K4900 - no glow

[texasmame]

Getting 120v in from the power supply to the monitor.

Getting 145v at R503 end nearest the fuse (which tests good out of circuit, of course) and 160v testing the chassis case to the HOT. HOT not testing good for continuity so no short.

Are these voltages within tolerance or are they too high, specifically the HOT one?

Got no glow nor crackle and discharging the suction cup after testing yields no pop at all.

TIA

 

[texasmame]

Sunday morning bump

 

[channelmanic]

If the fuse is good and the HV isn't coming up, check the horizontal drive section. It must be running to give you high voltage.

The CRT heater voltage is typically grabbed off a tap of the flyback so if the horizontal section isn't running then you usually don't have a glow in the tube's neck.

RJ

 

[modessitt]

Sounds like it's in HV shutdown, but lets check for bad connections first. Check the solder along the back edge on the 130v line. It runs right along the edge. If that looks okay, then look around the flyback area for any small cracks, and check the neckboard, too. Then look around T351. After all of that, check Q351 and R363 to see if they are good. If you have a parts board, you can try swapping in IC301...

 

[texasmame]

Thanks for all the input but it sounds like a lot more trouble than it is worth for me, given that I don't even have the need for a 22" monitor!

It's available if anyone wants it. Neo Geo burn on the tube. $69 come and get it?

 

[modessitt]

22" monitor? The 4900 was only made for a 13" (they called it a 4800), 19" and 25" (although they called it a 5500 for the 25")"

 

[texasmame]

22" monitor? The 4900 was only made for a 13" (they called it a 4800), 19" and 25" (although they called it a 5500 for the 25")"

Says WG 19k4901. Has the 19VMKP22A tube, which is listed as one of the proper tubes for it.

Is this not a 4900 then - thought that's what the 4901 part was? Pic added above.

 

[modessitt]

The 19 mean 19". The 4901 means 4900.

There is no 22" tube for arcades...

 

[texasmame]

The 19 mean 19". The 4901 means 4900.

There is no 22" tube for arcades...

Well then. Yes.
/frankdrebin

So, it's the 4900 but a 19"? Looks larger than that - aaah. . . you must just measure the grey part, not the black around it. Grey part is 19" but corner to corner, it's 22".

 

[modessitt]

US tubes are measured by viewable area - aka the grey part. Japanese tubes are measured corner to corner...

 

[texasmame]

US tubes are measured by viewable area - aka the grey part. Japanese tubes are measured corner to corner...

Ah, good to know, thx.