Conion C-100f - No FM Stereo Light

[beverlyjean2]

A[ popular problem I hear second only to tape deck 1 not playing is the FM radio not playing in stereo,,,, mono is fine but the Green light refuses to Glow. Here is a tip to solving the problem On the tuner board there is a surface mount trim-pot Its location is VR002 It's value is 5k OIhMs you'll find it towards the right front of the pc board...if you measure across and find meg OhMs it is open and should be replaced. it's tricky to get to the bottom of the board and you may not want to mess with the dial cord and pullys or remove the chassis from its cabinet...so you can mount a new control from the top by carefully clipping old control from board leaving the metal tabs....then you can solder a new one carefully to the metal tabs that remain. Don't use too much heat or you'll melt the solder beneath the board. I suggest this short cut method of replacement b/c sometimes that dial pulley can get away from you and the sting becomes unraveled and turns into an all day affair for some. If you feel confident that you won't let the pulley get away from you then you can remove the tuner board and replace the pot in the conventional manner. i always recommend to those not familiar w/ dial cord stringing to steer clear of and work carefully around the dial cord....I myself have melted one w/ a soldering pencil and let me tell you it is a most unpleasant occurrence! it might be wise to check other surface mount trim pots while you're in there since they lay flat on the board dust and stuff settles on them and they corrode and go bad. you can also check vroo1 ,,, its a 220 ohm and is about 2 inches away from the other trim pot on the tuner board. Lets all get our Conions playing is stereo turn em all on at the same time and knock the earth off its axis.

 

[redbenjoe]

thanks for the tip --

last nite - i bought a few motors from your ebay account

 

[beverlyjean2]

Thanks Much...bev

 

[baddboybill]

A[ popular problem I hear second only to tape deck 1 not playing is the FM radio not playing in stereo,,,, mono is fine but the Green light refuses to Glow. Here is a tip to solving the problem On the tuner board there is a surface mount trim-pot Its location is VR002 It's value is 5k OIhMs you'll find it towards the right front of the pc board...if you measure across and find meg OhMs it is open and should be replaced. it's tricky to get to the bottom of the board and you may not want to mess with the dial cord and pullys or remove the chassis from its cabinet...so you can mount a new control from the top by carefully clipping old control from board leaving the metal tabs....then you can solder a new one carefully to the metal tabs that remain. Don't use too much heat or you'll melt the solder beneath the board. I suggest this short cut method of replacement b/c sometimes that dial pulley can get away from you and the sting becomes unraveled and turns into an all day affair for some. If you feel confident that you won't let the pulley get away from you then you can remove the tuner board and replace the pot in the conventional manner. i always recommend to those not familiar w/ dial cord stringing to steer clear of and work carefully around the dial cord....I myself have melted one w/ a soldering pencil and let me tell you it is a most unpleasant occurrence! it might be wise to check other surface mount trim pots while you're in there since they lay flat on the board dust and stuff settles on them and they corrode and go bad. you can also check vroo1 ,,, its a 220 ohm and is about 2 inches away from the other trim pot on the tuner board. Lets all get our Conions playing is stereo turn em all on at the same time and knock the earth off its axis.

Sounds useful I have adjusted this pot , as explained by member Superduper...... set station on strong channel closest to right of tuner. Then turn pot all the way to right, and then turn slowly back to left and once stereo led lights, memorize setting. Then do oppostie by turning all the way left, and slowly turning turning to right and once stereo led lights, memorize setting. Then set the pot between 2 memorized spots and thats how I got a few of mine to work including my C100

 

[stynger007]

I know this is an older thread, but managed to replace the trim pot at VR002 from the top- unbent the two crimped tabs on each side of the old trim pot, removed, and replaced new one on the old tabs, worked like a charm..

Thanks Poster !

 

[JustCruisin]

Sounds useful I have adjusted this pot , as explained by member Superduper...... set station on strong channel closest to right of tuner. Then turn pot all the way to right, and then turn slowly back to left and once stereo led lights, memorize setting. Then do oppostie by turning all the way left, and slowly turning turning to right and once stereo led lights, memorize setting. Then set the pot between 2 memorized spots and thats how I got a few of mine to work including my C100

I need to do that to mine, the FM stereo light wants to flicker and not "LOCK-ON"...even with good reception

 

[stynger007]

Sounds useful I have adjusted this pot , as explained by member Superduper...... set station on strong channel closest to right of tuner. Then turn pot all the way to right, and then turn slowly back to left and once stereo led lights, memorize setting. Then do oppostie by turning all the way left, and slowly turning turning to right and once stereo led lights, memorize setting. Then set the pot between 2 memorized spots and thats how I got a few of mine to work including my C100

I need to do that to mine, the FM stereo light wants to flicker and not "LOCK-ON"...even with good reception

Try adjusting the pot at VR002 , sounds like it doesn`t need changing

 

[Transistorized]

ok. my Conion has no stereo light at all and plays the radio in Mono. I checked this Trim Pot a VR002 on the Tuner board and I get an open reading when Probed to the back two crimped locations. Im guessing I should be reading 5,000 Ohms. So its open right? If I probe the left rear leg and the sweeper dial I get a shorted signal no matter where the sweeper is. If I probe the back two crimped legs during operation Legs 1 and 3 I get a stereo light but a static sound through the radio. This is with my meter set to 2000K. I didn't do this for long because I didn't want to possibly damage anything.

The reason I ask is because I tested the 3 Trim Pots on the Lower cassette deck and I get nothing out of them either. They're all open. Of course my cassette decks MSI doesn't work either and I know that one on the board works it as far as sensitivity for detection between tracks. The other two I'm not sure what they adjust but they test open also.

The only trim pot I got a reading on was VR001 on the tuner board. It read 2 or 3K ohm.

So A: Are they bad? and B: should I just go ahead and replace all of them that are reading open?

My plans are to cut the trim pot off the tope of the board leaving the legs and carefully solder the legs of the replacements on the top. I definitely don't want to get tangled up with the tuner dial string....nooooo waaaaay!

 

[Superduper]

If you are asking for a suggestion, then remove the trimpots the "correct" way, then retest to confirm OUT OF CIRCUIT. If the pots still read bad, then replace them. Sealed units are best.

However, before you start the rest, do VR002 first. That one, if it's the 19khz trimpot, can be adjusted to proper spot rather easily. The other ones however, could be problematic as there is no service manual to aid or provide data insofar as proper adjustment setting. Therefore, you will want to confirm that you are taking proper readings before you do wholesale replacement. A bad pot is not uncommon. All the trimpots being bad is far less likely. If the cassette trimpots are for the bias circuits, and they weren't bad to begin with, then you could introduce a whole can of worms.

However, I will say that before you start anything, to mark and note the current position of the trimpots, then work contact cleaner into them by rotating them with the solvent. Put them back into the proper position and retest. You may be suprised to find that they actually work and was simply oxidized.

 

[Transistorized]

Hmm. Mono sounds pretty good to me Everything else plays great so I'm thinking I should just be happy with what I have. I was going by the first initial post of testing however it was not specified out of circuit. I did blast it with tuner cleaner but got the same readings.

I would think if you measured across pin 1 and 3 you would get the resistance of the pot since you are completing a circuit through the actual pot although I can see how being in circuit could skew the readings. Reading open even in circuit seems to conclude it is bad as current takes the path of least resistance. Reading open in either case means there is no circuit through the pot nor bleeding to ground through the board.

Sometime when one of us as their C100 apart (that plays FM in stereo) can test this VR002 while in circuit and see if resistance is found that would be great. In the mean time I will enjoy what I have. May let an experienced tech look at it if I ever get disparate

Thanks for the input. This is a grail and I don't want to mess it up more than this one little hiccup.

 

[Superduper]

Actually, if tested in circuit, I would expect you to read the same, or lower resistance than the value of the pot itself. That you are reading nothing makes me wonder whether you are getting good connection with the probe. Keep in mind that many PCB's and components are conformal coated and this could affect your ability to get a good reading. Also, probed locations could have an oxidation layer that takes more than normal pressure to make good contact sufficient to get reliable reading. Removing that pot could make it easier to obtain a reading.

A couple of observations that disturbs me.

1. You said "...............If I probe the back two crimped legs during operation Legs 1 and 3 I get a stereo light but a static sound through the radio................" It sounds like you are probing/testing on a live circuit. You must NEVER conduct resistance tests on an energized circuit. The led is trying to source ground through the chip and by probing, you have apparently inadvertently provided that ground signal path and also dragged down the chip so it was no longer working, hence static. This alone suggests to me that you really shouldn't be in there. No offense, but you blow something up in there, and nobody here is going to be able to help you. There was absolutely zero reason to probe around there with the circuit energized, meaning just probing to illicit some kind of response. Ask around here and you'll find a number of members who have probed (or dropped something) with a live circuit only to see a flash, puff of smoke, heard a pop, or otherwise blew something. In other words, it's not the first time that's happened.

2. Pin 1-3 "usually" should read the total resistance of the pot. However, in this case, only one leg of the resistor and the wiper is connected. The other leg is free, on both VR1 and VR2. So while legs 1-3 is usually connected, if the internal resistor is fractured from one leg, it might still work if the other leg is the one connected. Regardless, you also stated that the wiper and one leg reads short all the time, in any position. Well, unless the pot is mechanically broken and these board mounted pots are exposed and easy to see, it's hard to picture that happening.

3. As these pots are installed and adjusted one time during final setup at factory, and usually never adjusted again, they sometimes oxidize but rarely do they simply fail outright unless moisture (or coffee, or soda) damaged. To have them all fail like this is exponentially less likely.

4. You want to snip a component from topside and solder a new one onto the remaining legs. Not that such practices isn't employed from time to time but usually it's only done when it's far too involved to disassemble a unit for good access. In this case, the C100 isn't all that hard to disassemble for access. That you would find this challenging enough to want to snip the resistor makes me wonder a bit.

So given 1,2,3 above, you can see how I am a bit skeptical of your readings. I've helped too many people here, seen too many faulty readings, to just take someones word for granted unless I "know" that they know what they are doing. Not saying that all you say isn't true. But I'm a skeptic.

 

[Transistorized]

I understand and I'm not offended. I enjoy learning and I have repaired quite a few circuits whether it be by luck or what have you. Your right. Taking a ohm reading on an energized circuit is always a bad idea. I knew this and took a gamble. Luckily no damage. I'm pretty sure I had a good connection when testing the POT. These appear to be the standard 3 pin trim POT. PIN 2 I had to look for but its under the sweeper dial at the front. I took note of their locations and place them back where they were.

I decided to just put it back together and enjoy it. See, I'm smarter than most...lol. While I am very familiar with a volt meter I am by no means an electrical engineer. Without schematics its also very difficult and the fact this thing is worth so much I just decided to install new belts, pinch rollers and leave it at that.

If I want to listen to the radio in stereo I can just connect my IPOD to the Aux inputs and listen to it that way Everything else is stereo and works great.

 

[stragulus]

If you have the chassis out, removing the tuner PCB is actually really easy, and you don't have to rewire the tuner dial string. You just remove the one screw holding the tuner wheel mounted to the tuner PCB, remove the 2 screws that hold the metal plate to the chassis, and you can pull out the board from behind without even moving the tuner dial string. If you ever need to access the PCB, that is the way to go.

EDIT: Gee, what do you know, my vr002 was open as well, replaced it with a 10k vr salvaged from an old tape deck and wired a 10k resistor in parallel. Looks great, works great. Thanks!

 

[Dbzerk]

Swapped my vr001 and vr002 with brand new ones.. best and easiest 80cent fix.
FM light comes on strong.

 

[Radio raheem]

i used servisol on vr 002 adjusted and worked fine after that

 

[caution]

Swapped my vr001 and vr002 with brand new ones.. best and easiest 80cent fix.
FM light comes on strong.

Indeed. I had to replace mine, the track was shot, didn't even register a resistance anymore.

 

[Transistorized]

Yep...and later once I educated myself better and gained knowledge I succeeded in my stereo indicator lighting again myself

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[Cpl-Chronic]

Holy fark bud! That's alot of top shelf chatter!!!

There is a ton of excellent advice here that I love this community for. I stumbled on this because I'm having the same symptom. The FM stereo flickers but the 2 channels just break up as soon as the Stereo led comes on & then it flickers with just a staticy mess from the speakers. Mono sounds fine & stations come in strong with the "tuning"(Right VU) meter pegging all the way to the right, dead center of the yellow area, when I center on a station. I'm five miles away from downtown Detroit so stations come in strong & there's always literally 50 FM stations or more to choose from. Was wondering if it really needed the IC like I was told or if the 'alignment' needed adjusting somehow.

Eh, that's a steaming pile of know-how, that'll get yer crank started right!