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Yamaha digital tuner -- memory preset problem

myu701

myu701

Vintage futurist
I have a Yamaha T-1020 tuner that has a station preset memory issue. After a few years of ownership, the problem cropped up. Then, I got a Yamaha HT receiver and put the T-1020 away.

Years later, I took the T-1020 out of storage and recalling the memory problem, tested it to see if the problem still existed. I plugged it in, set some stations, then unplugged it. About 5 days later, I plugged it back in and... remarkably the stations were still stored. Great!

Well, the joy didn't last. I installed it as an auxiliary component in one of my audio systems with it's own unswitched power source... then found that the presets were being dropped within a couple of days.

According to Brian Beezley on FM Tuner Info, "There is a wide green capacitor near the two micros. Looking closely, you can see the marking .047F, a twentieth of a Farad. Evidently this is the memory backup. "

So I'm guessing the memory capacitor is faulty on mine. At first it seemed OK, so I'm thinking that the lack of use let things "settle" inside the capacitor, but once put back into regular use it degraded again. Apparently I'm not alone, as I've seen another AK member mention this same problem.

Yamaha_T-1020_circuitboard1.jpg


There's not much imprinted on that capacitor in the way of a model number. "TN", "189" and "FZ", in addition to the voltage and Farad specs.

From what I can see, it's a double layer capacitor meant specifically for computer memory storage (rated 5.5v and .047F). I've no idea what the Ohm rating is. I went up to DigiKey to look for a suitable replacement... there are a couple rated 5.5v/.047F there, but one is 120 Ohm and the other is 300 Ohm. Any ideas on which would be the right one?
 
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I would say don't bother with the ESR value (although a lower value is theoretically
better), just pick one that has the correct capacitance and voltage rating,
and preferably the correct pin spacing, and that is in stock!

You can check the pin spacing by looking at the spec sheets available from
the Digikey page. Good luck!

Also, I see that those supercaps are all rated for 1000 hours at either 70 deg.
C or 85 deg. C. I assume that those with the higher temperature rating will
actually last longer at room temperature.
 
Thanks, Electroking. :)

I didn't find much on DigiKey, but Mouser has a very comprehensive list. They've got NEC Tokin capacitors (same as OEM), plus ones by Panasonic and Cornell Dubilier. The Cornell brags a minimum operating life of 15 years and seems sized most appropriately (13.5mm; the original is 14mm). I'll have to take the unit apart just to verify the pin spacings, just to be sure. But in any case, this could be a very straight forward repair. :thmbsp:
 
myu701 said:
Thanks, Electroking. :)

I didn't find much on DigiKey, but Mouser has a very comprehensive list. They've got NEC Tokin capacitors (same as OEM), plus ones by Panasonic and Cornell Dubilier. The Cornell brags a minimum operating life of 15 years and seems sized most appropriately (13.5mm; the original is 14mm). I'll have to take the unit apart just to verify the pin spacings, just to be sure. But in any case, this could be a very straight forward repair. :thmbsp:
Click to expand...
Thanks for pointing out your thread to me, I'd missed it. Let us know what you discover. For now it isn't a big problem for me as my T-1020 gets used pretty much every day and so has no problems remembering stations. Should I be so lucky as to go away on vacation for long enough it might be another case. Ha, I wish.....

It really is a good-sounding and selective tuner and at Tuner Info I read about some mods that would improve it yet more. I'm not really a digital fan, but i have to admit it does a nice job.
 
You're welcome, FiddleFye. :)

I haven't bought the capacitor yet, but expect to do so very soon (looking into a few other things to add on to fully utilize the shipping).

Although the T-1020 is a fairly common tuner, and can be had fairly cheaply from time to time (sometimes lower than $30), I'd say it's well worth getting at any price below $50 if it's free of issues or need of alignment.

Brian Beezley of FM Tuner Info had a good time modifying it, noting that Yamaha had packed some impressive technology into it. I wouldn't have the patience to try doing what he did, even if I had the knowledge. ;) The thing is, he had poor filter performance that wasn't rectified by an alignment. Other than the memory issue, mine is working fine for my purposes.
 
I had exactly the same thing happen with my T-420. Rather than fiddle with it and possibly burn something else out using a soldering iron and considering the age of the unit I'm going to buy a TX-479 I think.

I even bought a maintenance manual for it thinking that perhaps there was a fairly easily replaceable rechargeable battery somewhere inside as is the case with some makes, obviously it's more complicated so am not going to risk it with my lack of experience in such matters.
 
I bought a TX-497 on eBay from a US store but unfortunately the seller inflated the declared value on the UPS waybill by 200%+ (obviously in error) and so UPS tried to charge me extra taxes on top of their already inflated brokerage fee and I refused the package.

I am now trying to persuade the seller to fax an adjusted invoice to UPS. I hope they cooperate.

Paid $167US (+ S/H) and UPS tried to charge me $117 because the seller stated the value at $372, while I'm used to paying something on imports as I do this all the time, I'm not paying that, sorry.

Advise to eBay buyers, make sure the seller puts the correct declared value on the waybill if you are importing from another country and, even though their service is excellent, try to avoid UPS if you can as their brokerage fees are the highest in the business.

In my case I had no choice.
 
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Strange. In my case it took years for the problem to surface. I guess something has to wear out eventually and that capacitor is it...?
 
Ehhh...what the hey...just go with the 1.5F cap...should remember a LONG time..if it doesn't burn out the charging circuit. ;)
 
Ex_Brit said:
Strange. In my case it took years for the problem to surface. I guess something has to wear out eventually and that capacitor is it...?
Click to expand...

Same for me. The tuner was fine for quite a number of years. I think it's simply a bad batch of super capacitors that NEC produced at some point, as quite a number of receivers from that era have the same reported problem (see thread linked above).

I wouldn't take a chance of going with a super capacitor outside the original specification. You just don't know what issues it may introduce. The main thing is installing one that does the job reliably for a very long time. If it holds memory for a week or more, then it's fine. The main issue is dealing with a power interruption lasting more than a day or two, either by a power outage or simply moving the component to another location.
 
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