Kenwood NX 5700K / KCH-20R

[FiremanJim23]

I have the above Kenwood radio in my fire response vehicle. The KCH-20R head does not light up. I have VHF, UHF and MARKS decks. Nothing has changed since it was last working. I can hear transmissions from other departments but I have no idea where I am on my display - channel selection. I have checked all fuses, I believe, and all seem to be good and the connections are clean and bright. The display just stopped one day and I have been driving myself nuts trying to find out what it is. Any assistance would be really appreciated. I use this radio to let the fire department and dispatch know I am responding and sometimes communicate the situation on scene if I arrive first on scene. Thanks again and may God bless.

 

[n7maq-1]

Try reseating the CH cable. I have not seen a display just go out on a KCH-20 as you describe, but that does sound like what it is. If it is under a year old then it will be covered under warranty, if not it is a flat rate repair now at United Radio. I DO NOT recommend FTH Group.

National Service Centers | KENWOOD USA

Welcome to KENWOOD USA Site. In pursuit of further value creation by integrality our three core business segments and establish [ mobile & home multimedia system ] business

www.kenwood.com

 

[FiremanJim23]

Try reseating the CH cable. I have not seen a display just go out on a KCH-20 as you describe, but that does sound like what it is. If it is under a year old then it will be covered under warranty, if not it is a flat rate repair now at United Radio. I DO NOT recommend FTH Group.

National Service Centers | KENWOOD USA

Welcome to KENWOOD USA Site. In pursuit of further value creation by integrality our three core business segments and establish [ mobile & home multimedia system ] business

www.kenwood.com

Ok, dumb old man here - what is the CH cable and where is it located?

 

[tweiss3]

CH is short for control head, the KCH-20. The cable goes into the back of the control head.

 

[WB5UOM]

FTH and United both do good for us.
fyi. YMMV

 

[AYoung2600]

I’ve only had 1 KCH-20 head out of the hundreds I’ve installed do the exact same thing. I ended up pulling the back plate off of the head and reseating the ribbon cable inside and it has been working ever since.

 

[FiremanJim23]

CH is short for control head, the KCH-20. The cable goes into the back of the control head.

This is in a Ford Explorer and a major pain to get to. The car console must be removed to get to the retainer bolts for the head. I will start the process of pulling everything to get to it. Any other ideas while I have the car torn apart? Thanks for your reply.

 

[n7maq-1]

Sorry to hear you have to tear the rig down that far to service. If you do end up opening up the head you will need to use ESP Protection. You will also need to de-solder the two tabs that are circled in the below picture. If you can get a service manual it does have a very detailed troubleshooting guide for your exact issue. "5.1 Fault Diagnosis of the BGA (Ball Grid Array) IC
■Overview
A flowchart for determining whether or not the transceiver can be powered on (the LCD does not function even if the power switch is turned on) due to broken BGA parts."



Let us know what you find, I hope it is something simple.

Edit. I forgot to add remove the SD Card before doing anything internally.

Jim

 

[n7maq-1]

you will need to use ESP Protection. You will also need to de-solder the two tabs that are circled in

ESD not ESP, sorry...

 

[AM909]

To start, check for 3V on L43 and 3-5V on pins 5/6/7/8 of IC38 (the dimmer control).

 

[FiremanJim23]

Sorry to hear you have to tear the rig down that far to service. If you do end up opening up the head you will need to use ESP Protection. You will also need to de-solder the two tabs that are circled in the below picture. If you can get a service manual it does have a very detailed troubleshooting guide for your exact issue. "5.1 Fault Diagnosis of the BGA (Ball Grid Array) IC
■Overview
A flowchart for determining whether or not the transceiver can be powered on (the LCD does not function even if the power switch is turned on) due to broken BGA parts."

View attachment 191007

Let us know what you find, I hope it is something simple.

Edit. I forgot to add remove the SD Card before doing anything internally.

Jim

Ok, oh-boy. This might be getting past my ability - lol. What good would de-soldering those 2 tabs do for me? Wouldn't that eliminate any power to the 2 connection points? By the way where is the SD card?

 

[FiremanJim23]

To start, check for 3V on L43 and 3-5V on pins 5/6/7/8 of IC38 (the dimmer control).

Are you referring to where the dimmer control attaches to the circuit board?

 

[FiremanJim23]

Is there somewhere I can send the head and have it repaired? Someone that won't try and remove my left eyeball to pay for it?

 

[n7maq-1]

Is there somewhere I can send the head and have it repaired? Someone that won't try and remove my left eyeball to pay for it?

See post # 2, you also might want to check with a local Kenwood shop that DOES bench work.

The tabs that are soldered are only a physical contact, not electronic. Not to discourage you, but if you don't have experience in basic board level repairs then it should go to United Radio or another shop.

Jim