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Aiwa AD-F770 cassette deck ― channel imbalance
Aiwa AD-F770 cassette deck ― channel imbalance
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Old 1st November 2017, 04:30 PM   #1
eimis is offline eimis  Europe
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Unhappy Aiwa AD-F770 cassette deck ― channel imbalance

Good day,
This brilliant machine has a few problems and I really need some advice on where to start on it.

Left channel is slightly louder (hiss and music). It's more severe with NR enabled. Signal indicator confirms this consistently.
If I lift the cassette while it's playing as mach as the slot allows it improves somewhat, but sounds muffled.
Could this be a head alignment issue? Seller told me it was already aligned but I'm doubtful.

I did check the service manual for channel balance pots but couldn't find anything.
So before I start replacing every electrolyte capacitor in this beast or try 'fixing the symptom' some other way, what can I do to narrow down the problem, at least figure out whether it's electrical or mechanical?

It also seems like the reel motor hasn't got enough torque - has trouble spinning some cassettes. The motor had already been replaced with a different one, and local electrician told me it's likely because they're hard to source... but let's leave this for last.
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Old 1st November 2017, 04:51 PM   #2
adason is offline adason  United States
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Get perfectly recorded cassette tape from well working deck, use it in your Aiwa machine, and adjust head azimuth according to the instructions in service manual.
Typically, there is small screw right under the head. Sometimes you must remove outer door to see it. Do not lift anything!
Once you get confirmation that head is aligned, focus on electronics. There must be playback pot level for each channel inside. I had few Aiwa's in the past, but none now, so I can not look inside. Each Onkyo I have has it nicely labeled on the board.
Good luck.
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Old 1st November 2017, 05:18 PM   #3
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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See page 7 of the service manual but ensure the alignment is correct and it is not a record problem. DON'T just twiddle!
If you use the Philips test tone tape and playback the 5.125kHZ tone, you can easily check playback levels and speed.
Download the Aiwa ADF-770 manuals for free - Hifi Manuals
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Old 4th November 2017, 08:38 PM   #4
eimis is offline eimis  Europe
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Alright so it sounds like I sorted the balance problem. I recorded 10khz tone onto a cassette then played it back and tested output with voltmeter while adjusting the azimuth screw.

But the reel motor problem is still there.
There's this Cream Goodbye cassette that almost stopped 1 minute before the end of side A. Side B played fine.
I manually unwound tape from left reel (span the reel with fingers) and it played normally.
This slowdown only occurs with 2 cassettes I have (they're both NOS). I've even put those 2 tapes into new shells - same issue. Also cleaned both capstans and pinch rollers with ISO.
Maybe the tape just slips through the capstan? Some different slippery tape coating or something...I don't know much about these things.

Have you ever experienced anything like that?
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Old 4th November 2017, 09:34 PM   #5
turk 182 is offline turk 182  Canada
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i used to think the same way put the tape in another shell it will be ok....
problem is it's usually the the inner hub that the tape sits on that has the wear that causes binding...
and if the idlers and belts in your machine are as old as the model release date (1985) their likely to need replacing.

Last edited by turk 182; 4th November 2017 at 09:50 PM.
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Old 4th November 2017, 09:39 PM   #6
turk 182 is offline turk 182  Canada
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and ok you aligned the playback to the record head, now how do verify that it will align with other decks?
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Old 5th November 2017, 12:40 AM   #7
TR1TIUM is offline TR1TIUM  United States
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ADF-770 Tape deck.

There is a pair of daughter boards on the right side. As I remember about 2" X 3" this might be the HX pro boards.

There is a long line of solder connections under them, Very common for them to go bad.

Gives intermittent level and noise problems.

Great deck!
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