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Blast City and Astro City Resto Thread

BlinG said:
Cold solder joints on the neck board is common on the nanao 2930. I had the exact same issue in this thread on KLOV

https://forums.arcade-museum.com/threads/nanao-ms-2930-fyi.326475/
Click to expand...

Just pulled the CRT! Waiting on some tools to measure and document all the caps to try and get closer to what the PCB expects (ESR and lead spacing).

Gave the CRT a wash, it was definetly filthy but Krud Killer + Simple Green took care of it. Only thing I dislike is the main tube manfuacturer label got the model number scrubbed off... oops.

Once it was fully dried I pulled the chassis out. From first glance the boards look clean and fine. Worst thing I saw was some resistors lost bits of their outer coating (probably due to heat).

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hmmmm. My orange cap was replaced by the much smaller one using these kits. I have not measured the ESR.
 
I've had the tiny cap from Arcade Parts and Repair.
Didn't have any issues with their kit in the 2931 I serviced.
I replaced the tiny cap with a low esr cap while trying to eliminate strange behavior (took like 15 minutes to come into focus) in my 2930 and it had no effect. Turned out my issues were on the neck-board in the end and likely not related to that tiny cap at all.
 
Cool, bought two cap kits. If anything I'll buy any extra caps that might look weird.

Today grabbed the MS-2931 manual and matched the transistors, diodes, and mosfets it suggests to check if the tube heater is on but no HV. Interestingly some parts of the circuit have matching ref codes. My guess is these sections were copied from the different board schematics when designing. Any codes with a `XXX -> YYY` is the MS2931 -> MS2930 match. Otherwise I didn't find one.

H. Deflection

Q511 -> Q501: Transistor; NPN; HOT
D511 -> D501: Diode
Q952: MOSFET
Q501: MOSFET
Q503 -> Q503: Transistor PNP (Checked all transistors and diodes anyway around this circuit)

V. Deflection

U401 -> U401: LA7846N

High Voltage (All three matched)

Q701: MOSFET
U701: Daughter Board (IIRC xray protection?)
T701: Flyback

I think I found a short with the HOT, might have kicked the bucket and the reason why the HV isn't turning on. A reading of 0 on the diode test means a short right? Between the Base and Emitter both ways.

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yeah expect somewhere between 0.5 and 1 volt. What is the reading when it is configured to measure resistance? would expect to read as a short if the HOT is blown out.

Maybe pull it from the board and measure once more to be certain.
 
snakeGrave said:
yeah expect somewhere between 0.5 and 1 volt. What is the reading when it is configured to measure resistance? would expect to read as a short if the HOT is blown out.

Maybe pull it from the board and measure once more to be certain.
Click to expand...
Huh, Grantspain on Arcade Otaku mentioned might be a false reading due to being in circuit. Will remove it and double check it out of circuit.
 
Lotta recapping work done since my last post. Got a MVS Slot-1 board and it played fine but still had it's battery and old caps. No corrosion though! One of the caps looked like it was about to leak. The stereo/mono switch was also damaged. Fixed it all up!

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I also received the cap kit from ArcadePartsandRepair. For the most part it was fine but their power supply caps are waay too big causing some of them to not sit flush and butt up against each other. Resoldered the CRT pins too. Couldn't get the daughter card out to get the last two caps, is there a trick to it? I also kept the orange cap, it had 0.08 ohm ESR vs like 2ohm on the replacement caps. Looked in good condition too. Used the best ESR LGW caps from Nichicon for the filters.

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Will do one last confirmation check and see if anything else needs resoldering. Also ordered 2.5mm zipties to reinstall the neck cover and some dielectric grease. Crossing fingers it works after this!
 
This the chassis that was part of the cab that had blue problems? Check the blue gain trimmer pot while the whole thing is out ?
 
Ioncannon said:
Will do one last confirmation check and see if anything else needs resoldering. Also ordered 2.5mm zipties to reinstall the neck cover and some dielectric grease. Crossing fingers it works after this!
Click to expand...
Looks very nice and very clean work there sir ! Waiting your results ! Happy for the enthusiasm :saint:
 
ItsBobDudes said:
This the chassis that was part of the cab that had blue problems? Check the blue gain trimmer pot while the whole thing is out ?
Click to expand...

No this is the one that was fine except for a weird power loss flicker, and then stopped getting high voltage. Heater still worked. Will tackle the other CRT once this is done.

AlxUnderBase said:
Looks very nice and very clean work there sir ! Waiting your results ! Happy for the enthusiasm :saint:
Click to expand...

Thanks! I am both excited and terrified of turning this thing back on. Seen a lot of necked tube horror stories with these monitors. One theory was that little PCB that deals with XRay protection breaks and the chassis over volts killing the tube.

Oh yeah, and I tested that MVS board on the Astro City. Nice colors but deffo needs a recap as the screen slowly loses blue half way up the screen. Also some geometry wobble.
 
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Ioncannon said:
Thanks! I am both excited and terrified of turning this thing back on. Seen a lot of necked tube horror stories with these monitors. One theory was that little PCB that deals with XRay protection breaks and the chassis over volts killing the tube.

Oh yeah, and I tested that MVS board on the Astro City. Nice colors but deffo needs a recap as the screen slowly loses blue half way up the screen. Also some geometry wobble.
Click to expand...
You treat them damn good until now ... the problem for me is not too much guys from Europe handle these cabinets overseas and it's not easy to get one . I have a promise for a New Astro City and i'm thinking on the day when i will have ok from the seller that can be shipped freight on the sea until the port from my city . Hope to jump in the boat too in the near future because i spend alot on arcade pcbs but never put money aside to get a cabinet , also i passed 2 times the chance to an Egret 2 , once in 2018 from Canada and once in 2019 from Japan .
 
Was too excited and reinstalled the board over lunch. Still waiting on zipties for the plastic cover and grease for the anode cap to finish it.

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Degauss, AC, and third connector plugged in. Remote board and inputs plugged in. H-DY and V-DY in. The two grounds to the chassis and one to the neck plugged in. Think I got everything (besides the anode cap).

I was dumb and undid all the screws when I originally removed the chassis. Putting it back I am surprised only 2 screws (the grounds) hold it in place.
 
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AlxUnderBase said:
You treat them damn good until now ... the problem for me is not too much guys from Europe handle these cabinets overseas and it's not easy to get one . I have a promise for a New Astro City and i'm thinking on the day when i will have ok from the seller that can be shipped freight on the sea until the port from my city . Hope to jump in the boat too in the near future because i spend alot on arcade pcbs but never put money aside to get a cabinet , also i passed 2 times the chance to an Egret 2 , once in 2018 from Canada and once in 2019 from Japan .
Click to expand...

Yeah Canada is already hard but I couldn't imagine Europe being any easier. Wow an Egret in Canada? Once my basement is renoed I'll prob go for a Neo 29.
 
Welp still no video
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. Was really excited to play this machine.

I did notice that the HV squeal does return when setting the remote board to 15khz AMP. No video from my MVS board though. No static on the screen surface either.

In terms of other things: Heater still turns on, no arcs that I can see or hear in the neck, and the only other noise I hear is some static and noise in the yoke; probably from loose convergence strips inside.
 
Further investigation in complete darkness I can see arcs flying off the anode cap and at the yoke. More investigation needed with the EHT cable (according to Grantspain). Transformer might be failing.

Just to confirm but a necked tube only arcs inside the glass tip right? Still don't seem any sparks there.

View: https://www.youtube.com/watch?v=ipbjPiLGbdM
 
Well! Getting somewhere! Reinstalled the anode cap and the arcing disappeared, well there is a blue flash from the yoke still. However I am getting a white raster (I assume) for a second before it fades; probably due to the protection circuit. Feel static on the screen too! So tube seems good and I ended up fixing whatever killed power before. Now what is causing the protection circuit to kick in?

View: https://youtu.be/2s9rkmXjGkQ
 
Been a while since I posted; a lot of different things have happened since! In the original pic the "Left" Blast City is BS1 and the "Right" one is BS2.

Control Panel from Blast City One Cleaned and Back Together

Got a new BC and AC panel from @alberto1225 and LOVE it! Put the thing together with brand new Sanwa parts and kept the original wiring. New coin slot and bolts too. I also kept the original wire ties, removing the old sticky residue and replaced it with double sided tape. Works like a charm and is back in it's original position. I threw the panel back into Blast City 2 because it's CRT is working and I wanted to test it out. I realized the Sega I/O is kinda weird and uses Button 4 and 5 on the JAMMA edge for the first two kick buttons, so cannibalized a wire from player 2 (the harness already had btn4 added from whoever had it before). Been playing it since!

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Busted Blast City Monitor One

After trying different things; none of which seemed to get me anywhere, I grabbed a used-but-working flyback from TeknoService. Resoldered it in and turned the machine on. No crackle! No arc in the yoke! The meter read a 20kV voltage coming off of the anode cap! Calibrated HV and was greeted with a beautiful Naomi logo, already colour balanced.

Turned it off, grabbed my phone, and turned it back on.... no video and the board was tripping XRay protect. Sigh, at least I knew it wasn't the tube. Put work on that CRT off for now. I'll document all the different resistors and dioes and replace the ones that are rusted. Any ideas why the board is killing transformers (or causing a OV mode) would be helpful.

Blast City Monitor Two - Fixed Up!

The second monitor had an issue with a lack of blue and some a bit of a washout effect. Took the CRT out and pulled the board (I have become pretty good at it). Thought it could be a busted transistor and bought a pack (really cheap). Traced the B line through the transistors and to the socket.... noticing the pin was completely severed from the solder. Sucked up and resoldered all pins. Luckily the board was already recapped so I threw it all back in and had a marvelous blue!

The "washout" effect seems to only happen when the brightness is cranked up (anyone know what causes it? does it need focusing?) so after getting the colours calibrated I lowered the brightness. It still looks good! Convergence is a bit iffy on the right side, I'll get some strips to fix it later.

Threw it back into the second BC and hooked up my Naomi 2 + NetDimm. I have been playing a ton of MvC2, SF:A3, and CvS2001. Also Rhythem Tengoku with my gf.

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