Kenwood SM-220 Station Monitor DOA, Let's Make It Right - Part 1 of 2
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- Опубликовано: 5 июл 2024
- Watch as I go through this SM-220 Station Monitor to get it back to operational condition. Sadly this unit didn't have a chance in hell of firing up without taking out critical components in the HV supply.
Not shown here was the poor state of the cabinet which also required a clean up and thorough polishing. When the Melbourne weather warms up, it will receive a new coat of paint.
Watch part 2 here to see me restore functionality of the critical focus and trace controls: • Kenwood SM-220 Station... 
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I have one of these as well and I had to change all the high voltage caps as well.
But working nicely now.
Thanks mate, my 220 has the same problem. I must have been unlucky as the two HV diodes are open circut as well. 73
Wow! One more and you've got a Hat trick!
Your tx signal sine wave needs to be a lot sharper. I run a 220 also, and granted I have outboard processing going on from my rack. But I utilize the band scope to give and tune your audio to studio quality. The mc50 with processing is lively and punchy with a bandwidth of about 3.4k. 4k is better to the listener and even 6k which I can get out of my Orion 2.
4k however is the favourable choice so as not to take up unnecessary bandwidth on 40mtrs. I use an MXL770 condenser mics and yes different mics will present an audio pattern of variable kinds. But my point is even when you think that looks good, slim out your scope to a thin line of focus. Turn off your processor, key your mic at power and observe a clean audio signal as opposed to fat and lumpy. You'll sound like the BBC, and the band listeners will thank you for such a clean signal. Use of Kenwood in the past here to with now yaesu, Icom and ten tec gracing the bench. But each tx gets the same audio clean up routine no matter what. This is great practice in the amateur arena where we are continuing to learn constantly from each mans station. Thx for your video!
Thankyou as well! And yeah have a look at part 2 on my channel when you get a chance (just uploaded) and see what you think of the pattern on there. In this video the focus control was not working due to R-175 going open circuit. I think I was able to achieve what you're talking about and indeed I've had many compliments on air. The scope now has a much sharper reading and I did readjust the mic gain and compression settings as a result.
The other day, one of my regular contacts on 20m thought I sounded like Barry White when I came up on this set up lol.
I had same focus problem. R175 1 Meg resistor had went bad and replacing it solved problem. It changed value but don’t remember which way. You probably cleaned focus pot but saying it anyway.
Hi Steve, no silly suggestions at all on my channel :) Yes I tried cleaning the pot and figured something must have gone out in the circuit. I'll check that resistor and see what else may be out of tolerance. I'm guessing both yours and mine increased in value. So might as well grab the schematics/parts list and check em all. Something is definitely acting up with the intensity control as well. Maybe the same thing.
Tnx. Pertinent to me. I have a SM220, and a Yaesu YOxxx monitor scope. Both suffer the same issue. After about 30 minutes the traces cease. Power down for a few hours and all is ok for another 30 minutes. I need to investigate both.
Yeah and I've just verified R175 the 1 Meg Ohm resistor is completely open circuit in mine and obviously the cause of the trace issue. Waiting on replacement parts. I poked around all other resistors and all are in tolerance. It looks like the wattage might be a bit underrated. We'll see what the thermal camera shows when I power back up :)
I used a larger wattage rating on mine. I felt the same way, and if the intensity is turned down which it is in a dim environment it might Be drawing more current
@@steveberg3014 That makes sense. New parts turned up today. Didn't get a chance this evening but I'll get around to doing the repair within the next couple of days. Really keen to see how warm that resistor gets. Part 2 out hopefully by the weekend :)
Nice unit, although it really looks like the trace is out of focus. You lose some resolution because of that. 73, Bert, VE2ZAZ/VA2IW.
Thanks Bert, yeah noticed that and will be doing some further investigation. Unfortunately adjusting the focus control on the front panel doesn't really help it that much so more work to do!😏
All knobs to the right should fit in just fine with the radio that had the 11 meter modification-thats standard operating procedure for that band here in the US it seems
Haha! I've got nothing against 11m or the guys that love to do it, abuse and distorted signals just kind of wreck it for me.
@@VK2XXL Same here-if you are going to get on the air-sound the best you can no matter what band of frequencies you hang out on-in the US the fellows that have to modify their 11 meter set for obnoxious audio thinking it sounds great-its termed "putting it on the bench to clip and peak it"
Great video but your not done. Clean or change the 2 bnc connectors. Would make it look even better. Love the older kenwood stuff.
Yes absolutely correct 👍 I gave them a clean up after this video. Have a look at part two and let me know what you think 🙂
I have one of these also but no bad HV caps yet, but I had thought those nylon couplers purpose was to isolate the shafts from the front panel?
Narr mate, in all of the hybrid gear the shafts themselves are grounded and have no connection to the circuits. Their only purpose was cost cutting on a large manufacturing scale. K4EAA wrote a good post on the subject.