9090DB with poor FM reception

[Matt Mincer]

Hey folks,

I have a 9090DB on the bench and the FM isn't getting much reception. I do get static and can tune in one or two stations but barely and only when FM mute is off. Even when I do get a station, the tuning and signal meters barely move. I am using an FM antenna also AM seems fine. Any thoughts on what might be the problem?

Thx
Matt

 

[markd51]

I'm no wizard to say what and where to look? But I do know somebody in Chicago who's a true master at what he does and will exactly know. Kaspar at Stereo Rehab on 5800 N Western Ave.

He just went through my Marantz 2238B with a full refurb. FM was totally out. Tuner was aligned, fully lubed-cleaned, calibrated (internally) to zero on both AM/FM. Meaning 94.7 is exactly such on the Dial, and so forth.

He doesn't just fix one thing, he will go through the entire Receiver with recapping, etc, no stone unturned, he goes through a unit from one end to the other. And once he's done, the unit will have a one year warrantee.

Kaspar is one heck of a guy,and probably none better in the entire midwest. That's how good he is.
I now have comfort that my little Marantz will now probably outlive me.

No, he's not dirt cheap, but he is very fair, such work was never cheap, and such highly experienced and competent techs grow smaller by the day.
He's not the kind of guy who will tell you, "well, I never worked on a Sansui 9090 before, but I'll give it a go".
I have no doubt that he's repaired a good number of 9090's.

Sure, lot's of people get cold feet when it comes time to spend money, would rather try their hand at hacking-butchering a good unit to death, and then when there's a problem have no idea where to turn.

I'd very much doubt that after he goes though it, you'll ever again have to again open that unit back up for the next 30 years. Tubes, Solid State, no problem.

All units are assessed right in front of their owners, and they are all auditioned and inspected in house by the owner after the repair.

I like Kaspar so much, it comically crossed my mind to just start breaking some of my ****, so he could work his magic on them! LOL

I auditioned my lowly Marantz yesterday through the larger JBl Studio Monitors that are hanging in his home page photo of his listening lounge in house.

https://stereorehab.wordpress.com/

 

[dr*audio]

You can try cleaning the tuning cap per the instructions in my thread in the Tuners forum. If that doesn't work it either needs alignment or there is a part that failed. This requires specialized test equipment to go through the rf circuits and see where the gain is being lost.

 

[EastPoint]

Hey folks,

I have a 9090DB on the bench and the FM isn't getting much reception. I do get static and can tune in one or two stations but barely and only when FM mute is off. Even when I do get a station, the tuning and signal meters barely move. I am using an FM antenna also AM seems fine. Any thoughts on what might be the problem?

Thx
Matt

Check the voltage from the F-2619 tuner power supply board on the top front left. Those sometimes have issues.

 

[dr*audio]

Check the voltage from the F-2619 tuner power supply board on the top front left. Those sometimes have issues.

Good point, but I think it uses the same supply for AM, which is working ok.

 

[Tom B]

I had a Sansui of that type, touched the antenna terminal with a wire I was attempting to use as a cheap antenna. Static discharge occurred, and lost almost all FM. No real movement on strength, only worked at all with muting off. Turns out I had popped the RF Amp Fet (3SK41) in the tuner section. Replaced and it was fine after. But of course try cleaning tuner as suggested by others.

 

[markd51]

As for what I wrote above, I only of course suggested this as a last ditch option. I have no affiliation with Stereo Rehab other than being a satisfied customer.

Most certainly, and if I could in all cases, when something doesn't work, a power tool, an appliance, or other items, and if I can successfully initiate a sound repair with just a needed part, and a little time-labor, I'd surely rather do that than pay out the nose to have someone else do such. Just common economic sense.

My best advice at this point, would be to keep this thread going so it may help you correct the problem without a large cost. That you can correct this specific problem.

The one goal is to of course cause no further harm.
Do keep the fine folks here informed.

 

[Matt Mincer]

I had a Sansui of that type, touched the antenna terminal with a wire I was attempting to use as a cheap antenna. Static discharge occurred, and lost almost all FM. No real movement on strength, only worked at all with muting off. Turns out I had popped the RF Amp Fet (3SK41) in the tuner section. Replaced and it was fine after. But of course try cleaning tuner as suggested by others.

How do get at the FET in the tuner? I think that may be the problem because I can get a better signal if I put my fingers on a resistor on top of the tuner. The problem accessing it is that it's in a shielded case and removing the screws removes the entire cap.

Thx
Matt

 

[Tom B]

Not sure, but I know the whole radio section is easily removable from the chassis by removing 6 or 8 screws holding it in. While not required, removing the front panel makes it a little easier. After removing the screws, you need to unplug the 3 connectors on the equalizer board and the 2 conductor plug by the tuner (that plug was connected right? because that is the antenna input. Lifting up the radio section, you may need to unplud another connector or 2. Then the whole assembly comes out. The top cover usually pops off the tuner. Not sure if I cut out the old fet, and tack soldered a new one in, but if I did, this is not as good of a repair as doing it the right way, and dismantling whatever is necessary so that the fet can be removed and replaced from underneath. You can also check the auction side for the Tuner unit, which comes up when someone strips a 9090db