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Thread: Hi-Fi Guidance

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    Hi-Fi Guidance

    Hi folks, I am attempting to assist my brother who recently acquired a pretty nice 1968 Philips Solid State console stereo. I have mainly worked on tube guitar amps.
    I have very limited solid state experience. We cannot locate a schematic. Is there anyone here who can help us identify a few things? Ground scheme? Cap polarity etc? There are some real good folks here who have helped me a lot with guitar amps. I was wondering if a few of you are into other electronics as well.

    If this Hi-Fi stuff is not welcome here, do you have any recommendations for a good forum with helpful folks for us Newbies?

    Model is a Phillips R448. If there is some help here, and ok to post, I will start uploading photos and asking questions. Thanks, Keith

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    Lifetime Member Enzo's Avatar
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    See if "Sams Photofact" has an issue for this model.

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    It's odd that there is so little showing up for this model, (using single L philips spelling).
    Is it a german unit? Any other model numbers on it? Post some pics?

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    Quote Originally Posted by The Dude View Post
    But, I did learn something. There are protons, neutrons, electrons, ............ and morons.

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    Thanks guys for checking in. No luck finding anything in Sams Photofact. It does appear that at least the guts were built in Germany. here are some pics. The final wood console may have been assembled in Canada.



    This is the turn table:



    Unsure where this is located:






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    Last edited by keithb7; 01-14-2018 at 01:41 AM.

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    The radio works and plays. There is some crackling. Upon initial inspection we see some blistering caps. For starters I thought all e-caps should be replaced.

    First question:
    How can we identify polarity on these original 1968 e-caps? I believe they are Plessey brand.



    Another cap here. I am unsure of polarity. Black wire from cap node seen here does go to the chassis. I assume the chassis is ground. Does that seem logical? Power cord is two prong. No ground to wall it seems.


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    Quote Originally Posted by g1 View Post
    It's odd that there is so little showing up for this model, (using single L philips spelling).
    Is it a german unit? Any other model numbers on it? Post some pics?
    Brother to keithb7 here...yes it is a German unit. The TT is a GC046 model ( I believe it is the same as a Grundig 46 series), and according to the original sales brochure the amp chassis is listed as model HC4. Not sure if the amp shares anything with Grundig components but so far I have not been able to track anything down online either.

    I did check "Sams Photofact" but no luck there. Thanks for any help you might have!

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    G.

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    Lifetime Member Enzo's Avatar
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    Yours is a 448, but the one photo you posted shows the same chassis was used in the 458 and 468 models. A search for those two MIGHT turn something up.

    As to your can caps, the upper one has a single terminal and can tabs. Unless otherwise indicated, I assume the single terminal is the plus, and the can tabs negative. See the tiny square stamped into that single post on its base?

    Now look on the two legged cap. I see four diodes there making a bridge. The left terminal has the positive ends of the rectifiers. The right terminal has the negative ends of rectifiers. Note the left terminal has the tiny square stamped on it, while the right one has a tiny triangle.

    On both caps, look for a legend stating the cap rating. See if there is not a square and triangle printed on there, with one claiming positive. On the single leg one, see if ther is a + on the side.

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    Ahh yes! I see the square an triangle now. Thank you.

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    Does this pic help with further polarity clarity?


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    Not much on the caps to ID polarity it seems:

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    Lifetime Member Enzo's Avatar
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    perhaps further around the can to the right, is ther any symbol after the rating?

    In general, I assume the can tabs are negative unless specified otherwise.

    In the case of the two leg one with no can tabs, I stick with my diode theory.

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    Enzo, what is up with the labelling on those diodes, seems backwards to me?

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    Quote Originally Posted by The Dude View Post
    But, I did learn something. There are protons, neutrons, electrons, ............ and morons.

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    4 names g1's Avatar
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    Quote Originally Posted by keithb7 View Post
    We cannot locate a schematic.
    It's worth a try to check with justradios.
    They say 'antiques' but seem to have stuff right into the 70's :
    Canadian Antique Radios Schematics Diagrams Service - JustRadios

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    Quote Originally Posted by The Dude View Post
    But, I did learn something. There are protons, neutrons, electrons, ............ and morons.

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    Quote Originally Posted by Enzo View Post
    perhaps further around the can to the right, is ther any symbol after the rating?
    Twisted to reveal, further to the right:


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    Quote Originally Posted by g1 View Post
    Enzo, what is up with the labelling on those diodes, seems backwards to me?
    My basic understanding is that the arrow points toward cathode (-) on the diode.


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    To me the triangle (arrow) looks like an A, so ANODE, the bar is cathode. That is the flow of "conventional current", not electron flow.

    If I send AC into the anode, I expect positive DC on the cathode side.

    I expect the square symbol terminal on the two leg cap to be positive.

    I am just guessing, but from the photos, I think I am seeing this as a single supply power amp, the large two leg cap being for that. Then there are two smaller 1-leg can caps next to it, with the 0.5 ohm resistors. I see those as output speaker caps for the two channels. Anyone else get that impression?


    I cannot see it well, but it LOOKS to me like the bare wire lead from the positive leg of the 2-leg cap might go to a ground lug? Meaning this amp is running on a negative supply, like maybe PNP types, likely germanium?

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    Your explanation of the 3 caps makes sense, the large for the power supply and the 2 smaller for the speaker channels. There is a fourth large cap as well but I believe it may be for the cassette portion of the unit.

    The bare wire is coming from a shielded lead, the inner wire of that lead runs to a circuit board. The black wire running from the same post as the bare wire runs to a chassis ground.

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    Quote Originally Posted by g1 View Post
    It's worth a try to check with justradios.
    They say 'antiques' but seem to have stuff right into the 70's :
    Canadian Antique Radios Schematics Diagrams Service - JustRadios
    Thanks for the lead, I will shoot them an e-mail.

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    Last edited by gbarron; 01-14-2018 at 06:44 PM.

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    4 names g1's Avatar
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    Quote Originally Posted by Enzo View Post
    I cannot see it well, but it LOOKS to me like the bare wire lead from the positive leg of the 2-leg cap might go to a ground lug? Meaning this amp is running on a negative supply,
    Ok, I only thought the diode labelling appeared reversed because I expected a positive power supply.
    From the way the diodes are connected, yes, it must be a negative supply voltage at the triangle lug, with the square lug grounded.

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    Quote Originally Posted by The Dude View Post
    But, I did learn something. There are protons, neutrons, electrons, ............ and morons.

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