R7000 More Icom R7000 Issues/Questions

[W9DPY]

Happy Thanksgiving! I have an Icom IC-R7000 that has the "receive drop out" issue. This was discussed in-depth in this forum under the title "Unusual ICOM R7000 problem". Here's my issue - I know I have the DC-to-DC capacitor issue. I'm about to order a cap kit from a guy on Flea-Bay to replace those. However, many of the posters said that the real issue is the heat generated by the internal AC power supply. And that using an external DC power supply is a work-around for this issue.

Here's what happened. My DC plug is on the back of the unit, next to the AC plug and fuse. Some are like this and some units don't have the external DC plug. In an effort to see if an external DC supply would work, I cut the jumper wire on the external plug (used for AC operation as a trigger) and soldered on some leads for external DC power. I turned on the unit, got the meter to work - but not the display. I tried a different supply (Astron 35M) but the same thing happened. I re-soldered the jumper, plugged it back in and checked it on AC. Everything good (meter and display), but I'm sure the RF sensitivity drop issue is still there.

Anyone run into this? Also, anyone know where you can get a pre-made 12 VDC power cable for this unit? FYI, for those who didn't read the original post; my unit has RF for about 5 minutes and then starts dropping. You have to shut the power off then on to get it to work again. As the unit warms up, the interval between shut-downs grows shorter. That indicates a thermal issue.

Feedback appreciated!

Dave - W9DPY

 

[majoco]

For those who say they don't have the 12v connector on the rear panel - take a look inside - you'll find the Molex connector and it's jumper in there. There's a blanking plate held on with two small screws - remove the plate and use the two screws to mount the Molex connector. Now if you have an old computer hard drive connector you can push out the small sockets and make your own with the old jumper. Do NOT leave the the little jumper wire in place.
I thought my 7000 was getting rather too warm so I drilled a grid of 1/4" holes all over the top and bottom of the case and glued fly screen mesh inside to keep the dust out. it's appreciably cooler now. I run mine from a homebrew 13.8v supply and it's never missed a beat since.
Early on I had problems with the display fading out. Recapping the display driver board didn't help. I noticed that in the dark the heater wires were not glowing' Looking at the bit of flexible connector that joins the display to the driver I thought that the two outer traces looked a little to thin to pass the required current so I bridged them with wire-wrap wire and problem solved! If you try try this - make absolutely certain that the you have the right connections from the transformer to the display - a meter is useless as the whole lot looks like a short circuit.

 

[RFI-EMI-GUY]

I may be mistaken, however I recall that when you bought the DC cable kit from ICOM that there were instructions to remove a rectangular blank panel on the rear of the unit and thread an existing mating pin MOLEX receptacle with shorting plug out of the chassis into that slot.

Also there was a service bulletin for the ICR7000 that described receiver problems due to power supply hum (ripple) affecting the tuning varactors used for the VCO and the receiver RF filtering. So I would check to see if it operates properly on an external DC supply and if it does, then replace the filter capacitors on the power supply board. There are just a few, change them all. The internal supply is fine though it does get warm. * These are 40 year old receivers, yet they still are valuable and excellent performers. Well worth restoring to original condition.

* Note that if you remove the load of the receiver from the internal power supply by opening the DC Kit shorting plug, it will become unregulated and produce about 19 volts DC. This is normal. However if you reattach the jumper under this condition you will blow out panel or meter lamps. Turn off the AC and let the power supply drain down to zero before attaching the jumper. Always use the jumper when operating the internal AC supply or testing.