Resistor fried in central board

Found that the reason I was not getting 12v and 16v LED lights lit on my NSM central board, there was a slo-blo 1amp fuse that was bad. I may have put in a 2amp fuse, which may account for the resistor at R204 on the board frying. Had all LEDs lit for a short time, and this one resistor went up in smoke.

Do you think simply because I may have had wrong fuse, so technically fuse should have blown first? I can easily replace the resistor and get correct fuse. I'm not sure if or what could cause it getting too much power, assuming it got too much power and fried the resistor?


Tim

Replacing fuses with a HIGHER rating is a NO NO.
People think they can "force" electronics to "work" by doing this idiotic and dangerous act.
That resistor is frying because of something it feeds B+ down the line is faulty.
Replacing the resistor is not going to fix a thing.
You have to troubleshoot and locate the offending components - any/all of them, replace them, and then success will be at hand.

Yes, I had made the mistake with the fuse, now I know better. Only possible culprit that I can see is there is an over voltage coming from the main transformer for what should be 22v going into this point. I'll get a known good transformer to replace it.

Power went from transformer connector into the central board, through the fuse, passes through four diodes and then hits this particular resistor. So there's not much until it hits that point, so either main transformer is faulty and put out too much voltage or the resistor itself was potentially bad and was time to fry.

Now will fix/replace that resistor, and pick up proper 1amp fuse, and track down a guy locally here who may have the correct transformer.

Tim

Tim,
In my mind--you have it backwards--very unusual that the transformer is delivering "too much voltage". More likely "something" (down-line) is drawing too much current ! This can be simply determined with an AC meter. Just lift the secondary wires and test voltage. If the fuse is on the primary side, I would use a 1/2 amp fuse to test this. If, as I suspect, the fuse is on the secondary, it is not needed for this test--Ron Rich

Thanks Ron. Not sure if this helps or not. This is the circuit or section of, that the resistor blew in.



Am trying to figure out/picture what you mean when you say if fuse on primary or secondary, sorry. To test, am I replacing the resistor, putting in proper fuse, and hooking it up to main power?

I had tested voltages from transformer supply, prior to putting in the incorrect fuse and voltages seemed fine. Not sure what could be drawing enough to fry that resistor. I can take many pictures of the board if it helps.

Thanks again for your help.

Tim

Hi Tim,
No offence intended, but IMHO, you are "above your skill level here", and could cause more damage, either to the equipment, or, quite possibly, yourself ! My advise to you is, to quit "working on" this now, and to get some help, either from a "pro", or at least someone who understands what he's doing. Ron Rich

Hi Ron, yes, I'm no expert, but have a fair bit of life experience with electronics, soldering etc. I guess I was just trying to picture and make sense of how you were describing to next test it. I was assuming it would have to be hooked up again to test the power this way. I've replaced the resistor now and have a 1amp slo-blo correct fuse in place. Either I power it back up and see what happens (I can leave everything unplugged, minus the power feed into it), or?

I can follow directions, but I'll definitely ask questions if I'm not quite reading things right.

Tim

Hi Tim,
It is my contention, based on your question(s), that you do not have the skills needed to proceed. I recommend that you either get help, or do some reading as to what "parts" do, and how to test individual parts. Under no circumstances, would I leave a 1 amp fuse in that circuit for "power-on, testing". IMHO, you MAY have already "compromised" that transformer, and the risk is high that the 1 Amp. fuse, will not protect it---Ron Rich

There's no fuse at/near the transformer. Fuse in question is on the central board, and I had picked up the 1amp fuses as this particular fuse block requires a 1amp slo-blo.

Maybe some mis-communication. Just trying to pinpoint what on/near the central unit board, could have caused the resistor to fry, apart from that I had a 2amp fuse in this spot when I had powered it up.

Tim

Hi Tim,
I agree--there is a "failure to communicate" here--
It matters not, if that fuse is directly mounted to the transformer, on the board, or in "mid air". IMHO, you seemingly do not understand what that, or any, fuse is intended to do, nor do you seem to understand that basic circuit.
Therefore, I suggest that if you wish to DIY, you "get some help", or, do some reading about basic electronics, before proceeding. Ron Rich

Knowing some Basic Electronics Theory would easily determine what is faulty here.

Without seeing the whole schematic, all I can say is - ANYthing to the RIGHT of that fuse could be the problem.
Caps, diodes, transistors, regulators, ANYthing.
If you don't know enough about how components work and the theory behind each one, take it to someone who does, or else an endless thread of "what if's " will carry on into the next millenium.

Thank you. Yes, schematics are not readily available. The above picture shows the particular portion of this circuit, and the R204 resistor in question. It could be a transistor, VR203 is next in line from R204 resistor. I had this pic in another post, the white fuse (was found to be bad) is the one that I had put a 2amp fuse in, instead of 1amp fuse. The diodes above it (206-209) are first past this fuse, followed by R204 resistor that fried, then the VR203 transistor.

Tim

Also per suggestions, seeing if I can get a guy here locally to come by to take a look at it. He does repairs and is familiar with NSM apparently. Just thought the cause of this resistor blowing may have been a bit more obvious or someone else had encountered same/similar with the centrale PCB board.

Tim

Just an update, and an apology. I know you guys do not feel that I know enough, I understand and respect your opinion on that. You have to understand, I do 99.9% of my own troubleshooting and repairs. I don't repair machines for people, these are my personal machines. I just tend to ask a lot of questions, this may come out sounding like I do not know enough. In my line of business, it's always good to have an extra set of eyes and an opinion on direction to take.

So the update, I'm quite sure now at this point that it is the control and credit unit. Decided to hook up the centrale unit, I plugged everything in one at a time (leaving control and credit unit til last, as I had my suspicions), and sure enough with everything plugged in, I have all voltage LEDs lit and nothing smoking. My best bet is just replacing this unit with a known working one. I've pulled the board from it and see no obvious signs of anything that could be causing the problem. Still have this fellow coming by to take a look, he's been repairing jukes for 50 years. He may just have an extra control and credit unit.

Tim

Hi Tim,
Glad it's working---
You are "braver" or, "luckier" then I am ! I would have "tested" ALL "downstream items" prior to power up --
I would suggest installing an 8/10 amp SB fuse in that 1 amp holder--at least for "awhile"---
Ron Rich