Pioneer TX9800 tuner goes off tune

stevieg · 2nd August 2012, 06:48 PM

I have a battleship Pioneer tuner from thirty years ago that has just recently started to go off tune, and also lets its little birdies sing. Any ideas where to start looking? One of these fellows.

Cheers Steve

Mooly · 2nd August 2012, 07:07 PM

Where to start... service manual for starters and whatever you do don't twiddle anything internally

Something like that could be difficult to fix. I would check the basics such as making sure the rails are clean and correct. If they vary or drift that will affect the tuning and alignment.

If it is a real RF fault then things get tough. It could be anything... a ceramic cap going leaky, old electroylitics etc etc. Tuner faults are rare.

A can of freezer may help, not blasting parts but just dripping a little onto any suspect items.

stevieg · 3rd August 2012, 08:11 PM

Thanks Mooly. I've removed thirty odd years of dust, and can't see anything that seems to have let the magic electric smoke out, so I will start experimenting with the aerial environment (plant growth) and move slowly inwards. I have a couple of other tuners to check.

Cheers Steve

kevinkr · 4th August 2012, 06:56 PM

Probably about time for a recap, electrolytics only.. And as Mooly has indicated twiddle not yee internal coils, and pots!

Anecdotally speaking my Mitsubishi DA-F10 had started to die, replacing all of the electrolytics (a day's work in itself) brought it back to the expected levels of performance.

stevieg · 4th August 2012, 07:45 PM

Thank you Mr kr. I promise I won't mess with the pots and coils, in an effort to solve the wrong problem. I will take your words on board, especially as I did troubleshoot my Leak Troughline 3 tuner (the conceptual opposite to the Pioneer) by replacing a cap. If all fails I shall console myself that with metal prices the way they are, scrap value of this battleship will probably be more than I paid for it!

Cheers Steve

hallteks · 4th August 2012, 07:53 PM

If the tuner is PLL, I would change the varicap diode.
I have no experience of this, only told by others.

rsavas · 5th August 2012, 07:09 PM

With a slide dial I doubt very much it is PLL. I agree start with the Ecaps and then see what happens. I have Pioneer SX950, same vintage, i found the var cap gets noisy with age, so I designed a Si4735 receiver, so no moving parts and RDS +++

Rick

2nd August 2012, 06:48 PM	#1
stevieg diyAudio Member Join Date: Nov 2009 Location: Gwynedd North Wales	Pioneer TX9800 tuner goes off tune I have a battleship Pioneer tuner from thirty years ago that has just recently started to go off tune, and also lets its little birdies sing. Any ideas where to start looking? One of these fellows. Cheers Steve __________________ steve if it ain't broke, I ain't fixed it

2nd August 2012, 07:07 PM	#2
Mooly diyAudio Moderator Join Date: Sep 2007	Where to start... service manual for starters and whatever you do don't twiddle anything internally Something like that could be difficult to fix. I would check the basics such as making sure the rails are clean and correct. If they vary or drift that will affect the tuning and alignment. If it is a real RF fault then things get tough. It could be anything... a ceramic cap going leaky, old electroylitics etc etc. Tuner faults are rare. A can of freezer may help, not blasting parts but just dripping a little onto any suspect items. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

3rd August 2012, 08:11 PM	#3
stevieg diyAudio Member Join Date: Nov 2009 Location: Gwynedd North Wales	Thanks Mooly. I've removed thirty odd years of dust, and can't see anything that seems to have let the magic electric smoke out, so I will start experimenting with the aerial environment (plant growth) and move slowly inwards. I have a couple of other tuners to check. Cheers Steve __________________ steve if it ain't broke, I ain't fixed it

4th August 2012, 06:56 PM	#4
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Probably about time for a recap, electrolytics only.. And as Mooly has indicated twiddle not yee internal coils, and pots! Anecdotally speaking my Mitsubishi DA-F10 had started to die, replacing all of the electrolytics (a day's work in itself) brought it back to the expected levels of performance. __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

4th August 2012, 07:45 PM	#5
stevieg diyAudio Member Join Date: Nov 2009 Location: Gwynedd North Wales	Thank you Mr kr. I promise I won't mess with the pots and coils, in an effort to solve the wrong problem. I will take your words on board, especially as I did troubleshoot my Leak Troughline 3 tuner (the conceptual opposite to the Pioneer) by replacing a cap. If all fails I shall console myself that with metal prices the way they are, scrap value of this battleship will probably be more than I paid for it! Cheers Steve __________________ steve if it ain't broke, I ain't fixed it


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4th August 2012, 07:53 PM	#6
hallteks diyAudio Member Join Date: Jun 2006	If the tuner is PLL, I would change the varicap diode. I have no experience of this, only told by others.

5th August 2012, 07:09 PM	#7
rsavas diyAudio Member Join Date: Aug 2012 Location: Ontario	With a slide dial I doubt very much it is PLL. I agree start with the Ecaps and then see what happens. I have Pioneer SX950, same vintage, i found the var cap gets noisy with age, so I designed a Si4735 receiver, so no moving parts and RDS +++ Rick

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