SX-1980 Tuner Alignment

[DaWoofer]

My dial does not match the radio frequency. Is their a rather simple procedure to match these two up without hindering or the need for further alignment procedures? I was hoping there was a 1 or 2 pot adjustment. Thanks for your insight men.

[Jon_Logan]

If it's off equally at both ends say to the right (How's AM by the way?), then just slide the pointer up or down the dial string. If it's off at one end and not the other, you need to electrically 'squeeze' (or expand) the tuning range.

basically, that's done by adjusting the front end trimmer caps. They are in parallel with the front-end's tuning 'vanes'. So, adjust the LO (Local Oscillator) coil so that the pointer is right on the low end of the dial. Then tune to a station at the top end of the dial and use the LO's trimmer cap to get that pointer position to read correctly. Oh wait, you're not done, Repeat this (you'll see the interaction) until the stations are right at the top and the bottom of the scale. Now, you're ready to peak the front end by peaking the signal strength meter adjusting the RF amp's coils for low dial stations and adjusting the RF amp's trimmer caps for the high dial stations.

It can get ugly quick. Go in with caution.

[DaWoofer]

From what I recall AM is right on. FM is right on at the low end and just gradually falls off as the freq goes up. Some thing tells me this has to be done by using a spatula type of instrument to adjust the outer vanes on the VC. Waitng for more experienced individuals with the 1980 to also to chime in before I attempt this procedure because the manual states that this receiver has no adjusting core for the FM tracking.

[Jon_Logan]

Spatula on the tuning vanes would be the extreme last ditch effort to pull them in. Look for trimmer caps in each tuned section.

You can ask for more experienced assistance, but I assure you spreading/compressing the vanes is not the way to go.

[DaWoofer]

Thanks for that insight. By the schematic it looks to have several trimmer caps. I'll have to pop the hood to take a look and see here shortly. EDIT: I've been searching past threads and I want you all to know that I will NOT nilly-willy my way around the FM section! I am just hoping that there is a SIMPLE procedure for this symtom, if not I will leave it alone, it does not really bother me. I have other pioneer's that I can play with for learning on.

[DaWoofer]

I found this post:http://www.audiokarma.org/forums/sho...ignment&page=2
Put the service manual shows no FM osc. coil, one for AM but not FM. It does show a FM DET coil but I don't think it is the same, anyone? In fact I don't think the service manual lists the parts for the front end but I guessing the trimmer caps are C1 and c17.

[DaWoofer]

I appreciate your insight Jon Logan but I don't know which is the LO on this front end. Here is a pic hoping you could point it out for me, thanks for you time, Bryan

[dr*audio]

The osc trim cap appears to be at the front right. Use a non - metallic alignment tool, or one with just a small metal blade at the tip. And just turn a tiny bit, it is very sensitive.

[Jon_Logan]

Hey DaWoofer, Dr*Audio is right about the trimmer. I looked in the service manual and you're right, Pioneer has a spatula on tuning vanes method to adjust the dial pointer position. Insane if you ask me. So, the LO coil is fixed.

My strategy would be to align AM after the FM, because the FM alignment will dictate where the dial pointer rides on the dial string.

I would try without the spatula method first.
So, you wan't to get the "width" of your tuning scale right. Using the trimmer cap that Dr*Audio mentioned, tune to a known low dial station and a known high dial station. You want the error to be the same. Not necessarily on station, but say 1/4" to the left at the bottom of the scale and 1/4" to the left at the top of the scale. When that happens, the tuning "width" is correct.

Now, slide the pointer on the dial string so it lines up correctly on a station. Check the high scale and low scale stations and confirm that the dial pointer accuracy is good.

Now you can peak the RF.

Tune to a low scale station with low signal strength and using a non-ferrous implement (Swab stick, etc) squeeze, or expand those coils in the other "boxes" of the Front end. The FM coils have just a couple of turns. Watch the signal strength meter and peak it's value. The Antenna trimmer on the left side of your Front-end picture has a core, using the correct plastic alignment tool, peak that core. The right tool is critical. Once those cores make the 'tick' sound, it's equivilent to the magic smoke being let out. ..and it's adjustability days are over. Don't adjust the can with the slotted driver adjustment. That looks like the mixer transformer or AM.

Now tune to a high scale station and peak the trimmer cacitors EXCEPT for the LO trimmer. It's already adjusted and your trying to align the RF sections to the previously adjusted LO.

After that, you'll have to align the AM to the new pointer setting. That's not hard. It's the same type of thing except the AM will have a LO coil that allows you to "move" the stations the the pointer position. Adjust AM RF coils for low scale stations and the AM trimmer caps for the high scale stations. With AM, you can peak it by listening/measuring maximum output.

The FM tuning vanes are more widely spaced and have fewer elements. That should help identify what trimmer caps are FM and which are AM.