Sansui Six Receiver Tuner Issue

Can anyone suggest replacements for the trimmer resistors on the driver boards? They are 1KOhm and 5KOhm, but the tricky thing is finding pots that can be adjusted while looking down at the top of the receiver. The two driver boards mount vertically into slots. Thanks.
 
Finally getting back to this.I got the transistor listed above and replaced TR 201 on F-1450.

I fired it up on the dbt first and it worked well, then full line where it worked well for a while. FM pops in and out abruptly and when it's out it's a rushing sound like a bad transistor. Should I go ahead and replace TRs 202 and 203?

Much thanks!
 

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Update, made the signal tracer using a .01uf cap soldered to middle of rca cable. Tested TR 202-206 and got what sounded like feedback on each lead.
 
What you will probably need to do is yes have the 0.01uf cap connected to the center wire of the RCA cable, but you will need to connect a wire to the shield of the RCA cable and connect that ground wire to the unit you are testing.

You can peel pack the insulation on the RCA cable to get a decent amount of the shield exposed. Then get a piece of wire (any wire like a piect of speaker wire or line cord, or hookup wire. Get it connected to the shield and tape it so the bare shield wire isnt exposed. On the other end I suggest you either put an alligator plug so you can attach it to your Sansui chassis, or you can just connect the ground wire to the ground lug on your sansui.
 
Thanks, made the change to the probe by adding the ground wire as described.

I turned on the sansui and while fm was on the fritz tested the based of TRs 202 - 206 and pins 3 and 5 of the chip and got nothing.

Then on a whim I tested TR 201, the new 512-ksc1674YBU that was just installed, and fm popped back on perfectly. When I removed the probe, each time, it went back on the fritz.
 

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I tested the base. Also went back and touched it with a toothpick to make sure it wasn't a cold solder joint, got no response.
 
You may have an issue with the components near the base of this transistor. Try jumping across or replacing C201 and C202. Also check resistors R201 to R206. At times resistors can get noisy, and open while looking fine.
 
Will give that a shot. Do I need to totally remove the resistors to test or can I just desolder one leg?
 
Having had to replace transistors that had different pin-outs, I took some 20ga. mic wire, I had from work, and cut off a chunk of the insulated wire and stripped the insulation off at the correct length. I could then slowly work the plastic insulation up each of the pins of the transistor. If the pins were to large and made it difficult, I would use a heat gun sparingly to soften the plastic enough to slide it up the pins. Having done this, I did not worry about braiding the pins on the transistor. If the 20ga. is to big, you need to size down to 22ga.
 
When I replaced TR 201 I was able to insulate the base lead as you describe. I didn't insulate the collector.

I will verify that the leads aren't touching at any point, particularly near the transistor body

Thanks.
 
Verified that the leads of the new TR 201 aren't touching.

Been probing and have more info.
When touching the probe on one side of R 201-202 and C 201 the tuner comes back to life. When doing the same with C202-203 and R203-206 nothing happens. Would that point to R202 and C201? Any suggestions for ceramic disc caps?

Thanks
 
You can test resistors by lifting 1 leg. Not sure if they are carbon film or carbon comp. But either can fail. Testing of ceramic disk caps can be done with a cap tester or multimeter with a cap function, although this doesn't always identify a problem. Using another .022uf capacitor and jumpering it across the installed capacitor will correct the problem if the original is open, but not if it is leaky. This also appears to be the same problem all along, so I may suggest that you keep track on any parts replaced, and think of reinstalling the original 201 transistor if it made no change to the problem. Not fully required, but if you start replacing some resistors and caps, you want to keep the "number" of replaced parts down to a minimum.

Why don't you get cheap replacements locally for R201 to R205, and C201 and C202, so that you can substitute them one at a time if necessary.
there are some local ebay sellers that for just a few dollars can supply you what you need, many times with free shipping.
 
Looks like I missed radio shack by a few months, the closest one now is about 20 miles away, and is closed on Sunday's. See my avatar.

Found the caps on eBay and the resistors on Amazon.

My meter doesn't have a cap tester but I will test the resistors.
 
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Just wanted to update. Still testing, so far have tested R201 – R203, all have tested good. Unfortunately I broke the lead on R201(220ohm) flush with the resistor body so I’ll have to replace it anyway.

I got a new batch of .022uF 50V ceramic caps and so far replaced just C201. I tested with this new cap before I broke the resistor and still the same issue after warming up for a while. I should have more 220ohm resistors, and most of the other values by tomorrow.

Still need to test R204 and R205.
 
So far have replaced R201, the one I broke, and R202, and 203. Also replaced C201 – C203. None made much of a difference.

I couldn’t test the caps but the resistors tested good. When I tested R204 it tested good but I gave a new one a shot anyway. Fired it up and FM worked great for about an hour and a half. Then FM died and the cracking sound

Common denominator is that when I touch 2A on F-1450 with a meter probe FM starts playing again, remove the probe the crackling sound comes back and FM goes out. Does this mean it is a grounding issue, like R025 on the tuning cap? I haven’t tested R205 and 390ohms is one resistor value I don’t have.

I tested TR202 and 203 and the voltages are close to whats is on the schematic.


Thanks!
 
Much thanks. Finally got the tuner together, you were right on, the issue was the 390 ohm resistor at R205. Changed it on Monday and has been running flawlessly ever since.

I have inadvertently come up with a new light mod for this receiver where despite the unit being on none of the lights ever come on. All you have to do is carelessly not recognize a broken wire on one of the tuning meter terminals and blow a fuse.
I think its the 5 amp f001 on the fuse block, at least it is the closest on the schematic.

Other than that I'm about ready to finish with the recap.
 
Question about setting the dc offset.
The manual says an 8-16 ohm 50watt resistor is needed, but I had another receiver, also direct coupled, I worked on where the manual said something similar and it turned out not to be the case. Do I need the load for this?

I haven't done anything on the driver boards yet. Plan to replace the three caps on each, the variable resistors, and maybe matching transistors. Thanks
 
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IIRC the 50W 8-16ohm resistor was used to do the initial factory setup and would not be needed for subsequent running setup's unless you changed out the trimmers. If you set the trimmer to match the old one resistance wise then the resistor isn't really needed.
 
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