Search results

The Sansui 3000A dates to 1967/1968 time frame so its design was unusual. The protection circuit is very uncommon I believe. The 3000A has + and - 40v rails and a .3 ohm resistor is fitted in the 3000uF main filters ground line to sense rail supply excessive current flow and then feed a voltage...

I'll share my electrolytic capacitor experience from my working years (retired 4 yrs ago) in nuclear power plants. I calibrated and repaired various equipment that monitored and controlled reactor pressure, level, temperature etc and various neutron monitoring equipment. Thats a very brief...

The drawing in the opening post isn't correct. The original power switch contact should be in series with the gate resistor. I have done the triac mod on three SX-750 receivers so far. I mount the triac along side the power transformer using one sheet metal screw. I attach a small solder...

Dan, I replaced the transistors per this thread: https://audiokarma.org/forums/index.php?threads/top-ten-worst-transistors-noisy-failure-prone-whatever-and-replacements.731653/ Jef

Paging @markthefixer ............

That suggests to me the circuit is flowing excess current to ground (to terminal #1), from the base of Q1 going through Q2 and through D6. Check D6 as pete suggested. The 3.7v to ground on the base on Q1 is essentially reading the voltage drop from the base of Q1 to the anode of D6..... Check...

As to the 28v supply reading 12v, the problem could be with the power supply OR the Equalizer Amp AWF-011. If not too hard, de-solder and lift pin #6 on AWF-011 then check if the 28v goes back normal when unloaded. Or you could do a similar lift at the power supply board. That 28v is derived...

As much as we strive to troubleshoot logically, it can give us tunnel vision and bite us........

A few things...... - Q9 collector should have about 45 volts instead of the +.47v you show above. Double check that. - You show Q7 collector voltage at -1.03 (which may be ok) but Q11 base should be the same, not -.13 as you show. Check on that. Same issue with Q8 and Q12. Q8 collector should...

The 28v only feeds the "Equalizer Amp" which is your phono amp or pre-amp. So you have two issues to chase down. Without knowing your skill level, can you take voltage readings per the schematic on the power amp transistors Q5 and Q7 (Q6 + Q8)?

Hey CT Jim....I did do a post yesterday but seconds later I deleted it when the included schematic link was dead. I also didn't want to needlessly dilute your thread. I am just finishing up a full restore on a SX-838. I replaced all E-cap's on the tuner board, which is almost the same as...

I don't usually chime in on these questions but I feel compelled for some unknown reason. I am 63 yrs old so similar in age. I had a SX-1080 (120WPC) that I gave to my son about 8 yrs ago. I just didn't care for the sound compared to my SX-750 that I have owned since 1979. I restored both. But...

Good to hear that the voltage fluctuations were due to components on the EQ board. I find it very interesting that the removed components checked good even though it fixed your problem. Something inside a cap or transistor was breaking down or leaking in a cyclic manner with no easy way to...

In regards to the fluctuating voltages, it could be caused by the power supply itself OR the loads on those supplies. My suggestion is to desolder the -24 volt pin from the power supply board and see if it still wobbles, for example. Or maybe you could desolder and lift a component lead on the...

I did mail it out to you yesterday.

I will send it to ya. I'll let you know what the shipping cost was. Jef

You are right John! It made a big improvement is the sound of my SX-9000. I replaced 92 electrolytic cap's. Fourteen 2SC458LG transistors and two 2SC871's. It absolutely improved the sound. Cleaner with lower background noise. Jef

I leave mine full clockwise or close to it and then use the volume as normal. I view that source pot as a preamp output level control. I fully restored my SX-9000 last month. The unit was made in Nov 1970. I tested the output wattage after restoration, into 8 ohms, and got 49 watts per channel...

I also installed four MJ2114G in mine last month, no issues here.

Re-stringing the SX-9000 is more complex than the average receiver....good luck! I do suggest to allow for plenty of time with a clear head and no other things of life tugging at you to hurry up. I know you previously said you have studied the service manual drawing for stringing it up, so if...

I sent you two Aux light housings with good original bulbs in them. Tracking shows they were delivered yesterday so they are from me. I also mailed you a new resistor (mailed in a regular envelope) for the Tone Light Module. Seems like all the original resistors fail. I removed mine to test it...

Here are some pic's of my fully restored SX-9000. It has LED's in every position except for the meter illumination, which didn't look right with white LED lamps. So new incandescent bulbs there. I replaced EVERY electrolytic capacitor, 92 total. Replaced 14 problematic 2SC458LG transistors and...

I'm not familiar with the SX-880 at all. @markthefixer probably could add something factual about your proposal. Could you link in some threads that you are referring to? This would save us the time of poking around about this "famous transistor".

I am retired from a career which involved much troubleshooting, repair and calibration. You didn't say if it is a properly working SX-880. DeoxIt cleaning should be done early in the restoration process, probably first. My approach has always been to start with the power supply because if it...

Mustang...THANK YOU !! I just snatched it up. I have been watching ebay but hadn't looked yet today. Jef