AMI Blowing fuse

Hello again,

I have to admit that I am not very good with electrical when it comes to electronics. ( only good with home wiring ) My problem now is that I am continually bowing the middle fuse in the Junction box.( picture one )

Sorry computer error, repost has more information. ( looks like all my electronics are failing me.)

Hello,
Inside the power supply (if it is original) will be a selenium bridge, and a large electrolytic capacitor (probably around 1000 uf at 50 volts or so).
If these items have not been updated ie.(newer silicon diodes or a full wave bridge [using only half of the "bridge" of course]) Install new electrolytic capacitor and you should be ok.
However, judging by the "looks" of your 110 volt wiring, it looks like it might be rotten as well. This might be the cause of the blown fuses.
Replacing them all, is a big job. However it is doable if you do one at a time , and take your time as well.

Hope this helps
Tony

Thanks, Tony

The wiring is pretty rough in there. I looks like it had been rewired one before. ( I'm not to sure when ) The other post I put up has a little more detail.( what's working and what's not ) I tried to delete this one but I can't figure that out either. ( ha, having a rough day ) I do need to re wire the line in, I've just changed the plug so far ( that was still the original.) So is it a good idea to update that capacitor? If so what other things might be a good idea to update?

Hello Houstin

I don't think that the rectifier or the capacitor are the cause of the fuse blows. The fuse is behind these parts.I suspect that the selector pin is not deleted. Thus, the transfer motor remains energized and runs tight. The increased current through the blocked motor can blow the fuse. When that happens, the muting relay does not drop out and the amplifier remains silent.

It is necessary to examine why the selector pin is not deleted. There are several possibilities. Mostly the cam switches (on the right side of the gripper mechanism) or the transfer switches (far right on the mechanism) are the cause. These contacts must be cleaned and adjusted. It is also possible that there is a mechanical problem. The selection pins or the reset lever could be sluggish. Also the stop switches (the large micro switch behind the pin wheel) can cause the problem. There is an entry in the archive in which almost all possibilities are described. [www.jukebox-world.de]ückstellhebel

The 110V wiring must be renewed at all AMIs from this period. The insulation over time has been hard and brittle. It has however nothing to do with the blown fuse.

The fuse is labeled with 1 A. It must necessarily be a SLO BLO. It may nevertheless be that the fuse sometimes blows without any apparent reason. In my experience, there is no harm if you use a 2 A SLO BLO fuse.

Best regards - charly49

Hello Houstin,

I have to agree with Charly49 you need to sort out all of the 110 volt wiring first before you go any further.
I would look for a suitable professional in your country to undertake this for you by replacing the mains wiring and making sure the power supply is safe to use.
Most of these I have worked on in the past were a sorry state brittle cables and fitted with over rated fuses, all bad news.

Regards
Alan

Alan Hood
ami-man
UK

Thanks guys, I appreciate all your help. I will get start on this and get back to you to let you know my findings.

New problem. ( I can't help but feel like one step forward two steps back ) I went down and cleaned the contacts for the slip ring connections. They were really tarnished and had some corrosion on them. After this I when through a selection as before, the center fuse blew again but after the record got to the end it just keeps spinning and does not return the record. Is it safe to say at this point I should start with new wiring? It seems like every time I get some all cleaned up and through one working rotation something else breaks. ( I do want to you all to know I am laughing, and finding this funny, I don't get frustrated very easily)

What country do you live in so we can give you advice of where to get help.

Regards
Alan

Alan Hood
ami-man
UK

Alan I live in Wisconsin in the US.

Fixed the last problem, use gave the transfer motor a small turn with my thumb and everything reset

Hello Houstin

We should proceed steps by step. The selection process is completely independent of the operation of the changer mechanism. It also has each part its own fuse. Therefore, if the fuse would burn out during the selection (during work of pulse generator and pulse converter), no selection pin would be set. But the changer mechanism would still work if it is started manually.

You've described that the record is being placed and played, but is not removed, because the fuse is blown in the meantime. It is likely that the fuse blows, because of the transfer motor is not switched off. The motor is switched off when the select pin is reset and thereby the stopping switch is pressed again. You can track the process with reference to the "SCHEM-A-GRAMS" in the service manual.

There are many possible reasons why the select pin is not reset. In your case it seems to be that the select pin is reset however on the second try (after replacing the fuse). This ruled out some possibilities. It may be that something is stuck (eg the select pins or the reset lever). It is also possible that the plunger of the reset coil is greasy and thus moves too slowly. In early versions, there are two sets of contacts close to of the stopping switches. These contacts are in circuit of the reset coils. They are useless and must be shorted, if that's not happened yet.

In the circuit of the reset coils are also the transfer switches. It must be checked whether they switch correctly and whether the linkage and the common plunger of the toggle shifter coils is smooth. Similarly, there is a contact on the camshaft switches, which switches on the reset coils, once the record is to be played.

One possibility would be that the stopping switch switches over with time delay. For all other possibilities, the fault would not be fixed by renewing of the fuse and perhaps manually turning the motor.

Best regards - charly49