[rfeenstra]

I'm working on a Sherwood S8900A that I bought cheap in the 1980's.  It was cheap because the FM hardly worked.  Lots of static when tuning, unreliable stereo when I did get a station dialed in.  That was ok at the time since all I wanted was the amplifier for use at the office.  I haven't used it in years.  This thread caused me to dig it out of the equipment archives to see what I could do with it.  The bass control is missing. I think I remember something falling on it and physically breaking the control so I bypassed it with fixed resistors at a most used bass level.  I obviously must have changed one of the filter caps at one point though I don't remember doing it.

The static occurred when the tuning dial was turned so I suspected a bad ground or cross plate contamination.  A solid blast of contact cleaner cleaned up the tuning cap and the static was gone and has worked great since.  I found the alignment WAY off so i suspect someone tried to correct the problems by twisting slugs, gave up and traded it in.  That's when I bought it.  It is now working great with excellent sensitivity, great stereo and good sound. I've ordered caps to replace the filter caps (I will re-stuff them) and e-caps for the rest of the circuitry, just to be proactive.  But I need help!

I cannot get the dial to track properly.  Using the slug in the oscillator coil, I can zero in on the low end of the dial. Using the cap, I can set the high end.  So, the two frequencies I use the most are dead on at 88.5 and 106.9.  The middle of the dial is about 500KHz off.  For 100.5, I have to tune to 100.  It bugs me and  no matter how much I diddle with the coil and trimmer, I cannot improve it.  Does anyone have suggestions?  Or, is there an instructional paper or video out there that I have not been able to find?  Thanks for any help you give!

   

[rfeenstra]

While I'm asking questions...  this thing has a zillion tantalum caps in the audio chain.  Is it worth replacing them for who knows what reason (audio quality, shorting, etc.)?

[Ron Ramirez]

I split this into its own thread. Should be a good one! Man, that S-8900A brings back memories of listening to Nashville like a local station when I was living in Kentucky back in the 1980s, using one of those roof mounted Radio Shack omnidirectional FM antennas, on my S-8900A.

It's funny, I still have the antenna but not the receiver.

I'll let others answer the tracking question and the tantalum question. I think I would replace the tantalums - and replace anything 1 uF and smaller with film caps - but others may disagree.

[rfeenstra]

Thanks, Ron.

[morzh]

Tantalum caps....they are excellent caps and would be even better if not for their MnO2 dielectric which ignites.... sometimes.
New tantalums don't have it (polymer etc).

I would replace those that decouple power. Those that are DC blocking etc, that is are not subject yo potentially high current if shorted, I'd leave be.

[rfeenstra]

I've decided to blitz the thing.  I'm mostly finished, just need to do the tone board which is mostly tantalum's.  I'll wait with that until I get a new bass control cuz things kind of needs to be disassembled, knobs and all.  It's playing again until then.  I can't hear any difference but really didn't expect to.

Sensitivity is really good on this receiver.  Stereo sounds great.  Quite pleased.  I don't really know what I'll do with it or where I'll use it, but it's kind of fun to get it going again.

Back to the original question - dial tracking.  Any ideas/experience out there?  I've gently played with tuning cap plate spacing but can't really say I've improved things.  Not quite sure where or which direction to go with that.  I just put it back to original.

[Ron Ramirez]

Do you have the factory service manual? If not, you can get it from hifiengine.com, or I can send you a copy.

I would suggest resetting the high and low oscillator adjustments to close to where they were, and then try adjusting each one a little at a time until you get the band spread out to your liking. You may never be able to get the dial to track exactly with the scale but...sometimes, "close enough" has to be good enough due to aging of components, etc.

[rfeenstra]

Yes, I have the complete manual with alignment instructions from hifiengine.  didn't help with this.  I may just have to shoot for a reasonable average and be happy.  I was able to get the EH Scott 16A and the HH Scott 350D to track very close.  I learned a lot from those, but it it didn't help with this one. I was hoping someone had a magic bend for the tuning cap that would help, but I guess not. This unit sounds better than I remember.  But then, I have much better speakers on it now.

Thanks!

[Ron Ramirez]

I really like my S-7900A. I wish I had had it back in the 1980s as I still listened to AM radio back then...WLS in Chicago was still playing music then...but no AM on the S-8900A, as you know. I did have several vintage radios then, but it would have been nice to hear WLS on my home stereo system. Oh well, those days are long gone and WLS has been a talk station for decades now.

Like you, I have better speakers now as well. Back then, I found a used pair of B-I-C Venturi towers and thought I really had something. Now, I'm running Bozak Urbans with my 7900A. Older speakers but higher quality, better sound.

[morzh]

I wish I had my Klipsches back in early 90s.
I got my 1st pair of Cornwalls locally (got lucky - the price was good) 2 years ago and loved them so much that when I saw an ad for second pair for just $500 in New Paltz (150 miles) i swiped them (the guy had two pairs). Now, starting from a month ago, they are my daily players with the second system I built.
You barely need to put any power into them for my wife yelling from the second floor (and I am in the basement) that "This is not a discotheque, turn the volume down!".
And this is when I play classics.

[rfeenstra]

If I do any serious listening, I use my DAW with Legacy amplification and speakers.  I have most of my Legacy demo stuff from back when I sold the stuff.  Most of the time now, though, I have the DAW hooked up thru the Scott LK-72-B.  Something about the glow of tubes that makes the music sound better (it doesn't really as the Legacy mono-blocks have much better dampening on the low frequencies and more precise imaging; but it's fun to use the old stuff that I built when a kid.)  I don't know where I'll use the Sherwood.  I'm using a Sansui 5000A out in the organ showroom/airplane hanger.  It does fine for what I need it for.  So, maybe I'll just have to sell one them!

WLS - I used to go to sleep at night listening to WLS (1960's). Yes, music.

[rfeenstra]

After a few hours of adjusting, bending plates on the cap, bending them back when that didn't work, tweaking some more, bending some more, and on and on, I finally got the thing to track reasonably.  Most of the dial is now no more than about 100K off, with much of it much closer or right on.  The only exception is the very lowest end of the dial where there is a jazz station I listen to at 88.5.  It's at 88.7.  Close enough!  No more bending.  No more tweaking.  It has been a frustrating experience, but the unit sounds great. So, I guess it was worth it.  Maybe it will replace the Scott 16A as the shop radio.  Then again, I would miss the glow.  The sensitivity is far better than the 16A.  Not sure it should be so maybe I'll work a bit more on the 16A.  Every time I play with the alignment on these FM units, I learn some more so maybe I can do a better job!

[Ron Ramirez]

I wouldn't worry about any slight mistracking. After all, these weren't laboratory grade instruments.