NOCO GB70 repair help - Page 1
Forum section: electronics / repair

author: AN86
author_rank: Contributor
timestamp: September 15, 2024, 04:51:18 pm
content: Hello, a friend of mine give NOCO GB70 to me. Its dead,Just red light is iluminated, dont charge, cant turn on.I open it and on quick look, its all ok. Battery is on 11.8V ,its not full but i guess its not empty either. Fuse is good, not burned.Can you give me some directions if there is any know fault or where to look for problem.Thanks in advance.

author: jerryk
author_rank: Regular Contributor
timestamp: September 16, 2024, 04:25:17 am
content: First - Disconnect the JST connection from the battery to the board.Second - Do not try to desolder any components as parts of the main board are still under power.From there can you post a photo the board and the date code of the device which is printed on the side of the case. Good new is the battery is still viable. The GB70 can blow the relays and that can be a daunting repair. However, most of the time it's not terrible to repair. As a start, confirm all switches are functional.Jerry

author: eurgenca
author_rank: Regular Contributor
timestamp: September 16, 2024, 05:33:23 am
content: Which red 25% or !.

author: AN86
author_rank: Contributor
timestamp: September 16, 2024, 10:37:15 am
content: Thanks for fast repay.Switches are ok. I tested that first. This evening ill take a picture of the board numbers. "!" Error light is on.

author: jerryk
author_rank: Regular Contributor
timestamp: September 16, 2024, 03:54:23 pm
content: Also disconnect both the relay and NTC plugs and check both for proper function.Jerry

author: AN86
author_rank: Contributor
timestamp: September 17, 2024, 06:55:54 am
content: I fall a sleep evening so i didnt do anything, i did take a picture before i left to work.Idid try to disconnect everything and start it but nothing happen.Its dead as before

author: jerryk
author_rank: Regular Contributor
timestamp: September 17, 2024, 05:10:24 pm
content: It will not start with any of the plugs disconnected. If able you need to check the resistance across the NTC and the relay coils. If you have a 12V power supply power the relay coil and check that the relay is engaging and it's internal points are making a connection. Do this with the cables disconnected from the board. Then check each cell voltage and make sure they are even. Then reconnect all cords and check that there is power to S1 On/Off switch. If the switch is powered then press it and see that it powers up IC6 which is the LDO that powers the microcontroller. The LDO output should be 3.3V. This should get you started.Be careful when probing this board under power. The Holtek MCU's seem to zap quite easily. Under no condition do you want to remove any of the board components under power. This means you have unplug all connection plugs and desolder the black ground wire that's connected to the board below the R106 in your photo.Good luck - Jerry

author: AN86
author_rank: Contributor
timestamp: September 17, 2024, 05:16:18 pm
content: Thanks for directions. Ill put kids to sleep in hour or two and start to test.In meanwhile i test as i believe is temperature sensor for battery.2 pin connector and it said around 15-16kiloohm. So i believe this part is working. Was 16.8 a bit later was colder few degrees and it was 15.3.Later ill try test and ill post what i find.ThanksEdit:All cells are 3.7v

author: AN86
author_rank: Contributor
timestamp: September 18, 2024, 01:04:59 am
content: I did the test you recommended. Big two relays are working, connected tham to 12V and they clicked and continuity test said it connects inside the relay, but testing IC6 is strange. I measure and write it on the picture I attached. Did i measure something wrong or there is the problem? Since you said Holtek MCU is a little tricky to measure i decide to leave it as it is for now.

author: jerryk
author_rank: Regular Contributor
timestamp: September 18, 2024, 01:25:44 am
content: Those measurements are definitely wrong. You have a short to ground on the board somewhere and just hope it's not at the MCU. Can you read me the number off the MCU. I think I know what it is but you need to identify the input pins and the measure the resistance across the input decoupling capacitor.Also this fits the error you are seeing. I assume the red error light was solid?Jerry

author: AN86
author_rank: Contributor
timestamp: September 18, 2024, 02:35:00 pm
content: Now it dont even illuminate "!". But if i need 3.3v and i have 1.2 that drops to 0.7 in few sec then its definitely a problem.I add picture of the oder side of the board. I hope the number helps. It said veersion G, its blocked by the wire in the picture.

author: AN86
author_rank: Contributor
timestamp: September 18, 2024, 03:00:05 pm
content: MCU picture

author: jerryk
author_rank: Regular Contributor
timestamp: September 18, 2024, 04:11:40 pm
content: C21 should be your decoupling capacitor to VDD and VSS. With all plugs removed can you check the resistance across C21. It should read around 4K. It should not read in the low ohms region. When you tested your relays did you disconnect all plugs?Jerry

author: AN86
author_rank: Contributor
timestamp: September 18, 2024, 07:33:14 pm
content: On C21 it reads 3.4 ohm. And continuity test is beeping.When tested relays i disconnect all plugs, didnt want to risk anything. How can i know the rating of this component? I believe its capacitor according to looks and C name on it.

author: jerryk
author_rank: Regular Contributor
timestamp: September 18, 2024, 07:59:44 pm
content: Your MCU is most likely shorted as in failed. I don't recall the capacitance value of C21 but the symptoms here are not good.The LDO which is IC6 has a direct path from its output to pin24 on the MCU which is VDD. I doubt the short is at the capacitor but you would have to remove it to be sure.Jerry

author: AN86
author_rank: Contributor
timestamp: September 18, 2024, 10:47:41 pm
content: Guess ill have to remove capacitor and see. Ill do it and let tou know what i find out, and hope for best

author: AN86
author_rank: Contributor
timestamp: September 21, 2024, 04:31:48 pm
content: I did remove capacitor and replace it with lets say similar, i know its not good choice but i wanted to see if there will be any difference, and it didnt make a difference. But i notice something. On the board next to the IC6, which gives output of 1.2 and than drop to 0.8V, there is a probably test dot that said 3.3v. and when i probe it i have exactly as on the output pin on IC6, and then another test spot that has label 12v and on that spot i have 0.004V which is crazy and i guess maybe there is a problem. On the cylindrical capacitor behind the board near that spot i dont have 12v only ground. And capacitor is polarised. Ill try to snoop around. Picture attached just in case i didnt explain good.

author: jerryk
author_rank: Regular Contributor
timestamp: September 21, 2024, 07:43:38 pm
content: Your voltage regulator IC6 is shorted between the output and ground. This can further drain your battery. Odds are the short is at the MCU. Can you measure the temperature of IC6 by chance?Jerry

author: AN86
author_rank: Contributor
timestamp: September 21, 2024, 09:49:44 pm
content: I have that ebay digital laser thermometer. I try with him and let you know.

author: eurgenca
author_rank: Regular Contributor
timestamp: September 22, 2024, 06:35:59 am
content: Check ZD2 and ZD5 for short. Usually 5V1 diode go short. If so replace it and if you are lucky you good to go.

author: AN86
author_rank: Contributor
timestamp: September 22, 2024, 07:34:16 pm
content: ZD2 is beeping on continuity test. And on diode test on DMM it said 0.002V. but continuity test is beeping so i guess its bad.Is there any value specific i need to ask in store?

author: jerryk
author_rank: Regular Contributor
timestamp: September 22, 2024, 07:44:08 pm
content: You cannot test ZD2 in circuit. You have already taken the resistance at C21 which was 3.4 ohms so this will be the same at ZD2. The only way to test ZD2 under current conditions is the remove it. FWIW if ZD2 is shorted when you remove it your jump pack will start working if was the only issue. Once you remove ZD2 if no change in symptoms then check the resistance again across C21 or ZD2 pads and see if it is still 3.4ohms or thereabouts.Jerry

author: eurgenca
author_rank: Regular Contributor
timestamp: September 23, 2024, 04:54:44 am
content: Like I told you. Replace ZD2 with 5V1 diode, and if you LUCKY you are good to go, but probably not. Next step is to check douther board if you will have problems with charging. If CPU is bad you are stuck.

author: AN86
author_rank: Contributor
timestamp: October 05, 2024, 12:54:34 pm
content: In my store they dont have zener diode in smd variant,so i did solder this one just to try and i guess its working. I will order smd from the internet and after i solder it ill send if its working on car or not.

author: eurgenca
author_rank: Regular Contributor
timestamp: October 07, 2024, 05:49:54 am
content: Connect charger and check if consuming current. You still have chance for ghost charging effect.

author: AN86
author_rank: Contributor
timestamp: October 09, 2024, 04:05:00 pm
content: You were right, i have ghost charge effect,it charge all night on that round charger from cigaret lighter plug and nothing, but when i put it on USB it charge on 100% and green light is on. After i connect it to car battery, charge % leds starts to flash from 25-100% but nothing happen. I guess i have to hear some relay. Those 2 big ones on negative terminal if i remamber right.

author: eurgenca
author_rank: Regular Contributor
timestamp: October 10, 2024, 06:28:59 pm
content: Check pin 26 of CPU (from memory, will confirm tomorrow) resistance to GND and write it down.

author: eurgenca
author_rank: Regular Contributor
timestamp: October 11, 2024, 12:58:34 pm
content: No sorry pin 27.

author: AN86
author_rank: Contributor
timestamp: October 13, 2024, 02:12:04 pm
content: I measure it and take a picture, not sure if that ok or not but i guess its not.I mark arrow where did i measure, just in case i did miss PIN 27.

author: eurgenca
author_rank: Regular Contributor
timestamp: October 14, 2024, 05:55:58 am
content: Well, this is the end, my friend.Your CPU is busted. You will confirm that by lifting this pin, and if resistance is still low on CPU pin, then...Here is a chance to invite other members. I don't ovn holtek programmer if someone have we can try to read content if not locked.

author: jerryk
author_rank: Regular Contributor
timestamp: October 14, 2024, 06:33:18 am
content: Quote from: eurgenca on October 14, 2024, 05:55:58 amI have a Holtek programmer but if you look closely at the circuit board pics in the early posting, notice the lack of programming headers that is present on most all of the other NOCO jump pack line. On the GB70 it's an OTP MCU so even if...The R series MCU in question is not for sale to the public and is only available to the OEM vendor (AFAIK).I sure felt bad about being the grim reaper about the MCU but when you said to check the input protection diode I sure was hoping it was the only issue as this would have been such a simple fix. I am curious as to why you checked pin 27 for resistance. Typically that pin (PA5) is the latching circuit in the power on scheme on some of the other jump pack models. From what I see on the GB70 it may be different.Jerry

author: AN86
author_rank: Contributor
timestamp: October 14, 2024, 05:12:11 pm
content: Im not the expert in this stuff but there is something about it when somesaid its dead and i revive it. It gives me satisfaction, its wierd i know but i like to fix stuff. And learn in the proces . If that 3 pin connector is responsible for those two big relays it was logically to search from end of the problem to the top, if iyou know what i mean. Maybe im wrong but continuity test on D17 beeps in both direction.And one crazy thing is if i put on continuity test and probe Lower left and upper pin on Q15 the big relay clicks.Is that strange or not?

author: jerryk
author_rank: Regular Contributor
timestamp: October 14, 2024, 07:12:56 pm
content: Not. Disconnect your relay plug and then check D17 which is your flyback diode for the relay coils. Using the continuity test on Q15's base you have activated the transistor that drives the output relays. As a general rule I do not test for continuity on live circuit boards. Randomly activating transistors can cause bad outcomes unless you fully understand the circuit.Back to the problem at hand and since you are exploring you could do a resistance check across R305. It should read 4.7K.If you were closer I would be glad to go over that board in the remote chance there is something we are missing here. The true test is as @eurgenca stated. Carefully with power disconnected lift pin 27 and recheck resistance.Jerry

author: jerryk
author_rank: Regular Contributor
timestamp: October 15, 2024, 04:15:30 pm
content: Can you HOLD OFFon any more exploring of this circuit board until I test some things on my end. Pin 27 goes to R305 and P27 of the daughter board connector.There is a chance that the short to ground at pin 27 is a problem is on the daughter board. Your MCU may be OK!I am going to remove the daughter board on the one that I have and trace that circuit down.I will get back shortly and let you know what I find.Of course the next question is are you capable of removing the daughter board?Jerry

author: AN86
author_rank: Contributor
timestamp: October 15, 2024, 04:25:06 pm
content: I can hold my exploring. But i didnt tell one maybe crucial info, when i did explore with probing the Q15, i turn the booster on and than i probe again, when it click i have voltage on clamps around 16.3v and the leds flash from 25 to 100%.Maybe this info is good maybe its useless but just in case.

author: jerryk
author_rank: Regular Contributor
timestamp: October 15, 2024, 05:07:20 pm
content: Quote from: AN86 on October 15, 2024, 04:25:06 pmThat kind of voltage is very concerning. That would mean you have overcharged this battery and each cell is at 5.4V. Please confirm the individual cell voltages in the three cells.Jerry

author: AN86
author_rank: Contributor
timestamp: October 15, 2024, 06:01:36 pm
content: Guess bad battery was in that other device.All 3 cells are at 4.15V. guess that 16.3 was some kind of a mistake in measuring device

author: jerryk
author_rank: Regular Contributor
timestamp: October 15, 2024, 06:38:28 pm
content: So you have been able to charge the battery.Start from the beginning.1.Press On/Off buttonUnit should turn on and all four battery indicator lights should be lit all the way up to the green led. You should also hear a click from 12V output transfer relay that's on the board.2.Press and hold override switch for 3 seconds.You should hear a significant click and the battery indicator lights should repeatedly flash from 25% to 100%. Then check voltage at clamps and it should be around 12.3V or so.3.Press override switch.Flashing Leds stop and unit should return to the original on state described in step 1.4.Press On/Off buttonUnit should turn off.5.With the unit off Press the light buttonUnit should turn on with all battery leds lit and the light should turn on.Do these things and nothing else and tell me the results.Jerry

author: AN86
author_rank: Contributor
timestamp: October 16, 2024, 08:17:10 pm
content: Yes battery can be charged but only on USB port not,barrel port but thats not important as long as i can charge it anyhow.so. lets go1. Works2. works3. not work. when not in override mode on clamps i have 0.7V when override mode i have 1.6V, not good.4. it turns off as it should.5.Led works, and every variation of LEDS, dimed and strobing and stuffI did check resistance of R305 and it was 4,69k ohms, i guess that is ok.

author: jerryk
author_rank: Regular Contributor
timestamp: October 17, 2024, 12:58:23 am
content: You answers to item 2 and 3 seem a bit contradictory.Starting with item 2. Can you confirm this is what happens. While unit is on and with nothing connected to the clamp you press the override for 3 seconds - this will cause the two output relays to engage with an audible click. At this point measure the voltage at the clamps and it should be 12.3 or so.Your response to item 3 confuses me because you mention that in override mode the voltage is 1.6V but in item 2 you say it "works" which would mean the voltages at the clamps are 12.3 like I stated in item 2 test. It would be helpful to know if the override is working correctly.When the override is engaged all battery power transferred directly to the clamps via the two relays. When not in override there is close to no voltage at the clamps. It's that simple.If you could clarify this confusion that would be helpful.As for further testing measure the resistance between R305 on the side closest to the number 5 and the main battery ground above R106.Take this resistance measurement with all JST plugs disconnected and then with just the relay plug connected.Remember the battery balance plug and the relay plug are the same. Don't mix those two upJerry

author: AN86
author_rank: Contributor
timestamp: October 17, 2024, 04:34:52 pm
content: Sorry my bad, it was late and kids and wife was crazy around me so i write it wrong. i ment works on 2.nd statment as it works that it wants to start override, i thought that button works when i press it and it goes in override mode, but nothing after happen. Leds flash but no real output.Ill check what you suggested and post again.Sorry for confusion

author: AN86
author_rank: Contributor
timestamp: October 17, 2024, 05:58:41 pm
content: Quote from: jerryk on October 17, 2024, 12:58:23 amYou mean they are not the same? or Im confused nowI did measure with all plugs dissconected. 4.52Mohms, and with JST relay plug connected it said 0.8ohms.

author: jerryk
author_rank: Regular Contributor
timestamp: October 17, 2024, 06:27:59 pm
content: With all plugs disconnected:Edit to add: Measure the resistance across D17 ( this should have already been done per reply #32)Measure the resistance between the red and white wire on the relay pair. Then measure the resistance across the two parallel bus bars on the relays.Measure the resistance across the following resistors - R74, R75, R76, R77, R79.Just list the values if you like.Then measure the resistance between all the pins on Q14. I'm not concerned about specific values. Two of your measurements should fall under .5 M ohms range and one around 10k. Anything in the low ohms range would indicate an issue.Jerry

author: AN86
author_rank: Contributor
timestamp: October 22, 2024, 08:06:11 pm
content: R74 - 3.194 kohmR75 - 3.195 kohmR76 - 10.07 kohmR77 - 4.7 kohmR79 - 246.9 kohmQ14 - 2 pin next to the R74 and R75 are at 3.195 kohmOthers are 0.531 mohm and 238.1 kohm.

author: jerryk
author_rank: Regular Contributor
timestamp: October 22, 2024, 11:08:01 pm
content: Even though this is in circuit testing they should read sort of close to the value on the resistor with the exception of R79.This is about how it should read. This can vary between multimeters and switching the probe polarity can effect the reading.R74 - 4.7 kohmR75 - 10 kohmR76 - 10 kohmR77 - 4.7 kohmR79 - 245 kohmAre you saying 0.531 milliohms here? Or did you mean megaohms?Quote from: AN86 on October 22, 2024, 08:06:11 pmAgain with all plugs disconnected -Did you test for resistance across D17? You can also do a diode test in circuit here too.If you can confirm the milliohms vs megaohm question. If the answer is megaohms AND D17 tests as a functioning diode the next test is to plug all plugs back in, turn the unit on, engage the override/boost to you get the progressive leds flashing. At that point test the voltage at the test point next to R74. It should read 3.3V.The underlying assumption here is that when you engage the override/boost button the battery status leds flash progressively but there is no click at the main relays and no transfer of power to the clamps. Pin 11 on your MCU controls the base of Q14 thru R74. When Q14 turns on it the powers Q15 that drives the main relay coils. We are just trying to see why this circuit is not functioning correctly. Keep in mind that this could still travel full circle back to the MCU but there is a possibility that Q14 has an issue or D17 might be shorted.Jerry

author: AN86
author_rank: Contributor
timestamp: October 23, 2024, 03:54:31 pm
content: I think its megaohms its big M on the multimeter.But maybe im wrong, il take a picture and post it.I test it all with all plugs disconnectedQuote from: AN86 on October 14, 2024, 05:12:11 pmI did measure D17 few posts before. and it seems like its bad also. Correct me if im wrong.So far i didnt get diodes i order from the internet, but ill try to solder regular one not SMD just for testing only and let you know.

author: jerryk
author_rank: Regular Contributor
timestamp: October 23, 2024, 04:57:56 pm
content: Quote from: AN86 on October 23, 2024, 03:54:31 pmPossible confusion on my part.In your earlier post you were testing things with the relay plug engaged since you activated Q15 via a continuity test and the relay engaged. As long as all plugs are currently disconnected and D17 measures as a low resistance short in either direction the diode D17 is faulty. If this is the case, then you can replace it with a 1N4148 or similar. Keep in mind it's the flyback diode for the main relays and needs to be installed before you attempt to activate those relays.Jerry

author: AN86
author_rank: Contributor
timestamp: October 24, 2024, 07:44:58 pm
content: Diodes finally came from post office. Ill change both ones and post if its working or not.

author: AN86
author_rank: Contributor
timestamp: October 31, 2024, 09:17:50 pm
content: Got strucked with feaver so i was offline for a few days.I did change diodes but still the same. No right signal on that transistor that engage the big relay.

author: jerryk
author_rank: Regular Contributor
timestamp: November 01, 2024, 05:32:13 am
content: It would be helpful if you would refer to any diode, transistors or other circuit component by the silk screen label on the board.You said you replaced "diodes but still the same".Can you tell me which diodes you replaced and what diode did you use as the replacement?The only defective diode I'm aware of in this discussion is ZD2 which is a 5V1 Zener diode. I'm not sure what other diode you replaced. As for ZD2 you have already replaced it with a 5V1 (axial lead) diode so putting the original smd version in it's place would do nothing. It's just a protection diode for the MCU and you could remove it and your circuit would still not change in it's behavior.As for "No right signal on that transistor that engage the big relay." If you checked the test point near the label R74 after holding down the boost/override button for three seconds and did not see 3.3V then you need to remove R74 and try that test again. The purpose of this test is to completely isolate pin 11 from any possible ground faults down stream of the pin. If you have R74 removed and after a three second press of the boost/override switch you get the flashing leds from 25% to 100% but no 3.3V at that test point then I cannot see any other fault possibility than the MCU.Good Luck - Jerry