Analog TV Redux

Discussion in 'Retro & Arcade' started by iMic, Apr 25, 2018.

  1. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    Something had to blow eventually.

    [​IMG]

    Unfortunately these speakers have no part number or manufacturer code on them, and appear to be an uncommon size, 6.25" x 2.25" (159.2mm H x 57.7mm W). They're similar to RCA 234172 speakers and the speakers used in RCA's ColorTrak TVs from the 1980s. Those speakers are rated for 3.2 ohms, 3.5 watts, so they're probably similar in specs, but I'll have another look at the circuit diagram and see if it provides any hints.

    But new or recent production replacements are almost impossible to find. Nobody seems to produce these. I've queried about having the foam replaced but nobody seems to do that either. Some suggested I use external speakers, but I'm more interested in repairing this TV and keeping it working.

    It doesn't appear as though a different sized speaker could be modified to fit the cabinet either. There isn't much room to move in there.

    [​IMG]
     
  2. /invariance\

    /invariance\ Member

    Joined:
    May 23, 2012
    Messages:
    847
    Location:
    Brisbane
    I don't know if Qld Spear Repairs would have that, but have a look anyway. qsr.net.au
    I sourced the surround for the subwoofer that was in my old Metz, although it wasn't anywhere near as unusual as that.

    Edit: doesn't appear to be anything at qsr. Might even be time to roll your own (this and this). What's a retro forum without homebrewed repairs.
     
    Last edited: Sep 25, 2018
  3. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    I've sent messages to both Queensland Speaker Repairs and Speakerbits in case they have some ideas on how to address this problem. Some custom fabrication isn't a concern, neither is throwing some cash in to have someone professionally look at them.

    It's been excellent for old games, movies and everything in between, and the CRT and electronics are still in great shape, so it's easily worth repairing in my book.
     
    /invariance\ likes this.
  4. mAJORD

    mAJORD Member

    Joined:
    Jun 4, 2002
    Messages:
    9,747
    Location:
    Griffin , Brisbane
    Awesome thread -not sure how I missed it!

    I'm a bit of a CRT tragic. have 3 34cm CRTs in active use.

    My 1982 Japanese made Thorn "thorny" which we've had since late 2000's - was our main bedroom TV, now it's a 'retreat' TV next to my desk. ultrasonic remote still works a treat.

    An early 80s white plastic Toshiba which I posted up in the general thread I think, which is my Daughters TV

    and another newer , mid to latish? 80s toshiba for console duties.

    The first two have NO composite inputs - So I run just the standard yumcha RF modulator's with a set-top box feeding it composite.. so we can watch FTA on them.. Picture is brilliant on all of them, but especially Thorny.

    I recently cleaned it out and replaced a couple of caps - I'd recommend against replacing ALL caps if it's behaving OK - you're 'fixing what isn't broke' ..





    What about mounting a good 2" or 2x4" on a thin ply baffle sized to the original speaker with the original mounting hole pattern in it? I'll be doing this to solve a similar issue with my old car's in-dash speakers - also an uncommon oval shape, and I want up the SQ which I can only do with smaller, common sized circular drivers
     
    Last edited: Sep 26, 2018
    elvis likes this.
  5. elvis

    elvis Old school old fool

    Joined:
    Jun 27, 2001
    Messages:
    36,653
    Location:
    Brisbane
    Agreed. The amount of people I see doing full cap kits for no reason is mind blowing. And way too many end up with a non-functional display as a result, with no way to diagnose the problem as too much has been changed.
     
  6. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    I'm considering this exact option at the moment, and it seems to be the most promising. Although mine was a little more overkill -

    [​IMG]

    A thick machined steel bracket (or brackets) that affix to each end of the speaker, with holes drilled in each to screw onto the existing mount points inside the TV, and studs threaded into the bracket so the speaker can be attached onto the posts with a nut and washer.

    Plywood would be better for its acoustic properties, but I'd have to undersize the speaker just a bit to ensure that once the speaker hole is cut out, there's still enough material around the border so it's not ridiculously flimsy. It would seal against the front panel better though.

    Time to make friends with someone that has a CNC cutter. :lol:

    For speakers, something like this perhaps - https://www.parts-express.com/visaton-sc-59-2-x-35-shielded-full-range-driver-8-ohm--292-551 - at least in dimensions. I still need to check the electrical specs if I can. Maybe there's something in the schematic or some markings on the speaker I missed last time.


    There are unused secondary speaker mounts inside the TV as well, toward the top of the cabinet. It has me wondering if I could potentially add some additional speakers in there too, provided the onboard amplifier is able to handle it.

    [​IMG]

    Something like this perhaps - https://www.parts-express.com/visaton-fr-58-4-23-full-range-speaker-4-ohm--292-634 - which appears to be a perfect match, but the driver itself isn't shielded, so some additional work is needed to prevent it from interfering with the CRT.
     
    Last edited: Sep 27, 2018
  7. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    Something else that hadn't occurred to me is that while the speakers are 2.25" x 6.25" dimensions, the actual screw mounts are spaced 47.5mm W x 120.58mm H or 1.87" W x 4.747" H. This places it within the specifications of a 2" / 2.25" W x 5" driver, which seems to be a little more common. Some rubber or nylon spacers may be needed, but those are much easier to get.

    Maybe I'll order some different sized speakers and see what I can make with them.


    Update: By some unbelievable chance I managed to find the exact match speaker for this TV. Part number YDT616-03, seems to be available from some suppliers out of China. At least we have some specifications now:

    Code:
    YDT616-03
    
    A    57 x 159 mm
    B    49
    C    50
    D    47.5 x 120.5 mm
    E    4-5
    
    Impedance    4,8,16 Ohms
    Noise Power    5W
    Max Power    10W
    Sensitivity    88dB
    Fo        170 Hz
    Freq. Resp.    Fo - 20,000 Hz
    The YDT616-02 also appears to be the same dimensions, but with 20W maximum power and a lower 16,000 Hz maximum frequency response.

    The TV schematics reference 8 Ohm, 10W and 15W speakers, along with 4 Ohm, 30W speakers depending on model. Narrows it down somewhat, and I suspect 8 Ohm, 10W Max is the speaker I need, but I'll need to disassemble the TV and take a closer look to be certain.
     
    Last edited: Sep 27, 2018
  8. Badooleoo

    Badooleoo Member

    Joined:
    Oct 25, 2007
    Messages:
    290
    Location:
    Adelaide
    Probably doesn't need to be higher. Wasn't broadcast TV audio WFM like FM radio? Past 16kHz is just the pilot tone and anything else like RDS.
     
  9. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    Found this listed for sale the next suburb over.

    P1010788.jpg

    It's an NEC N-6380, manufactured and assembled by NEC Home Electronics Australia in Penrith, NSW.

    There isn't much in terms of connectivity, one RF antenna input, one Composite Video input and one mono audio input. It does have twin speakers however, and an on-screen display for volume and channel controls. It has manual vertical and horizontal hold controls. I'd estimate it was built sometime between 1988 and 1990.

    The CRT looks fantastic and bright at medium brightness, but needs the contrast adjusted to the maximum. The picture itself is sharp and clear.

    But it has some issues. The raster image and geometry deforms depending on what's showing on screen. The top left corner bends inward and outward depending on the colour and brightness of whatever is showing in that corner. The top edge is skewed clockwise by around 2 to 3 degrees as well.

    P1010789.jpg P1010795.jpg P1010796.jpg P1010797.jpg

    (The picture is sharper than the camera captures here, but it's difficult to capture a completely accurate picture of the CRT image.)


    Assuming it was manufactured in 1988, the chassis is 30 years old. It's overdue for a service, and the capacitors are almost certainly due for replacement. A yoke adjustment should take care of the tilted picture, provided there isn't another reason for it that needs to be addressed first. However the top corner issue requires some further investigation.

    And as tempting as it is to RGB modify it, it's a live chassis design, so there are some safety considerations that need to be taken into account.

    At least the speakers on this one are a more common shape.
     
    Last edited: Dec 28, 2018
    elvis likes this.
  10. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    [​IMG]

    Found this Sony Trinitron KV-2184AS 21" TV on Gumtree. It's pure classic 90's Sony aesthetic and industrial design, and it's in great condition. The tube looks extremely good, producing a bright and sharp picture with vibrant colours. It has RF and Composite connections for video and mono sound, and appears to accept both PAL and NTSC signals without issue.

    The Sony tuner is much better than the other sets. With a passive antenna connected to the Kingray MD100VS modulator, the TV receives a clear signal from the next room, and a watchable signal with some noise from across the house.
     
    badmofo, elvis and mAJORD like this.
  11. OP
    OP
    iMic

    iMic Member

    Joined:
    Feb 11, 2016
    Messages:
    163
    Location:
    Adelaide, Australia
    Made some improvements to the transmission setup. Found this RadioShack branded antenna with F-type connectors and a heavy shielded cable. It's massively improved the throw distance.

    [​IMG]


    No cables connected, the magic is entirely in the antenna.

    [​IMG] [​IMG]


    Still thinking about interesting things to do with this setup. Sending video from My 90's TV somewhat works, but the YouTube video player is visible when switching channels. Creating playlists in VLC continues to be the best option so far, but it would be nice to automate the scheduling and episode selection somehow.


    Also, the NEC N-6380 sold yesterday. I considered keeping it, but because it was a larger diameter and deep-neck tube, it was taking up a lot more space than I had available for it. Another collector and filmmaker took it, so at least it went to someone that understands its rarity and can appreciate it.
     
    Last edited: Apr 8, 2019

Share This Page

Advertisement: