TX-9100 problems...

[carl pants]

I picked up a Pioneer TX-9100 a few months ago for $30. It sounds great....for awhile. After listen for a bit one, or both channels will almost completely cut out. They're still there, but barely. If I turn it off and then back it will usually work fine, but not always. Any ideas?

[Twenty20Man]

can't help, but I will be watching with interest

[pioneervato]

Does your signal strength meter drop when cut out occurs? If not, you may have to go in and clean all of your switches with Deoxit if you haven't already done so. Could be just dirty contacts in the switches.

[carl pants]

Signal strength doesn't drop. I cleaned using Deoxit today, hoping the problem would improve. I might give it another cleaning tomorrow.

[pioneervato]

Are you running the tuner through the variable outputs or fixed outputs? Try switching the output connections from one to the other and see if that makes a difference.

[carl pants]

Variable and Fixed Outputs both are screwy. Headphones too.

[pioneervato]

Try posting this in the Pioneer forum and maybe markthefixer will chime in and give you some other alternatives to fixing your issues.

[bobschneider]

I picked up a Pioneer TX-9100 a few months ago for $30. It sounds great....for awhile. After listen for a bit one, or both channels will almost completely cut out. They're still there, but barely. If I turn it off and then back it will usually work fine, but not always. Any ideas?

Sounds like it may be bad capacitors in the output stage. I had a similar problem in one channel of my TX-9500. It turned out to be a bad cap.

[markthefixer]

Variable and Fixed Outputs both are screwy. Headphones too.

On FM and AM? Try switching to AM when it is misbehaving. Also try tuning it off station in FM and then back on station, we are trying to activate and clear the muting circuit.

[carl pants]

Sounds like it may be bad capacitors in the output stage. I had a similar problem in one channel of my TX-9500. It turned out to be a bad cap.

How easy are these caps to replace?

[jblmar]

Could be a power supply issue. You'll need to measure voltage from the power supply to the input of the audio circuit.
If both channels go out at the same time, look for common component(s) at the output of the power supply. Don't overlook the relay as a possibility.

[bobschneider]

How easy are these caps to replace?

Not that hard, although if you're not good at soldering you should get some practice with something you can afford to throw away first. What you're looking for are the electrolytic caps, which are the small metal cans on the output PC board. You want to replace them with the same uF value, and the same or better voltage rating (you shouldn't have to worry about physical size, since modern caps are normally much smaller than the same values from 30 years ago). Good sources to get replacements are www.digikey.com or www.mouser.com - Digikey carries Panasonic caps which are quite good, but Mouser's stuff is decent, too, and they don't have a minimum order.

Forget Radio Shack for caps - they have a very limited selection of values, and what they have are usually low quality and overpriced. However, they do carry a desoldering iron which is cheap ($15 or so), and works well. It looks like a regular soldering iron, with an extra metal tube sticking up from the business end, with a rubber bulb on the other end.

Make sure you install the replacements with the same polarity as the originals (+ and -). Usually there's some kind of polarity marking on the PCB, but sometimes you just have to remember which polarity the ones you take out are. The caps themselves usually have a white stripe on the negative side, and new caps usually have a longer lead on the positive side.

[carl pants]

So I took the tuner in for repair. I just talked to the guy and he said the output board is bad and basically there's nothing I can do besides coming across another TX-9100 and using it for parts. Anybody have any ideas on this?

[jblmar]

Yea, the outboard board is bad. Repair the board.
Find another shop not another 9100. Anything can be repaired.

Ron

[SPL db]

Yea, the outboard board is bad. Repair the board.
Find another shop not another 9100. Anything can be repaired.

Agreed...

"Find another unit" is tech speak for "I have no clue what's wrong with it". :)

Scott

[pustelniakr]

What the tech means is, "At $75 per hour, you will not want to spend what it will cost for me to fix this old thing (I hope)."

Enjoy,
Rich P

[carl pants]

Any suggestions on where to get a new board? Do any other Pioneer models use the same board? I'm not giving up on this tuner!

[backmd]

I have the same issue, the L channel cuts radically in volume, down to about 10 percent. Then when I power off and then power back on the channels are equal volume. However specifically, the problem occurs on headphones, and also the fixed and variable outputs. The schematic diagram is available through audiokarma and this is very useful. Now I will go to radioshack and try C24, C27, C42, and C43 and see if these capacitors measure 220uf on my capacitor analyzer. I will also check to see if B+ at pin 18 is 30 volts. Also I will replace C35, C38, C44 and C45 with polypropylene capacitors as an upgrade. I had a dynaco preamp that was also intermittent then later had no output on one channel. This preamp responded nicely to a new coupling capacitor that I alluded to in the upgrade sentence. Actually now I am listening real carefully and the bad channel sounds like it does not pass any low tones, highly likely a capacitor which is too low in value, likely a coupling capacitor. When caps age they decrease capacitance, and they sound like a tinny radio; no bass at all. In retrospect a coupling capacitor is highly likely. I will know tomorrow when I have time to diagnose it.

[markthefixer]

On FM and AM? Try switching to AM when it is misbehaving. Also try tuning it off station in FM and then back on station, we are trying to activate and clear the muting circuit.

Any suggestions on where to get a new board? Do any other Pioneer models use the same board? I'm not giving up on this tuner!

Close to two months ago I asked a question. pioneervato also made a suggestion that seems to have been ignored.

You don't need a new board because some clueless trade school reject said so, or just plain doesn't want to bother. Or he doesn't have the right equipment to try.

I am NEITHER. I have the correct equipment. And I'm not trying to make a living at it, nor do I have to pay rent on a shop.

Finally tuners are light, so they are cheap to ship. The difference in cost can be put into a real service manual.

So if you post about this in the Pioneer Audio forum, it will mean you really want to do something about this, and if so be prepared to answer a lot of questions about the conditions present when the thing misbehaves. And to do some experimenting, BEFORE you decide what needs to be done based on OUR findings from these tests.

[backmd]

Any suggestions on where to get a new board? Do any other Pioneer models use the same board? I'm not giving up on this tuner!

This tuner has been very mysterious! The L channel cuts out after a 30 minute or so warmup. I systematically analyzed it, spraying really cold DustOff on different L channel components, and surprisingly the L channel was resurrected when the low pass filter was cooled! I did not believe it, as usually a bad transistor, bad capacitor or bad resistor is the culprit. Measuring with a multimeter, sure enough, there was infinite resistance across the low pass filter when it was warmed up and 1 ohm or so across it when it was cold. I simple bypassed the unit and the Pioneer TX-9100 truly sings. Also erected a 6 element yagi aimed directly at the classical music station, and you would not believe the depth of the soundstage. Later I will upgrade to polypropylene capacitors and get rid of those 2uf electrolytic caps. Really got a treasure here! Hope you can fix yours!

[lguise]

Definately! Sounds like a leaking capacitor problem to me also. I would definately look for another mechanic. I wish I could find a tx-9100 for 30 bucks! I have a sa-9100 amp with a tx-7100 tuner.