2220b - Dial indicator light - flickering

[Gustavsson]

The dial pointer lamp was dead in my unit (along with most of the other incadescents). I bought a kit from aliexpress, link. The regular LEDs work fine and the dial pointer lamp lights up fine. But there's a faint flickering. It's not very obvious, but thought I'd ask just in case. Any way to get rid of the flickering? In the listing it's the small 3mm lamp that I have installed for the pointer.

Thanks

 

[rBuckner]

You'd have to place an electrolytic cap, at least 47uF across the LED after any rectifier diode. If they used an LED that has an integrated diode to deal with backwards biasing, to deal with AC voltage sources, you're screwed!

 

[Gustavsson]

You'd have to place an electrolytic cap, at least 47uF across the LED after any rectifier diode. If they used an LED that has an integrated diode to deal with backwards biasing, to deal with AC voltage sources, you're screwed!

So what does "screwed" mean here? The flickering is not really a huge problem and I can easily live with it. Is there a type of LED that I can buy that will not flicker? The LED look identical to to all the different kits available from more "reputable" sellers.

 

[markd51]

Maybe for Dial Pointer, and Stereo Beacon Lamp, might be best to just stick with the stock Lamps instead of LED,

 

[Gustavsson]

Maybe for Dial Pointer, and Stereo Beacon Lamp, might be best to just stick with the stock Lamps instead of LED,

Can you buy stock like dial pointer lamp? The one I had was broken. I have left the stereo light alone since it's still working.

 

[markd51]

First, may I ask do you have the service manual, or know of the correct type-value original lamps on your receiver?

There's a person who sells virtually all of the Lamps you could ever need, his address is below, and I'm sure he'll also know exactly what your Unit requires as well.

One problem is, you live in Barcelona, and shipping and time could be issues? Any local electronics shops by you who would carry such parts?

dwojo69@msn.com

 

[JJCalvillo]

Dial pointer is what they call "grain of wheat" bulb. Something like 3-5mm. Best to go with incandescent there, they don't cause any problems like the meter or dial lamps can by getting warm and melting their housings. Dave at dwojo69@msn.com will know just what you need.

 

[rBuckner]

So what does "screwed" mean here? The flickering is not really a huge problem and I can easily live with it. Is there a type of LED that I can buy that will not flicker? The LED look identical to to all the different kits available from more "reputable" sellers.

Well, screwed was too strong, you're just stuck in the case I mentioned unless you change it out. What I do is use a standard T1-3/4 warm white LED for the dial pointer. You have to remove the flange at the base so that it fits. I solder on the old wiring for which you have to be fast to not cook the LED. Then pull the dial pointer wire that goes up to the back of the lamp board and reroute it to the +13Vdc supply via a current limiting resistor, usually 3.3 to 3.9K for the LEDs I get. Absolutely no flicker then!

 

[markd51]

Just curious, as I don't consider myself an audio tech, but, as far as a Dial Pointer Lamp, and the factory use of standard Lamps, has anyone ever really noted damage caused due to an incandescent lamp used?

That such warrants the need-use of an LED?
Sure, I understand some benefits, perhaps cooler operation and longer life.

 

[Gustavsson]

Well, screwed was too strong, you're just stuck in the case I mentioned unless you change it out. What I do is use a standard T1-3/4 warm white LED for the dial pointer. You have to remove the flange at the base so that it fits. I solder on the old wiring for which you have to be fast to not cook the LED. Then pull the dial pointer wire that goes up to the back of the lamp board and reroute it to the +13Vdc supply via a current limiting resistor, usually 3.3 to 3.9K for the LEDs I get. Absolutely no flicker then!

Those are some very clear instructions. Thank you very much.

In my beginner head that translates to this LED (link) and a resistor at 510 ohm 1/4 Watt according to this calculator (link). Given 13Vdc. Would that be correct?

But, where do I find the dc source? The dial pointer currently connects to the to JZ14 pin that gives 7.4Vac. I've checked the schematic but I can't find any dc source. (should be noted that I have no experience with electrical schematics and I'm randomly looking for anything that says DC.)

 

[spicer]

I have the service manual and it's shown as part M002 in the schematic. But it's missing from the parts list. There's no additional information in the manual about any of the lamps.

When I purchased my kit from aliexpress I looked around at the different offerings from both reputable sellers in the US and direct imports with aliexpress. The regular LEDs for the dial indicator and tuning meter


Those are some very clear instructions. Thank you very much.

In my beginner head that translates to this LED (link) and a resistor at 510 ohm 1/4 Watt according to this calculator (link). Given 13Vdc. Would that be correct?

But, where do I find the dc source? The dial pointer currently connects to the to JZ14 pin that gives 7.4Vac. I've checked the schematic but I can't find any dc source. (should be noted that I have no experience with electrical schematics and I'm randomly looking for anything that says DC.)

If all else fails use a little bridge to rectify the ac followed by a filter cap and voltage dropping resistor for the LED... it won't flicker. It would be irritating.

 

[markd51]

So, from what it appears, this little bugger (LED FM Dial Indicator Lamp) is not a "plug and play" affair.
I guess you bought a Lamp Kit, and the kit did have the right parts, but all was not so simple as a swap.

So, by no means trying to be harsh, but let me ask, and suggest this.
I can understand well, when inside a component, tool, appliance for repair-refurb, it is best to do what is needed, if I myself had acquired a 2220B, or a 2385B, I would probably like opening her up, and do some shadetree cleaning, lubing, lamps if needed, full cosmetic clean up whatever is needed.

But I was also always inclined to not fix something that wasn't broke. There's been a few times where I "dug too deep" with fixing something, and caused much more problems than I originally had. Same applies here.

I gather that the original Lamp was burnt out, but, was there any evidence of heat damage to its Housing from that Lamp?

If not, then my simple solution would be to get the right Incandescent lamp, install, test, and be done with it.
The ole "KISS" keep it simple principle.

Sometimes such lamps are 40-45 years old, still going.

I've done some re-lamping over the years to a number of Recievers,and yep, once had to replace a Dial Indicator Lamp on a Sansui QRX-7500 Receiver.
Yeah, it's a pistol, some delicate treacherous work, but I got it.

 

[Steven Tate]

Over the years, I have bought several LED kits from irebuildmarantz.com, and they included a grain of wheat sized cool white LED with the long wire pigtails for the dial pointer. I have replaced several of them and never noticed any flickering using the original power source. I don't know if these bulbs have built in circuitry to eliminate it or if I'm just blind enough that I don't see the flickering. But they look very good to me when I change them along with the input select bi-pin bulbs.

 

[Gustavsson]

So, from what it appears, this little bugger (LED FM Dial Indicator Lamp) is not a "plug and play" affair.
I guess you bought a Lamp Kit, and the kit did have the right parts, but all was not so simple as a swap.

So, by no means trying to be harsh, but let me ask, and suggest this.
I can understand well, when inside a component, tool, appliance for repair-refurb, it is best to do what is needed, if I myself had acquired a 2220B, or a 2385B, I would probably like opening her up, and do some shadetree cleaning, lubing, lamps if needed, full cosmetic clean up whatever is needed.

But I was also always inclined to not fix something that wasn't broke. There's been a few times where I "dug too deep" with fixing something, and caused much more problems than I originally had. Same applies here.

I gather that the original Lamp was burnt out, but, was there any evidence of heat damage to its Housing from that Lamp?

If not, then my simple solution would be to get the right Incandescent lamp, install, test, and be done with it.
The ole "KISS" keep it simple principle.

Sometimes such lamps are 40-45 years old, still going.

I've done some re-lamping over the years to a number of Recievers,and yep, once had to replace a Dial Indicator Lamp on a Sansui QRX-7500 Receiver.
Yeah, it's a pistol, some delicate treacherous work, but I got it.

Yes, I got a kit when the dial pointer and a few of the other dial lamps didn't work. Swapped all the incandescents for LEDs except for the stereo light (still original lamp). I mostly asked the question about the LED dial pointer since that was what everyone seemed to offer in their kits. But maybe I might as well get a 3mm incandescent instead. Found some 6v that I could use with a resistor. I assume I can reduce the voltage the same way as with an LED.

 

[Gustavsson]

Just to summarize. There seems to be three possible solutions to the light flickering problem.

1. Using a 8V LED. Rewire the power source to DC and use a resistor to reduce the voltage.
2. Using a 8V LED. Keep the same AC power source but using a diode, resistor and an electrolytic cap in order to block reverse voltage and stop the flickering, as explained here in the third post (link).
3. Using incandescent bulb. Direct replacement. Keeping the same 7.4VAC power source and using a resistor to reduce voltage if needed. The most readily available rice grain bulbs seem to be either 6v or 12v.

Number 3 currently sounds like the easiest route to go.

 

[markd51]

Just to summarize. There seems to be three possible solutions to the light flickering problem.

1. Using a 8V LED. Rewire the power source to DC and use a resistor to reduce the voltage.
2. Using a 8V LED. Keep the same AC power source but using a diode, resistor and an electrolytic cap in order to block reverse voltage and stop the flickering, as explained here in the third post (link).
3. Using incandescent bulb. Direct replacement. Keeping the same 7.4VAC power source and using a resistor to reduce voltage if needed. The most readily available rice grain bulbs seem to be either 6v or 12v.

Number 3 currently sounds like the easiest route to go.

Hi,
Yes, option #3 should be the easiest, and wasn't difficult at one time to find these Lamps. But now the majority of these Lamps sold appear to be LED.

I've seen some on that auction site, and a few other places that might have such Lamps. Not sure if you can locate and source such locally? Or the person we linked to above may have them?

Of course time is one factor, I wouldn't be very tickled waiting a month or more for a Lamp.

I'll take a guess and say these 8V Lamps are probably what, 35ma or 40ma at most? I would think one wouldn't require or desire a Lamp-Bulb with more light output than that.

They are commonly referred to as "Grain of Wheat" Lamps. And such usually came with ample wire leads, perhaps 150mm-200mm long.

https://www.ebay.com/itm/224701392996?hash=item34513f2864:g:el8AAOSwClZhmEwN

 

[Gustavsson]

Hi,
Yes, option #3 should be the easiest, and wasn't difficult at one time to find these Lamps. But now the majority of these Lamps sold appear to be LED.

I've seen some on that auction site, and a few other places that might have such Lamps. Not sure if you can locate and source such locally? Or the person we linked to above may have them?

Of course time is one factor, I wouldn't be very tickled waiting a month or more for a Lamp.

I'll take a guess and say these 8V Lamps are probably what, 35ma or 40ma at most? I would think one wouldn't require or desire a Lamp-Bulb with more light output than that.

They are commonly referred to as "Grain of Wheat" Lamps. And such usually came with ample wire leads, perhaps 150mm-200mm long.

https://www.ebay.com/itm/224701392996?hash=item34513f2864:g:el8AAOSwClZhmEwN

It's hard to make sense of what exact bulb to get. Supply is a bit limited. I believe I found a perfect replacement from Farnell, It's 8V 35ma. But the shipping costs are just ridiculous. Everything from the US is ruled out du to shipping costs unfortunately.

The closest I can get to that from an EU seller so far is 8V 50ma on.ebay. But with the increased amperage I imagine it will get hotter. It's 0.4W vs 0.28W. But maybe that's overthinking.

 

[rBuckner]

Just curious, as I don't consider myself an audio tech, but, as far as a Dial Pointer Lamp, and the factory use of standard Lamps, has anyone ever really noted damage caused due to an incandescent lamp used?

That such warrants the need-use of an LED?
Sure, I understand some benefits, perhaps cooler operation and longer life.

Just once due to a wrong bulb though.

 

[markd51]

It's hard to make sense of what exact bulb to get. Supply is a bit limited. I believe I found a perfect replacement from Farnell, It's 8V 35ma. But the shipping costs are just ridiculous. Everything from the US is ruled out du to shipping costs unfortunately.

The closest I can get to that from an EU seller so far is 8V 50ma on.ebay. But with the increased amperage I imagine it will get hotter. It's 0.4W vs 0.28W. But maybe that's overthinking.

Hi,
Did you perhaps try contacting the person another and myself mentioned earlier in this thread?
I might think that 8V 35ma would be the correct Lamp. A Lamp with too much output of course will not look right.

 

[soundguy9]

Hello All, I acquired a 2220B and the pointer bulb is out. This one is strange as the bulb itself is good (not blown or burnt) but it is not getting the supply voltage. The tuner bulbs are working fine! Any idea where I look for the problem? I noticed some of the higher wattage resistors on the power supply circuit that are showing small burnt marks. Any help would be appreciated.

son of a gun, I found the answer to my own question. I traced the dial pointer wires to a terminal on the source selector switch. It is ON only when it is in FM or AM mode! I would have never guessed it.