Trying to fix an Icom IC R8500 receiver

[@FrozenDoberman]

Thanks. I watched the entire video from start to finish. Interesting to see a technician work on both the top and bottom sides of an IC R-8500. I bought my first R-8500 new back in 2001. Best radio decision I've ever made. The last few years it has developed a crackle pop audio fault that is present even with the squelch at maximum. It could be an audio stage issue because everything else works perfectly. Around 80% of the time there is no audio crackle fault. But just in case it completely fails, I bought an almost new in box IC R-8500 via eBay. This will stay in the box until it is needed. I also have a almost new in box IC R-8600. But ergonomically, I still prefer the R-8500.

[@ptronix]

Glad you like the video and congratulations for getting to the end, not many people do on my channel. It is a lovely radio indeed. Bought to replace the R 7000 (I think). I bought it for use on VHF and UHF as I've other radios for for 0 - 30 Mhz. But sadly over the years there is less and less to listen to, all emergency services have gone to digital or cell phone use and I don't find aircraft that interesting so that just leaves FM radio and that's not worth listening to, there is so little choice of music. But I will never get rid of this receiver, just hope I can keep on fixing it as its unbelievably complicated. Yours sounds like it may have bad capacitors in the audio stage. Electrolytics are the main failure point in old radios.

[@stefanz6502]

It was a long boring video, but man, I love this stuff. Thanks from across the pond.

[@lesliedymond9484]

Interesting video Nick. Thanks for your time

[@danishnative9555]

Terminator to Nick: "I'll be back." This illustrates the complexity of trouble shooting complex radios. My R-7000 still works, but the original power transformer failed early on (of all things). Replaced with a toroidal. Good luck sir, hope she stays stable.

[@ptronix]

Hello Danish, I've got a feeling I'll be back on this radio many times in the future. It nags away at me that it still doesn't work above 1024 MHz. I also had the R7000, a nice radio but not as nice as this one. The reception on SSB was poor I remember. I had several faults on that as well, capacitors on the display board and in the dc -dc converter module. thanks for watcing

[@benhumphrys1656]

What a lovely way to receive Radio 4.

[@ptronix]

Hi Ben, or you could say a very expensive way to receive radio 4!

[@dayleedwards3521]

Those two diodes in the beginning of the video are a simple OR gate. If PLL 1 OR 2 takes the lock detector low, it will activate the error signal and flash the display. If both PLL LD outputs are high, the PLLs are locked, the fault is then elsewhere. The third input is to deactivate the LD for the higher ranges. Let me watch the rest of the video, I may comment again.

[@ptronix]

@@dayleedwards3521 yes I get the idea of using diodes as an OR gate. That particular problem mysteriously fixed itself and the radio worked fine for about a year. Then it decided to randomly flash the display and loose all its memories and there was a burning smell. Traced the burning to a low value resistor feeding a small 5 volt regulator. Basically the 5 volt rail would randomly short to earth but this only happened every few days and then it would work OK. Something on that rail was causing a short. Took me two months to find it! It finally went short long enough to look for something getting hot with an external 5 volts fed to that rail. Turned out to be a tiny SMD filter that feeds 5 volts to a different module. There are 4 filters in one package basically a capacitor down to earth. Removed it and and haven't bothered to replace it as it was impossible to find one. Radio works fine without it, just Icom being ultra careful about filtering any incoming or outgoing signals to that board. Thanks for the comment

[@dayleedwards3521]

@@ptronix Thank you for your comprehensive answer. Intermittents are the worst to find, I feel your pain.

[@IZ0MTW]

Looks like I have something to watch later tonight!

[@IZ0MTW]

So Nick, if I got this right it was a problem of supply voltage. Sometimes problems are well hidden and one don’t think to them, guessing something more complex is going on. Obviously there’s still a problem above 1025MHz but as you said who cares. Two points I’d like to emphasize here. 1. Before working on something do a master reset and check thoroughly the manual for basic specs. 2. Having had a look at the manual it says that accepts DC of 13.8+/-15% so it should work with 12V too. What really caught my attention is that it talks of providing 13.8dc OR use the AC power adapter. Now there’s an european and an american version of it and I’m guessing if the one you have is the right one. I know the plug should be different but when you buy something used you never know what they did to it. Have you checked the power adapter under the electronic load? Anyway good job repairing Nick, well done! Would be nice now to have a general look at it and go through an adjustment to bring it back into max performance. Btw I just sold my base scanner from UNIDEN on ebay. It was perfectly working but didn’t really use it anymore nowadays. By for now! Diego

[@ptronix]

@@IZ0MTW Hi Diego , thanks for the long comment. I checked it today, it works fine on 12 v as you would expect, so the mystery remains as it's obviously not a voltage problem. I could get a replacement converter module from Israel for £92 but by the time the customs get hold of it they will screw me for import duty and VAT so it's not worth it for a part of the spectrum with nothing on it. In case I didn't make it clear the ac adaptor plugs in to the radio and then uses an internal regulator to produce 12v or whatever, it also makes the radio quite hot. There is also a plug on the back to disconnect the regulator and run it on external 12 - 14 v. This is a better option as the mains adaptor gets quite hot even with the radio off, so it's now running on my switchmode supply that runs my other radios and the mains adapter is the right one for Europe. I did do a factory reset years ago, all that achieved was losing a fair amount of memory channels I had programmed in! It is now installed in my shack and happily scanning a few channels I've programmed in. I put up a simple antenna today for it, just a 2m j pole but it works very well from FM band up to 70cm. I must have listen on the air band. Also would be interesting to see if there are any pmr stations left on VHF, I think most now use cell phones. The next job to do is replace the bulbs and I've ordered some warm white leds. Good you sold your scanner sold, hope you got what you expected. Best wishes nick

[@IZ0MTW]

@@ptronix thanks for the answer Nick and for the further explanation. In facto you did say it in the video, it’s just me that got lost a bit into it. So it was the internal regulator. Well, what matters at the end of the day is that you got it working again! I came to Edimburgh recently, I guess you could be able to here me as I fly over as I’m up high at 36k feet ish. Regarding the scanner no really auction happened as the only one putting an offer got it for the starting price, but I was already happy with that so no complaints. Somebody will enjoy it better than me. Oh and another thing. I was watching a video here about an old analog multimeter and remembered of mine. A video will come soon. Bye for now! Diego

[@marckellec8217]

Hello Sir, Thank you for your very informative video, I have an R8500 with the same fault as yours, my question is the following, what parts did you change to make it work again? Sincerely MarC

[@ptronix]

I didn't change any parts in the end. After many hours of trying to diagnose the problem it suddenly started working! And still is 2 years latter. The only benefit was I got an understanding of how this very complicated radio works!

[@overbuiltautomotive1299]

Thanks for video sir God bless. i got the same china FM mw transmitter board it works but is stuck on 107.1 and none of the buttons do any tjhing any more it been that way for half a year now so ill need a new one .

[@ptronix]

Those transmitters are very good for the price. Audio quality is excellent as far as I can tell. The helical filter is there to filter out the poor fm signal they produce with unwanted noise several Mhz either side of the main frequency. I'm a perfectionist so I like things to be as good as possible, thanks for watching

[@overbuiltautomotive1299]

​@@ptronix i am a bit of perfectionist to look at this video i dig into his other videos look like he did his home work into transmitting and stuff kzbin.info/www/bejne/hZ3aqo2BmrKtfqc

[@lesliedymond9484]

Lovely receiver

[@gabryst2945]

hello, but on the ic-r8500 there are 3 attacks for the antennas, but can I use only one (the uhf-vhf one) and put an antenna that starts from 30 KHz and reaches 2GHz and listen to the whole band?

[@ptronix]

No it's not possible to cover the full frequency range with one antenna. You need one that covers up to 30 Mhz and one that covers 30 Mhz - 2 Ghz plugged in to the appropriate socket

[@raybokor2]

did you contact icom uk they have a great support staff for any tech issues with there products . the engineers are always helpful

[@ptronix]

No, my impression is as its quite old now it would be difficult to find anyone who's actually has knowledge of these radios now. But a good suggestion none the less

[@raybokor2]

The staff are very knowledgeable re the 8500

[@ptronix]

@@raybokor2 thanks I'll bare that in mind. Its faulty again now. Randomly makes a rude noise, flashes the display and burning smell. Traced it to a 5 volt rail going short and causing the resistors before the regulator to overheat. I've measured as low as 0.6 ohms on that rail with respect to earth. But this is such a random event its driving me nuts trying to find the cause! It will work fine for a few days then suddenly dies. If it went permanently faulty of course it would be easier to fix

[@Homer19521]

I agree. Leave it that orangey look. Blue would kill the rig. 👍

[@ptronix]

Hate blue lights, I changed it to warm white leds, and it looks original

[@lesliedymond9484]

It ain't a dry solder joints is it Nick

[@ptronix]

Quite possible les, but you try finding it in something this complicated. Anyway it's working fine and has been for two days now. It still doesn't work above 1024 Mhz but I'm not bothered about that, there's nothing up there anyway. I'm just happy it's now working

[@vastoking7653]

Hi ptronix, where can I download a clear circuit diagram? thanks

[@ptronix]

download the service manual like I did, which is free

[@vastoking7653]

@@ptronix the circuit diagram in the service manual is not clear.

[@ptronix]

@@vastoking7653 in that case sorry I can't help you

[@vastoking7653]

Hi ptronix ,why is the 13.8V power connector very hot of my R8500?

[@ptronix]

If the connector itself gets hot that suggests a poor connection and may need cleaning. In other words some resistance, and resistors get hot with current going thorough then

[@vastoking7653]

@@ptronix Thanks a lot

[@vastoking7653]

​@@ptronix It seems that this machine consumes a lot of power and draws a lot of current.

[@ptronix]

@@vastoking7653 well mine doesn't have this problem. I use a 13.8 V power supply rather than the supplied transformer which does get very hot. Also when using the supplied power supply it uses a regulator in the radio to get 13.8 V and this makes the radio hot

[@vastoking7653]

@@ptronix so it is. I use DC in jack

[@arenaengineering8070]

Good. Thanks for the video!👍🏻

[@onthebench3606]

I would like to know about your modification please.

[@ptronix]

Do you mean the low powered fm transmitter I put in it? Sorry its a while since I did the video

[@onthebench3606]

@@ptronix yes , that would certainly be of interest!

[@ptronix]

@@onthebench3606 you can buy them on ebay, fully synthesised low power fm transmitters. Around 2 mw output. Very poor spectral purity. They need filtering with a band pass filter. I can then listen to audio from the receiver on a pocket radio with earpiece around the house garden whatever. Cost about £5 last time I bought one

[@solarpower3669]

This mod seems a little bit weird，why not using a bluetooth earphone@@ptronix

[@ptronix]

@@solarpower3669 I don't want to use Bluetooth, I'd much rather use a pocket fm radio with an earpiece, works for me! And I have a range of a few hundred feet

[@TommyTimebomb100]

I have one of these that I would like to sell. The problem is that I took the casing screws off to reach the descriminator jumper and then lost them. Then to make matters worse the m-ch delay/speed plastic knobs (inner and outer) broke due a fall which bent the potentiometer. So I need the componant as well as the plastic dials. Aside from that this works perfectly with no scratches ETC so it's a shame that because of the faults mentioned it has knocked a considerable few bob of this, thats if I can sell it at all now? Would Icom still do these parts does anybody know?

[@ptronix]

That's a sad story. They are lovely receivers. In good condition probably worth about 500 - 600 but less than half that I'd guess the state yours is in. I think you'd be wasting your time with icom, they'll tell you it's to old & they have no parts for it any more. Mine has a cracked squelch knob but I think it's very unlikely I'll ever find a replacement. Thanks for watching

[@TommyTimebomb100]

@@ptronix Yep, your confiming what I am suspecting, thanks for your replie. I'm no tech but enjoyed watching you vid. I actually didn't realise how much kit goes into this.

[@matambale]

Yeah, I enjoyed this, Nick. No hope for me I suppose :^)

[@ptronix]

This is an old video now Joe. Although the symptoms are much the same with flashing display etc. But then it wasn't cooking the regulator and of course it fixed itself for two and a half years!

[@matambale]

@@ptronix I saw the date on it and wondered exactly that, if the regulator issue occurred back then, too Guess not. Rig is possessed.

[@jannehls8788]

Hallo Der selbe Fehler wurde von mir erfolgreich behoben. Den oberen Deckel entfernen, dann den Abschirmdeckel rechts neben der Stromversorgung entfernen. Den oberen SMD Elko mit der Aufschrift 220uf 16A 916 durch einen neuen ersetzen. In meinem Fall habe ich einen in normaler Größe und 220uf 50V eingelötet. Der Verbaute kann nach oben mit einer Zange abgezogen werden, und die Anschlüsse können abgeknickt werden. Solltet Ihr kein Audio haben ist ganz links in der NF derselbe SMD Elko verbaut. Gefunden mit einem Infrarot Thermometer, der Elko machte 50 Grad Temperatur, das kam mir zu warm vor. Die Fehler waren: Blinkende Anzeige, kein Ton. Oder zwischendurch mal 5 min Betrieb und ein Kratzen im Lautsprecher mit anschließender blinkender Anzeige. Das originale Netzteil habe ich entsorgt, da es mit einer zu hohen Spannung lief. Viel Erfolg.(Es muss nicht euer Fehler sein, meine 8500 läuft aber wieder.) Sorry das ich Deutsch schreibe, aber ich muss mir auch immer Euren Kram in Englisch durchlesen. :-) Gruß Jan

[@ptronix]

Thank you Jan for the detailed information. I will keep in mind the problem you found should the radio go faulty again. It has now worked perfectly for 2 and a half years. I don't understand this behavior. Why it should suddenly fix itself without me doing anything. German is no problem, I just had to translate it. Regards Nick

[@jannehls8788]

Hallo Nick Es ist genau das passiert, was Du gesagt hast. Radio aus, und Anzeige blinkt nach 6 Stunden Laufzeit. Test2: Neuer Kondensator und die Spannung auf 10 Volt heruntergedreht. Radio läuft. Ich melde mich wieder. Gruß Jan

[@ptronix]

thanks again Jan. I've translated your two comments and stored them in a folder for the 8500. So if it goes wrong again I will check what you've suggested@@jannehls8788

[@jannehls8788]

Hallo Nick Die Spannung auf 10V herabzusetzen war nicht erfolgreich. Nach 4 Stunden blinkt die Anzeige. Esl iegt also nicht an der Spannung. Test 3: Die obere Abdeckung demontiert lassen, mal sehen ob es mit der Wärme zu tun hat. Gruss Jan

[@vastoking7653]

@@jannehls8788 Hi jan thank you for the information. has the machine been completely repaired?