SP300v blowing fuse f2 and transistor

[mondo1967]

Hi Guys. first thanks for all the posts over the last 8 years, really helped me keep my Roland up and running smoothly.

i now have a problem surfaced a week ago.

first I blew fuse F2 stopped mag/ylw head from printing. replaced to find that it blew again.

had advice to test some components on the mainboard, and a transistor was out. had that replaced and it immedietely blew again once sub power was turned on and a print test was executed.

I've checked all cables connected ok. the fuse is blowing as well when the transistor blew. I've read on a post that a faulty thermistor could cause the transistor to trip, but not sure how to check.

has anyone had similiar problems that can guide me through troubleshooting without spending £2000 on a new mainboard and engineer visit?

thanks in advance

Danny

 

[CS-SignSupply]

Any hint on what was done or may have been done to cause the first blowout?

 

[mondo1967]

no idea what caused the original fuse to go.

I was on a contract job for a week with another company and came in friday to do the cleaning routine when it failed to print m/y during a test print. I Immedietley checked fuses and replaced the faulty one. once it blew the second one I took the board out and inspected it and found the transistor to be blown. (burnt looked areas on the solder side of the board directly beneath the transistor. Tested the transistor with a multimeter for resistance found it to be an open circuit. Also a capacitor was covered in soot so had that replaced as well.


also note: I always unplug from power supply before any work is done under the hood

 

[SignEx]

Have you dripped anything on the printhead, A faulty printhead will blow the fuses also

 

[mondo1967]

not that im aware of. i did check all ribbon cables, and connectors and with a fine tooth comb.. no drips at all. the machine wasn't in use all week the week it failed.

and its not so much the fuses blowing.. as the transistor that keeps blowing, thats baffling me.

thermistor? from black head causing m/y head to blow transistor/fuse? i'm at a loss for now.

 

[ToTo]

Blown F2

Try to startup machine with "repaired" Mainboard, but leave the cables from printhead disconnected.
If the fuse is still blown, there is a Problem on the board.
Also you can try to connect y-m PH to c-k connectors and check if PH has blown the board...

 

[perfectblindering]

same problem

I have the same problem with my roland VS-420. the moment i replace the fuses and i turn on the power supply the fuses get blown. this all started after a collega of mine put the cables of the printhead on the wrong place. After this i replaced the printhead and the fuses. Now i have removed the main board , what should i look for on the main board??

 

[brightbanner]

How do you blew fuse at first time?
It can burn your printer heads too.
I suspect your printer heads was burned and they can blow the fuse again.

I have same problem months ago, printer can not work before I send the mainboard to Adam for repair.
And he give me guide file for boards fit, replace the printer head.
It is OK now.

Brent

Hi Guys. first thanks for all the posts over the last 8 years, really helped me keep my Roland up and running smoothly.

i now have a problem surfaced a week ago.

first I blew fuse F2 stopped mag/ylw head from printing. replaced to find that it blew again.

had advice to test some components on the mainboard, and a transistor was out. had that replaced and it immedietely blew again once sub power was turned on and a print test was executed.

I've checked all cables connected ok. the fuse is blowing as well when the transistor blew. I've read on a post that a faulty thermistor could cause the transistor to trip, but not sure how to check.

has anyone had similiar problems that can guide me through troubleshooting without spending £2000 on a new mainboard and engineer visit?

thanks in advance

Danny