K7000 25in B+ Voltage

[oddsock]

So I acquired a cheap K7000 monitor that was DOA and am trying my hand at repair. I was able to repair a G07 so thought "hey! lets try another one!". I'm pretty sure that there was some kind of surge that came through the chassis because before plugging it in I fixed all the things that I knew were bad that I could see and test. 3 of the diodes near the filter cap, the HOT (shorted) and the VR, replaced the Flyback (I couldn't tell if it had a small crack or not - but replaced it anyway) and did a cap-kit and replaced the blown fuse along with repairing a few burned traces (which I had no idea how to do until this project). Wired everything back up and got neck-glow and now when I'm testing the B+ voltage I get 160v on the tube side and 120v on the "blue wire" side. The VR that I got is the STR 30130.

so here are my questions:

When I test the back-side (blue wire) of the white ceramic resistor should I bet getting 130v instead of 120v ? The VR that I replaced was also a STR 30130.

I am getting a very dim image on the tube, would the low B+ voltage cause that or might that be caused by something else ?

thank you for any help!

Ed

 

[cleure]

If any of the Bridge Rectifier diodes are bad, you should replace all of them, instead of just the ones that are bad.

You could have a bad/counterfeit VR, or something could be loading down the power supply. Voltage should be about 130v.

Where did you buy the VR?

 

[oddsock]

If any of the Bridge Rectifier diodes are bad, you should replace all of them, instead of just the ones that are bad.

You could have a bad/counterfeit VR, or something could be loading down the power supply. Voltage should be about 130v.

Where did you buy the VR?

I got it here : http://www.arcadeshop.com/i/995/130v-1a-voltage-regulator.htm

I will replace all the bridge rectifier diodes...

Is there a way I can test the VR out of circuit to see if it's bad/counterfeit ?

Any suggestions on where I should be getting the VR ?

Thanks!

 

[cleure]

Since you bought the VR from a reputable source, it might be worth proving that the power supply is working correctly.

General procedure is to remove the HOT (this disables HV), and wire in a 75 watt incandescent light bulb parallel to the B+, while also checking the voltage.

Connect one lead to the chassis frame (ie: the metal around the flyback), and the other lead to the B+ test point. Then do the same with your multi-meter.

When you power it up, if the voltage regulates to about 130v, then the power supply is good. If not, then the power supply will be where you need to focus.

 

[security0001]

Since you bought the VR from a reputable source, it might be worth proving that the power supply is working correctly.

General procedure is to remove the HOT (this disables HV), and wire in a 75 watt incandescent light bulb parallel to the B+, while also checking the voltage.

Connect one lead to the chassis frame (ie: the metal around the flyback), and the other lead to the B+ test point. Then do the same with your multi-meter.

When you power it up, if the voltage regulates to about 130v, then the power supply is good. If not, then the power supply will be where you need to focus.

there has been quite a few threads on this VR from arcadeshop and i suspect they are remarked chips and technically are STR30120 and remarked as STR30130 and you can't test them other than in circuit to see what they regulate at. OP should just replace the VR.

all of our sanken VR we test each batch because its so common for them to be original sanken but remarked so try ours as i know they are good and if you find yours is bad from arcadeshop make sure to let them know so they can check their stock and correct them.

https://www.arcadepartsandrepair.co...tage-regulators-integrated-circuits/str30130/

 

[oddsock]

there has been quite a few threads on this VR from arcadeshop and i suspect they are remarked chips and technically are STR30120 and remarked as STR30130 and you can't test them other than in circuit to see what they regulate at. OP should just replace the VR.

So I ended up finding this https://youtu.be/o7yl--A1nBQ?t=850 which was showing EXACTLY the issue that I was seeing and he apparently bought from the same source as I did (Arcadeshop)...so I suspect your are correct and I've order up the VR from your site.

I'll report back after I swap in the new VR and if it's 130v I'll definitely be contacting Arcadeshop.

 

[mecha]

I wouldn't buy any monitor parts from Arcadeshop or Twisted Quarter. I get everything from security now.

 

[cleure]

there has been quite a few threads on this VR from arcadeshop and i suspect they are remarked chips and technically are STR30120 and remarked as STR30130 and you can't test them other than in circuit to see what they regulate at. OP should just replace the VR.

all of our sanken VR we test each batch because its so common for them to be original sanken but remarked so try ours as i know they are good and if you find yours is bad from arcadeshop make sure to let them know so they can check their stock and correct them.

https://www.arcadepartsandrepair.co...tage-regulators-integrated-circuits/str30130/

My bad, I read Arcade Parts and Repair

 

[oddsock]

so just to follow up and provide some resolution on this thread. Replaced the VR from Arcadeshop with the VR from Arcade Parts and Repair and boom-shacka-lacka-boom the b+ went from 120v to 130v and everything just started working as it should...

I rechecked and the Arcadeshop VR was definitely branded as a 30130 but operating as a 30120. Kinda sucks because I'm probably not going to buy anything more from them now...

Anyway thanks again to all who helped with this!

Ed

 

[security0001]

so just to follow up and provide some resolution on this thread. Replaced the VR from Arcadeshop with the VR from Arcade Parts and Repair and boom-shacka-lacka-boom the b+ went from 120v to 130v and everything just started working as it should...

I rechecked and the Arcadeshop VR was definitely branded as a 30130 but operating as a 30120. Kinda sucks because I'm probably not going to buy anything more from them now...

Anyway thanks again to all who helped with this!

Ed

glad to hear you got it all working.

 

[jjhudgins]

Just encountered the same here. Acquired a p538 with a cap kit from Arcadeshop. Op complained it was dim and hard to adjust. I tested b+ and it was almost 120v. Replaced with same part number but from Peter, and boom, 130v

 

[mecha]

@zenomorp in one of the 600 K7000 videos he's posted was doing a demonstration on testing VRs and discovered he had counterfeit 30123s I think they were. we had a tray full of VRs at the shop and I could spot the fake ones based on how the text is printed on them. and they didn't pass the diode test. probably a month ago I came across a broken chassis that had a funky VR, same thing. it's not very common but shorted VRs can pop the fuse too apparently.

but some 3 years later I still have to say, don't buy any electronic parts of any kind from Arcadeshop. they sell a multitude of other great things, but pass on those. it's like Bob Roberts 2.0

 

[putyoursoxon]

@zenomorp in one of the 600 K7000 videos he's posted was doing a demonstration on testing VRs and discovered he had counterfeit 30123s I think they were. we had a tray full of VRs at the shop and I could spot the fake ones based on how the text is printed on them. and they didn't pass the diode test. probably a month ago I came across a broken chassis that had a funky VR, same thing. it's not very common but shorted VRs can pop the fuse too apparently.

but some 3 years later I still have to say, don't buy any electronic parts of any kind from Arcadeshop. they sell a multitude of other great things, but pass on those. it's like Bob Roberts 2.0

What pins on the VR are you using for testing these 2-4, 3-4?

 

[mecha]

What pins on the VR are you using for testing these 2-4, 3-4?

I think you can just do it at the R301 legs where the red and blue wires connect. those wires run to the pins at the VR that you would test at. if in the event the VR were shorted I think R301 just shows shorted then. which would make sense... the unregulated 160V would be coming out the regulated 123/130V side and the most telling symptom of bad VR is the monitor would then be in shutdown.

 

[Ohmerone]

What pins on the VR are you using for testing these 2-4, 3-4?

There are bad New Vrs and are marked wrong part number also.

I just measure on the Neck board because I know the B+ is on the neck board
with the regulated B+ easy to reach in the cabinet.
Before i pull the chassis to fix.
Good to do, then I have a reference with some details
before its on the bench.
Bad connections alone will cause unregulated B+
at the traces around R101 which are well known
and have a good Vr, Everybody should know
its in the sticky!

I use the Bulb load test when testing VR's
like Post #4 to check regulation and More!
If you adjust the screen or brightness and the B+ changes
then the VR is bad!
It is controlled by the Zener that's in the IC!
if it doesn't go to the correct voltage at startup with a correct load then its bad.


I know i have see the STR30130v Vrs at 131vs that's bad
Question you think the diode checker would tell you that?
Have you seen what's in the IC.
A resistance test makes more sense then diode test.
Or just a Load test!


Heres the circuit

STR30123 Datasheet - PDF Download

Download the STR30123 datasheet for detailed specifications and information on the STR30123 electronic component.

datasheetspdf.com