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Marantz 2270 Tuner problem

B

BurntMaple

New Member
GoodDay AK. I was a newbie in '21 but lost my ToastedMaple ID. Staying in the theme!
I am looking to re-cap electrolytics in FM boards on my 2270: P200 FM IF Amp, P300 MPX Stereo Decoding Amp, P500 FM Detector and P550 Muting Amp.
I've cleaned FM Tuning Cap following AK sticky; I can tune to centre at 3/5 signal strength across the dial and get clear signal, then signal jumps 0.5 MHz (guess) and I have to tune to the new offset. Hoping that problem may be electrolytis caps. Trimming caps haven't been touched/adjusted. Is is this a worthwhile effort? If so, does anyone have a link to a parts list for the caps on these boards? Searched AK and HF Engine, no luck. Thank you in advance.
 
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BurntMaple said:
Hoping that problem may be electrolytis caps.
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I'd say that's extremely unlikely. The problem pretty much has to be in the FM front end, and I don't think there are any electrolytics in that.

If you're confident that it's not the tuning capacitor, then I'd suggest looking for some other mechanical sensitivity, like a flaky solder joint. Using something like a chopstick to tap on things in the FM front end assembly might be revealing.

Welcome back!
 
chazix said:
I'd say that's extremely unlikely. The problem pretty much has to be in the FM front end, and I don't think there are any electrolytics in that.

If you're confident that it's not the tuning capacitor, then I'd suggest looking for some other mechanical sensitivity, like a flaky solder joint. Using something like a chopstick to tap on things in the FM front end assembly might be revealing.

Welcome back!
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Thanks Chazix (on both counts). I did some tapping on the tuning cap and the trimmers (5 variable capacitors in front of the FM tuner.) No luck. I wonder if an alignment may be needed.
 
BurntMaple said:
I wonder if an alignment may be needed.
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I don't think that will solve the problem, but going through the procedure often helps to diagnose the problem.

With these symptoms, I'm surprised that there's no mechanical sensitivity. I guess the next straw that I'd clutch at would be freeze spray. If you try that, be aware that temperature changes will throw off tuning by itself - hopefully not by as much as whatever the real problem is.

It's possible that some other AKer has run into something similar, and the thread might be more eye-catching in the Marantz-specific forum. If you want to move the thread there, I think you can click "Report" on your first post and, in the pop-up, ask a moderator to move the thread. Can probably change the title for you, too.

(Obligatory pro-AK pitch: if you become a subscriber, I believe you can edit titles yourself. Another major benefit is being able to post ads in the subscriber-only "Bartertown" forums.)
 
I bet the dial pointer is no longer mechanically centered. Most likely it goes off the end of the log scale on the left and not all the way to the right. I have had luck popping the dial cord carefully off of the pulley where the dial cord comes off the tuner drum to the top right - the first pulley it hits to the right. I first mark the dial cord with a red felt pen (color is your choice!) where it loops through the spring on the front of the dial pointer. You have to figure out which way the dial cord needs to be slipped to make it travel evenly and move the cord. Just don't let the cord unspool from the tuner drum wheel!
 
Hey rBuckner, good morning. I think that you meant this for the other guy with 2270 tuner problems. You're right though, this will reduce tension to let the cord slip on the drum. vr/dgc
 
BurntMaple said:
Hey rBuckner, good morning. I think that you meant this for the other guy with 2270 tuner problems. You're right though, this will reduce tension to let the cord slip on the drum. vr/dgc
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Oh sorry, I meant it for you but I sure didn't read it right. I thought it was stuck off freq. and you said it's jumping around. Try a small amount of light oil or DeOxitD5 on the tuner air cap bearing points. Where the shaft that the fins are on got through the bulkheads/sections. Careful with the DeOxit, even spray it into a small cup and use a needle or the like to transfer the liquid. Overspray can detune the works to a degree for a few days until the carrier liquid all evaporates. Other than that I'd guess it's in the local oscillator section, based on transistor H103.
 
BurntMaple said:
Thanks again Chazix. Have never tried freeze spray. Will investigate.
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Well, Ive put the 2270 back in service with much better reception than before. I think the cleaning helped, deviation that I mentioned before is not as severe. Thanks for your help/
rBuckner said:
Oh sorry, I meant it for you but I sure didn't read it right. I thought it was stuck off freq. and you said it's jumping around. Try a small amount of light oil or DeOxitD5 on the tuner air cap bearing points. Where the shaft that the fins are on got through the bulkheads/sections. Careful with the DeOxit, even spray it into a small cup and use a needle or the like to transfer the liquid. Overspray can detune the works to a degree for a few days until the carrier liquid all evaporates. Other than that I'd guess it's in the local oscillator section, based on transistor H103.
Click to expand...
Well thank you! I did have to adjust my pointer previously and basically followed your procedure but empirically! I'll check out the local oscillator!
 
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