Sansui 9090db tuner in Sansui 9090

Discussion in 'Exclusively Sansui' started by elt93, May 29, 2014.

  1. elt93

    elt93 New Member

    Messages:
    31
    Location:
    Goa, India
    Hi everyone! i have a Sansui 9090 with a screwed up tuner... would there be any issues if i dropped in the full tuner assembly of a 9090db??? are there any differences in the tuner sections of the 9090 and 9090db??? :scratch2:
     

     

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  2. rcs16

    rcs16 Super Member

    Messages:
    3,631
    Location:
    Baldwin, Ontario, Canada
    Download the service manuals for both and see what the differences are!!
    I recall the DB models are for the FM Dolby processor which is redundant these days.
    Both use F-2549 FM IF/AM pcb so it should be doable but is it the AM/FM front ends as the problem or the F-2549 FM IF/AM pcb?
    Bit of work to verify the exact differences!!

    Good luck
    Rick
     
  3. LBPete

    LBPete Rolling Along Subscriber

    Messages:
    11,318
    Location:
    Long Beach, CA
    The Dolby processor is not in the tuner. It's on a separate board. The tuner assemblies are very similar but I've never looked to see if all the connectors are the same. For what it's worth, the 9090 has a better tuner than the 9090DB.

    - Pete
     
  4. audiobee

    audiobee Active Member

    Messages:
    175
    your first big hurdle.. the connectors are not the same.
     
  5. elt93

    elt93 New Member

    Messages:
    31
    Location:
    Goa, India
    Thanks for the replies... I guess I'll stick to the stock tuner itself??? it drifts very badly... to make matters worse, theres is nobody within 600km of me who will align it and bring it up back to specs.. :no:
    anything i can do to even slightly improve the reception?? i use a long piece of copper wire with which my sansui tu9500 picks stations with ease
     
  6. vigman

    vigman SUBSCRIBER

    Messages:
    4,015
    Location:
    Valencia CA
    If memory serves, wasn't there an issue with a power supply regulator on these… If the voltage drifts, so does the tuner….
     

     

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  7. dr*audio

    dr*audio Fish fingers and custard!

    Messages:
    18,548
    Location:
    Cleveland, Ohio
    Resolder all the connections on the regulator board to the front left.
    Clean the tuner. Instructions are in the Tuners section.
     
  8. DougBrewster

    DougBrewster AK Subscriber Subscriber

    Messages:
    475
    RF power supply drift

    I can vouch for the comment above about 12V drift on the power supply causing the tuner to drift off. I've had it on an 8080DB and a 9090DB..

    FWIW
     
  9. elt93

    elt93 New Member

    Messages:
    31
    Location:
    Goa, India
    So I tried going in to give it a clean but the varicap assembly is shielded... How do I get inside it? The power supply will be checked after I finish the cleaning part..
     
  10. dr*audio

    dr*audio Fish fingers and custard!

    Messages:
    18,548
    Location:
    Cleveland, Ohio
    Use a non residue cleaner and inject it into the tuner through any opening, aimed at the shaft through the center, as many places along the shaft as possible, then work the tuner back anf forth across its entire range 30 times. Allow to dry completely and see if it fixed it.
     
  11. audiobee

    audiobee Active Member

    Messages:
    175
    no.. you are doing it in reverve..

    - check the tuner supply first.. then clean the varicap..

    DO NOT disassemble the varicap assembly.. it is very difficult to assemble it back. you will be sorry.
     

     

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  12. elt93

    elt93 New Member

    Messages:
    31
    Location:
    Goa, India
    Got that... Since I'm not an expert I'll get a friend to help me out and check the tuner supply tomorrow morning... Its 10.30pm here :boring:
     
  13. tnsilver

    tnsilver AK Subscriber Subscriber

    Messages:
    3,323
    Location:
    Boston
    I know this is an old thread but I've dug it up a few times this week as I've been busy transplanting a 9090DB tuner PCB into a regular 9090.
    The stock tuner PCB was shot and botched with trails lifting, missing pads, epoxy gluing and too many jumper bypasses. I had a spare 9090DB
    tuner PCB which I saved for a case like this. The good news is, it's doable and I thought I might share, so here's some pointers...

    First of all, the 9090 none DB has the daughter piggy back F2550 Multi-Path PCB riding on it so it's infrastructure needs to installed:
    Second, the 9090DB tuner doesn't distinguish between FM Auto and Dolby FM as everything is routed to the dolbey board. The none DB version
    has two different FM outputs, "auto" and "dolby". Third, there's a whole bunch of ceramic caps and resistors in the AM section of the 9090DB tuner that are
    not the same as the 9090 none DB. I'm not sure how critical these are, but I've swapped them to match the 9090 SM.

    Here's a 9090DB tuner and the missing connection posts that come down the MPX daughter PCB are marked in yellow

    [​IMG]

    To adjust this board to the 9090 none DB version, I've done the following:

    [​IMG]

    1. installed the MPX PCB Molex footer
    2. installed the three posts
    3. added resistor R98 (3.3KΩ)
    4. installed Germanium diodes D05/D06
    5. replaced the 0.0022µF ceramic cap (red 'X') with 0.022µF and re-oriented it (like plus to minus instead of diagonal)
    6. Resistor (R83 3.9KΩ was different on the 9090DB tuner)
    7. Possibly matched some ceramic caps in the yellow square near the AM tuner IC, as per the 9090 SM (sorry, I don't remember all of it by heart and didn't take notes on this one)
    8. Replaced AM tuner HA1197 with HA1152 (the HA1197 still works after the transplant though)
    The transplanted tuner conductor side now looks like this:

    [​IMG]

    The component side, like this:

    [​IMG]

    During the transplant I had great AM reception but the FM was dead. Based on the trouble shooting guide I've checked TR-01~TR03, and the TO01/02 inductors,
    I then continued to check the coils, transistors and FET on the front pack. I used the opportunity to give it a complete IPA bath and scrub. Notice how dirty the thing was (it's not water):

    [​IMG]

    After the rinse, I could recap some of the smaller values ceramic caps with MLCC's and verify the values of the other CC's. Interestingly, none of the 0.022µF
    CC's kept their values. They all drifted up to 0.03uF and higher, way over their tolerance. I replaced them with good 0.022µF caps.

    [​IMG]

    The variable capacitor was cleaned too and the shaft gear greased:

    [​IMG]

    Opening the dang thing was nearly impossible with my 15watt iron. I think they used led instead of solder. In the process I damaged some of the ground trace on the PCB
    and I had to fix it later to create good solder anchors to the case.

    [​IMG]

    Now it's all cleaned up and looks like this:

    [​IMG]

    The transplant worked although I'm still debugging an issue. I get very good AM reception and very good FM reception. My stereo indicator lamp is missing, but my DMM shows the voltage out of TR09 in stereo mode. The only dang problem is my FM auto and FM dolby output is so low, I need to crank up the volume to max in order to hear it. My AM tuner works fine so if I'm not careful and switch to AM from FM, I get the full might of the 9090 through my bench speakers. Not cool! Luckily my DBT saved those speakers. I'm still working on it but I'm pretty sure I messed some connection in the tone control boards. I temporarily hacked this (power supply issue) and got FM, but it ain't totally right yet. I may need your guys help later on with this. Thanks for reading.
     
  14. LBPete

    LBPete Rolling Along Subscriber

    Messages:
    11,318
    Location:
    Long Beach, CA
    Nice! Great information. Thanks.

    - Pete
     
  15. tnsilver

    tnsilver AK Subscriber Subscriber

    Messages:
    3,323
    Location:
    Boston
    My 9090DB tuner in the 9090 unit is now complete and perfect. To add the finishes touch to my transplant, I had to take a look at the Hitachi HA1196 test circuit in the IC specs. It appears Sansui did not follow it to the letter and had performed modifications in capacitors values and locations, but that was way above my pay grade and I could not second guess them. So I had compared both of my units and found the differences that allowed me to finish the job and they are with capacitance values with EC's and a Tant cap coupling some pins on the HA1196. Notice the C46,C47,C48 to the right of the IC:

    Sansui 9090DB version:

    [​IMG]

    Sansui 9090 (none DB):

    [​IMG]

    My recapped 9090DB tuner in my 9090 none DB unit:

    [​IMG]

    In addition, I have found my stock 9090 tuner FM low pass filter was suspect shot. I have tested it with an LCR meter and it appeared either one of the coils is open, or the total has a much lower inductance than the 9090DB LPF. I will debug this some time in the future b/c I've used the 9090DB LPF and everything seems fine, yet, I found some more differences (not sure how real they are) I wanted you guys to see:

    [​IMG]

    [​IMG]

    My tuner is now perfect and the transplant a success. The front pack (9090 none DB) needed no tuning, but some of it's out of specs low value ceramic caps were recapped.

    EDIT: The LPF Sansui part number is different in the 9090 vs. 9090DB manual. I'm not sure how real the differences are. It appears the 9090DB's LPF is a newer run...
    I might delve into this in the future, but I lost the incentive once everything worked.
     
    Last edited: Apr 14, 2018
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  16. Overundr1

    Overundr1 AK Subscriber Subscriber

    Messages:
    2,478
    Location:
    Mississippi
    Wow :eek2:, and I thought doing a G9000 tuner transplant was fussy. Outstanding
     
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