MPC4500 -- "front door open" and PCU/PSB

[mapsanji]

Hi all.....someone out there might shed some light on this problem here it go's.......mpc4500 keeps on blowing fuse's on Power supply so I'd replace it (new PSB) - so after replacing it found out that the BCU is foulty aswell, ok so replaced the BCU board now its coming up with " front door open" , test the front door switch and harness..all good but noticed its blowing a different fuse on the PSB, its been 3days now can't figure out WTF is wrong.....Part no of original board is AZ240110 -- Part no of new board is AZ240150 ( replacement part number ) I noticed there's one connector WRONG... " don't have the connector number with me now "
Cheers Martin

[TonerMunkeh]

What do you mean by "wrong" connector? I've fitted a few of these power supplies to MPC3500/4500's and as far as I can tell they are identical. Has the IH PSU been taken out too? Which fuse on the power supply is being blown?

[tcs04]

Hi all.....someone out there might shed some light on this problem here it go's.......mpc4500 keeps on blowing fuse's on Power supply so I'd replace it (new PSB) - so after replacing it found out that the BCU is foulty aswell, ok so replaced the BCU board now its coming up with " front door open" , test the front door switch and harness..all good but noticed its blowing a different fuse on the PSB, its been 3days now can't figure out WTF is wrong.....Part no of original board is AZ240110 -- Part no of new board is AZ240150 ( replacement part number ) I noticed there's one connector WRONG... " don't have the connector number with me now "
Cheers Martin

The numbers are OK, there was a "Vendor change" for the part. However, the PSU is a known problem, Ricoh were aware of a certain number literally going "BANG" (In the UK) and they changed them under warranty. we have one machine which has had at least 3 (!) including the new number.

We had a machine which blew a fuse on the PSU and it was caused by a trapped wire in the duplex rubbing on the frame.

What made you think the BCU was faulty?

If I went to a machine and it showed door open after the boards had been changed I would ask "What did the engineer do?" Have you another machine you can sneak a look at and maybe take pictures of the board connections to compare?

There's a fuse table on the PSU section of the point to point.

My money would be on either FUSE 7 or 8 blown as these relate to CN911 which connects the interlocks. Remove the CN911 and check continuity from all pins on the PLUG to the chassis. If you get continuity it's a trapped wire somewhere in the front cover safety switch circuit. If not you either have another faulty board, or have connected a plug in the wrong place.

[zyqwiz]

The power supplies blow up when the customer just switches off at the main switch instead of first switching off at the control panel. The modified board had a different diode on it that can handle the current spike.

[hjvol]

fu 101 could be blown again .... check out!!!

[mapsanji]

[QUOTE=tcs04;112200] What made you think the BCU was faulty?.....

Thanx for the feedback mate.....sorry my fault, its not the BCU its the I/O board..... What I could'nt figure out is that connector CN910 on the new board is facing wrong way round, in other words by twisting the connector the ather way to fit on CN910....now you've got 'Groundwires' on the 24Vfu8 and 24Vfu8 and your +5V is now at 24VFu9, shit its bit difficult to explain.....So I took a Powersupply from another m/c ( original PSB )and the I/O board and stuck it the faulty m/c thats when Fuse FU7 pops and on the display -- close front door.....by the way this m/c was working fine for ages and all of a sudden this problem!!
I'm working between xmas and new yr so I'll spend some quality time with my good friend the #@$$% mpc4500