Some TU9900 Mods worth the effort

bktheking

Gitter Done!
I got in touch with Bill Ammons who is represented on fmtunerinfo.com, he has made some PCB's for the TU9900- one replaces the stock filter on the FM IF board named SFW Narrow IF PCB , PCB's with modern DIP IC's (OPA134's) to replace the old TA-7136 SIP's and a Stereo Separation Control PCB- This PCB adds a second stereo separation control to the 9900. When the tuner is switched in the narrow IF mode, the PCB applies the proper compensation to optimize stereo separation. Typically this PCB increases stereo separation in the narrow mode by 20 dB.

Today I installed 2 of the 3, the Filter PCB and the PCB's to replace the IC's.
The installation, all said and done, was approx an hour. The results?

I've been playing the tuner for a couple of weeks now, stereo and stations tune in well but I heard artifacts behind the music- it wasn't the quietest of tuners, especially in stereo. After the upgrade the artifacts are GONE and stereo comes in crystal clear now. I emailed Bill today with my comments and results, he also replied with the same results:

I have a TU-9900 in for an upgrade. The narrow IF measured just over 3% in the narrow IF mode. With the new PCB and filters in place, the distortion has dropped down to 0.18%.

These numbers are HUGE which also solidifies my findings, distortion with the TU9900 in stock form is audible.

Shot of the stock filter:

2q0ltzq.jpg


Shot of the PCB with new filters installed:

2eeiz6a.jpg
 
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Here's a shot of the stock board with the TA's installed.

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Here's a shot with the components removed- 10 components made up of resistors and caps are removed- 4 caps are jumpered instead. This removes quite a few components from the signal path.

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Final pic with the PCB's installed with the new ic's.

a3fbpg.jpg


I will update when I do the full resto which will include the stereo separation PCB.
 
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All said and done it for 3 mods it was $72 shipped to my door.

TA-7136 to DIP PCB: $5.95 each (two needed)

SFW PCB w/ matched filters $21.95

Stereo Separation Control PCB $22.95 (haven't done yet)

single channel Op Amps $4.00 each
 
Glad you like your TU-9900. Also, Bill Ammons is a very nice gentleman to work with. He installed filter boards and fully aligned my Kenwood KT-7500 and KT-8300 as the last step in a series of major mods to both. Very happy with his work on both of these.

I think you'll be very pleased with that TU-9900. Currently my Mike Williams modded TU-9900 is the best sounding tuner in my collection. Mike did major cap and PS upgrades as well as doing BB 2134 op-amp board replacement among other items. My TU-9900 just sounds beautiful on a good FM station (I'm blessed with several in my area).

My TU-9900 has some stiff competition. At #2, I have a Joseph Chow fully modded Accuphase T100. In 3rd place is my own heavily modded HK Citation 18.

Remember, you can never get enough good sounding FM tuners!
 
On tuners where I have done most of the upgrade work, I always like to have one of the pro's do a complete alignment since I have none of the specialized equipment (nor training) to do this. The one exception was the aforementioned Citation 18. That tuner has not been professionally aligned,..., yet. I would bet a week's pay that it could really benefit from one. For one thing, the center tuning light is sometimes tough to get it to lock and stay on. This is almost certainly an alignment issue. It will lock but I have to make some fine adjustments with the tuning knob. It's scary really how good it sounds with no alignment. It does sound superb and I know a good alignment will only help it.

I have used others like Mike Williams (Nikko Gamma V) and Joseph Chow and Terry DeWick (Mc MR74, Sony ST-J88B, Sherwood S3000V/2200) to fix/mod tuners when I don't want to tackle a particular tuner.

On the TU-9900, I'm not sure of all the mods Mike did to it. You see, I picked this tuner up off the 'Bay from a guy who had Mike do this work. I saw the caps he replaced in the audio/MPX/PS sections and the new opamp board to know that there were extensive mods made. The sound quality also bears this out. I replaced the RCA's on the fixed/variable outputs and redid the caps on the dolby(?) fixed output section so that the pre-emphasis was correct. But that was all I did. For one thing, I don't think I could have improved on what Mike had already done and I didn't want to mess with anything that could affect the alignment anywhere, since again, Mike did a great job there (from what my ears tell me). I also have a Mike Williams modified Pioneer TX-9500II that is the same story as the TU-9900, except that I haven't touched a thing on that tuner. It's also a very good sounding/performing tuner.
 
The two mods I just did DO NOT require any type of alignment after install. The stereo separation mod will and I should be able to do it myself.
 
Did you end up doing the stereo separation mod? And as a someone just getting into tuners, I would love to hear how the alignment process went.
 
I'm halfway through moding my 9900. I rebuilt the power supply. I changed a bunch of resistors and jumped a few per bill ammonds instructions on TIC. I have all the caps but somewhere along the line I lost the left channel in fm. both channels work in am and when the calibration tone is pushed it sounds on both channels. Im ready to recap but obviously want to get this channel working first. I'm guessing my problem is on the mpx board but I went over it real well and everything looks great. Can someone confirm the mpx board holds my problem with my symptoms? Any help would be awesome.
 
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Did Bill do anything such as a post-detection filter to remove HD hash? That's the bane of my otherwise terrific 9900.
 
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