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Old 08-09-2011, 07:18 AM
AnalogueInQatar AnalogueInQatar is offline
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First stages of Aiwa AD F800 alignment. Help needed.

Hi all,
Arrived back in Qatar last night with an Aiwa AD F800 from ebay and immediately started messing around, trying to play my 18 year old AD F910 recordings on it.

Belts are useable for now, but I've got spares which I'll use soon, once I'm more confident on this tech stuff.

Output on the VU is always 3db down on right channel, even on its own recordings (see note 3).

Wanted to try to learn more about deck alignment so here we go, the story so far. Please consider that until last year, I was too scared to open a hifi component, now I'm keen to master them. With help, of course.

Here's the checklist from the service manual:

1. Tape Speed adjustment: Done roughly with a tone from the school's studio machine. Will do properly in future, but it appeared 'dead on' at 3000hz.

2. Azimuth adjustment: Used a tone generator to give input at 10khz, the tape output fed into AudioTester scope. Adjusted until diagonal line was apparent.
Checked, up to 16 khz; the line wobbled a bit here and above this frequency but it was obviously still in phase.

I am concerned that I could be in phase here, but out of azimuth by going back/forward a full 360 degrees. There really wasn't much play in the screw which made me feel better, and I actually took it out of the hole at one stage by trying to turn it too much (took me 2 hrs to get it back in today and sealed)

Do the high frequency readings mean this is unlikely? Would an azimuth alignment tape make this easier?

3. Playback Sensitivity adjustment: I NEED TO USE A LEVEL TAPE TTS-200 at the dolby mark and output 640mV. I think I need a particular tape of Alex's here. I'll P.M. you, mate.

Incidentally, the output of all my old recordings was down by about 3db. on the right channel, even shop-bought ones, at all stages of azimuth adjustment so I tweaked the right channel Playback Sensitivity variable resistor to match them. Now, this needs checking properly, but first signs are that it is tracking my old Dolby B recordings perfectly so maybe, this did need adjusting and I haven't simply compensated for something else being out.

4. Playback frequency response check: Here I need to compare 1khz tone with 10khz tone. NOT DONE THIS YET.

5.Bias Osc. frequency adjustment: NOT DONE THIS YET. A little bit too far, as yet, for my knowledge.

6. Erase Head Hight Adjust: NOT DONE THIS YET. Don't think I'll touch this one

7.Bias trap coil adjustment: NOT DONE THIS YET. Won't be touching it either! Sounds a bit over my head!

8. MPX filter adjustment: Don't use the filter so I'll leave this one!

9. Record/Playback frequency response adjustment: NOT DONE THIS YET! Need to Input 1khz and 10khz and match output.

10. Record Sensitivity adjustment: NOT DONE THIS YET!

As you can see, I've done 1, sort of done 2 and potentially messed around with 3.
All I really require is to be able to share Dolby B/C recordings perfectly with my AD F800, 810 and 910.

Of the other seven checks/adjustments, which really need doing and which can I really ignore?

Oh, and Finally, the record level knob needs switch cleaning as it is scratching and intermittent on left channel at low values. Does anyone know how I get at it? It is hidden behind the face PCB and I'm not really ready to remove it yet. I'm not that good! Can I access the pot from somewhere else?

Once again, thanks for your generous help. I'm late to all this electronics stuff, but keen to learn and to share my experiences with anyone who will listen/help.

I'll start the youtube posts within the next month, tracking my all analogue project.

Cheers and a big thank you in advance,

Dave.
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Old 08-09-2011, 07:46 AM
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Skywavebe Skywavebe is online now
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Join Date: Jul 2008
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Hi Dave,
You have to follow service manual procedures and correct methods to do these jobs right. You did OK with the speed adjustment BUT as soon as I saw what you did in step two, well that has me stopped there as all other calibrations depend on that being to a standard which from an external oscillator is not one. When you moved the head screw much less take it out without an alignment tape in good condition you forever made the deck out of specs and out of standard with the rest of the World. The alignment tape must be used for azimuth alignment with a peak amplitude also detected on the scope. All other tests and adjustments can be discarded until this condition is met.
As I tell other about working on their own decks- many of them have adjusted head screws using FM noise or to make it sound better- they were FAR off the mark as far as standards go. Many heads I see are so far off as to look crooked in their mounts when they are done adjusting the deck to optimum. In other words, until you have all the right equipment, don't think you are going to be able to do the job. People with 30 years experience would not even try it- you need the right stuff!
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