Sanyo M9994 FM tuner pointer alignment.

[Matrixambience]

Hi Sanyo owners/ admirers. I just purchased a 1979 Sanyo M9994 boombox. Just got the tape deck all back and running perfect with new belts (4), cleaning, lube, and speed increase adjusted on motor in deck. The AM tuner is fine and aligned with pointer/ broadcasts on scale, but FM portion is off across the whole scale from 88 up to 108.
It picks up all the stations fine with stereo light coming on in super strong FM local stations but it off all the pretty much equally up scale. Example: 88.5FM is broadcast at pointer pointing at 90 on scale, 96.1 FM at 98 on scale, 105.7FM at 108. The pointer cannot and didn't move on string. It has a small amount of glue on it, and reference point at beginning of scale below 88 the pointer lines up perfect. The service manual stated that is a reference point for tuner pointer to start. I suppose an alignment is in order for tuner? RF alignment? Please assist. Love this lone Sanyo among my full collection Of Panasonic and one JVC M70 boomboxes. Thanks!

 

[Superduper]

You need to set FM band coverage, which is a tedious back and forth adjustment. Typically, you’ll need an FM signal generator and set it to output a modulated output at one end of the bandwidth (88mhz), tune radio to same frequency (88mhz; you may already hear tone if close), then perform adjustments at set points prescribed in service manual to strongest output (you’ll hear a tone, usually 1khz through boombox speakers), then set generator to output at other end of bandwidth (108mhz), and turn tuner dial to same frequency as generator (at this point you might not even hear tone if adjustment is far off), perform the prescribed adjustment until you hear strong tone through speakers. Even though tuner receive frequencies were adjusted at both end of dial, each adjustment affects the prior to some extent, so this process is repeated several times. You’ll need the service manual and an FM signal generator to perform this adjustment, which is a bummer. On the other hand, the process is pretty straightforward and clearly described in the manual and this adjustment is probably the easiest of the tuner adjustment procedures if you have the tools. Although actual alignment of the tuner front end is also described, I do not recommend you try that however, as it’s a much more involved and difficult repair and if you mess it up, you’ll never get it to tune right again.

 

[BoomboxLover48]

Check if the gang condenser large wheel pulley moves and makes all the way, when you turn the tuning knob all the way. There must be 4 or 6 turns on the tuning knob axle with the cord. They are wound next to each turn on the tuning knob axle. If somehow the cord winds one over the other, the tension increases and the springs at the gang flywheel will stretch more and this misalignment at the upper readings might happen. Take a good look at how the cord is run on the pulleys also. Somewhere in the cord path it is jumping over a turn or catching the pulley and somehow causing this issue.
~Royce

 

[Matrixambience]

Thanks you guys! I don't have any kind of equipment to do anything like Superduper stated. He brought up the points perfectly. That's the electrical side that's beyond me because I have no equipment to do it. I find it so interesting though! I do have the service manual. I am confused as to which antenna lead goes to which point on board. The blue and yellow lead wires from dual antennas. I may have those switched after I buttoned unit up after cassette deck restoration.
TP1 and TP2 lead points on board, one is hot, one is ground. Which wire goes where?? The service manual doesn't show that info.
Boombox lover: you know?? You brought up a good point! On the mechanical end of this issue, I did notice as I turned the dial and watched tuner string do its thing, everything works smoothly everywhere except one little place...... exactly at the point on spool where tuning wire wraps around initial post at tuning dial cog, it actually crosses over and makes a slight "ping" sound and the wire overrides part of the wire underside. Didn't know if that was a factory thing or a mishap of 40 years of usage/ non usage.you think that knocked it off kilter??

 

[BoomboxLover48]

Thanks you guys! I don't have any kind of equipment to do anything like Superduper stated. He brought up the points perfectly. That's the electrical side that's beyond me because I have no equipment to do it. I find it so interesting though! I do have the service manual. I am confused as to which antenna lead goes to which point on board. The blue and yellow lead wires from dual antennas. I may have those switched after I buttoned unit up after cassette deck restoration.
TP1 and TP2 lead points on board, one is hot, one is ground. Which wire goes where?? The service manual doesn't show that info.
Boombox lover: you know?? You brought up a good point! On the mechanical end of this issue, I did notice as I turned the dial and watched tuner string do its thing, everything works smoothly everywhere except one little place...... exactly at the point on spool where tuning wire wraps around initial post at tuning dial cog, it actually crosses over and makes a slight "ping" sound and the wire overrides part of the wire underside. Didn't know if that was a factory thing or a mishap of 40 years of usage/ non usage.you think that knocked it off kilter??

Boombox lover: you know?? You brought up a good point! On the mechanical end of this issue, I did notice as I turned the dial and watched tuner string do its thing, everything works smoothly everywhere except one little place...... exactly at the point on spool where tuning wire wraps around initial post at tuning dial cog, it actually crosses over and makes a slight "ping" sound and the wire overrides part of the wire underside. Didn't know if that was a factory thing or a mishap of 40 years of usage/ non usage.you think that knocked it off kilter??

All it takes is a little flex in the cord to do the variation. From my experience that is all can do a slight variation on the higher end of the scale. I have re-corded so many complex boxes re-cording including GF777 and Rising 2020 and all, plus a lot of tube radios dials and all. It all looks simple but we have to be more detail oriented. I am glad you could follow my suggestions well.



~Royce

 

[Matrixambience]

Thanks Royce. I took off back cover of radio again, and really studied the cord routing, and gearsets and tuner cap, and I looked at my service manual, and it is correct in routing, and how many times it wraps around shaft at tuner knob correctly. Yes, still one point when dial knob is turning, the cord kinda slip over the cord that's already wound on spool. It doesn't catch or anything, just normal mechanics of cord wrapping and overlapping on takeup spool.
Now , I am leaning towards a true pointer alignment with electronic FM equipment. I guess I will try to find someone that can do this, as I cannot. I like the radio to be correct. I do listen to FM still, and have some great stations in my area.

 

[BoomboxLover48]

Yes, still one point when dial knob is turning, the cord kinda slip over the cord that's already wound on spool.

That winding over the cord will reduce the total length in between the dial pointer and the part where it slipped and wound over.

Something is not adding up right.

All pulleys in it's path will not make a full round on it. Only on the tuning dial axle it will make a few turns on it for better grip and traction, and that even will not make one over the other, will be adjacent.

~Royce

 

[Superduper]

Royce, none of the symptoms you speak of will cause the dial indicator to read incorrect which is what OP is wanting to fix. It’s not uncommon for the slight catch he speaks of, especially on older tuners where the slick exterior of cord has worn to a rougher texture. Most people automatically assume an incorrect tuner needle position is a mechanical problem, instead it’s almost always a case where the tuner bandwidth tracking is off due to aging & worn components that have drifted slightly in value. The phrase eluded me earlier but I think the adjustment is called FM tracking, which is the adjustment to the circuitry that ensures the dial accurately tracks tuned frequencies. Only on molested boomboxes where someone removes a needle and repositions it would it be off. In all other cases, it’s a circuitry adjustment issue.

 

[BoomboxLover48]

Royce, none of the symptoms you speak of will cause the dial indicator to read incorrect which is what OP is wanting to fix. It’s not uncommon for the slight catch he speaks of, especially on older tuners where the slick exterior of cord has worn to a rougher texture. Most people automatically assume an incorrect tuner needle position is a mechanical problem, instead it’s almost always a case where the tuner bandwidth tracking is off due to aging & worn components that have drifted slightly in value. The phrase eluded me earlier but I think the adjustment is called FM tracking, which is the adjustment to the circuitry that ensures the dial accurately tracks tuned frequencies. Only on molested boomboxes where someone removes a needle and repositions it would it be off. In all other cases, it’s a circuitry adjustment issue.

Okay Norm! Great information!

I thought for some reason if the length in between the dial pointer and the gang flywheel gets wound pulling the tension spring, that will pull the spring and cause this issue!

~Royce

 

[Matrixambience]

Thanks to you two for helping me on this issue with Sanyo. I'm now trying to find a local guru who is still capable and has the equipment to do this lost art of aligning FM stereo tuners. I now realize that my tuner cord is basically fine because in service manual they state that dial pointer is set at indicator mark just left of the lowest number on fm scale, which is 88. It is currently lined right up to reference point perfect.
I would love to send it to Superduper for tuner alignment but I think your way across country. Not feasible really with shipping and potential for damage with carriers. These radios are getting more rare!
Superduper, can you still help me with which wire lead goes to antenna leads in board? I'm confused as to what factory has it. Blue and yellow wires go to TP1 and TP2, one hot, one ground. Does blue go to hot, yellow to ground, or vise versa? The service manual shows I may have it wrong by schematics, but they mention color of wires. You think you may know what goes where? Thanks.

 

[hopey]

if you have the service manual it's just a mater of adjusting trimpots on the tunner board with a screw driver, very easy. You can do it by finding a station at bottom scale then left or right turn of trim pot will move it up or down on the register.

 

[jimmyjimmy19702010]

if you have the service manual it's just a mater of adjusting trimpots on the tunner board with a screw driver, very easy. You can do it by finding a station at bottom scale then left or right turn of trim pot will move it up or down on the register.

Please ignore this ‘advice’. Tuners are a specialist only area of Boombox restoration. Leave tuner work to those who possess both the expertise and the necessary equipment.

 

[BoomboxLover48]

if you have the service manual it's just a mater of adjusting trimpots on the tunner board with a screw driver, very easy. You can do it by finding a station at bottom scale then left or right turn of trim pot will move it up or down on the register.

Please ignore this ‘advice’. Tuners are a specialist only area of Boombox restoration. Leave tuner work to those who possess both the expertise and the necessary equipment.

That is correct! Don't bring anything close to the trimmer adjustments unless you are a pro and know what you are doing. Even by flexing any components in the tuner area can mess up the whole thing. Don't even touch that area.

 

[Superduper]

I thought for some reason if the length in between the dial pointer and the gang flywheel gets wound pulling the tension spring, that will pull the spring and cause this issue!


~Royce

Royce, MA said that the tuner needle parks at 88mhz. That means mechanically, the tuner dial needle is correct. The tension spring only really supplies tension at around the area of the drum to prevent slippage at the tuning wheel/drum. The rest of the cord routing doesn't take hardly any effort to traverse unless the cord slips off one of the pulleys or if a pulley gets cocked. If you want to do a test, you can pull on the cord somewhere along the path away from the drum and I think you won't be able to affect the spring at all with 4 turns around that pulley. In fact, you'd likely snap the cord before the spring stretches. In any event, MA says dial is anywhere from 1.5 ~ 2 MHz off. That's a significant distance that can't be accounted for by the spring theory. Although a tuner that needs adjustment is never a desirable thing (and the reason to trying to find any cause "other than" circuitry adjustment), in this particular case, it's time to face the music. Good thing is that this is a service that any tech with a FM signal generator should be able to do with assistance of service manual.

 

[Matrixambience]

Appreciate the advice and help I'm receiving from this post I started. Superduper is dead nuts on with all he stated. I downloaded the service manual for the M9994 from service manuals.net. It. Was like 16 bucks and they take PayPal. I was very curious firsthand with belt routing, tuning cord routing, and just overall knowledge of this killer beast! I absolutely love this professional device. This is not a boombox. I can see this radio being bought by a doctor, dentist, lawyer, and professional recording studios and pro bands back in 1979/80. I was 13 in 1979, and there was no way I could have afforded one of these new. I have no idea what they MSRP'ed at back in the day, but I'm sure it was over $300.00. That's a lot of money in 1979. I know it's a '79 because of build date code states February 1979, and on motor of cassette player states same.
I did not touch a thing on tuner board anywhere! That's a no no! I found a great place to take it near Baltimore,MD.. Just Audio Vintage Electronic Repairs. I chatted with someone and described problem, and they are truly confident they can bring tuner back to factory alignment and are very happy I have the service manual to it. It's a 50-60 mile drive so I can make it a nice day trip. I will keep you informed of progress then. The tape deck works super awesome thanks to my sweating and swearing over it. I think the person was majorly surprised of what they are asking for these radios, since she asked model number over phone, I told her, there was silence, then a gasp......$2500.00 for one on ebay.! I said I know....I'm watching that auction! Lol! Really?! Whatever! I paid way lower than that, but still more than most in my collection. Stay tuned guys!

 

[Superduper]

Superduper, can you still help me with which wire lead goes to antenna leads in board? I'm confused as to what factory has it. Blue and yellow wires go to TP1 and TP2, one hot, one ground. Does blue go to hot, yellow to ground, or vise versa? The service manual shows I may have it wrong by schematics, but they mention color of wires. You think you may know what goes where? Thanks.

Functionally, it really doesn't matter which antenna goes to which TP connection. They are essentially mirrors of each other. It would be like does the boombox receive better if it was facing you, or would it sound better if rotated 180* and the backside was facing you. If you don't believe, you can swap those wires and see if it makes an difference. I think not unless the antenna rods were pointed differently. Of course it's likely not as loud or crisp if you were looking at it's butt, compared to the face but the tuner would perform the same. However, this isn't always the case with every dual antenna type of system if you get those wires mixed up since on some systems, the circuitry between the tuner board and antenna tip isn't necessarily symmetrical, so getting the wrong wires plugged in might make a difference.

 

[Matrixambience]

Thanks! According to the service manual, I am did install wires correctly. Blue on left, yellow on right looking at radio board tuner from back with cover removed.

 

[hopey]

if you have the service manual it's just a mater of adjusting trimpots on the tunner board with a screw driver, very easy. You can do it by finding a station at bottom scale then left or right turn of trim pot will move it up or down on the register.

Please ignore this ‘advice’. Tuners are a specialist only area of Boombox restoration. Leave tuner work to those who possess both the expertise and the necessary equipment.

That is correct! Don't bring anything close to the trimmer adjustments unless you are a pro and know what you are doing. Even by flexing any components in the tuner area can mess up the whole thing. Don't even touch that area.




Thats not my experience done it many times before last on Pioneer sk757