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Thread: Scott 350 Tuner

  1. #1
    Join Date: Jan 2013

    Location: Bristol

    Posts: 4,558
    I'm Justin.

    Default Scott 350 Tuner

    Took these pics for Jazid so he could see what a decent case for the Scott 350 I gave him in the classifieds looks like. Well almost - 20!

    Posted here as I thought he may wish to add some prose at some stage. And some members might like to hear something about how he gets on with it.

    Somehow mine looks mint. But it is from 1961. Amazing I think.

    He already has it up and running, producing 'creamy sound' as he put it.

    These things do sound so far removed from later day solid state efforts that in some ways it almost makes you want to cry. They are not accurate but they do sound amazing in many ways.
    "I travelled far and wide through many different times. What did you see there? I saw the saints with their toys. What did you see there? I saw all knowledge destroyed. I travelled far and wide through many different times."

  2. #2
    Join Date: Jan 2013

    Location: Bristol

    Posts: 4,558
    I'm Justin.

    Default

    "I travelled far and wide through many different times. What did you see there? I saw the saints with their toys. What did you see there? I saw all knowledge destroyed. I travelled far and wide through many different times."

  3. #3
    Join Date: Apr 2012

    Location: London

    Posts: 468
    I'm James.

    Default

    Hi Justin

    Many thanks for the tuner , I worked on it a bit and have now run into a logjam of that thing that people call work

    So far I've cleaned it up a bit but of course its near impossible without the transfer details coming off. Either way there's about half a kilo of nicotine removed, dead spiders, cocoons, and other assorted debris from 50 years of life.

    So far I have got it to work with decent reception and reasonable selectivity, switch cleaned the umm switches and pots, all good. A couple of paper capacitors were a bit leaky so they were replaced but I've no chance to check the rest. Thankfully the smoothing electrolytics seem to have reformed nicely, and the hum at the beginning was due to insulation problems on the 6x4 which I swapped out . The remaining valves worked but most only just when measured so I swapped them all out for strong ones, invested in an aerial from Amazon to replace a home made dipole of two core mains cable.

    Sound is indeed 'creamy' and vintage; its roll up and enjoy delicious, however it is currently only in mono. So obviously summat amiss in the front end or maybe in the separation/balance trim pots which I haven't had a chance to check. I have searched high and low to get a schematic for the 350A, even the H.H. Scott website haven't got one...eventually I found an adequate one on ebay for which I am most grateful (from Canada). Now I have no time. Bah!

    More anon.

    PS. Has anyone got an FM sig genny I can borrow for a while to get the front end aligned? Pretty please

  4. #4
    Join Date: Jan 2013

    Location: Bristol

    Posts: 4,558
    I'm Justin.

    Default

    In all honesty I could do with the alignment procedure as detailed in the manual being done on mine.

    The unit you have always worked in stereo with stereo selected. Mono would give better sound quality on weaker stations.

    Selectivity will never be amazing on a 350. I had a Sansui TU-9900 and that, in my entire life, is the most amazing tuner I have come across technically. Sensitivity and selectivity are unreasonably good.

    That said, being able to receive a poor signal better than anything else is almost pointless. You never really want to listen to even vaguely compromised reception.

    And additionally, those technically great mid-70s Jap tuner/receivers sound like a complete bucket of shit by way of subjective comparison. Why is perplexing. But relatively the gain in technical performance is absolutely NOT worth the sacrifice in sound quality these old valve tuners can provide if they don't have to contend with useless input signals.

    I am back to real work too. There's no pressure to fix it, but I would really like to see you document the alignment process visually on this thread with some prose and the help of an AoS member's sig gen unit.

    So, anyone with a sig gen unit for Jazid would be greatly appreciated. Temp loan of course
    "I travelled far and wide through many different times. What did you see there? I saw the saints with their toys. What did you see there? I saw all knowledge destroyed. I travelled far and wide through many different times."

  5. #5
    Join Date: Apr 2012

    Location: London

    Posts: 468
    I'm James.

    Default

    Hi Justin,

    The selectivity is an issue for me because of the cretin nearby who liked to jam radio 3, and the other super-massive retard who likes to jam radio 4, both with some life destroying drivel perhaps best described as teenagers bedroom rap.

    The mono has been a constant for me since arrival, maybe poor signal as I can't get above a low 4 on the signal meter. However with the new tubes the output is equal volume with mono or stereo switched in, more hiss in stereo though. AGC makes no difference, another issue to sort.

    The signal drop out was easy, it's a wonky 7 pin socket, not fixed except with the odd wiggle!

    More anon



    Sent from my BLA-L09 using Tapatalk

  6. #6
    Join Date: Apr 2012

    Location: London

    Posts: 468
    I'm James.

    Default

    New 7 pin sockets on the way, I got 40 mins so checked a few voltages. Looks like there's one leaky supply cap section, if so I can disconnect, leave the can as is, and install a new one underneath. But I have to check first.
    Given my level the investment in a functioning RF sig genny is overkill, and the affordable ones are most likely 'yet another project' . So I have uncovered a cunning ruse: Use an mp3 fm transmitter for a car with a frequency counter, and a sweep generator on my phone. I'll check the levels and so on with the scope (within spec) and make do. Pics to follow

    Sent from my BLA-L09 using Tapatalk

  7. #7
    Join Date: Jan 2013

    Location: Bristol

    Posts: 4,558
    I'm Justin.

    Default

    I think I have a printed version of the Scott 350 alignment procedure somewhere James. Have you got a copy?

    FM Tuner Info seem to reckon it is a mysterious black art, not to be attempted by the uninitiated.

    It can't be that hard, surely.
    "I travelled far and wide through many different times. What did you see there? I saw the saints with their toys. What did you see there? I saw all knowledge destroyed. I travelled far and wide through many different times."

  8. #8
    Join Date: Apr 2012

    Location: London

    Posts: 468
    I'm James.

    Default

    I'm hoping it's not a necessary black art! The components seem to be well chosen to remain on spec so fingers crossed it's in the oscillator/demodulator sections. Currently there is a mysterious 25V gone missing on the wideband amplifier's power rail. I am crawling crabwise through the knitting of P2P wiring, it's rather slow work as everything's wound and soldered onto its mounting point and to test any of the small caps involves their destruction . There's a motley selection of carbon comp resistors that are now fractionally out of spec and one of the 6 main PSU caps still to test.
    ...

    Sent from my BLA-L09 using Tapatalk

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