Keshenatech1
Senior Member
Last Activity: 04-23-2024, 02:58 PM
Joined: 04-27-2018
Location: Shawano, WI
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Just to clarify, I was testing in the diode scale and ran across this one that made the meter beep and showed a 0V drop so then I went down to the ohms scale to see what the actual resistance is. And on a working board, it measures just like a normal diode even in circuit. Drops .458V across the junction in the diode scale and several meg in the resistance mode. Also I found a couple more good boards in machines we currently have in storage and found one that's legible. The markings on the diode are V6 on the top row and 58 below it. (new picture attached)...
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Yes measures 3.5 ohms removed from the board as I wrote above. And I also tried cleaning it and looked at a couple more boards, and they're all hard to read. The 24V power supply board made by the same company has diodes labeled "G6" in that same position so I'm thinking possibly a 60V 1A Schottky but I want to be certain before throwing something into the high voltage circuit. I even emailed the company and their reply was they can't disclose info about products currently in production for liability purposes among other reasons. This is used in the power supply for a Konami Concerto...Leave a comment:
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Q3 is a YG98156. Can barely see it between the other components. The diode goes between the center lead and the + of the high voltage caps. Also including a few more pictures of the unit....
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Not a dead short but 3.5 ohm is definitely not normal for a diode....Leave a comment:
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TDK ZWS150BAF-12
Does anyone have a schematic or parts list for a ZWS150BAF-12 12V power supply? I have a dead one and I've determined the surface mount diode on the back side of the board that connects from the center leg of Q3 to the + side of the 420V 60uf capacitors has a 3.5 ohm short. I'm not having much luck trying to identify the diode as the part number is not very legible. In the attached picture, it's the black rectangular diode in the center. There are some numbers on it but I can't even tell if it's right side up or upside down. The picture is from a 2nd good working unit which is more legible...
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Yesterday I swapped crystals with a working board, got a nice clean waveform but the board still doesn't work. I then put the crystal from the bad board onto the good board and also have a nice clean waveform and that board still works as well. Maybe I had a bad ground or something?
Also at my work I only have an old 20mhz scope. I've been here 22 years and it was here when I started. I don't really use a scope often enough to budget for a new one. I also have a Fluke 97 scope meter rated at 50mhz so that gives me a little more detail....Last edited by Keshenatech1; 02-27-2024, 09:20 AM.Leave a comment:
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Question on microprocessor crystal oscillator circuit
I'm troubleshooting a reel controller board for an IGT slot machine. The digital section seems to be dead. There is no USB communication, PC or utility program for flashing firmware do not see it but they do see good/working boards. I noticed the waveform on the crystal is very erratic/asymmetrical/glitchy on the bad one compared to the nice even waveform on a good board. My question is would this most likely be caused by a bad crystal or something gone bad in the circuit loading it down? I'm attaching a couple pictures of my scope probing the good and bad boads.Last edited by Keshenatech1; 02-26-2024, 11:29 AM. -
Yeah I figured as much, just wanted to make sure I'm not overlooking something before I junk it. Thanks much for the reply.
For some reason, I have not had much luck with this particular model and about 2 out of 3 end up like this but I've had close to 100% good results with just about all the other monitors I've done around the casino floor. The glass screen panel is really stuck down hard to the frame so I have to carefully work a thin plastic guitar pick under the edge to get it loose. It didn't crack but it took quite a bit of force and a little flexing so I guess I could have internally...Last edited by Keshenatech1; 12-15-2023, 11:13 AM.Leave a comment:
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Is this LCD panel shot?
I'm the bench tech at a casino. Working on a Tovis LTG-1750UR used in an IGT Game King upright machine. The screen had no backlight when it came in. So I carefully disassembled the LCD panel, took our the burned out CCFL's, and put in LED strips as I've done dozens of times on several other monitors. The ends of the CCFL's were burned black on the end and even severed in a couple places. Happens all the time in these old LCD's that run 24/7 for 5 years+
When I put it back together and powered it up, about the bottom 1/3 of the screen is black with a ghost image below the "unsupported"... -
Re: Older Bose Cinemate home theater system failure
Well I decided to take apart the interface unit and it's directly wired, Red and Green LED's, IR, audio jacks directly connected to wiring with no components in-between. And I have continuity from every one of the 9 pins to the wires on the inside. So I answered my first question, problem is definitely in the main board. So new question, is there anything that can be done to troubleshoot and repair something like this when the digital section dies, or is it junk? Usually I see a power supply failure when something like this happens...Leave a comment:
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Older Bose Cinemate home theater system failure
I have an older Bose Cinemate home theater audio system. It only has 2 RCA inputs, no optical connector. The interface module is also what communicates with the IR remote control. The interface module and speakers are connected with DB9 serial cable type connectors. When the unit is in standby, a red LED lights up on the interface, and a green one when it is turned on. Or I should say it used to. I went to turn mine on the other day and no LED's were on, and there is no response to the remote. So I took it apart and verified the power supply seems to be working. Transformer has continuity on primary... -
Re: Can these speakers be repaired?
Update: I rewired it putting the 2 speakers in series and it still runs hot. Still sounds good too. I'm going to leave it because the static resistance of the old speakers (alligator clip leads on what's left of the lead wire) measure around 12 ohms and my new ones with the 8 ohm impedance rating measure just over 6. So I figure it's better to go a little high than too low and overload the amp. Hopefully the running hot is normal and that nothing burns out. I did read somewhere that these old amps are biased high but haven't had much experience...Leave a comment:
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Re: Can these speakers be repaired?
Thanks for the suggestion. Borrowed a round file from my tool box at work for the weekend and minimal filing I got them to fit and install. Most of the issue was just the thick gasket material covering most of the inside edges of the holes so once I got that out of the way I only had to do a little metal filing in a couple spots.
Now I have one further question. I'm not sure if I should continue here or start a new thread. But my original speakers as you can see in the picture are labeled 8-16 ohms. I've never seen that before. Usually...Leave a comment:
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Re: Can these speakers be repaired?
I found a pair of 12" 70W guitar amp speakers on Amazon Prime for only $45. Thought that would be more cost efficient for the customer than the hours I'd spend trying to re-lead the old ones. But just one problem, they don't quite fit. Same diameter, same number of mounting holes. but won't quite fit over the 4 studs. The holes in the original speakers are larger and more oblong than the smaller round holes in the new ones. Should I attempt to file or drill them out bigger, or send them back while I still can?Leave a comment:
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Can these speakers be repaired?
I was asked to look at some guitar amps by the owner of the local pawn shop. One is a Kustom model 11-L and the problem with it is "no sound". It has 2 12" speakers in parallel and I found the 1/4" jack coming from the speaker harness going into the amp measures wide open, no continuity whatsoever. At first I suspected a broken wire but the problem is on the speakers themselves. I don't know if someone vandalized it, or if it deteriorated, but both leads on both speakers coming from the cones to the terminals are severed. The leads are a very soft flexible material with cloth... -
Re: WS-WN523N2 WiFi AP Power Supply
Quick edit, I just figured out the 22uf 100V was originally across the bridge and the 4.7uf 400V on the other side of the inductor. They are radial capacitors and they were installed laying flat with the leads bent at 90 degrees. The polarity is opposite in the 2 locations so the leads are bent opposite directions. So my original resistor that burned out may have been either higher resistance than I'm interpreting the color bands indicating 10 ohms or it somehow had some inductive properties. But at only 60hz, that wouldn't drop a lot of voltage...Leave a comment:
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Re: WS-WN523N2 WiFi AP Power Supply
I finally had enough nerve to power it up today. I was a little gun shy after that cap blew out last time lol. With another 4.7uf 400V cap in place of the 22uf 100V one that popped, I'm measuring 173.5V across it, and 4.68V on the output. The output is a little low, should be 5V. I assume it's low because I only have a total of 9.4uf filtering at the bridge where I previously had 26.7. (a 22 and a 4.7)
But what I'm trying to figure out is how it worked in the first place with only a 100V cap. When I made the mistake of assuming all 4 were...Leave a comment:
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Re: WS-WN523N2 WiFi AP Power Supply
Yes exactly something had to have kept the voltage on C1 under 100 volts previously. So I'm thinking one of 2 things changed. Either the initial 10 ohm resistor was wire wound and acted like an inductor and dropped some voltage or the other inductor fused together and lost its impedance because I actually had a 470uf 16V cap in both higher voltage locations the first time around. I didn't look carefully and thought all 4 were the same. The inductor does measure around 15 ohms with my meter so I know it's not dead shorted. Or the 3rd scenario is...Leave a comment:
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Re: WS-WN523N2 WiFi AP Power Supply
IC is a "Hotchip" HT2535, zoomed in picture attached.
I just measured the bridge, very good idea but no shorts. I assumed that the high inrush current from having a 470uf 16V cap in place of the 4.7uf 400V immediately burned the fusible resistor open and the rest of the circuit never powered up enough to damage the IC, but I could be wrong. When I powered it up today it actually ran for about 20 seconds before the cap popped. I saw the green LED's on the router board light up, go dark, then come back on. I believe they were still...Leave a comment:
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Re: WS-WN523N2 WiFi AP Power Supply
Added a rotated view of the top side of the power supply so you can see inductor "L1". That's the one between the positive side of the bridge and the 22uf 100V cap I mentioned above. The cap goes in location C1, currently removed from board after it blew....Leave a comment:
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