Help diagnosing Pyle Receiver PTA66BT with burned resistors

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

OK I took some fresh readings and saw I was not reading my meter correctly.

So first, I wanted to check those zener diodes. I read that in one direction, Black lead to black side and red lead to brown side, I should get low resistance, and flipping the probes should be high resistance or even OL

So I tested Negative power path zenner diode in circuit, and was getting high resistance, like in the Mega Ohms, in both directions. So I decided to remove it to test it out of circuit, plus I needed to take it out to see the letters on it if I need to buy a new one

Out of circuit, it tested like this:
Black probe to black side, red probe to brown side: 6.5 Mega Ohms
Black probe to brown side, red probe to black side: OL

That sounds like it is wrong since it is high resistance in both directions? Also the letters "12V" are printed on the board underneath the zenner diode. the Diode itself has IN4752A written on it and either "5T" or "ST" written below it.

I then checked the other zenner diode on the positive power path in cirucit and was getting the following:
Black probe to black side, red probe to brown side: OL
Black probe to brown side, red probe to black side: 9 Mega Ohms and slowly dropping

Which also seems high in both directions. I'm assuming I got readings in the opposite probe orientation because of the positive and negative power channels

I continued testing the components along the V- path, the first resistor was .57 Ohms, the second resistor was .59 Ohms, and all three transistors measured .5 Ohms from E to C

So I put the diode back in, and rechecked the resistance from resistors to V- and V+ and paid more attention to the meter this time (near leg is the leg closer to V-/V+ pin)

Good resistor to V-
Near leg: ~5.45 Mega Ohms (fluctuated a little, 5.43 to 5.46 or so)
Far leg: ~5.45 Mega Ohms (fluctuated a little, 5.43 to 5.46 or so)

Good resistor to V+
Near leg: 7.1 Mega Ohms
Far leg: 7.08-7.09 Mega Ohms

Double checked resistor, it's read 179 Ohms. I am assuming I am not seeing a difference in the two legs because an 180 Ohm difference will be to small for my meter to show in Mega Ohms.


Burned Resistor to V-
Near leg: OL
Far leg: OL

Burned Resistor to V+
Near leg: 5.4 Ohm
Far leg: 180 Ohms
(Yes these were both Ohms not Mega Ohms. I checked 5 times)

Double checked resistor, it's read 174 Ohms.


All the readings from the GND area still read the same, rapid increase to 1.9 Kilo Ohms, then flash OL, then discharge from there. I tried measuring from V- and V+ to a black speaker terminal, and got the same thing, I looks at where the power came into the board and tried to trace that ground, the issue is the ground connects to the + and minus paths, and both of those each go through a fuse and then into a series of relays which are currently open (since the unit is unplugged and off) so nothing can get to ground.

I checked all around the V+ and V- for a ground but couldn't find anything that would give me a reading other than capacitor legs which just charged up and then discharged.

Ramps up quickly to 1.9 kilo ohms, then flashes OL, then shows 7.8ish kilo Ohms, it will slowly keep climbing, and if I take my probes off and then put them back on it will show it slowly going down. If I wait a few minutes I can repeat that process. I do see where the green is connecting them, to my untrained eye it looks like 2 capacitors in series.

Ideas for next steps?

You messed up badly about which power supply is for V+ (+ Voltage supplied by BURNT resistor) and the V- (Minus Voltage supplied by good resistor).

1) Your measurement: I continued testing the components along the V- path, the first resistor was .57 Ohms, the second resistor was .59 Ohms, and all three transistors measured .5 Ohms from E to C.

The section with 3 Transistors is for the V+ which is fed by the burnt out resistor. So why are you referring it as V-?

Since your resistance reading of the 3 Transistors (connected in parallel) E-C is 0.5 Ohms, these Transistors for the V+ ARE SHORTED!

2) Also these readings from you:
Burned Resistor to V+
Near leg: 5.4 Ohm
Far leg: 180 Ohms
(Yes these were both Ohms not Mega Ohms. I checked 5 times)

The resistance of the near leg of the resistor to V+ should be 0.5 Ohms because you indicated that the 3 Transistors E-C show 0.5 Ohms as you stated., you must recheck that, also see the schematic as how E and C of the Transistors are connected to the burnt resistor and to the V+ terminal.

3) I do not know why you are messing with the V- section. Hope fully you did not mess up putting the parts back in wrong.

4) Did you not look at so many pictures I spent so much time to provide to you? It clearly shows which one is for V+ (the one with burnt out 180 Ohms resistor) and V-.

5) My patience is running out due to getting bad data and attention not being made by OP after I spend so much time explaining and providing the pictures and the schematics. Nothing to do with being a noob, but for not paying attention and not think logically when looking own data.

6) We are up to over 40 posts and still getting wrong DATA.

Conclusion, you have shorted Transistors (3 are connected in parallel) in the V+ regulator circuit:
1) It can possible mean that the Loads on the V+ are shorted, more testing to be done.
2) If the Transistors shorted out first then more than 12V will be dumped to the loads connected to the V+ which can cause damage to the loads.
3) More damages could have been done to the loads when OP put in the new resistor but the Transistors were already shorted out so more than 12V is dumped into the loads again.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Look, I appreciate the help, but there's no need to be aggressive. I'm doing my best and people make mistakes. If you think I did something wrong just point it out and I will recheck. I am not used to working with circuit boards and it's difficult for me look at a jumble of solder points and try to make sense of it all. Thank you again for all your help so far, going forward I will endevour to be more meticulous in my testing and try to get cleaner data.

You messed up badly about which power supply is for V+ (+ Voltage supplied by BURNT resistor) and the V- (Minus Voltage supplied by good resistor).

OK I just rechecked the picture and you are right, I got confused. So, going forward, I will only test the V+ path, which is the path connected to the burned resistor. I was testing both to have a comparison, but since that is confusing me, I will limit myself JUST to V+ from this point forward. I'm going to take some heat tape and physically put tape over the V- path so I know it is out of consideration.

Since your resistance reading of the 3 Transistors (connected in parallel) E-C is 0.5 Ohms, these Transistors for the V+ ARE SHORTED!

OK, so that's progress! I have more of those transistors on the way to me, I'm assuming I will need to replace them?

2) Also these readings from you:
Burned Resistor to V+
Near leg: 5.4 Ohm
Far leg: 180 Ohms
(Yes these were both Ohms not Mega Ohms. I checked 5 times)

The resistance of the near leg of the resistor to V+ should be 0.5 Ohms because you indicated that the 3 Transistors E-C show 0.5 Ohms as you stated., you must recheck that, also see the schematic as how E and C of the Transistors are connected to the burnt resistor and to the V+ terminal.

I will recheck again but I am pretty sure those are the readings I got. I will triple check the transistors as well.

Conclusion, you have shorted Transistors (3 are connected in parallel) in the V+ regulator circuit:
1) It can possible mean that the Loads on the V+ are shorted, more testing to be done.

What would you like me to test to determine that?

2) If the Transistors shorted out first then more than 12V will be dumped to the loads connected to the V+ which can cause damage to the loads.

I don't know what you are referring to by "loads" can you clarify? Do you mean the other components?

3) More damages could have been done to the loads when OP put in the new resistor but the Transistors were already shorted out so more than 12V is dumped into the loads again.

I have checked that new resistor many times and it's still good, the one time I turned the unit on (before you cautioned me not to) I only had it one for a few seconds and the resistor did not burn up.


Edit: A massive storm just rolled through and flooded out my basement where my workstuff is, so this whole project will have to go on hold for a few days until it is dryed out and cleaned up

[petehall347]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

good part is those transistors should be easy to find by the bagful .. and cost pennies . to test remove them all to test as circuit is parallel transistors ..... you will need 3 matched ones or maybe upgrade to one big one . cant remember seeing any balancing resistors in the circuit . check them if present . hope i aint talking shit as been on the pop tonight in this meltdown weather

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

good part is those transistors should be easy to find by the bagful .. and cost pennies . to test remove them all to test as circuit is parallel transistors ..... you will need 3 matched ones or maybe upgrade to one big one . cant remember seeing any balancing resistors in the circuit . check them if present .

I have 25 pairs of S8550 & S8050 1.5A 0.625W TO-92 PNP / NPN audio transistors on the way to me now, which should be what I need. At that point I will have the caps, resistors, zener's, and transistors to replace every component on both V+ and V- if I wanted to. Will be here next week, just in time for the basement flooding to be recovered from

hope i aint talking shit as been on the pop tonight in this meltdown weather

I had water literally shooting out of my basement walls, and pouring like a fountain in through the window. I've never seen that happen outside of bugs bunny cartoons before.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Water is finally gone and I can get back to the project, although there's not much to do but wait for parts to arrive. When they do I think I'm just going to replace everything on that V+ rail. It's only 9 components, 3 of which are transistors that budm said were shorted, so whats a few more solder joints.

I'll report back with the results when the job is done.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

https://www.badcaps.net/forum/attach...1&d=1596764661
How about point A to point B resistance?
Also V+ and Gnd?
V- and Gnd?

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

https://www.badcaps.net/forum/attach...1&d=1596764661
How about point A to point B resistance?
Also V+ and Gnd?
V- and Gnd?

A to B resistance: 0.1 Ohms. Checked 3 times

I cannot test to "GND" because as you indicated, GND is two points, A and B

A to V-: ramp to 1.9 kilo ohms, then flash OL, then 6.5 kilo ohms and climbs slowly

A to V+, same thing

B to V-: same thing

B to V+: same thing

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

A to B resistance: 0.1 Ohms. Checked 3 times

I cannot test to "GND" because as you indicated, GND is two points, A and B

A to V-: ramp to 1.9 kilo ohms, then flash OL, then 6.5 kilo ohms and climbs slowly

A to V+, same thing

B to V-: same thing

B to V+: same thing

I have you test the resistance between A and B because in one of your post you indicated about 5 Ohms reading which I know it must be measurement error, so A is connected to B as I described, they are connected to GND so that is why I marked it to be used it as GND ref points for testing.
So V- and V+ are not showing low Ohms readings, but it does not mean there is no problem with loads connected to V+, V-, 5V.
Once you replace the damaged parts in the V+ regulator section and perform good visual inspection and soldering works then you have to disconnect that connector that goes to the other board before powering up the unit to verify if the Output Voltage of the regulators are good or not.
I still need to see the pictures of other boards to see what they have on the boards.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Once you replace the damaged parts in the V+ regulator section and perform good visual inspection and soldering works then you have to disconnect that connector that goes to the other board before powering up the unit to verify if the Output Voltage of the regulators are good or not.

Would that be a DC Volt measurement between GND (either A or B) and V+ and V-? Would my expected readings be 5V (for GND to V+) and -5V (for GND to V-)?

I still need to see the pictures of other boards to see what they have on the boards.

I can take a picture later. There is only one other board, its what the knobs and display are attached to. Mostly just a big row of potentiometers.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Would that be a DC Volt measurement between GND (either A or B) and V+ and V-? Would my expected readings be 5V (for GND to V+) and -5V (for GND to V-)?

I can take a picture later. There is only one other board, its what the knobs and display are attached to. Mostly just a big row of potentiometers.

Since you indicated that the Zener diode is 12V, that will mean the V+ and V- will be about + 12V and -12V.
Use either A or B as GND ref.
Right now we are hoping that the circuits fed by shorted out V+ are not damaged since the Voltage can be 20V or more.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Since you indicated that the Zener diode is 12V, that will mean the V+ and V- will be about + 12V and -12V.
Use either A or B as GND ref.
Right now we are hoping that the circuits fed by shorted out V+ are not damaged since the Voltage can be 20V or more.

My hope is that the resistor acted kind of like a fuse and didn't allow the excess voltage by it and then when it burned up and it broke the circuit. I guess we'll see.

[petehall347]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

yes resistors can be like fuses .but fuses are to protect against fire not further damage .

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

yes resistors can be like fuses .but fuses are to protect against fire not further damage .

Hence the word "hope"

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

OK, update time.

My transistors showed up today. I removed the three transistors in the board, when one of the was coming out the legs just snapped right off it and I was barely tugging on it. I tested the other 2 out of circuit and they were definitely testing bad based on what Google told me they should test.

So I put in the 3 replacement transistors. I then plugged the unit it, turned it on with my finger on that resistor, and same thing, after about 5 seconds or so it got really hot, so I turned it off.

I the replaced the three capacitors on that same power rail. Plugged it in, finger on resistor, same thing. I literally had the device on about 5 seconds each time so I don't think it hurt anything, and besides, I am going to have to turn the thing on someday.

I checked the small resistors and they tested the exact same as the same resistor in the good V- rail, so I didn't bother replacing those. That only leaves that one zener diode and I am still waiting on my replacement to show up.

However, while I was in there and my new 3300mf caps had arrived, I figured I would swap those out too. So I removed the 6 caps that were there, went to install the new ones ... and they were the wrong kind. They have 1 wire coming out of each end, instead of two wires out of one end, and it's way too cramped to get 6 of those in the holes in the space allotted. So I am going to order another batch of big caps. Which means more waiting.

I did test those with the Ohm setting on my meter and one of them did seem to test a little differently, but it was hard to tell with the numbers jumping around. Either way now that they are out I'm not putting any of them back in

Here's a picture of the front board

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

The Zener Diodes are showing up monday and the new capacitors will be here Tuesday.

Also if me turning it on for a few second damaged the transistors, I bought 25 of them so I can swap them out again. Once the zener's show up I will have more than enough parts to replace anything on that power rail multiple times.

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Did you disconnect the connector that goes to the front panel as suggest before powering up the unit to make sure the regulators section are working OK and putting out +12 and -12V?

My post #48:
"Once you replace the damaged parts in the V+ regulator section and perform good visual inspection and soldering works then you have to disconnect that connector that goes to the other board before powering up the unit to verify if the Output Voltage of the regulators are good or not.
I still need to see the pictures of other boards to see what they have on the boards."

[budm]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

So the connector on the right edge of the panel board goes to the power amplifiers/power supplies board connector that have 5V, V+, V-?
There are lots of IC's on that front panel board that get the power from 5V, V+, V- power supplies.

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Yes that connector goes to the front board. A while ago I had check for continuity between the end of the wire and it all checked out

When the components show up I will put them in, take the connector off, and try and grab that voltage

Btw does anyone know where to buy more if these? The little tapered plastic tips for solder suckers. I can't find them anywhere

[SluggerB]

Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

OK, update time.

My Zener diodes and new capacitors showed up. I took out the old Zener Diode and tested it out of circuit and it actually seemed to test fine (it matched the new one) but I put the new one in just in case.

Here's one weird point, for those 6 large capacitors, as I started putting them in, I noticed on the board it was printed 2200mf 35v. But the original capacitors were 3300mf 35v. I quadruple checked to make sure I wasn't hallucinating. I don't know why they would be different. Either way I put in the new caps (They are 3300mf 35v).

I made sure all my solder connections were good. I then removed that black cable from the connector on the front board (the connector on the power board side we are working on is not removable) and turned the unit on. With the unit on, I took DC Volt measurements from GND to V+, and got 11.62v. I also checked GND to V- just to compare and got -11.96v. I was elated since that's what budm told me to expect. I flipped the board over and felt the resistor and it was cool to the touch. I kept the unit on for a few minutes and it stayed that way.

So I powered off the unit, plugged the ribbon cable back in, turned the unit on... and the resistor started heating up again. I was heartbroken. I took the ribbon back out, and again it was stable (although unusable since the front controls are unplugged).

With the ribbon cable out I checked the voltage from the V+ and V- pins in plastic connecter to ground (the heatsink worked for a ground) and got 11.64 and -11.99, as expected.

So at this point the power rails all seem to be working, but that resistor is still overheating when the front panel board is plugged in. An ideas what to check next? I checked all the knobs using the Ohm setting on my multimeter and they all checked out the same. Those IC chips on the front board have KIA4558P 928 written on them, Google tells me they are amplifier IC's. I got the pinout but am not sure what to check.

Ideas for next steps?

[budm]

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.