Intermittent Power Issues

[Dominic1967]

One of my Kenwood R-5000 receivers has an issue I first assumed was related to the power supply section but now I'm not so sure.

For a split second, the receiver will just die and then imediately resume. Like, blink and you'll miss it. It's as if I (very) quickly hit the power button off and on. No dots on the screen, everything just works perfectly otherwise. It happens both powered via AC or DC, so that's why I question whether it's the power section.

I was going to list it on eBay as a "for parts" radio but would love to know the underlying issue and possibly fix it. I just repaired another R-5000 by replacing the display board, which was daunting but worked out great. Any tips would be appreciated.

 

[N1EXA]

I ended up mounting high speed server fan in my r5000 to keep air flowing though it because mine would get real hot inside and start acting quirky after an hour being on. I used 12volts off the power supply to run it.

I also pulled the display board section out and replacing the memory battery seeing mine was dated 1988. I have not had issues since.

If you get the Dots across the display screen thats because the PLL is off frequency.
It usually is caused by the Bee's wax they used to seal the Calibrated section of the PCB. Resolving this is complicated but can
be done. This is on the early models later on Kenwood changes to a Synthetic wax that was not natural.

And no this is not Folklore !

Pete N1EXA

 

[Dominic1967]

Thanks for the reply. Yeah, I run mine on DC and heat isn't an issue, but this problem can happen even seconds after turning on. Not to say that perhaps the damage from heat wasn't caused by a previous owner but I've had this receiver for 14 years now and this symptom seems to have only started in the last year. The radio gets very little use.

 

[N1EXA]

You might have to clean the Connections to the PCBs and the controls or just reaseating them could also be a solder joint needs to be retouched.
I know your asking Where ?
Could be a Capacitor On the Power supply starting to Leak and short Out ! Could be on the PCBs too !
I know your on external power so im just throwing odd duck issues i had with mine.
Your not alone I bought mine on ebay knowing it was dropped and used parts from a TS-440 to get my controls all running again.
that was back around 2014.
Also Check all the Filter connections seeing they are installed after buying the unit new - These optios are installed by some
people with little to no soldering tools at the time of install.

Mine is used everyday for my FT-8 monitor and Checking Band Conditions. If you use it all the time you find the Quirky issues go away.

Ill note these radios Hate A random wire antenna - If you run dipoles ,delta loops or a long wire with a 9:1 balun an antenna tuner to match the line impedance does wonders for this radio and cut to frequency !
Having A grid dip meter and Impedance meter and checking each antenna is a big help in receiving.
Pete N1EXA