Dim Display - Yamaha KX-580 SE - UK Vintage Radio Repair and Restoration Discussion Forum

SpyguyUK · 7th Jan 2022, 5:31 am

Hi Everyone,

I have a Yamaha KX-580 SE but the Display (Led Audio meter/monitor) is quite dim now. If it's a possible power supply issue with say needing a new capacitor does anyone know which capacitor/s has to be replaced and it's location?

Thanks.

DMcMahon · 7th Jan 2022, 11:39 am

Very difficult to know what this might be.

If the whole of the florescent display indicators are dim then you may be very unlucky in that the display itself has degraded.

Looking at the schematic in the service manual the display is V1 on the MAIN-2 board.

It has two 16.1V DC supplies (from power supply section) connecting though to its F1 and F2 pins (pins 1/2 & 46/47), these DC supplies are from the collectors of transistors Q42 and Q44 with the emitters of the transistors connecting to a -21V supply via zener diode D27 & resistors R180/R181.

It is only a wild guess but maybe there is an issue with the -16.1V voltages

Looks like there may be some sort of switching control on the transistor bases as they connect through to IC 13.

I personally would start with monitoring the -16.1V voltages to see if they are present/correct voltage, it may well be physically difficult to locate and get access to the connections.

David

Welsh Anorak · 7th Jan 2022, 3:02 pm

I have a Yamaha CRX-332 in for repair that had the same fault. It was the display at fault, I'm afraid. I had to order the whole front PCB for it. Unfortunately no such part exists for yours that I can see, so it's worth checing the negative voltage as David suggests.

SpyguyUK · 8th Jan 2022, 8:27 am

Hi,

Thank you for your responses. I I bought it off Ebay so I figure it has been used quite a lot.

I also have a KX-580 also and it looks much brighter when compared.

The dimness is even though. It's not just in one part of display and not in another. All segments/led's.

I wouldn't mind changing the caps near the power supply and measure them if this is most likely the cause? Is it easy to access?

I know you said it might be the whole board though. Or it could be the resistors.

I was even tempted to try to take the front off of the 580 and replace in 580se just to see if that does anything. Would that be easy to do or not compatible?

Thanks.

DMcMahon · 8th Jan 2022, 4:45 pm

I can only easily see a service manual for the SE (Special Edition) so do not know what technical differences there might be compared to the non SE KX-580.

I would imagine they are very similar and the display board may well be the same, you should be able to compare the part numbers between the 2 display boards to see if they are identical.

Impossible in this case to guess if the fault might be a resistor, capacitor, transistor, display itself or something else. Voltage measurements may help to home into problem area.

Personally I would not just change components at random, it could create additional problems.

Cassette decks can be very difficult to work on even for experienced people.

David

SpyguyUK · 9th Jan 2022, 5:23 am

Hi David,

Thanks. Mine is a KX-580 SE. Could you tell me where I can find the service manual for it?

Thanks.

chriswood1900 · 9th Jan 2022, 5:45 am

You can find it here, you need to sign up but I have not had any problems with this site.
https://www.hifiengine.com/manual_li...a/kx-580.shtml

SpyguyUK · 9th Jan 2022, 6:09 am

Thanks Chris, that was fast!

SpyguyUK · 9th Jan 2022, 6:32 am

Hi,

Thanks. If I wanted to test 2 resistors can you use a multi meter to check it without removing resistors or do you have to break one end off - detach from board or do you really have to remove resistor completely to check it?

It's just I've seen all 3 ways of doing this online but wondered which one is right?

Thanks

DMcMahon · 9th Jan 2022, 11:03 am

You do not have to completely remove the resistor in order to test it.

Removing one end may sometimes be required. It depends upon the surrounding connected circuitry, if there are components connected around the resistor in question then sometimes this will reduce to measured resistor value due to series/parallel resistance combinations.

Have to be careful lifting resistors/components not to damage the artwork tracks particularly if double sided board with plated through holes connecting top track to bottom track.

David

DMcMahon · 10th Jan 2022, 12:01 am

Quote:

Originally Posted by DMcMahon

Removing one end may sometimes be required. It depends upon the surrounding connected circuitry, if there are components connected around the resistor in question then sometimes this will reduce the measured resistance value due to series/parallel resistance combinations.

David

Typo edit in bold above.

Boulevardier · 10th Jan 2022, 1:21 am

I don't know this unit at all, but does it have an OLED display? These are known for their shortish life-expectancy - particularly, I think, the earlier ones. So, the display may just be reaching the end of its life. You will probably find it difficult to find a replacement in equipment of this age.

Mike

7th Jan 2022, 5:31 am	#1
SpyguyUK Tetrode Join Date: Aug 2018 Location: Coventry, West Midlands, UK. Posts: 67	Dim Display - Yamaha KX-580 SE Hi Everyone, I have a Yamaha KX-580 SE but the Display (Led Audio meter/monitor) is quite dim now. If it's a possible power supply issue with say needing a new capacitor does anyone know which capacitor/s has to be replaced and it's location? Thanks.

7th Jan 2022, 11:39 am	#2
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,604	Re: Dim Display - Yamaha KX-580 SE Very difficult to know what this might be. If the whole of the florescent display indicators are dim then you may be very unlucky in that the display itself has degraded. Looking at the schematic in the service manual the display is V1 on the MAIN-2 board. It has two 16.1V DC supplies (from power supply section) connecting though to its F1 and F2 pins (pins 1/2 & 46/47), these DC supplies are from the collectors of transistors Q42 and Q44 with the emitters of the transistors connecting to a -21V supply via zener diode D27 & resistors R180/R181. It is only a wild guess but maybe there is an issue with the -16.1V voltages Looks like there may be some sort of switching control on the transistor bases as they connect through to IC 13. I personally would start with monitoring the -16.1V voltages to see if they are present/correct voltage, it may well be physically difficult to locate and get access to the connections. David

7th Jan 2022, 3:02 pm	#3
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,925	Re: Dim Display - Yamaha KX-580 SE I have a Yamaha CRX-332 in for repair that had the same fault. It was the display at fault, I'm afraid. I had to order the whole front PCB for it. Unfortunately no such part exists for yours that I can see, so it's worth checing the negative voltage as David suggests. __________________ Glyn www.gdelectronics.wales

8th Jan 2022, 8:27 am	#4
SpyguyUK Tetrode Join Date: Aug 2018 Location: Coventry, West Midlands, UK. Posts: 67	Re: Dim Display - Yamaha KX-580 SE Hi, Thank you for your responses. I I bought it off Ebay so I figure it has been used quite a lot. I also have a KX-580 also and it looks much brighter when compared. The dimness is even though. It's not just in one part of display and not in another. All segments/led's. I wouldn't mind changing the caps near the power supply and measure them if this is most likely the cause? Is it easy to access? I know you said it might be the whole board though. Or it could be the resistors. I was even tempted to try to take the front off of the 580 and replace in 580se just to see if that does anything. Would that be easy to do or not compatible? Thanks.

8th Jan 2022, 4:45 pm	#5
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,604	Re: Dim Display - Yamaha KX-580 SE I can only easily see a service manual for the SE (Special Edition) so do not know what technical differences there might be compared to the non SE KX-580. I would imagine they are very similar and the display board may well be the same, you should be able to compare the part numbers between the 2 display boards to see if they are identical. Impossible in this case to guess if the fault might be a resistor, capacitor, transistor, display itself or something else. Voltage measurements may help to home into problem area. Personally I would not just change components at random, it could create additional problems. Cassette decks can be very difficult to work on even for experienced people. David

9th Jan 2022, 5:23 am	#6
SpyguyUK Tetrode Join Date: Aug 2018 Location: Coventry, West Midlands, UK. Posts: 67	Re: Dim Display - Yamaha KX-580 SE Hi David, Thanks. Mine is a KX-580 SE. Could you tell me where I can find the service manual for it? Thanks.

9th Jan 2022, 5:45 am	#7
chriswood1900 Octode Join Date: Jan 2007 Location: Dorridge, West Midlands, UK. Posts: 1,486	Re: Dim Display - Yamaha KX-580 SE You can find it here, you need to sign up but I have not had any problems with this site. https://www.hifiengine.com/manual_li...a/kx-580.shtml __________________ Chris Wood BVWS Member

9th Jan 2022, 6:09 am	#8
SpyguyUK Tetrode Join Date: Aug 2018 Location: Coventry, West Midlands, UK. Posts: 67	Re: Dim Display - Yamaha KX-580 SE Thanks Chris, that was fast!

9th Jan 2022, 6:32 am	#9
SpyguyUK Tetrode Join Date: Aug 2018 Location: Coventry, West Midlands, UK. Posts: 67	Re: Dim Display - Yamaha KX-580 SE Hi, Thanks. If I wanted to test 2 resistors can you use a multi meter to check it without removing resistors or do you have to break one end off - detach from board or do you really have to remove resistor completely to check it? It's just I've seen all 3 ways of doing this online but wondered which one is right? Thanks

9th Jan 2022, 11:03 am	#10
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,604	Re: Dim Display - Yamaha KX-580 SE You do not have to completely remove the resistor in order to test it. Removing one end may sometimes be required. It depends upon the surrounding connected circuitry, if there are components connected around the resistor in question then sometimes this will reduce to measured resistor value due to series/parallel resistance combinations. Have to be careful lifting resistors/components not to damage the artwork tracks particularly if double sided board with plated through holes connecting top track to bottom track. David

10th Jan 2022, 1:21 am	#12
Boulevardier Octode Join Date: Sep 2017 Location: Bristol, UK. Posts: 1,657	Re: Dim Display - Yamaha KX-580 SE I don't know this unit at all, but does it have an OLED display? These are known for their shortish life-expectancy - particularly, I think, the earlier ones. So, the display may just be reaching the end of its life. You will probably find it difficult to find a replacement in equipment of this age. Mike