem okay to you??

    Yes that circuit does need careful analysis but what you see sounds
    correct. T7 and T8 keep dry battery separate from the rechargeable and
    do the switching in the negative rail so it may look strange at first
    glance.

    Do you have dry cells installed as well or just the rechargeable? I am
    hoping that when switched ON (the switch between terminals 6A and 6B)
    you should see the voltage at T8 emitter to ground become a few tens mV
    instead as T8 conducts.

    I worked a little on Uhers in Munich in the 1970s but always much
    preferred Nagras :)

    piglet


    piglet

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Mon Sep 11 18:10:44 2023
    On Mon, 11 Sep 2023 15:46:02 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 11/09/2023 14:59, Cursitor Doom wrote:
    On Mon, 11 Sep 2023 12:57:59 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 10/09/2023 9:29 pm, Cursitor Doom wrote:
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out >>>> the polarity. The actual psu is getting 8VDC in from my measurement.
    Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

    The regulated output on the left of that pic at TP1 is +4.9V the other
    output to the right labelled 6A is the switched battery voltage +5.3 to
    +7.8V

    piglet

    Thanks, Erich. This design seems highly unusual to me and it's hard to
    work out what's going on here. I'm seeing minus 8V on the emitter of
    T8 which makes no sense to me. Es gibt keinen sinn! Does negative 8V
    WRT GND seem okay to you??

    Yes that circuit does need careful analysis but what you see sounds
    correct. T7 and T8 keep dry battery separate from the rechargeable and
    do the switching in the negative rail so it may look strange at first
    glance.

    Do you have dry cells installed as well or just the rechargeable? I am
    hoping that when switched ON (the switch between terminals 6A and 6B)
    you should see the voltage at T8 emitter to ground become a few tens mV >instead as T8 conducts.

    I worked a little on Uhers in Munich in the 1970s but always much
    preferred Nagras :)

    Both Uhers and Nagras are becoming highly collectable now for some
    reason. There seems to be a renewed interest in tape. A used Uher
    Report Monitor in good working order can fetch over 500 euros
    currently. For Nagras - jeez - three or four times that price or more!
    You're obviously way better than I'll ever be when it comes to working
    out circuit diagrams, Piglet. I'll be for ever in your thrawl.
    I'm done today with the tonband but will take another look at it
    tomorrow.
    Thanks again.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Mon Sep 11 21:29:02 2023
    On Mon, 11 Sep 2023 15:46:02 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 11/09/2023 14:59, Cursitor Doom wrote:
    On Mon, 11 Sep 2023 12:57:59 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 10/09/2023 9:29 pm, Cursitor Doom wrote:
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out >>>> the polarity. The actual psu is getting 8VDC in from my measurement.
    Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

    The regulated output on the left of that pic at TP1 is +4.9V the other
    output to the right labelled 6A is the switched battery voltage +5.3 to
    +7.8V

    piglet

    Thanks, Erich. This design seems highly unusual to me and it's hard to
    work out what's going on here. I'm seeing minus 8V on the emitter of
    T8 which makes no sense to me. Es gibt keinen sinn! Does negative 8V
    WRT GND seem okay to you??

    Yes that circuit does need careful analysis but what you see sounds
    correct. T7 and T8 keep dry battery separate from the rechargeable and
    do the switching in the negative rail so it may look strange at first
    glance.

    It certainly did look very unusual indeed!

    Do you have dry cells installed as well or just the rechargeable?

    There are 3 options at least. You can put 7x D cells in the battery compartment. You can insert the monolithic NiCad battery into the same compartment. Or you can insert the PSU (which is the same dimensions
    as the NiCad block) into the battery compartment and run it from the
    mains supply, and that's what I've been doing for testing purposes.
    Despite there being power 'in' to the regulator board, there is
    nothing more than 0.7V to be found on any of the component leads. It
    should therefore be simple enough to trace the fault, which must
    obviously be very close to the 'power in' point.

    I am
    hoping that when switched ON (the switch between terminals 6A and 6B)
    you should see the voltage at T8 emitter to ground become a few tens mV >instead as T8 conducts.

    Well, I have my doubts, as T8 is a prime suspect here. I'm very
    grateful for your expert advice here, Piglet. What a stroke of luck
    you worked for Uher back in the day.

    CD.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Tue Sep 12 19:29:26 2023
    On Mon, 11 Sep 2023 21:29:02 +0100, Cursitor Doom <cd@notformail.com>
    wrote:

    On Mon, 11 Sep 2023 15:46:02 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 11/09/2023 14:59, Cursitor Doom wrote:
    On Mon, 11 Sep 2023 12:57:59 +0100, piglet <erichpwagner@hotmail.com>
    wrote:

    On 10/09/2023 9:29 pm, Cursitor Doom wrote:
    Gentlemen,

    Can some kind soul tell me what the output voltages of this psu
    section are stated as? It's not a very good scan I got off the net
    and my eyes aren't that great any more. In particular I can't make out >>>>> the polarity. The actual psu is getting 8VDC in from my measurement. >>>>> Thanks!


    https://disk.yandex.com/i/dmXDbFUsMeZBCg

    The regulated output on the left of that pic at TP1 is +4.9V the other >>>> output to the right labelled 6A is the switched battery voltage +5.3 to >>>> +7.8V

    piglet

    Thanks, Erich. This design seems highly unusual to me and it's hard to
    work out what's going on here. I'm seeing minus 8V on the emitter of
    T8 which makes no sense to me. Es gibt keinen sinn! Does negative 8V
    WRT GND seem okay to you??

    Yes that circuit does need careful analysis but what you see sounds >>correct. T7 and T8 keep dry battery separate from the rechargeable and
    do the switching in the negative rail so it may look strange at first >>glance.

    It certainly did look very unusual indeed!

    Do you have dry cells installed as well or just the rechargeable?

    There are 3 options at least. You can put 7x D cells in the battery >compartment. You can insert the monolithic NiCad battery into the same >compartment. Or you can insert the PSU (which is the same dimensions
    as the NiCad block) into the battery compartment and run it from the
    mains supply, and that's what I've been doing for testing purposes.
    Despite there being power 'in' to the regulator board, there is
    nothing more than 0.7V to be found on any of the component leads. It
    should therefore be simple enough to trace the fault, which must
    obviously be very close to the 'power in' point.

    I am
    hoping that when switched ON (the switch between terminals 6A and 6B)
    you should see the voltage at T8 emitter to ground become a few tens mV >>instead as T8 conducts.

    Well, I have my doubts, as T8 is a prime suspect here. I'm very
    grateful for your expert advice here, Piglet. What a stroke of luck
    you worked for Uher back in the day.

    Yup, turned out both T7 and T8 were blown O/C as expected. Strangely
    low spec choice of transistor for a position in the circuit like that.
    Must have been on the ragged edge a high percentage of the time....

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