Try connecting the emitter of Q504 to the secondary ground (any point connected to the C or K grounds).
Yes. A via could be open.
Yes. A via could be open.
im not sure what a secondary ground is? for testing purposes, do you think direct connection from emitter on q504 to rca shielding for non bridged outputs might work? just to see as that might be fairly easy to test.
I dont know that the C or K grounds are. If you are referencing that from the schematic, I was having a trouble deciphering how that all translated.
I dont know that the C or K grounds are. If you are referencing that from the schematic, I was having a trouble deciphering how that all translated.
Connect the emitter to one of the non-bridging terminals.
What is it that you don't understand from the diagram?
What is it that you don't understand from the diagram?
Jumpered from emitter at q504 to the inner non bridgeable speaker terminals and mute light went orange instead of yellow. then status light went orange. Removed jumper and now both light are orange. ugh.
The part on the schematic that is confusing is where on the right side on say, page 21, there are black circles with alphabetical letters and a brief description of the properties of that circuit. but those letters dont seem to match up elsewhere in the next diagram?
The part on the schematic that is confusing is where on the right side on say, page 21, there are black circles with alphabetical letters and a brief description of the properties of that circuit. but those letters dont seem to match up elsewhere in the next diagram?
let it sit for a minute unpowered and now the status light stays green, but mute light is still orange. Note, this is a different symptom from what I started with as the mute light used to be yellow, not orange.
is page 21 bthe printed page or the PDF page? Use the PDF page.
If the emitter of Q504 is still not at ground, there is still a problem with that.
If the emitter of Q504 is still not at ground, there is still a problem with that.
page 21 was reference to the pdf. actual page looks like its 27.
checking again and now it appears that the emitter on q504 has continuity to chassis ground. Its still open between the non bridgeable inner speaker terminals as well as the RCA shielding.
I do have continuity between the inner speaker terminals and the RCA shielding though.
checking again and now it appears that the emitter on q504 has continuity to chassis ground. Its still open between the non bridgeable inner speaker terminals as well as the RCA shielding.
I do have continuity between the inner speaker terminals and the RCA shielding though.
So, the emitter is at 0v instead of 5v?
Is the relay engaging?
PDF page 21 goes to PDF page 23. Your version has 38 total PDF pages, correct?
Is the relay engaging?
PDF page 21 goes to PDF page 23. Your version has 38 total PDF pages, correct?
emitter now is at 195mV on q504.
relays are not engaging and have not the entire time ive had this thing.
38 pages on my pdf. the schematic is titled "schematic diagram 1/2" for the part that i am not getting with the black circles to the right and and letters inside the circles.
do you think maybe there is more than one open gnd issue? I cant really see anything that indicates it, but looking at the schematic, the emitter connection from q504 connects to a ton of other components. Would a prudent approach be to test each connection based on teh schematic starting with the emitter from q504 as reference?
relays are not engaging and have not the entire time ive had this thing.
38 pages on my pdf. the schematic is titled "schematic diagram 1/2" for the part that i am not getting with the black circles to the right and and letters inside the circles.
do you think maybe there is more than one open gnd issue? I cant really see anything that indicates it, but looking at the schematic, the emitter connection from q504 connects to a ton of other components. Would a prudent approach be to test each connection based on teh schematic starting with the emitter from q504 as reference?
DCV on all terminals of Q504 and Q531 again?
At this point, I'm just trying to logically get through the circuit to see what the problem is.
I'm not understanding what you're not understanding. The letters show the connections between the circuits on PDF page 21 and 23 (or any of the other partial sections of those 2 diagrams).
At this point, I'm just trying to logically get through the circuit to see what the problem is.
I'm not understanding what you're not understanding. The letters show the connections between the circuits on PDF page 21 and 23 (or any of the other partial sections of those 2 diagrams).
testing today and both leds are orange. when the status LED was green, current draw from the power supply was about 3a. not its 250mA with both lights orange
q504-
b-140mV
c-8.37v
e-140mV
q531-
b-8.40v
c- 140mV
e- 8.40v
I see now on the schematic. I think it was throwing me off with the letters not being alphabetical.
so, while testing the above and leaving the power supply on. the status light has now changed to green (mute light still orange), and the current draw from the power supply is up to 3a now. In this state, here are the readings from teh two transistors
q504-
b-115mV
c-8.37v
e-115mV
q531-
b-8.40v
c- 115mV
e- 8.40v
another thing I observed is that the area around r734, r735, zd710, and zd709 were quite hot to the touch. This area of the board was pretty gross when I started and both r734 and r735 are new since the originals we basically black. the zeners are still the originals.
q504-
b-140mV
c-8.37v
e-140mV
q531-
b-8.40v
c- 140mV
e- 8.40v
I see now on the schematic. I think it was throwing me off with the letters not being alphabetical.
so, while testing the above and leaving the power supply on. the status light has now changed to green (mute light still orange), and the current draw from the power supply is up to 3a now. In this state, here are the readings from teh two transistors
q504-
b-115mV
c-8.37v
e-115mV
q531-
b-8.40v
c- 115mV
e- 8.40v
another thing I observed is that the area around r734, r735, zd710, and zd709 were quite hot to the touch. This area of the board was pretty gross when I started and both r734 and r735 are new since the originals we basically black. the zeners are still the originals.
perhaps the next step is to check continuity for the following components in case a via has an open circuit?
q507, q505, q504, r503, e502, q503, c501, e501, e530, zd530, e720, r730, r738, e718, e717, r737, e716, all to ch801 pin 5.
q507, q505, q504, r503, e502, q503, c501, e501, e530, zd530, e720, r730, r738, e718, e717, r737, e716, all to ch801 pin 5.
Please do NOT use a hyphen for a separator.
It appears that your 12v supply voltage has dropped. What is the DC voltage on the B+ and remote terminals?
It appears that your 12v supply voltage has dropped. What is the DC voltage on the B+ and remote terminals?
sorry, I get how that might be an issue. will use equal sign in the future.
DC voltage as measured on b+ with reference to negative dc polarity at the terminal block is 13.9.
an observation that I see is that if it sits a while, it will have an orange status light, but if its powered up for some time, the status light will illuminate green. this can be repeated in something like ten minute intervals. but if its left unpowered for an hour or so, it will illuminate the status light to orange. yellow is no longer present on the mute led since yesterday.
any thoughts on those resistors and zeners getting hot?
DC voltage as measured on b+ with reference to negative dc polarity at the terminal block is 13.9.
an observation that I see is that if it sits a while, it will have an orange status light, but if its powered up for some time, the status light will illuminate green. this can be repeated in something like ten minute intervals. but if its left unpowered for an hour or so, it will illuminate the status light to orange. yellow is no longer present on the mute led since yesterday.
any thoughts on those resistors and zeners getting hot?
Are you sure that neither Q504 or Q531 are shorted?
Are you sure that you have the pin configuration right?
Are you sure the voltages are accurate?
If the voltage across the Zeners is about what the service manual says they should be, the heating is likely normal.
Are you sure that you have the pin configuration right?
Are you sure the voltages are accurate?
If the voltage across the Zeners is about what the service manual says they should be, the heating is likely normal.
I am not sure if either q504 or q531 are shorted. Is there a way to test them in situ, or should I remove them and test them?
I am referencing the pin configuration based on the component position diagram in the repair manual the comes before the schematic. It shows base and emitter position on the board as seen by the soldered side of the board, so thats what I am going on.
I am testing with a fluke 97 scopemeter and verifying voltage from the power supplies digital readout and what is displayed on the meter screen. So, pretty sure the readings are accurate. I just double checked the voltages at the pins for q504 and q531 again and they are the same as they were yesterday.
looking through the service manual, I am not seeing a voltage spec for the zeners. So, I used chassis ground as reference and checked them with the following results:
zd710 anode= -16mV
zd710 cathode= +3mV
zd709 anode= +6mV
zd709 cathode= +7mV
I am thinking there may be an issue with the zener readings? But also there is the ground that we are missing too. Would it be prudent to do a continuity test between the components I listed above in the other post to see which ones may be missing a ground?
thanks again for taking the time to help me. Its much appreciated!
I am referencing the pin configuration based on the component position diagram in the repair manual the comes before the schematic. It shows base and emitter position on the board as seen by the soldered side of the board, so thats what I am going on.
I am testing with a fluke 97 scopemeter and verifying voltage from the power supplies digital readout and what is displayed on the meter screen. So, pretty sure the readings are accurate. I just double checked the voltages at the pins for q504 and q531 again and they are the same as they were yesterday.
looking through the service manual, I am not seeing a voltage spec for the zeners. So, I used chassis ground as reference and checked them with the following results:
zd710 anode= -16mV
zd710 cathode= +3mV
zd709 anode= +6mV
zd709 cathode= +7mV
I am thinking there may be an issue with the zener readings? But also there is the ground that we are missing too. Would it be prudent to do a continuity test between the components I listed above in the other post to see which ones may be missing a ground?
thanks again for taking the time to help me. Its much appreciated!
For the Zeners, measure the voltage across them with the amp powered up.
Shorted transistors will read 0 ohms between the shorted terminals in the circuit or out.
If you remove Q503, does the relay engage?
Shorted transistors will read 0 ohms between the shorted terminals in the circuit or out.
If you remove Q503, does the relay engage?
zd710 reads 0 volts when amp is powered up regardless of meter probe polarity.
zd709 reads +840mV with negative lead on anode and positive lead on cathode. -840mV with positive lead on anode and negative lead on cathode
checked both transistors in situ and no direct short. lowest resistance observed was about 10k ohm.
removed q503 and no change.
Regarding the relays, it should be noted that neither one of the relays have been engaging at any point. There are two. I dont know if its possible for one side of the amp to engage a relay and the other not to.
zd709 reads +840mV with negative lead on anode and positive lead on cathode. -840mV with positive lead on anode and negative lead on cathode
checked both transistors in situ and no direct short. lowest resistance observed was about 10k ohm.
removed q503 and no change.
Regarding the relays, it should be noted that neither one of the relays have been engaging at any point. There are two. I dont know if its possible for one side of the amp to engage a relay and the other not to.
DCV on all terminals of Q504 with Q503 out of the circuit?
Were the resistors R733 and R734 heating up when you read the voltage on the Zeners?
Were the resistors R733 and R734 heating up when you read the voltage on the Zeners?
q504= b=154mV c=8.6V e=154mV
q503= b=154mV c=6.4V e=154mV
I made a mistake in the previous test and removed q504 to see if the relays would activate, not q503. Presently, both q504 and q503 are removed from the board. Should I redo the test with q503 removed and q504 installed to see if the relays activate?
Its a little difficult to touch the resistors next to the zeners on the board, but its quite hot on the solder side of the board where the resistors are. This is happening when I am not testing the zeners with the meter.
q503= b=154mV c=6.4V e=154mV
I made a mistake in the previous test and removed q504 to see if the relays would activate, not q503. Presently, both q504 and q503 are removed from the board. Should I redo the test with q503 removed and q504 installed to see if the relays activate?
Its a little difficult to touch the resistors next to the zeners on the board, but its quite hot on the solder side of the board where the resistors are. This is happening when I am not testing the zeners with the meter.