Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to sci.electronics.repair
|
|||
|
|||
Icom IC-7000 VHF/UHF Transceiver "Adjustment Mode"
Hi,
I recently bought an Icom IC-7000 transceiver from the estate of a "silent key". The UHF power output, although the radio is set to "100 percent power" (all bands), puts out about 50 percent on the UHF band. UHF watt meter indicates around 18 watts when it should be 35 watts. Note: Other bands are just fine at 100 percent. I downloaded the service manual from www.mods.dk and followed the procedure to enter the "Adjustment" mode. However, I can not change any settings beyond the "Total Gain (430)! My intention was to increase the "100 percent" value, which is beyond the "Total Gain" adjustments, to see if the power goes up. Note: I am using a proper dummy load. I couldn't find in the service manual or service manual addendum any information regarding this issue. By any chance, did you encounter the same situation? Thank You in Advance, John N3AOF PS, Remove "ine" from my email address |
#2
Posted to sci.electronics.repair
|
|||
|
|||
Icom IC-7000 VHF/UHF Transceiver "Adjustment Mode"
Do a web search for iCom. They will answer your questions...
I would suspect a problem in the final output, or in the drivers. If you have the service manual, follow through by verifying the supply voltages to the final and modulator sections. Also, verify the carrier amplitude. I don't know the unit, but also check in the user book to see if there are any settings for reduced power output. I am assuming that all the standard procedures of antenna match and etc has been done... Jerry G. On Oct 13, 1:10*pm, wrote: Hi, * * *I recently bought an Icom IC-7000 transceiver from the estate of a "silent key". * The UHF power output, although the radio is set to "100 percent power" (all bands), puts out about 50 percent on the UHF band. * UHF watt meter indicates around 18 watts when it should be 35 watts. *Note: Other bands are just fine at 100 percent. * * I downloaded the service manual fromwww.mods.dkand followed the procedure to enter the "Adjustment" mode. *However, *I can not change any settings beyond the "Total Gain (430)! * My intention was to increase the "100 percent" value, which is beyond the "Total Gain" adjustments, *to see if the power goes up. * Note: I am using a proper dummy load. * * *I couldn't find in the service manual or service manual addendum any information regarding this issue. * * *By any chance, did you encounter the same situation? * * * *Thank You in Advance, *John N3AOF PS, *Remove "ine" from my email address |
#3
Posted to sci.electronics.repair
|
|||
|
|||
Icom IC-7000 VHF/UHF Transceiver "Adjustment Mode"
On Fri, 15 Oct 2010 08:37:50 -0700, Jerry G. wrote:
Do a web search for iCom. They will answer your questions... I would suspect a problem in the final output, or in the drivers. If you have the service manual, follow through by verifying the supply voltages to the final and modulator sections. Also, verify the carrier amplitude. I don't know the unit, but also check in the user book to see if there are any settings for reduced power output. I am assuming that all the standard procedures of antenna match and etc has been done... 1. Make sure the SWR on the UHF antenna is 1.5:1 or below. If ok it could be the hybrid output device. Not knowing the 7000 I would assume that it would have a separate output device for UHF. However I would verify the power input to the device and its voltage and AGC circuits before deeming it bad. -- Live Fast, Die Young and Leave a Pretty Corpse |
#5
Posted to sci.electronics.repair
|
|||
|
|||
Icom IC-7000 VHF/UHF Transceiver "Adjustment Mode"
On Wed, 13 Oct 2010 13:10:28 -0400, wrote:
I recently bought an Icom IC-7000 transceiver from the estate of a "silent key". The UHF power output, although the radio is set to "100 percent power" (all bands), puts out about 50 percent on the UHF band. UHF watt meter indicates around 18 watts when it should be 35 watts. Note: Other bands are just fine at 100 percent. Easy. Q401 or something around it. See block diagram on Page 3-5 of the service manual. The driver blob, IC504, drives all the bands. There are 3 separate power amps. Q301/Q302 for HF, Q501 for VHF, and Q401 for UHF. Since everything except UHF is working, methinks everything up to and including the driver blob is also working. I have no idea what's wrong, but I have a guess based on experience fixing one of these abomination. The solder connection between the rear panel UHF connector and the PA PCB is possible broken. Anything else would case zero power output. The fact that you have some power output means that the output stage is probably working, but little of the produced RF is making it to the watts guesser. Ummm... that brings up an other problem. Make sure your wattmeter is working, accurate, and that you do your testing into a dummy load, not an antenna. There's nothing more frustrating that troubleshooting a working radio only to find your test equipment at fault. I downloaded the service manual from www.mods.dk and followed the procedure to enter the "Adjustment" mode. However, I can not change any settings beyond the "Total Gain (430)! My intention was to increase the "100 percent" value, which is beyond the "Total Gain" adjustments, to see if the power goes up. Note: I am using a proper dummy load. I couldn't find in the service manual or service manual addendum any information regarding this issue. Some free advice on working on the IC-7000. It's one of the worst mechanical radio nightmares I've ever had to deal with. Some hints and warnings: Pulling the boards are hell because the self stripping screws are only good for perhaps a few insertions and removals before the threads are stripped in the aluminum casting. Be VERY careful when removing and inserting screws. The plastic front panel on the radio section has a connector eventually going to the control head. Good luck getting it out and back in. Take photos of how the cable it tangled behind the panel or you'll never get it back together. Also, take photos of how the wires and cables are routed, as they're not obvious or easy to guess. Removing the PA board is a mess. The driver blob, IC504 is attached to the casting by two inaccessible screws (someone forgot to drill clearance holes in the PA PCB). Therefore, you have to unsolder the leads to IC504 in 5 places in order to remove the board. Lots of other unsoldering to be done. See: http://802.11junk.com/jeffl/Icom%20IC-7000/ http://802.11junk.com/jeffl/Icom%20IC-7000/PA-circuit-side.jpg The circles and ovals are what needs to be removed before the PA board can be removed. IC504 are the 5 purple circles near the top. Notice that the driver blob is still attached to the casting after removing the PA board: http://802.11junk.com/jeffl/Icom%20IC-7000/Everything.jpg Note the two (purple circle) solder points per UHF connector on the right. That's where I guess(tm) your problem is hiding. Also, don't get any water into the radio. The multitude of flex PCB ribbon connectors on all the boards tend to rot quickly. I have a mess of other non-complimentary things to say about the mechanical design of the IC-7000, but I must admit that as long as it's working, it sure is a nice little radio. It's just that it was never designed to be repaired. I have some more photos if you need them. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
I am looking for a local source for "Rockwool" / "Mineral Wool" /"Safe & Sound" / "AFB" | Home Repair | |||
Depth adjustment on Milwaukee "body grip" router accuracy | Woodworking |