Burnt Bridgeport power feed control board repair query

[Andy Tyrrell-ClarkParticipant @andytyrrell-clark73692]

Hello

 

I am finally getting round to fixing an issue on the Bridgeport series 1 BR2J2 Mill I acquired a little while ago. I purchased it knowing that the power feed on the X axis din't work and had just used it manually.

 

I'm now trying to get the power feed working again and it looks to have fried the control board in the past – hence why it wasn't working. As you can see in the pictures an area near the connector block has had some issues and burnt (possibly from the micro switches both being on at some point). Looking at the back of the board this is clearly not the first time it's happened judging by how a few of the components are attached and the jumper wires used.  Obviously I'll test the micro-switches and motor etc in the unit before powering it up again if I can fix it

 

It controls a 6F (B or C) drive with a 12 wire connector

 

The problem I have is trying to track down a schematic for this board to try and figure out what the components that have fried were. It is not the common Erskine board that I have seen and I have been unable to locate images or schematics online that would appear to match this particular board.

 

Does anybody on the forum happen to know the make of this board and by any chance have either a photo or schematic so I can replace the burnt out components.

 

Many Thanks

Andy

 

Board front:

Burnt area:

Back of board:

Rear of burnt area:

Edited By Andy Tyrrell-Clark on 20/04/2020 11:09:31

Edited By Andy Tyrrell-Clark on 20/04/2020 11:11:18

[Andy Tyrrell-ClarkParticipant @andytyrrell-clark73692]

[Keith LongParticipant @keithlong89920]

Andy – I can't guarantee that this is the right one but it's supposed to be a 6F drive board

Hope this helps, it's in one of my albums

Keith

[Clive FosterParticipant @clivefoster55965]

Andy

12 wire connection is the American power feed circuit rather than the Erskine one usually found on UK built machines.

I have 2 pdf format versions of a circuit that appears to be the same as the one in Keiths post which were allegedly copied from official Bridgeport manuals of differing vintage so there may be minor component variations. I also have a nice copy of how the wiring to the various switches is arranged.

If you want them PM me your E-Mail and I'll send them over.

Allegedly this board is a little fragile, especially in old age. Current consensus in the USA seems to be that the best option is to buy a modern off the shelf DC motor drive board of appropriate voltage and current capability. It is said that modern board will give better control too. KB brand drive boards are frequently suggested. They can be got for around £100 in the UK. I believe similar 1/2 hp 90 volt DC drives can be found from £50 upwards but how good / bad / suitable the less expensive ones may be I do not know.

Clive

Edited By Clive Foster on 20/04/2020 12:32:36

[Andy Tyrrell-ClarkParticipant @andytyrrell-clark73692]

Hello Keith,

 

Many thanks for your response and the schematic which I had seen in the Hardinge user manual but unfortunately it doesn't appear to match my board which has significantly more components on it (approx 30 more resistors than appear in the schematic).

 

If I can't find the correct schematic for this board, it might have to be a case of replacing the whole board with an Erskine unit where at least schematics are available for future issues – probably not a bad idea as this one has obviously had a hole burnt right through the board at some point in its past.

 

Many thanks again

Andy

Edited By Andy Tyrrell-Clark on 20/04/2020 13:43:01

[Clive FosterParticipant @clivefoster55965]

Andy

As mentioned before it looks as if the best way for you to get a good, reliable board is to buy a new one.

Problem with changing to an Erskine board will be finding a good one at a sensible price.

They can be repaired but the cost of repair on top of buying one probably isn't worth it. Professional repair seems to be in the £100 – £150 range. But if you have the skills for DIY I have a decent set of data and a box of dead ones. Could easily send you one if you fancy a lucky dip. I have no idea what the faults are. £5 plus postage?

The great advantage of the Erskine in a standard Bridgeport is the big, multi-point choc-block style connector unit. Easy to fit and pretty much impossible to get wrong. Bottom line is they are getting very old. Production ceased over 20 years ago. Replaced by similar ones made by Quantum. Drop in replacement but slightly different circuit (which I don't have).

Clive

[Andy Tyrrell-ClarkParticipant @andytyrrell-clark73692]

Hi Clive,

Many thanks for your messages – I've sent you a couple of PM's

Just to be a little clearer – the current board has a 12 pin connector but the wiring only uses 11 of those pins – there is an unused pin between the power inputs to the board and the first of the harness wires going to the unit itself. It looks just like the wiring I've seen in pictures of Erskine Boards (pic below).

Many thanks

Andy

[Taris JewellParticipant @tarisjewell61133]

Clive Foster hi I had just bought a Bridgeport that was sold with a power feed when I got it home and opened the electrical box I found the circuit board missing. the wiring looks like the pictures and it is a 12-pin connector missing one wire. it also seems to be a 6f power feed. I am interested to see if you still have any used boards left?

[Clive FosterParticipant @clivefoster55965]

Hi Taris

Sorry I no longer have any boards left. Passed them on to a guy willing to take pot luck on actually getting one to work. Which he managed. Unfortunately I've lost his contact details.

Realistically the originals are now so old that getting one to repair is chancy at best. Far as I know the pulse transformer details are not around so if that has gone you are stuffed. Maybe the professionals have the necessary information but professional repair will be expensive.

Best bet is to get a modern "90 volt nominal" DC servomotor control board and hook it up to the Bridgeport controls as per the Erskine system. A modern controller will work just as well, maybe a bit better.

If you don't have wiring details PM me your E-Mail and I can send you over my Erskine data pack which has everything you need to know and lots more. I also have a typical UK built Bridgeport wiring diagram in pdf if you need that too.

Clive

[Taris JewellParticipant @tarisjewell61133]

Clive Foster I've pm you chap

[Barry Smith 4Participant @barrysmith4]

Hi, I also replaced my Erskine box with a KB board and it's been working great ever since. I used a kbmg-212D (8331E). It's advisable to get a regenerative drive anti plugging if you want to be able to do a rapid forward/reverse.

The KB boards are much smaller than the Erskin which is nice. They also run off 230v/110v which means you don't have to use the transformer to supply it.

Radwell in the UK have a refurbished one going for £100 at the moment, they seem to be £200 new but come up on ebay now and then.

My advice would be to fully strip the motor as mine was full of black gunk, and replace the cables and switches. A new gasket also helps, you will also need to change the speed pot.

If you go down the kb route I can provide you with wiring details.

Barry

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