Sansui 5000
- Thread starter jnl1105
- Start date
TR804 warm on both channels?
Have you checked the bias? Voltage balance on the outputs?
I set the initial bias with the unit on a DBT, then do a final adjustment without the DBT when everything else is squared away.
FWIW I always replace the old trim pots on the Sansui 6013 boards. They're not always bad but can be problematic. If one is dexterous enough they can be changed without removing the boards. At least hose the crap out of the originals with DeOxit.
Have you checked the bias? Voltage balance on the outputs?
I set the initial bias with the unit on a DBT, then do a final adjustment without the DBT when everything else is squared away.
FWIW I always replace the old trim pots on the Sansui 6013 boards. They're not always bad but can be problematic. If one is dexterous enough they can be changed without removing the boards. At least hose the crap out of the originals with DeOxit.
jnl1105
Active Member
I normally test through an ampacity monitoring device a hardwired one and a Flir ampacity module. Right now it is drawing .2 amps so about 24 watts but no matter how much I adjust the pots I get no change
ho many volts should I one getting on the tr807 and tr808?
I think I should have the 70 volts on the collector but not sure as there are so many transistors in circuit
Note there is a naming difference in respect to the output transistors for the 5000X (think F-6013 boards) and the 5000A (think F-1040(-1) boards.
When working with the 6013 boards think TR809 and 807 as left channel, 808 and 810 as right channel. Also expect closer to 70V when on DBT, at least that's what I got.
Did you get a copy of Service Bulletin CE-037a? That is what the following is from. FWIW I've had a VR802 where I got no change over a wide range then had the reading jump way over spec. That was about the time I decided to replace those pots as standard procedure.
When working with the 6013 boards think TR809 and 807 as left channel, 808 and 810 as right channel. Also expect closer to 70V when on DBT, at least that's what I got.
Did you get a copy of Service Bulletin CE-037a? That is what the following is from. FWIW I've had a VR802 where I got no change over a wide range then had the reading jump way over spec. That was about the time I decided to replace those pots as standard procedure.
jnl1105
Active Member
I am so sorry about that didn't mean to leave that message as scrambled as it was, had an unexpected visitor and was distracted.
I am sorry the transistors TR809 & m TR8010. I am measuring the voltage between the case (-) and the ground of the unit and only getting 12 vdc
The tr804 on the right channel is getting quite hot.
First, are your readings from both channels? Your right channel is the one that was previously fried.
"I am measuring the voltage between the case (-) and the ground of the unit and only getting 12 vdc"
When you say "case" are you referring to the body of the transistor (collector)? Measure from the collector to the receiver's case. If you've added a ground wire for the power disconnect it at least until you have the unit running in its original 6013 board configuration.
What is the voltage at 807 and 808?
From my point of view everything on your right channel board that hasn't already been replaced is suspect, particularly TR803 and 804. There is a reason TR803 is physically attached to TR804: thermal conductivity. I believe to control bias as things heat up. (Somebody please correct me if I'm incorrect in that last sentence.)
The figures listed in the chart are the transistor's rated maximums not readings you will normally see in use. Really the only time I've paid attention to transistor specs is when looking for replacements. Even then I go with what more experienced people recommend. Specifying transistors is way above my pay grade.
"I am measuring the voltage between the case (-) and the ground of the unit and only getting 12 vdc"
When you say "case" are you referring to the body of the transistor (collector)? Measure from the collector to the receiver's case. If you've added a ground wire for the power disconnect it at least until you have the unit running in its original 6013 board configuration.
What is the voltage at 807 and 808?
From my point of view everything on your right channel board that hasn't already been replaced is suspect, particularly TR803 and 804. There is a reason TR803 is physically attached to TR804: thermal conductivity. I believe to control bias as things heat up. (Somebody please correct me if I'm incorrect in that last sentence.)
The figures listed in the chart are the transistor's rated maximums not readings you will normally see in use. Really the only time I've paid attention to transistor specs is when looking for replacements. Even then I go with what more experienced people recommend. Specifying transistors is way above my pay grade.
I see no specs on the schematic for the voltages at TR804. The one thing your measurements do tell us is the channel that fried is running higher voltages through TR804. Probably why it fried, though perhaps not certainly. My suggestion at this point is pulling TR803 and 804 and testing them out of circuit and replace the 50 year old trim pots. As I said before, any component on your right channel 6013 board that hasn't been replaced is suspect IMAHO, with TR803 being the most suspect. Did you try setting the bias and voltage as per the service bulletin? If not do that first.
In general I do not bother checking these if I do not have specs that tell me what they should be. That is why I suggest doing the bias and voltage adjustments first.
FWIW I measured TR804 at the collector (case), base and emitter. 70V collector, 36 at base and emitter on both channels, the schematic and manuals I have do not have specs for these voltages so the only use they have is for comparison. They do not covey the amount of information you may think.
FWIW I measured TR804 at the collector (case), base and emitter. 70V collector, 36 at base and emitter on both channels, the schematic and manuals I have do not have specs for these voltages so the only use they have is for comparison. They do not covey the amount of information you may think.
Note the voltages I mentioned are on a 75W DBT, voltages will be somewhat higher off the DBT.
What is the voltage coming off the fuses? Voltage off collectors of TR807 and 808?
Does the left channel play at all?
Is there any signal coming off F-1051? I suggest removing the fuse for the right channel while trying to set bias and output adjustment on the left channel so as not to fry anything else on the right for the time being.
What is the voltage coming off the fuses? Voltage off collectors of TR807 and 808?
Does the left channel play at all?
Is there any signal coming off F-1051? I suggest removing the fuse for the right channel while trying to set bias and output adjustment on the left channel so as not to fry anything else on the right for the time being.
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'Well I just recently came into possession of this bast of a unit that everything works on except right channel on all 3 channels'
Did you mean all three speaker outputs: A,B, and C?
Did you originally have sound on the left channel then lose it?
Note that all the voltages I've measured are on a unit where the bias and output adjustment has been done to spec.
Did you mean all three speaker outputs: A,B, and C?
Did you originally have sound on the left channel then lose it?
Note that all the voltages I've measured are on a unit where the bias and output adjustment has been done to spec.
jnl1105
Active Member
Ok I thought it was just me on these schematics, Like I have said I am used to industrial controls and pics for 30 years..... I couldn't believe the amount of math they leave up to the technician not to mention having to know the tolerances of all the components in the circuit to figure minimum vs maximum in circuit voltages at any given point....
I've no experience with industrial controls. You may indeed know more about circuits than I do, but you may be over thinking things. First work to what specs and adjustments you do have. If you find something out of spec then work backwards to locate a cause. For example, if I can't adjust the bias using the service manual/bulletin's method I look at the trim pot. If the trim pot isn't the problem on a 6013 board I remove TR803, which controls bias as things warm up, and test it out of circuit. FWIW all my bias problems on the 6013 boards have been the now 50 year old trim pots, though some lists of problem transistors includes what Sansui used for TR803. Note the time I tested TR803 I traced the problem back to an unstable connection on the trim pot.