Recent content by Mr. Nick

Have you checked the carbon comp resistors on amp boards that they are within tolerance? My 2230 had several of them drifted out of spec.

Ok, you guess one of those limiter diodes might be bad? Those limiter diodes are IT243 type R30. All 4 of them. Thanks!

I have narrowed the issue to limiter & detector section. I played with the scope and it sure indicates a clean signal up until the base of transistor Q301. On the collector side of the Q301 the signal is weak at startup thus I replaced the transistor Q301 with KSC945. No change. Then I figured...

Another observation as now the dial lights lit up well is that when I power on and circuits begin to warm, FM Muting being in OFF position and first time it enters to stereo mode there's a slight voltage swing brightening dial lights slightly. Also the background goes more quiet then. When the...

I replaced 4 big resistors, R14, R15, R16, R17 on the power supply board. Now I have correct voltages equal to service manual feeding the tuner boards, but it didn't solve the muting issue. What it did solve the dial lights are all lit up now and stereo lamp also illuminating (when signal...

Here's a photo of the bad guys. The 2 rightmost big resistors are bad.

Ok, I found out that the higher wattage resistor R17 (1K) on the power supply have gone south. It's suppose to feed MPX board. There should be 17.2 volts, while on the other end of the resistor I have about 18.5 volts and on the other about 0.5 volts. The adjacent R16 (330 ohm) to pilot lamp has...

I haven't worked on with tuners that much and I am not in possession of RF tools, except the adjustment key tool set. I used a scope while listening to the FM and it looks like what I can hear from the speakers does match with the scope signal pattern at Limiter & Detector section at base of...

Hey, Long story short. So I've got myself a beautiful mint Sony STR 6120. It's been laying in the shelf for half a year and until about a month ago I found some time to work on it. Now finally it's been fully recapped with thoroughout mostly with Panasonic low esr capacitors and Kemet in the...

Schematic for STR-7045 (model above) calls for 4700uF/50V filter capacitors. So this is a model below with 5600uF filters... I doubt they are originals. Looks sketchy.

I am currently working on a pair of SA-1000 and TX-1000. The power cord on SA-1000 is cut. Previous owner said the idea was that no kid can plug this thing in unchecked. This is extremely hefty machine for its size, even the flip switches are rock solid construction. Thoroughly impressing. This...

You said it. The problem existed on one channel only, before repair attempt. Now both failed. Just saying, fake transistors do behave that way, they take heat for few minutes and then go off boom. You also might be right about the channel that was originally blown might have another issue...

You say you've replaced the outputs with originals. These outputs have been long out of production. Where did you get them? The symptoms you describe are consistent with that you've purchased fake transistors from Ebay, which have caused all the damage you have there.

You tested for voltages on a power supply with a multimeter? If you see no voltage (=totally dead) I would pull the power supply components out for testing. Bridge rectifier, transistors and electrolytic caps. If you're lucky it's just open circuit, which is why there's no power. It might be a...

The service manual states the resistors on P800 are all within 10% tolerance. I don't know about resistances, there are errors in the manual and/or different revisions of the board. You should measure the originals and compare to the colour band coding. Then you know exactly what you had...