Help diagnosing Pyle Receiver PTA66BT with burned resistors

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

The front board or other boards that are connected to the front board are drawing too much current, there are many parts on the board that need to be checked, and there are many connectors on that boards that goes some where else.
You need to find out where those connectors goes to.
See what the pin labels are so we may get ideas if those connectors carry the +/-12V or not.

OK, that makes sense. There is just the one big board in front, and the board that the front display is hooked to. The front display is working so I assume that fine.

I will start poking around and following connectors and see if I can find anything that indicates it involves 12v. What components should I check?

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I need good clear pictures of the whole top and bottom side of the main board so I can see how the +12V (the one with burnt 180 Ohms resistor) and the -12V from the connector are routed to.
+12V and -12V are used for running those 4558 Dual OP-AMP, bu the +12V may also feed other circuit that require just the +12V only, that is why they use 3 Transistors in parallel for the +12V since the +12V has heavier load on it than the -12V.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I need good clear pictures of the whole top and bottom side of the main board so I can see how the +12V (the one with burnt 180 Ohms resistor) and the -12V from the connector are routed to.
+12V and -12V are used for running those 4558 Dual OP-AMP, bu the +12V may also feed other circuit that require just the +12V only, that is why they use 3 Transistors in parallel for the +12V since the +12V has heavier load on it than the -12V.

By main board do you mean the board we have been working on, or the front board that the ribbon cable connects to? I can take better pictures.

One note, I disconnected ALL the ribbon cables on the front board, then put just the main one connecting the power board to the front board, and the problem still occurred. So that would seem to eliminate anything attached to the front board by ribbon cable.

I flipped the front board over and was able to trace the V+ power line to the four 4558P chips on the board (as well as other stuff I didn't trace down yet). I found the datasheet for those chips (https://www.digchip.com/datasheets/p...A4558P-pdf.php) and so I got the pinout for the legs and figured I would check then against each other.

I put my multimeter on resistance, went to the first chip (the closest one to the ribbon cable connector), put the black probe on leg 1 (as indicated in the PDF) and the red probe on leg 2, and got a reading of 21.4 kilo ohms. I then moved the red probe to leg 3 (keeping the black probe on leg 1) and got a reading of 53.6 kilo ohms. I repeated the test on the chip next to it and got identical readings. I tested the next chip in line and got identical readings. But when I got to the 4th chip, I got different readings. With the black probe on leg 1 and the red probe on leg 2, I got 33.8 kilo ohms, and black probe on 1 and red probe on 3, I got a reading of 6.8 mega ohms, and it was slowly climbing. Could that indicate that chip went bad? Are there better ways for me to test those IC's, and what readings should I be seeing?

I will keep tracing that +12v line on the front board and see what else it connects to.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I am sorry, it is the front board where it has bunch of 4558 IC's.
4558 pin 4 is for -VCC (-12V), pin 8 is for +VCC (+12V).
https://cdn.badcaps-static.com/pdfs/...909c6fee16.pdf

Beside the 4558 IC's, what are other IC's on that front board?

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Any idea what readings I should be getting for the 4558p's? All the videos I can find on it are not in English. Unless I am mistaken I would need to turn the unit on to try and measure the voltage from the VCC leg and I don't want to keep the unit on for more than a few seconds so I can try and avoid damaging the components I have already replaced. I am going to put my multimeter to diode mode and check the various legs the diagram indicates as +, -, and out. On a promising note Googling around it looks like other people have had receiver failures that were the results of a 4558 chip gone bad, and they are cheap and look easy to replace. Mine says 4885p, but I see a lot of 4558d for sale, do you know what the difference is?

One thought I am having is removing the IC's 1 by 1 (starting with any that test differently from the rest) and turning the unit on and checking the temp of the resistor each time. If I am following correctly you are saying the issue is something is pulling more than 12v from the power board, which is frying everything in it's path, so if the offending component is one chip, removing that chip should eliminate the issue. I would also loose whatever channel that chip powers. But I would then know what chip to replace. Does that sound like a sensible plan?

Also no one knows where to buy more solder sucker tips? I've scoured Amazon and eBay and can't find them.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Do not keep on trying to power the unit.

Again, what are other big IC's in the left side of the board? Those big IC's may be running on +12V only but we do not know until you tell us what they are.

What resistance do you get on the +VCC pin 8 of the OP-CP and circuit ground?
Are all +VCC pin 8 of the OPAMP are directly connected together? You can easily check that by following the traces.

What resistance do you get on the -VCC pin 4 of the OP-CP and circuit ground?
Are all -VCC pin 4 of the OPAMP are directly connected together? You can easily check that by following the traces.

Where else doe the +12V go to beside +VCC pin 8 of the OPAMP?

I still need good clear pictures of the top and bottom side of this front board.
You have to provide me what I am asking for instead of repeating requests, so I can get the idea how the +12V/-12V are distributed around the board.

There are isolation methods that can be used to isolate the section of the circuit, it can be as simple as lifting jumper, but I cannot tell since I do not have the pictures of the board or the board in front of me to look at.

I am getting close to stop troubleshooting this unit for you.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I will take the pictures and get measurements tonight and post them

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I will take the pictures and get measurements tonight and post them

Make sure to get the part numbers of those large IC's on the left side of the front board so we can look up spec sheets.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I apologize for the pictures, it is a long board and the only camera I have is my smartphone so I have to stitch them together. I can take a better shot of one section if you want to see a particular part of the board.

Again, what are other big IC's in the left side of the board? Those big IC's may be running on +12V only but we do not know until you tell us what they are.

There's only 1 big IC. It has CD2399GP written on one line, and K920 below it. Google says it's an "Echo Processing" chip. I could not follow traces to it, and it did not have continuity to the V+ point I was using, however the datasheet on that chip does show leg one as being +5V (none of the legs are -5V) so that chip does appear to draw power from the V+ line.

All the other IC's on the front board are 4588's. I labeled them A-G in the picture of the top of the board.

What resistance do you get on the +VCC pin 8 of the OP-CP and circuit ground?

Chip A - 9.13 kilo ohms
Chip B - 9.16 kilo ohms
Chip C - 9.17 kilo ohms
Chip D - 9.17 kilo ohms
Chip E - 9.15 kilo ohms
Chip F - 9.20 kilo ohms
Chip G - 9.22 kilo ohms

Are all +VCC pin 8 of the OPAMP are directly connected together? You can easily check that by following the traces.

I used the continuity test on my meter. The VCC+ pins of Chips A, B, C, D, and E are all connected. F and G do not have continuity and I cannot see traces connecting to them.

What resistance do you get on the -VCC pin 4 of the OP-CP and circuit ground?

The resistance reading usually started off around 2.5 to 3.5 kilo ohms and was climbing slowly and then eventually settled on the following

Chip A - 4.72 kilo ohms
Chip B - 4.65 kilo ohms
Chip C - 4.65 kilo ohms
Chip D - This one started at 20 kilo ohms, then dropped to 19 kilo ohms, then the meter flashed and it dropped back down to 4.66 and settled there
Chip E - 4.71 kilo ohms
Chip F - 12.41 kilo ohms. This was a steady reading, no slow climb
Chip G - 94.7 kilo ohms. This was a steady reading, no slow climb

Are all -VCC pin 4 of the OPAMP are directly connected together? You can easily check that by following the traces.

I used the continuity test on my meter. The VCC- pins of Chips A, B, C, D, and E are all connected. F and G do not have continuity and I cannot see traces connecting to them.

Where else doe the +12V go to beside +VCC pin 8 of the OPAMP?

After coming off the ribbon cable, the V+ line goes right into a resistor. Then it loops around and forks, with the top fork going to the 4588's and as far as I can see stopping at the VCC+ pin of Chip E. I marked this (and the solder spots I tested for both V+ and V- on the 4588's) on the picture of the bottom of the board.

The other fork goes to one leg of a capacitor, and then it connects to a large green area that seems to go off in all sorts of directions so I don't know how to trace that.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Post #69
Resistance measurement of -VCC pin 4 of OPAMP 'F' and 'G' readings against Ground:
Chip E - 4.71 kilo ohms.

Chip F - 12.41 kilo ohms. This was a steady reading, no slow climb.

Chip G - 94.7 kilo ohms. This was a steady reading, no slow climb

This must be measurement error since Pin 4 of Chip F is connected directly to pin 4 of Chip G, the readings of both chips should be the same.

See the picture of the bottom side of the board where OPAMP IC 'F' and IC 'G' pin 4 are directly connected together, so the reading of pin 4 of IC 'F' and IC 'G' should be about the same as IC 'E' pin 4.
Please recheck your measurement.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

What are the values of these two resistors? I cannot see them in the picture of the full front board.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Where does the 'X' go to as marked in the picture attached?
What are the value of the two resistors in the picture attached?

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

I will double check the F and G measurements, check those resistor values and take close up pictures of them (front and back), and identify the resistors and "X" and take close up pictures of them (front and back) tonight at the latest.


I apologized that the edge of the board is covered by the black metal lip, that's the actual front cover, I removed every screw and every knob but the board will not come away from it. I used as much strength as I felt comfortable with and it just won't detach and I don't want to break anything

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

As you can see, you have:
1) A set of resistors (waiting for the values in post #71) for feeding +12V and -12V to OPAMP A ~ E.

2 A second set of resistors (100 Ohms as shown in post #70) for feeding the +12V and -12V to OPAMP F and G.

3) A set of resistors (unknown value in post #72) connected in parallel fed by +12v to feed 5.1V Zener to run IC CD2399G.

4) We have unknown point 'X' (see post #72) which is also fed by +12V. You also need to see if the trace goes beyond point 'X' that I marked.

So as you can see the +12V regulator feeds more circuits than the -12V with those extra two loads described in step 3 & 4, that is why they use 3 Transistors in the +12V regulator circuit to handle more loads than the -12V.

In my post #66 I talk about isolating the circuits, as you can see we can easily isolate each set of OPAMP's (A ~ E, F ~ G) from +12V and -12V by lifting the set of resistors, isolating the CD2399G by lifting the two resistors (connected in parallel) feeding the 5.1V Zener, Isolated the connection at the 'X' can be by disconnect what ever connected to 'X' and the trace beyond 'X'.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

See the picture of the bottom side of the board where OPAMP IC 'F' and IC 'G' pin 4 are directly connected together, so the reading of pin 4 of IC 'F' and IC 'G' should be about the same as IC 'E' pin 4. Please recheck your measurement.

I rechecked the measurement and here is what I got. For both F and G, with my meter on Ohm's, when I put the black probe to Ground, and the red probe on the pin 4, I got OL. When I switched the probes and put the red lead on ground and the black lead on pin 4, I got a lot of movement of the numbers, but eventually F settled on 98 kilo ohms and G settled on 97.7 kilo ohms.

What are the values of these two resistors? I cannot see them in the picture of the full front board.

The resistor fed from V- read 47.1 ohms, the resistor fed from V+ read 46.7 ohms.

Here is a better picture of the top of that part of the board.


Here is a better picture of the bottom of that part of the board.

Where does the 'X' go to as marked in the picture attached?

X is one leg of a resistor. The other leg connects to a wire, and that wire leads to the Power On Indicator LED on the front panel. Here are pictures with notes

Closer shot of the underside of that part of the board with X, I marked the resistor and the wire going to the LED


Top of that section of the board with X and the LED marked

What are the value of the two resistors in the picture attached?

Both of those resistores measured 0.245 kilo ohms. Here is a shot of the top section of that board showing the resistors and the zener

So as you can see the +12V regulator feeds more circuits than the -12V with those extra two loads described in step 3 & 4, that is why they use 3 Transistors in the +12V regulator circuit to handle more loads than the -12V.

OK, that makes sense

In my post #66 I talk about isolating the circuits, as you can see we can easily isolate each set of OPAMP's (A ~ E, F ~ G) from +12V and -12V by lifting the set of resistors, isolating the CD2399G by lifting the two resistors (connected in parallel) feeding the 5.1V Zener, Isolated the connection at the 'X' can be by disconnect what ever connected to 'X' and the trace beyond 'X'.

OK, that makes sense as well, removing the resistors will interrupt the ability of whatever on that front board is calling for more than 12V of current. Is that right?

So if I am understanding correctly, the following things are the only things connected to V+

4558 Chip A-F (over pin 8)
CD2399G (Over pin 1)
The Power Indicator LED

So only those things could be calling for more than 12V of power, which would indicate the root cause of the issue is one of those components?

I can say the LED Power indicator light worked fine when the unit was turned on in the past so I don't think it is malfunctioning. What would recommend as the next step? Should I isolate CD2399G since that is just one chip and see what happens then?

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

OK, thank you for all the info provide.
1) Leave the front board unconnected, then power up the unit and then put the meter probe on each end of the 180 Ohms for the +12V to see what the Voltage drops on that resistor is, the do the same on the 180 Ohms resistor for -12V.
Then we can calculate the current flow through each one of those two 180 Ohms resistors to establish the base line of current flowing through the resistors when no load (Front board) connected. Please make sure that the readings are repeat able.

2) Please check the resistance in both directions of 5.1V Zener diode that is connected to pin 1 of CD IC.

3) What is the resistance value of that resistor that is connected to the LED?

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

For #1 would that be a DC volts measurement from each leg of each resistor to the respective V+/V- point? Just want to make sure I am testing right.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

For #1 would that be a DC volts measurement from each leg of each resistor to the respective V+/V- point? Just want to make sure I am testing right.

You will put one probe on one end of the resistor, another probe on the other end of the resistor, it does not matter what color of the probe goes to which end since you have digital meter so it does not care about the polarity, this will show the Voltage drops on the resistor.

Once we get the Voltage reading, we will divide that Voltage reading by 180 Ohms to get the amount of current flow through the resistor, that will be our base line reading for each 180 Ohms resistor.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Vdrops: https://www.swtc.edu/Ag_Power/electr...s_circuits.htm

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

OK, thank you for all the info provide.
1) Leave the front board unconnected, then power up the unit and then put the meter probe on each end of the 180 Ohms for the +12V to see what the Voltage drops on that resistor is, the do the same on the 180 Ohms resistor for -12V.

I put my multimeter to DC Volts for this measurement.

Across the resistor on the V+ rail, I got 2.02V
Across the resistor on the V- rail, I got 2.03V

2) Please check the resistance in both directions of 5.1V Zener diode that is connected to pin 1 of CD IC.

Black probe on the marked side, Red probe on the unmarked side: 7.56 kilo ohms
Red probe on the marked side, Black probe on the unmarked side: 8.9 kilo ohms.

3) What is the resistance value of that resistor that is connected to the LED?

9.8 kilo ohms