Finally - a success!

After quite a bit of trying, I finally achieved some success!

 

Let me back up two months....

 

When I purchased the Hot Tip table, one of the solenoids was on continuously. I ran some diagnostics and even went so far as to unsolder transistors that I thought might be the problem and then test them. All the transistors tested ok so I still have no clue on why that particular problem is there.

 

However, after soldering the transistors back in, I put the boards back together and although the original solenoid still was in the same state, now the flippers would not work.

 

I pulled the boards again, double-checked that I had not shorted anything, reseated all chips, reflowed the solder on all the parts that I had touched....nothing.

 

The flippers have a very limited logic, they are not computer controlled as back then the computers were not fast enough, so the circuit for them is very simple on the schematics. Trying to figure out where the problem might be on the actual boards based on the schematics is really tough though and I have pulled the boards about a dozen times trying different things and checking ever more carefully.

 

Fast-forward to last night. I tested the fuse underneath the playfield. It should have had 28 volts on it since flippers, like all solenoids operate at 28v, but it did not, it only had about 5v......

 

.....great - some kind of voltage problem.....

 

 

......But it is really strange that it happened while I was pulling boards......

 

 

As I prepared to get out the multi-meter to start trying to follow voltages on the power-supply, I noticed a lone wire hanging inside the cabinet. It had a simple press-connector on it and was not connected to anything.

 

Was it supposed to be like that? or am I missing a connection somewhere...

 

After pulling up the playfield and looking around I found the other end of the wire, with the matching connector on it.  I connected them....

 

 

Low and behold the flippers started working!

 

Why every single other connection on the table goes through a board or a multi-wire connector and this one lone wire is all by itself I have no idea.....but at least the flippers work!

 

I have successfully made it back to the state the table was in two months ago!

Cleaning the dropdown - part 2 (disaster)

Time to own up. I have made a totally stupid mistake and have screwed up my table.

I took apart the dropdown and cleaned it. Afterwards the fuse blew.

After considerable head-scratching, I discovered two things:

1) I did not take good enough pictures. It seemed easy to take a couple shots and start taking it apart, but when it came time to put it back together the lack of pictures made it almost impossible to figure out which way the tiny lip was oriented on the sleeve or which wire went where.....I had lots of pictures but the wires were out of focus in every one.

2) after taking my best shot at putting it all back together and wiring it all back up and powering it on, I found I had put the solenoid in upside-down.

Which means it was wired backwards!

Naturally it pops the fuse. I took it apart, put it back together the right way and tried again. Still blows the fuse.

Checking the diode on the solenoid - Its fried....sigh.... so I ordered a replacement.

It finally arrived today and I eagerly soldered it in and turned the table on....it blew the fuse again!

...sigh...

So I disconnected the new parts and the table worked just fine.  I spent considerable time digging around in the parts looking for a short or something, without success. Finally I started checking voltages, I found that the wires to the cleaned dropdown assembly had 28 volts on them all the time instead of being switched.

I am pretty sure that means I have shorted out at least one transistor on one of the boards, possibly a chip.

Oh yaaa