Discussion in 'Pioneer Audio' started by CavScout, Jul 2, 2018.
What the hell is up with AK tonight? Can the moderators please delete these empty messages?
Check them with your eyes, look at them closely. Look for solder splash.
Well did you find anything wrong on the Amp board?
Not yet, out of town until tonight.
I might be best to build a spreadsheet of all the parts on the board and record all readings.
Being a novice the hardest thing for me is taking the readings from the front or back of the board.
I have taken a reading of all of the resistors on the right channel of the amp board and many of them are way out of spec. (Yes I will doing the left also)
30 resistors on the right side and 7 are way below what they should be and that is after checking them several times to be certain.
I started to check the capacitors and found a few out of spec.
Having a stock of extra caps that fit the requirements I removed the bad ones for replacement.
Before replacing I went ahead and checked the removed caps out of circuit and now they read just fine !!!
Is this a common occurrence?
Yes. The parallel circuit paths will affect any reading of components taken in-circuit. In-circuit measurements are effective to locate shorted devices, and sometimes opens, but for accurate analysis the component should be isolated. That can be as easy as removing one leg only, but transistors, SCRs, and similar devices really need to be removed.
What Watt hour said is fact! And we already knew the right channel is ok because it is working just fine. I can tell you that something is real squirrelly going on. As I said in an earlier reply, your readings have changed in the left channel. Q9 and Q11 were reading leakage at one point in time. Now they are reading normal. Q 5 was normal at one time and now reading leakage. You should really think seriously about letting someone with experience look at your amp!
My work schedule has finally allowed me some time to dig into this again.
The attached image is the reading from the resistors on the right channel.
All in circuit and read several times.
Can there really be that many bad resistors (assuming the readings indicate "bad")
sorry but i do not understand your spread sheet
Resistor R1 on the board
In the manual it says the resistor is rated at 180k ohms
The reading I got on it was 180k ohms
and so on
Just to rewind a bit...the last time I powered up the amp, neither channel was working. Right or left. It was a no sound situation (amp would not come out of protection)
You will not get an accurate resistance reading with the resistors in circuit. To get an accurate reading you have to un-solder one end of the resistor and and lift it out of the circuit.
Ok I will pull a leg on the ones that had bad readings and repost
If you want to save time and effort, why don't you just compare the resistors readings on each channel without unsoldering them and see if they match readings. I highly doubt you have a resistor problem.
Ok will do, thanks
Example: If right channel R13 100K reads 52.7K and left channel R14 100K also reads 52.7K, then you know those resistors are good.
So I went through all the resistors on the other side and they match.
I have moved on to rechecking the transistors out of circuit.
The image shown are accurate readings from my multimeter in diode mode
Is there a reference that I can look to for the transistors values ?
I take the readings but I dont know what is "normal".
I dont see them in the service manual
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