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Electronics => Repair => Topic started by: vortex_690 on June 26, 2017, 10:23:08 pm

Title: Spa Computer Help
Post by: vortex_690 on June 26, 2017, 10:23:08 pm
Hi all

I have a spa computer that I have been trying to get going...All it does is flash one light on the controller after a while being plugged in the controller
starts to show a few lights and partial digits


I have tried a few things with no luck I am not experienced in electronic repair very much at all but I am learning as I go

So far I have done the following

I have replaced the capacitors with new ones as this was suggested as a common fault

I have tested the bridge rectifier and got the following results
14.06 dc volts
11.83 ac volts

Then I have tested the Micro Controller AT9054433-8PC and got the following results
4.94 dc volts pin 7 vcc
pin 8 ground
3.86dc volts reset pin 1

Any help I would appreciate it

Cheers Chris
Title: Re: Spa Computer Help
Post by: DaJMasta on June 26, 2017, 10:36:24 pm
Does the spa still function, just with the display damage?  It sounds like the micro is at least active, I would take a look at any circuitry that are part of the display/input device, and perhaps another chip that directly controls the display (it could be directly connected to the micro, though).


Are there any obvious sensors coming from the spa?  Perhaps part it is a fault in a sensor that prevents the system from running.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 26, 2017, 10:55:01 pm
Hi mate

The spa does not function at all no response from the controller it doesn't even turn on the blower or pump as it should when you first Power it up

The only sensor it has is a water flow / temp sensor


Title: Re: Spa Computer Help
Post by: DaJMasta on June 27, 2017, 09:19:02 pm
Do you have a scope?  Could be worth monitoring the power and reset lines of the micro just to see and be sure.  Otherwise, multimeter on the sensor lines as a sanity check (and maybe some resistance checking on the pump and blower to make sure they're in the right ballpark).

If you can get into the front panel board (if it's separate from the one pictured), you may get some extra info.... if it can be disconnected from the micro board, maybe disconnect it and see if it gets any farther in booting.


Without knowing the system design and without a good idea of how it's all connected... it's tough to narrow it down.  You're getting at least a partial power up, but whether it's stopping because of an error or if something's corrupted or stuck is tough to say.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 27, 2017, 09:40:41 pm
Hey man
I don't have a scope only the the multimeter

The controller does unplug from the unit when unplugged it does the same

The blower and pump are external power plugs that pug directly into the computer

The computer turns those power plugs on and off with the controller saying that it doesn't know what those devices are it only knows to switch power on and off at command

On power up the computer should switch on the powet to those outlets to go through self diagnostics

So the heater whitch is connected to the computer directly detects if water is moving through the pipes and if not should switch the power off to the outlets

Last time i got one of these fixed it cost me like 500.00 so was trying to do it myself....not looking to positive for me lol
Title: Re: Spa Computer Help
Post by: DaJMasta on June 27, 2017, 10:14:49 pm
Ok, I missed that those were the relays in the first pic, and it's probably good that it acts the same way when unplugged from the front panel because you can narrow it down to this board.

It may be good to trace out the reset pin to see if it connects to something which could be bringing it down - while 4V should be sufficient to keep it from resetting, it may be an indicator of something being bad on it that is pulling it low at some point fast enough that your multimeter can't pick up on it.


I don't have a lot of experience with this sort of design, but it seems clear that the micro is driving the relays through the ULN2803... but I don't see any flyback diodes on the relays.  Could the surge generated from switching have killed the ULN2803?  If that's the case it's pretty bad board design.... but this guess is a shot in the dark, at best - it could be that the relays chosen have it integrated or generate small enough reverse currents to not be a problem for the Darlington array.


It could be worth checking power signals around the board, or maybe watching the signals coming into the ULN2803 (you can find which pins would be the transistor bases on the datasheet) just to make sure the micro is actually trying to turn them on.  If the micro is damaged or the firmware corrupted, then it could be replaced, but the problem is that you probably don't have a spare copy of the firmware, so even if it were replaced, it would still need the right firmware to work with the system.
Title: Re: Spa Computer Help
Post by: james_s on June 27, 2017, 10:21:05 pm
When mine failed it was bad electrolytic capacitors in the power supply. I had a previous problem with a cracked solder joint causing it to think the water flow sensor wasn't functioning but that was a long time ago.
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 28, 2017, 12:01:02 am
A Spa controller model number will hep...also some more pics of the PCB...from above/behind.

Are you in Australia...these appear to be Davey controllers??

Brendan
Title: Re: Spa Computer Help
Post by: vortex_690 on June 28, 2017, 10:13:18 pm
Hi all

Sorry for the late reply

It is a spa quip controller which is now Davey

Its a Spa Power 500A

I'm In Sydney Australia
Title: Re: Spa Computer Help
Post by: james_s on June 28, 2017, 11:38:28 pm
I'd start out by replacing those three electrolytic capacitors. Cheap to do and they are about the only electronic component that wears out with time and use.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 28, 2017, 11:43:37 pm
Hey dude

I already replaced the 3 capacitors
Title: Re: Spa Computer Help
Post by: james_s on June 28, 2017, 11:53:21 pm
Oops, sorry I missed that part.

There is not much to that board, just a microcontroller with a relay driver chip, should be able to trace which pins go to which function and then poke at the input and output pins to see if there's any activity.
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 29, 2017, 12:28:59 am
Thanks for pics...was looking at C11 polarity...its ok from the extra pics.    There are a couple of links J1/J2/J3 with +12V is that ok?  Also is pwr getting to the pwr pins of the IC's?  What is U4 part number...an opto coupler?  Its from the water flow sensor.  Is this shutting down the PCB?

As said by DaJMasta  check the ULN2803 for in and out voltages.  The Micro might be sending signals but they might not be getting thru.

edit:
re-reading the original post and looking at the controller documents...brings me straight to "any error codes"?.  In the original posy you said...
......I have a spa computer that I have been trying to get going...All it does is flash one light on the controller after a while being plugged in the controller starts to show a few lights and partial digits ......

Did any of the partial digits look like the error codes listedhere...warning downloads a small pdf (https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0ahUKEwip3pag6OHUAhWLV7wKHWthAdIQFgg-MAQ&url=https%3A%2F%2Fwww.spastore.com.au%2Fassets%2Ffiles%2FSP500%2520User%2520Guide.pdf&usg=AFQjCNEoJ0SSd_kdNciPyG1y73d2V6NHgg&cad=rja).  of in the controller documentation.

If the display is garbled then it could be usually a bad display controller IC...in this case this would be the micro-controller.





Title: Re: Spa Computer Help
Post by: vortex_690 on June 29, 2017, 01:42:31 am
So this time it displayed nothing after 5 mins i got random lights nothing corresponding to the error sheet

h11aa1 0315k is the chip U4

4.94 v j1    5v+

14.93 v j2  12v+

14.21 v j3  12v+


ULN 2803 14.03v both sides on all pins the control panel changes at random when I was testing this chip

Title: Re: Spa Computer Help
Post by: wasyoungonce on June 29, 2017, 02:32:15 am
Ok thanks....is there any inputs to the ULN28003 that are high?   Aka an output high from the microcontroller. I'm guessing a high from the micro turns on the respective ULN2803 driver which supplies a gnd path to the appropriate relay.  Just a re-read...14V on both sides of ULN2803, all pins, ...that's not right.

If none high or its not the ULN2803...and since you get garbled display...and the display has no driver IC...then the micro controller is looking suspect.  You also might be able to trace back the display to the microcontroller lines to see if they are ok.

If it is a micro....best thing is to try module repair in Ringwood (http://www.modulerepair.com.au/search-electronic-module) (there are in other places).  I've used them for a dishwasher controller repair I couldn't fix myself (yes I admitted defeat!).  They were a lot cheaper than a new controller.

The h11aa1 is an opto transistor coupler.

edit:
ok 12/14V both sides of the ULN2803...which will put the same voltage onto the outputs of the microcontroller.   Might be best to pull the ULN2803 out.  Cheap enough...cut the legs carefully hit the left over with solder and pull the left over leg pins with tweezers or pliers.  Clean up with solder  wick. 

Or at least cut one leg that goes to the microcontroller lift it and measure the microcontroller pin...is it ok now?  I'm assuming the microcontroller outputs a high to the ULN2803 which drives a low out to the relay coils making them actuate.

Its possible this has damaged the microcontroller.

Title: Re: Spa Computer Help
Post by: DaJMasta on June 29, 2017, 05:46:53 am
I think pulling the ULN2803 is the right call, then if the micro is still acting up (garbled display and all) you know it has also been damaged, while if the display seems to normalize, maybe just dropping in a new driver chip will fix it.

Normally, 14V is way too much for a micro, and I certainly don't see any significant protection, but maybe you're lucky and there are some protection diodes that have kicked in.

The 6 pin dip is definitely in the spot for an optoisolator, not totally sure what it's feedback for, maybe power line cycle timing?  Maybe it feeds into an ADC to get a level?
Title: Re: Spa Computer Help
Post by: james_s on June 29, 2017, 07:22:29 am
If the microcontroller is bad then it's pretty much game over, unless you want to try to write new firmware from scratch and load it into a replacement chip. That could be a fun project but it's not easy unless you're an experienced programmer.
Title: Re: Spa Computer Help
Post by: Armadillo on June 29, 2017, 09:55:43 am
Break up into 2 portion of Checks:

1: Microcontroller Health
2: Peripherals

Let's Check Item 1 first;

Pin 7 VCC: Measure this voltage with respect to Pin 8. Should be 5V.
Pin 20 AVCC: Measure this voltage with respect to Pin 22. Should be 5V
Pin 21 AREF: Measure this voltage with respect to Pin 22.  Between 2V to 5V
Pin 10 XTAL2: Measure this voltage with respect to Pin 8. Should be some voltage near around half VCC. Best is to use a digital logic probe if you have one. This pin is critical to whole operation. Because there is a ceramic resonator there, not destine to last. Consider to borrow one digital logic probe or buy one about $20 versus $500.
Pin 1 Reset: Measure Pin 1 to Pin 8. Should be 5V. Your reset pin is not normal at 3.86V. Its a Resistor connected to VCC to a capacitor. Check why not pulled to 5v. Example wet, moisture. Measure the resistor ohm. Lastly Change the capacitor at this Reset Pin.

let's identify is the microcontroller running normally or abnormally before Proceeding to Part 2.
Title: Re: Spa Computer Help
Post by: james_s on June 29, 2017, 05:03:12 pm
I suppose it might be worth replacing the resonator if everything else looks ok. I don't think I've had one of those fail but I have had a few quartz crystals go bad and oscillate wildly off frequency.
Title: Re: Spa Computer Help
Post by: drussell on June 29, 2017, 07:50:15 pm
+1 for having a logic probe, it makes troubleshooting many digital things MUCH easier when you haven't yet graduated to having a full blown oscilloscope.  :)
Title: Re: Spa Computer Help
Post by: vortex_690 on June 29, 2017, 09:28:13 pm
hi all

thanks all for the help I'm learning lots and lots lol

I'm not sure about pulling the ULN2803 that would be a very difficult task I think unsoldering the chip I recon I would bugger it up LOL

I will try to get a logic probe today not that I know how to use it yet lol

Writing new firmware no luck there wouldn't even know where to start....YET

I have measured the info as requested

Pin 7 VCC: Measure this voltage with respect to Pin 8. Should be 5V.               4.96
Pin 20 AVCC: Measure this voltage with respect to Pin 22. Should be 5V           4.95
Pin 21 AREF: Measure this voltage with respect to Pin 22.  Between 2V to 5V    4.95
Pin 10 XTAL2: Measure this voltage with respect to Pin 8. Should be some voltage near around half VCC. 4.96

Because there is a ceramic resonator there, not destine to last. Which one is that is it the little yellow bulbs at C5 and C9

Pin 1 Reset: Measure Pin 1 to Pin 8. Should be 5V. Your reset pin is not normal at 3.86V.  Still 3.86V

Its a Resistor connected to VCC to a capacitor. Check why not pulled to 5v. Example wet, moisture. Measure the resistor ohm. Lastly Change the capacitor at this Reset Pin.  No sure which resistor    .... The capacitor is the smaller one of the 3 next to c13 which I have already changed or is this wrong one I'm looking at

I suppose it might be worth replacing the resonator if everything else looks ok.    Where Is the resonator is that the blue one at CR1

Thanks all
Chris
Title: Re: Spa Computer Help
Post by: james_s on June 29, 2017, 09:40:19 pm
You can use a wire to jumper the reset pin temporarily to the +5V pin, that will force it out of reset, or to ground, that will force it to reset.

The ceramic resonator is the blue thing labeled CR1. It should have the frequency printed on it, 4MHz is a common value.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 29, 2017, 10:34:22 pm
Its funny i was actually thinking of doing that
Title: Re: Spa Computer Help
Post by: vortex_690 on June 29, 2017, 10:52:37 pm
Bumped it to 4.96 no change
Title: Re: Spa Computer Help
Post by: vortex_690 on June 29, 2017, 10:56:47 pm
This is the blue one with numbers
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 29, 2017, 11:22:28 pm
The ULN2803 is easy to remove..cut the pins...de-solder the left over.  Once removed...chuck it an get another...easy cheap as.   But this is why i said just cut one leg between this IC and the microcontroller, then take a measurement from the micro...... so you can solder it back together (or replace the IC).

Or you can cut the trace between then and solder a bridge later.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 29, 2017, 11:43:22 pm
The uln2803 where would u buy another and does require some firmware or something loaded into it

Would jaycar have it
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 30, 2017, 12:12:58 am
UlN2803 is a Darlington pair transistor amplifier....no firmware at all.  Fleabay,

RS...free post, pk 5 $1.88 ea (http://au.rs-online.com/web/c/semiconductors/discrete-semiconductors/darlington-transistors/?searchTerm=ULN2803&h=s&sra=oss&redirect-relevancy-data=636F3D3126696E3D4931384E53656172636847656E65726963266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E2E2A2426706F3D31313326736E3D592673743D43415443485F414C4C5F44454641554C542673633D592677633D4E4F4E45267573743D554C4E32383033267374613D554C4E3238303326&dym=uln2003)

Element14 post is ~ $7 IC is $1.62 in ea (http://au.element14.com/search?st=ULN2803)

WES, post is ~ $7 IC is $3.41 ea (https://www.wes.com.au/powersearch.aspx?&srctext=ULN2803)

Xon post unknown, $1.4 or IC ea (https://www.x-on.com.au/keywordSearching?kword=ULN2803)

Fleabay from $3 and up Qty 4 for $4.90 in Australia (https://www.ebay.com.au/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR1.TRC0.A0.H0.XULN2803.TRS0&_nkw=ULN2803&_sacat=0)

There might be cheaper ...I don't think Jaycar have them.

edit:
Altronics have them....$5.20...which is costly!
Altronics (http://www.altronics.com.au/p/z3010-uln2803-darlington-transistor-array/)



Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 12:15:28 am
Bumped it to 4.96 no change

Your clock is not oscillating. Nothing will work. ! Now it is important to get hold of a digital logic probe to confirm if Pin 10 is oscillating or not but the voltage reading show it is only at high. If your multimeter can read frequency up to 4 Mhz, then read Pin 10. Otherwise get the logic probe.

There are left with 2 possibility. One is critical end of Game and One is survival. So firstly confirm the above then decide if to buy the blue color 4.006325 Ceramic Resonator.

There is nothing else you should consider to buy else until you solve the above. [The ULN2803 is just a Darlington Transistors Array, there is no firmware required BUT.....]

You had better trace Pin 1 to the associated component and check/identify those because wire to high inhabit the proper reset timing and sequence for the microcontroller.


Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 12:45:17 am
https://www.jaycar.com.au/uln2003-darlington-transistor-array-ic/p/ZK8855 (https://www.jaycar.com.au/uln2003-darlington-transistor-array-ic/p/ZK8855)  would this one work
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 30, 2017, 12:53:16 am
https://www.jaycar.com.au/uln2003-darlington-transistor-array-ic/p/ZK8855 (https://www.jaycar.com.au/uln2003-darlington-transistor-array-ic/p/ZK8855)  would this one work

No it has 16 pins the ULN2803 has 18.  best if you try to read the data sheets on these items.  They have all the information you need.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 12:57:49 am
This is the underside

Is this what u need

I added another with pin 1 labeled  i think it connects to the little yellow bulb which is c5 is that a ceramic ......??
Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 01:21:52 am
This is the underside

Is this what u need

I added another with pin 1 labeled  i think it connects to the little yellow bulb which is c5 is that a ceramic ......??

OK it just connect to 1 capacitor and not other reset circuit. I don't think is the problem. [it just relied on Power on reset and there is no hardware reset ability so that means its unlikely to go into sleep mode, forget this pin for now]. [Edit: Remove any jumper wire, if you had installed one]

Solve the clock problem first.  It's like an engine, engine not rotating, nothing moves. Kick it [agitate it manually] maybe 1 revolution. Logic Probe it and better hope its the blue ceramic resonator. Otherwise End Of Game.
Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 02:11:07 am
Anyway, the blue ceramic resonator is just a few cents. If you do not have the logic probe still and not contemplating to have one, then you can buy the ceramic resonator and changed it and hope for the best because its either the microcontroller or the resonator. But as far as I personally know, ceramic likes to crack. Most people here knows about the MLCC failure rates. Its about the same. I would say its 70 faulty Resonator and 30 Atmel [as far as I know, atmel is pretty robust as much as I have abused it]. But I would still advice you to probe Pin 10, ascertain before buy Policy, because I am not the change, change change everything repair-type. If you can probe, press up and down buttons together momentarily to simulate wake up call, before probe just in case sleep mode entered. Unlikely but we always ascertain things from crazy programmer.

Even if is the faulty microcontroller, not  exactly end of game. You can get new game in the microcontroller/fpga section of this forum. The atmel microcontroller AT90S4433 firmware is easy to write if you know programming, you can even add new endless features. You can try to ask someone [maybe a student] to write the firmware for you at a token and own the firmware forever. Maybe at a $100, you can get the firmware and 5 programmed AT90S4433 as spared. :-) . [hopefully]

Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 02:47:01 am
I have just been running around trying to get the probe no one has  it the only place is ebay so looks like i have to order from them which is terrible cause now i will have to wait
Unless anyone else knows somewhere in sydney
Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 03:07:21 am
I have just been running around trying to get the probe no one has  it the only place is ebay so looks like i have to order from them which is terrible cause now i will have to wait
Unless anyone else knows somewhere in sydney

Do order the ceramic resonator same time, just few cents. But remember its 3 pins.,  not 2 pins.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 03:13:59 am
The ceramic resonator does it have to be exactly same one

I found them on ebay but lots off different mhz
Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 04:51:26 am
The ceramic resonator does it have to be exactly same one

I found them on ebay but lots off different mhz

4.000 Mhz, 3 pins
Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 04:53:07 am
https://au.rs-online.com/mobile/p/ceramic-resonators/5266075/

Does this look ok
Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 05:00:01 am
https://au.rs-online.com/mobile/p/ceramic-resonators/5266075/

Does this look ok

its higher than 4.00 MHz, would prefer 4.00 Mhz.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 05:30:23 am
https://au.rs-online.com/mobile/p/ceramic-resonators/7926555/
https://au.rs-online.com/mobile/p/ceramic-resonators/7288465/
https://au.rs-online.com/mobile/p/ceramic-resonators/7214893/

How about one of these
Title: Re: Spa Computer Help
Post by: Armadillo on June 30, 2017, 06:15:13 am
Any of the murata.
Have you read the delivery minimum charges?
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 30, 2017, 06:17:20 am
Yep has to be same frequency 4.0Mhz, 3 pin ceramic resonator.     

Its important to use the same parts, yes sometimes you can substitute but not for this, its too much stuffing around.  That said ceramic resonators are slightly less accurate than crystals and indeed usually can be replaced by crystals (but you need extra trimmer caps etc), but for this purpose...just get another resonator with the same freq (3 pin).

edit:
ahh beaten by Armadillo   Annnd sorry forgot...measure the old one to ensure you buy the correct size.
Title: Re: Spa Computer Help
Post by: vortex_690 on June 30, 2017, 06:24:26 am
Ok guys thanks for all your patience and help I really appreciate it.

I guess we will just have to wait now for the items to arrive

Cheers Chris
Title: Re: Spa Computer Help
Post by: noidea on June 30, 2017, 04:07:44 pm
I have just been running around trying to get the probe no one has  it the only place is ebay so looks like i have to order from them which is terrible cause now i will have to wait
Unless anyone else knows somewhere in sydney

Try Altronics they used to sell premade ones but now it looks like just kits, anyway it's something to practice your soldering skills on  :)
http://www.altronics.com.au/search/all/?sr=logic%2Bprobe (http://www.altronics.com.au/search/all/?sr=logic%2Bprobe)
Title: Re: Spa Computer Help
Post by: drussell on June 30, 2017, 09:18:49 pm
I have just been running around trying to get the probe no one has  it the only place is ebay so looks like i have to order from them which is terrible cause now i will have to wait

Wow, that is horrible....  used to be able to walk into any Radio Shack and pick one up for $14.95....  I'm sure I still have at least a couple of them around here somewhere from my pre-teen electronics days...  :)  I know I had at least two of them of my own, "back in the day" to watch multiple pins at the same time, though all my electronics friends had at least one each also so we often had three or four or more of them on the bench at any given time when we were working on projects as kids...  :)

I think my mom still has no idea what the heck we were doing down there but this was 20-30 years ago...  LOL
Title: Re: Spa Computer Help
Post by: wasyoungonce on June 30, 2017, 11:54:38 pm
..........Wow, that is horrible....  used to be able to walk into any Radio Shack and pick one up for $14.95....

Arsetralia...the electronics backwater of the world where everything is either more expensive or unobtainable. 
Title: Re: Spa Computer Help
Post by: james_s on July 01, 2017, 12:06:45 am
Well it's effectively an island out in the middle of nowhere so it's not too surprising that stuff is expensive and has to be imported. The situation is not what it used to be anywhere though, Radio Shack is pretty much gone out here too. Logic probes can be bought online easily enough but I don't know if there's anywhere you can just walk into a store and buy something like that anymore.
Title: Re: Spa Computer Help
Post by: DaJMasta on July 01, 2017, 12:37:15 am
Logic probes have become a lot less prominent... not nearly as many hobbyists are trying to do logic work and scopes and logic analyzers have come way down in price... it's not surprising to me that they wouldn't have a logic probe in stock.  Not like they're complicated devices, though, if you had a breadboard and some parts you could certainly build one up.  Actually, it looks like it takes a pair of transistors or a quad nand/nor (or a couple other things, depending on the circuit), then a pair of LEDs and some passives.  If you're that hard pressed for a logic probe, it's easy to build and there's really no need for super accuracy or high speed design or what have you - it operates in a very coarse adjustment window.

Though I'll be honest, my first instinct isn't to check the clock anyways.
Title: Re: Spa Computer Help
Post by: Armadillo on July 01, 2017, 01:58:11 am
You know, the problem is, we can have all the top range instruments, oscilloscope, spectrum analyser, logic analyser, signal analyser etc.... but when it comes to repair works, to answer the question, "Are you oscillating?", nothing beats the simple digital logic probe. No need to wait for the instrument to start-up, and the noisy fan whirling noises. Fast, simple and good and no nonsense. Will you turn on those instruments? Many times, I would not.

Also, I am of the opinion that it is not the simple electronic inside and then DIY kid sets.... I would advise beginners to avoid that... The important is the ergonomics of the casing or housing on the hand. It must come with a casing or housing. [Edit: The money is on the casing or housing]

Cursory browse on ebay will review that those slim styled ergonomically designed probes are of those branded brand types and normally higher in price tag. Before you buy though, it would be an added bonus if it will also work with 3.3v power supply level, preferably.

I would change the cheap crocodile style power clips which are prone to short out adjacent pins to those claw or grippers type, so beginners beware of locating appropriate hook up locations.

Will you need to have one?, Yes, in my opinion.


Title: Re: Spa Computer Help
Post by: DaJMasta on July 01, 2017, 04:06:46 am
And it's sort of off topic and very much a matter of preference, but even if you think a logic probe is an essential tool for your kit that you want a quality version of..... if there aren't any available and you just need to check oscillation, a basic circuit and a breadboard will do just fine.

And honestly, if I've gotten to the point that I need to know if the oscillator is working right, I'd much rather see the waveform on the scope and getting a probe out of the drawer takes about as much time as booting up the scope.  I've had access to a logic analyzer since I was a kid (my dad was into electronics too), but I never bought one for myself.  A simple circuit, a multimeter with an AC mode or a duty cycle readout, or a scope or other simple digitizer all will suffice and it's very rare that I want to see only the binary signal on a single bit (logic analyzer isn't worth it then) and don't care about the waveform, so I haven't found the need for it.


Anyways, it's neither here nor there, in a pinch (it sounds like the OP is in one of sorts) building the circuit to check basic operation is an option.  If you then choose to have and use a logic probe, go right ahead.  Even a spare micro would do in this case, just reading off a pin and displaying it over a serial port would give you a good idea if there's activity.
Title: Re: Spa Computer Help
Post by: vortex_690 on July 01, 2017, 11:26:32 pm
Hi all

Look what i found

Next question how to use it
Title: Re: Spa Computer Help
Post by: Armadillo on July 02, 2017, 05:48:22 pm
Great find. Can it be turned ON?

its a dual trace 25Mhz scope.

Transistorized.

But make sure its working safe before you poke the board.   ;D



Title: Re: Spa Computer Help
Post by: vortex_690 on July 24, 2017, 02:40:19 am
Hi all

I finally got my logic probe from china

Should I have on ttl or cmos

where should I test and I have connected the the power to the 5v line and a neg
Title: Re: Spa Computer Help
Post by: Armadillo on July 24, 2017, 02:59:58 am
Hi all

I finally got my logic probe from china

Should I have on ttl or cmos

where should I test and I have connected the the power to the 5v line and a neg

Slide to pulze mode,
Slide to TTL
Probe the tip onto Pin 10, you should see blinking Hi and Low [or both lighted because too fast].
The last time you measured Pin 10, it was close to 5V, so I reckon only Hi lighted if you have not changed the resonator.
Title: Re: Spa Computer Help
Post by: vortex_690 on July 24, 2017, 03:17:44 am
As soon i make contact with pin one light flashes then nothing...I have changed the blue resonator
Title: Re: Spa Computer Help
Post by: Armadillo on July 24, 2017, 03:26:56 am
As soon i make contact with pin one light flashes then nothing...I have changed the blue resonator

Touch the probe tip to 5v, red lighted.
Touch the probe to the ground, Green lighted.
Touch the probe to Pin 10?

Please be specific, there is the Red Led, Green led, Yellow LED on the probe, which one lighted?
nothing, do you mean, non of the LED lighted?
What Pin did you measured?
Measure Pin 10 with a volt meter, how many volt is on Pin 10?

Be careful of the positive and negative crocodile clips, they can bridged onto other circuit pins nearby. I changed mine to the claw type instead of crocodile clip.
Title: Re: Spa Computer Help
Post by: vortex_690 on July 24, 2017, 10:24:43 am
Hi Guys

Ok when I touch the probe tip to the 5v ,ground or pin 10 I get a single yellow light flash once then no light


the pin 10 has 4.96v
Title: Re: Spa Computer Help
Post by: Armadillo on July 24, 2017, 11:41:31 am
Hi Guys

Ok when I touch the probe tip to the 5v ,ground or pin 10 I get a single yellow light flash once then no light


the pin 10 has 4.96v

I don't understand what is "no light" when the photo shows the yellow light is lighted up.? this usually indicate oscillation.

(https://www.eevblog.com/forum/repair/spa-computer-help/?action=dlattach;attach=334731;image)

if you touch the 5v, you should see Red light

(https://www.eevblog.com/forum/repair/spa-computer-help/?action=dlattach;attach=334735;image)

If you touch the Gnd, you should see Green light.

(https://www.eevblog.com/forum/repair/spa-computer-help/?action=dlattach;attach=334733;image)

And if you use your finger to touch the tip, all should light up, red, green and yellow.

If you cannot get it, check your power supply connection and voltage. If still cannot, then return the probe to ebay.

Do update your profile so that the community can know where you are from.


Title: Re: Spa Computer Help
Post by: vortex_690 on July 25, 2017, 05:23:59 am
The single yellow led on the probe lights up only for 1 second as soon as i make contact but then goes off then nothing

Would the 5 volt source be enough or would i need to use a 12v

If i touch my finger to the probe the yellow light comes on and flickers like a heart beat or something
Title: Re: Spa Computer Help
Post by: Armadillo on July 25, 2017, 07:47:13 am
The single yellow led on the probe lights up only for 1 second as soon as i make contact but then goes off then nothing

Would the 5 volt source be enough or would i need to use a 12v

If i touch my finger to the probe the yellow light comes on and flickers like a heart beat or something

5 volt is enough for TTL circuit [this circuit].
If you touch with your finger the RED and the GREEN should also be lighted with the Yellow. Right? Is the RED and the GREEN LEDs working? Try touching to 5volt and then Gnd.