SS Chassis Trouble

[charlie b]

I start back to work Monday on AMF 8270's in the head mechanic's position. What a mess i am walking into in this center. Might need all of you great mechanic's help alot here on Bowltech! I have already took a tour of the backend. Wow, 3 pairs of lanes down! First problem, no spare chassis, blows the F1 fuse as soon as flip the main switch on the backend control box. Was a 5 board chassis, converted over to Omega-Tek MK70 with Expander board. Tried on several different machines, so it has to be in chassis. Send me some ideas to look for.

[wb8yjf]

Re: SS Chassis Trouble

If it is popping the F1 fuse, could be a lot of things. Bad XFMR, short inside from who knows what, etc. Those are a blast (sometimes literally). I rebuild these if you are interested & have a couple rebuilt & ready to go. [img]/content/btubb/images/%%GRAEMLIN_URL%%/laugh.gif[/img]

Good luck!
Jon [img]/content/btubb/images/%%GRAEMLIN_URL%%/usflag.jpg[/img]

website: <a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank"><a href="http://home.earthlink.net/~wb8yjf/" target="_blank">http://home.earthlink.net/~wb8yjf/</a></a></a></a></a></a></a></a></a>

[Macguyver]

Re: SS Chassis Trouble

I had this same problem on 2 chassis'. Turned out to be a shorted out power diode both times.

[MCSS]

Re: SS Chassis Trouble

It's probably the power diodes on the heat sink under the T1. The part numbers are 070-005-842 there is 2 of them and 1 of these 070-005-859.

I usally just replace all three when I have this problem. Usally takes care of it.

Make sure the insulator pads are there and in good shape, where the heatsink mounts to the chassis.

Hope this helps.
Mike

[charlie b]

Re: SS Chassis Trouble

Hey Macguyver and Mike, Thanks for the help! I ordered the power diodes, they should be here in a couple of days. I know one of the power diodes is REVERSE. How can I tell which one it is?

[BowlEquip]

Re: SS Chassis Trouble

Charlie b: Using a meter set on testing continuity, put one lead on the heat sink frame and the other on the lead from the diode. This will tell you which are different and also if bad. The AMF catalog shows which part number goes in which position. Good luck!!
By the way, check for continuity between the heat sink frame and the chassis frame. There should be none! If there is, you may have a small piece of hardware wedged between the two frames which will short out and blow either F1 or the wall breaker.

[Dutch]

Re: SS Chassis Trouble

The middle diode is the one that is reversed. When testing with your meter (as mentioned above) just reverse the leads of the tester for that diode &amp; it should read exactly the same as the other 2.

[Dutch]

Re: SS Chassis Trouble

Has anyone ever found a way to test the varistors? They are a rare beast. Most of the electronic techs I've talked to have never heard of a varistor.

[felix]

Re: SS Chassis Trouble



The varistor is a surge protection device that is connected directly across the AC input. When a power surge or voltage spike is sensed, the varistor's resistance rapidly decreases, creating an instant shunt path for the over-voltage, thereby saving the sensitive control panel components (hopefully). Because the shunt path creates a short circuit, the varistor and the line fuse are subject to be damaged or weakened in the process.

"Has anyone ever found a way to test the varistors? They are a rare beast. Most of the electronic techs I've talked to have never heard of a varistor."--Dutch

No [img]/content/btubb/images/%%GRAEMLIN_URL%%/laugh.gif[/img]



Long Haired Version

[charlie b]

Re: SS Chassis Trouble

Nice pic Felix! I liked reading the long-haired version! LOL! Update on the chassis problem, got the new power diodes in today and installed them. Still blows the F1 fuse when you turn on the main switch on the backend control box. Going to replace T1 tomorrow, will keep everybody posted.

[TheLegend]

Re: SS Chassis Trouble

Originally posted by charlie b:
Nice pic Felix! I liked reading the long-haired version! LOL! Update on the chassis problem, got the new power diodes in today and installed them. Still blows the F1 fuse when you turn on the main switch on the backend control box. Going to replace T1 tomorrow, will keep everybody posted.

<font size="2" face="Verdana, Helvetica, sans-serif">I've had small nuts and bolts get loose inside a chassis before and cause shorts like this. Sometimes they'll wedge themselves inbetween the diode block and chassis frame or down onto the motherboard.

[pulse-tech]

Re: SS Chassis Trouble

Has anyone ever found a way to test the varistors? They are a rare beast. Most of the electronic techs I've talked to have never heard of a varistor."--Dutch

Never tried to test one but they can be bought from AMF we bought some about a year ago just as spares (when i had my 70's)

[charlie b]

Re: SS Chassis Trouble

Great news, Bowltech members! Replaced the T1 today in the chassis and it works just fine. Thanks for everyones help and input to solve this problem. What a great website! Rock on Bowltech!

[wb8yjf]

Re: SS Chassis Trouble

G'day "Post"...I have been trying to figure out a good test for Varistors/Tranzorbs, etc. for a long time. I have NEVER gotten an answer! I see some tests you can do out of the circuit, but that takes a lot of effort. They are such a pain in the arse, I just get rid of 'em. [img]/content/btubb/images/%%GRAEMLIN_URL%%/laugh.gif[/img] I have seen many more problems caused by these things than a failure with the device (usually a relay)they are supposed to protect [img]/content/btubb/images/%%GRAEMLIN_URL%%/eek.gif[/img] Just cut them out and a lot of problems dissapear. [img]/content/btubb/images/%%GRAEMLIN_URL%%/laugh.gif[/img] In my opinion, they are the weak link in the chain... [img]/content/btubb/images/%%GRAEMLIN_URL%%/laugh.gif[/img] Cheers...
Jon [img]/content/btubb/images/%%GRAEMLIN_URL%%/usflag.jpg[/img]

[charlie b]

Re: SS Chassis Trouble

I have another chassis problem for everybody to help me solve! My boss ordered a rebuilt chassis from Magicscore Repair. This chassis has the pc boards instead of the old contactors for table and sweep motors. Put it on #24, the spotting solenoid would not energize to set full rack. Tried on #22, done the same thing as #24. Called and talked to John Mayberry at Magicscore Repair. He said he had never heard of a problem like this with rebuilt chassis with pc boards. Sent it back and received another chassis and done the same thing as previous chassis. These chassis were shipped without relays and chassis boards. This is a SS 5-board chassis.