Con't
I have a solder sucker too and it works great. I have pulled enough parts off of boards that I got for free this spring...I just hope I did not put too much heat on the components while 'desoldering' as I just learned to use 'gator clips' as heat sinks. No big deal though as I got experience in that and some numb fingers.
I am making a home made circuit board holder using a pipe clamp I will post when done...just have to find the file I found on that project.
What the heck is a VR Assembly?
This is on the schematic and the net likes to side step what I am trying to find out. My keywords did not narrow down the search other than Virtual Reality! LOL
Okay I will get back to that diagram and try to figure the hot side of those relays as the schematic in some areas shows a + symbol but on the Speaker Assembly board I take the hot side is "looking at it - left side" ..... I see some of those older Pioneers with the Tuner built in and I think I am a bit glad this is not one of those...being a bit dyslexic and all!
Cheers and thanks Chris and all who may wish to help!!
I have a solder sucker too and it works great. I have pulled enough parts off of boards that I got for free this spring...I just hope I did not put too much heat on the components while 'desoldering' as I just learned to use 'gator clips' as heat sinks. No big deal though as I got experience in that and some numb fingers.
I am making a home made circuit board holder using a pipe clamp I will post when done...just have to find the file I found on that project.
What the heck is a VR Assembly?
This is on the schematic and the net likes to side step what I am trying to find out. My keywords did not narrow down the search other than Virtual Reality! LOL
Okay I will get back to that diagram and try to figure the hot side of those relays as the schematic in some areas shows a + symbol but on the Speaker Assembly board I take the hot side is "looking at it - left side" ..... I see some of those older Pioneers with the Tuner built in and I think I am a bit glad this is not one of those...being a bit dyslexic and all!
Cheers and thanks Chris and all who may wish to help!!
Oh, from the schematic I thought you have heard of a VR assembly circuit board?
Voltage Relay? Pg 10 on the schematic...
-- Richard
Oh, okay, thanks for that lesson! LOL
I printed out the schematic to where I can put it together, when I am done it should cover 8ft x 6ft (no kidding - 200% off a pdf is a bit much) LOL!
At least I have some 'bling' for the garage!
Take care!
Hi 24moons,
Measure the DC offset of each amplifier. It should be less than 50 mV, anything over 200 mV is a real problem. Look for the emitter resistors and measure there. That's at test points "AA" and "BB". The centre point of the white resistors with three legs near the output transistors.
-Chris
Measure the DC offset of each amplifier. It should be less than 50 mV, anything over 200 mV is a real problem. Look for the emitter resistors and measure there. That's at test points "AA" and "BB". The centre point of the white resistors with three legs near the output transistors.
-Chris
Hi. Okay. I will look up DC offset again (sorry forgot the process). I was putting the black probe on the chassis and 'carefully' probing around.
Is there a way to post you guys photos on this forum? I can type the reading but would like to show you guys there are 'black' and 'green' SCR's (that is what I call them).
I will get at taping my 8ft x 8ft schematic (not kidding - the thing printed 26 pages for a 200% - LOL). This way I can follow back from the switch to the hot side of the relays and then do the DC offset and those two big 5W resistors with the 3 pins at the top...I did get low reading of ohms on them and I believe each one gave a ZERO but do not quote I will go do this very soon.
I appreciate it for sure Chris thank you for your time and help.
- Richard
Hi Richard,
The black probe goes to chassis ground, or speaker negative in this case. The red lead is connected to the output of the amplifiers at the test points which are before the relay. You can also use the centre terminal of the emitter resistors (the white rectangular things with three legs in a line).
-Chris
The black probe goes to chassis ground, or speaker negative in this case. The red lead is connected to the output of the amplifiers at the test points which are before the relay. You can also use the centre terminal of the emitter resistors (the white rectangular things with three legs in a line).
-Chris
Hi Chris,
I measured the emitter resistors and this is what I got.
With the amp's bottom closest to me (the side of the emitter resistors that has no writing) I get:
R189 (this is left Channel)
Pin 1 = 0.072 VDC
Pin 2 = 0.062 VDC
Pin 3 = 0.052 VDC
R190 (Right Channel)
Pin 1 = 0.061 VDC
Pin 2 = 0.052 VDC
Pin 3 = 0.045 VDC
At all speaker terminals reads: 0 VDC
Amp was turned on for 10 minutes before taking the readings...
PS just for the heck of it - all 3 relays had similar readings on their 6 pins but I did not jot them down as I was not sure if it was necessary right now...I was just seeing if there is power to them when the amp was on...Thanks Chris
I measured the emitter resistors and this is what I got.
With the amp's bottom closest to me (the side of the emitter resistors that has no writing) I get:
R189 (this is left Channel)
Pin 1 = 0.072 VDC
Pin 2 = 0.062 VDC
Pin 3 = 0.052 VDC
R190 (Right Channel)
Pin 1 = 0.061 VDC
Pin 2 = 0.052 VDC
Pin 3 = 0.045 VDC
At all speaker terminals reads: 0 VDC
Amp was turned on for 10 minutes before taking the readings...
PS just for the heck of it - all 3 relays had similar readings on their 6 pins but I did not jot them down as I was not sure if it was necessary right now...I was just seeing if there is power to them when the amp was on...Thanks Chris
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Hi Richard,
The readings on the speaker terminals would have to read like an open connection as they are not yet connected to the amplifier outputs until the relay closes. So, zero VDC is expected depending on your meter (some like mine will drift in the mV range due to noise pickup).
The amplifiers look okay, so now to figure out what is preventing the relay from closing. I'll look at the schematic and get back to you later today. I'm thinking you might have some defective supply capacitors in that circuit, or a current detection transistor has failed. They are just signal transistors, cheap.
-Chris
The readings on the speaker terminals would have to read like an open connection as they are not yet connected to the amplifier outputs until the relay closes. So, zero VDC is expected depending on your meter (some like mine will drift in the mV range due to noise pickup).
The amplifiers look okay, so now to figure out what is preventing the relay from closing. I'll look at the schematic and get back to you later today. I'm thinking you might have some defective supply capacitors in that circuit, or a current detection transistor has failed. They are just signal transistors, cheap.
-Chris
Hi Chris.
I figured a cap somewhere as I did some reading but I am in the middle of putting together that 8ft x 8ft diagram! LOL I printed it out as 200% and one inch overlap, so when I have to side by side that is okay but when page 3 goes under page 1 (this is the start of the wiring portion pgs 8 to 12) so it is tricky to line it up as I have to now trim it a bit (tricky)...my gosh I do not think I want to buy another amp again! Or get a printing company to print out a 'hifi-engine' schematic! LOL
This amp is worth saving and I would gladly PayPal you for your help as I appreciate anything...I will be able to follow the diagram better when I can follow the grid...I wish I had an ESR now (bit broke for the good brand - that purple one for around $190 CDN).
Thank you kindly!
-Richard
Hi Richard,
I'll try to help you out, don't worry about Paypal.
The ESR meter is next to useless. What you really do need to measure is Dissipation of the capacitor, and that is the inverse of "Q" in case you have read the term somewhere. For main power filters, look at the waveform with an oscilloscope. Use AC coupling, start in a high range and click down until you get something that looks like a sawtooth. On the leading edge of the charging portion, a capacitor will begin getting a "pip" right at the peak. The higher this "pip" is, the worse the condition of the filter capacitor is. All the other capacitors need to be measured for dissipation. Dissipation is a measure of how much energy is lost in the dielectric. Any loss indicates distortion.
Dissipation is more difficult to measure than ESR, which is just AC impedance, or an AC ohmmeter if you want to describe it that way. Therefore, you need to use a good LCR meter with that function. Older HP is excellent, but not exactly cheap. However, you can measure at a few frequencies (like 1 KHz - the mid of the audio band). These will also measure pure resistance and inductors too. Very handy when building something that would be better with matched capacitors. An old 4261A is an excellent start, I use a 4263A that I bought new over 20 years ago now. That would be excellent. I need a high frequency LC meter even though I have the 4263A (top test frequency is 100 KHz), better than nothing for RF work, but still inadequate.
PM me when you're ready with your diagrams. We will use our normal email addresses for this since we may need to send files - pictures back and forth.
-Chris
I'll try to help you out, don't worry about Paypal.
The ESR meter is next to useless. What you really do need to measure is Dissipation of the capacitor, and that is the inverse of "Q" in case you have read the term somewhere. For main power filters, look at the waveform with an oscilloscope. Use AC coupling, start in a high range and click down until you get something that looks like a sawtooth. On the leading edge of the charging portion, a capacitor will begin getting a "pip" right at the peak. The higher this "pip" is, the worse the condition of the filter capacitor is. All the other capacitors need to be measured for dissipation. Dissipation is a measure of how much energy is lost in the dielectric. Any loss indicates distortion.
Dissipation is more difficult to measure than ESR, which is just AC impedance, or an AC ohmmeter if you want to describe it that way. Therefore, you need to use a good LCR meter with that function. Older HP is excellent, but not exactly cheap. However, you can measure at a few frequencies (like 1 KHz - the mid of the audio band). These will also measure pure resistance and inductors too. Very handy when building something that would be better with matched capacitors. An old 4261A is an excellent start, I use a 4263A that I bought new over 20 years ago now. That would be excellent. I need a high frequency LC meter even though I have the 4263A (top test frequency is 100 KHz), better than nothing for RF work, but still inadequate.
PM me when you're ready with your diagrams. We will use our normal email addresses for this since we may need to send files - pictures back and forth.
-Chris
Okay for sure, I will let you know when I tape the 'wallpaper' in an accurate manner so I can follow the trace.
I just hope I got my switch in somewhat correctly but again the relays do not come on so I think that does not matter right now.
I will dig out the scope.
I am wondering if using the scope is safe as I read somewhere that the 'amp' or its circuit should be 'floating' - just in case I touch the wrong probe in the wrong spot and fry the scope and possibly the amp?
I know the amp plugs in without the ground prong as of course it only has two prongs, but I have to check my scope for two or three prong...otherwise would I need an isolation transformer (one where the earth ground is not 'connected')?
I have a dim bulb tester...I wonder should I plug both amp and scope to that? I know the tester is for preventing a short so the bulb will glow but will it prevent 'smoke theory' or a condition where I may have reversed my probes or put them in the wrong spot?
I will get in touch within the week and PM you when that time is for giving this a go.
I appreciate your time so much, I'd hate to let this amp go I know it is not in rough shape, it is just now a 'fun' puzzle and learning experience for me and may help someone else out there with a similar condition!!!
- Richard
Just read up on the DF, Q, ESR, and Tan. DF is for lower f and Q is you higher...I do not have a function generator, just the scope. I understand that most put a 1khz signal in (I know I have a video somewhere for this or a few but each is for something else for learning I believe).
If I do not have a function generator, would a temp meter/laser work to see if the 'bad cap' has a higher heat or would this amp need more than possibly a cap replacement (I know tough to say at this stage...).
But let me know if I need one if so, for what the amp is worth the cost is an bit of a waste unless I would be using it down the road (which I am thinking I will not - but a nice to have tool)...
If I do not have a function generator, would a temp meter/laser work to see if the 'bad cap' has a higher heat or would this amp need more than possibly a cap replacement (I know tough to say at this stage...).
But let me know if I need one if so, for what the amp is worth the cost is an bit of a waste unless I would be using it down the road (which I am thinking I will not - but a nice to have tool)...
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