Wiring advice on a PEB

[XLERB]

So I have my PEB which hasn't been used since the 1990s. It didn't turn on, so I looked inside. My older son tells me it wasn't working years ago, and the fuse we could check (next to the power cord) was OK. So he recalls that I had been thinking I'd probably have to replace the power supply, and was going to try to get one from someone on a BBS (I honestly don't recall that, but it makes sense that I would have thought that, because the fan was probably the only thing working). Anyway, one of us (one of my sons or I) had started to unhook everything, and so I found all the 110v side wires disconnected inside the box.  This is 25 years later, so I have no recollection. But in the process today, I also peeled away the plastic and looked inside the transformer, as helpfully described by Mainbyte, and sure enough that hidden fuse was blown. So while I wait for a replacement to arrive, I'm trying to reconnect everything. I also got the schematics that were helpfully posted here. But our hastiness in disconnecting everything and then shelving it 25 years ago has left a big puzzle to solve.

 

My main question is this: There is a fuseholder (holding the fuse that wasn't blown) built into the power cord receptacle, and it has five lugs, and also looks like it can be inserted different ways for different voltages. One lug goes in one end of the fuse, and four are for the other. All were disconnected, as were the wires to the power switch. (Only the fan was still connected via the wire joiners, so I'm good there). There are also three extra wires on the line voltage side of the transformer (black, brown, and orange), but only the whites and reds are shown in the schematic. Were those extra wires supposed to be for the voltage selection feature of the fuseholder, and if so, can I just leave them unconnected and just use the red and white wires like the schematic says?

 

Once I get everything reconnected and solder in the new secret fuse, I'll have to test the power supply board. As bad luck would have it, just before I decided to resurrect the TI, I had recycled about six PC computers accumulated in the 25 years since we put the TI away, and an I also threw out extra ATX power supply. Dang it. I see here that the guts of an ATX power supply might be substituted if the TI power supply board doesn't work. My bad luck, or my poor planning. My wife had finally convinced me I might be suffering from hoarding disorder and I wanted to prove my sanity to her... Should have looked at all the TI stuff first. And she still doubts my sanity because - ... "The TI???? I thought you got rid of that!"

[+FarmerPotato]

I wish you luck.  My P-box needed a new hidden fuse only once, in 1986.

 

An ATX power supply won't help, because the TI power supply outputs unregulated +16, -16, +8V. These are regulated on the cards. The project to replace it with a ATX supply involves taking out regulators on each card. (bad idea if you use another P-Box!)

 

[RXB]

Well as PC powersupplies are dirt cheap I guess I should replace all of my card regulators and just use a PC power supply.

They do sell ones that do not make a sound and ones that have very quiet fans.

(Though they cost more.)

[HOME AUTOMATION]

4 hours ago, Paul Fitzgerald said:

There are also three extra wires on the line voltage side of the transformer (black, brown, and orange), but only the whites and reds are shown in the schematic. Were those extra wires supposed to be for the voltage selection feature of the fuseholder, and if so, can I just leave them unconnected and just use the red and white wires like the schematic says?

If they weren't connected in the first place ...you'd have to pay me to figure it out! 

 

The schematic diagram I'm referencing, shows 2 different examples of power transformers...

 

TI 994/A Console And Peripheral Expansion System Technical Data (link)

 

...no red wire identified...

 

You probably want the second tap(115VAC), after common. But I don't know what your line voltage is.

 

Maybe these will help...

 

 

...If you really want, I'll try and find the right hex-socket and then move the x-former out of the way a bit!

 

         P.S. Looks like someone added another little transformer to mine ...It's primary is in series with the line voltage and it's secondaries are all shorted, so it appears to be functioning as a reactor, to reduce the incoming line voltage a bit(probably not significant).

[XLERB]

1 hour ago, HOME AUTOMATION said:

If they weren't connected in the first place ...you'd have to pay me to figure it out! 

 

The schematic diagram I'm referencing, shows 2 different examples of power transformers...

 

TI 994/A Console And Peripheral Expansion System Technical Data (link)

 

...no red wire identified...

 

You probably want the second tap(115VAC), after common. But I don't know what your line voltage is.

 

Maybe these will help...

 

 

...If you really want, I'll try and find the right hex-socket and then move the x-former out of the way a bit!

 

         P.S. Looks like someone added another little transformer to mine ...It's primary is in series with the line voltage and it's secondaries are all shorted, so it appears to be functioning as a reactor, to reduce the incoming line voltage a bit(probably not significant).

No thanks, no need to move it. Thanks for the photos. It sure looks like the orange and brown wires are attached to other posts of that fuse holder. But I’m gonna stick with just the red and white wires for now, since those also go to the fan and I know that's 110 volts like my house current.

[GDMike]

You can never send more power than what your house is supplying at the receptacle.

Throw your meter on it and see if your getting your 110out. And check your PCB for the other voltages..

Edited January 29, 2022 by GDMike

[HOME AUTOMATION]

1 hour ago, GDMike said:

You can never send more power than what your house is supplying at the receptacle.

Really!

 

Spoiler

 

 

 

[+Lee Stewart]

10 hours ago, GDMike said:

You can never send more power than what your house is supplying at the receptacle.

 

I know I am not telling you anything you don’t know, but this statement might be misleading. Though power cannot be more, voltage most certainly can. All you need is more windings in the secondary than the primary (step-up). The transformer under discussion has pass-through and step-down voltages, so the secondary voltages for this transformer, indeed, cannot be higher than the supplied voltage.

 

...lee

[XLERB]

12 hours ago, GDMike said:

You can never send more power than what your house is supplying at the receptacle.

Throw your meter on it and see if your getting your 110out. And check your PCB for the other voltages..

That's pretty much what I had planned to do. Not  an electronics expert, but I should be able to handle that without blowing anything up!

[GDMike]

Clarification, referring to the 110/220 output of this PEB transformer.. 

You won't get 220 if your home is 110 with this switch setting.

[XLERB]

15 hours ago, FarmerPotato said:

I wish you luck.  My P-box needed a new hidden fuse only once, in 1986.

 

An ATX power supply won't help, because the TI power supply outputs unregulated +16, -16, +8V. These are regulated on the cards. The project to replace it with a ATX supply involves taking out regulators on each card. (bad idea if you use another P-Box!)

 

Thanks, I feel better after throwing all that stuff out. The thread where I saw this did mention another method that didn't involve modifying the cards, but I think it did involve sending the wrong voltage through them and expecting them to compensate, which doesn't sound like a great idea either.

[XLERB]

3 hours ago, Lee Stewart said:

 

The transformer under discussion has pass-through and step-down voltages, so the secondary voltages for this transformer, indeed, cannot be higher than the supplied voltage.

 

...lee

Thanks, Lee, that was what I was thinking. I figured the wrong connection would actually put out a  lower voltage than the correct one if it was intended for 220.The pass-through appears to go to the fan, since the wires are right next to each other. I'll test those for continuity.

[HOME AUTOMATION]

3 hours ago, GDMike said:

Clarification, referring to the 110/220 output of this PEB transformer.. 

You won't get 220 if your home is 110 with this switch setting.

Actually, you will!

 

If the transformer is energized from any section of it's coils, primary or secondary, all other voltages are available, and at near to full ratings. By connecting the primary and secondarie(s) in an additive configuration, the sum of all voltages can be obtained.

[+OLD CS1]

To summarize, never poke your fingy where you would not poke your dingy.

[XLERB]

2 hours ago, OLD CS1 said:

To summarize, never poke your fingy where you would not poke your dingy.

Important safety tip.

[GDMike]

3 hours ago, HOME AUTOMATION said:

Actually, you will!

 

If the transformer is energized from any section of it's coils, primary or secondary, all other voltages are available, and at near to full ratings. By connecting the primary and secondarie(s) in an additive configuration, the sum of all voltages can be obtained.

I don't think we were taking this transformer apart and tinkering with coils? I thought the user was asking how to get this to work for his PEB? 

Left field is taken. Have you switched your PC PS to 220 and ever fried the PC?. Same thing I was talking about...phhhhffft hahaha ???

[XLERB]

So I used my ancient trusty Radio Shack analog multimeter and found that on the house current side of the transformer, red to white is no continuity, red to black is about 2 ohms, red to brown is about 7 ohms, and red to orange is about 10 ohms. The fuse holder has four positions, with 100 marked at the top when the contact is in the 8 o'clock position (Looking at the back panel), 120 at the 4 o'clock position, 220 at the 2 o'clock position, and 240 at the 10 o'clock position. So assuming that the more windings, the higher the ohms, and the more winding, the more it will step down the voltage, it would seem that red should logically be 100, black would be 110, brown would be 220, and orange would be 240, unless I'm getting this completely wrong. But the TI schematic (on the page that has both the PE power supply diagram and the console power supply diagram) calls the two wires to the transformer white and red, so maybe red is 120. In Home Automation's photo, orange is in the 10 o'clock position and brown is in the 8 o'clock position, and it looks like red is in the 2 o'clock position. So if that's set up for a 220v power supply, that would leave black as the 120 wire (hidden in that photo) in the 4 o'clock position.

 

All I can do when I get the new fuse in is try to attach some wires carefully to the output side plug (so I don't accidentally short it and blow the fuse AGAIN), carefully hook each input wire to my 120 power, and test each input wire to see what gets put out in terms of voltage.... Thanks for all the "input," everyone.

[XLERB]

5 minutes ago, GDMike said:

I don't think we were taking this transformer apart and tinkering with coils?

Nope, only to get at the fuse under the plastic that was blown.

[GDMike]

Yes, I did all this last year and many input their concerns as well, and I ended up getting a PC PS and using it with Newer PEB cards, no TI disk controller,etc . with no trouble. BUT because I had to work with an rs232 card I reverted back to a good PS transformer (original TI transformer). Which someone shipped to me.. and someone might send you one too. 

 

Edited January 29, 2022 by GDMike

[HOME AUTOMATION]

3 hours ago, OLD CS1 said:

To summarize, never poke your fingy where you would not poke your dingy.

 

This is technically permissible...

 

Spoiler

 

...As long as your Speech Synth. isn't hungry.

[HOME AUTOMATION]

27 minutes ago, GDMike said:

I don't think we were taking this transformer apart and tinkering with coils? I thought the user was asking how to get this to work for his PEB? 

Left field is taken. Have you switched your PC PS to 220 and ever fried the PC?. Same thing I was talking about...phhhhffft hahaha ???

Don't know why you're takin' it apart?

 

But, if you're taking a professional approach, while not an expert. Believing wrongly, that there are no exposed high-voltages ...could prove to be fatal.

 

Perhaps you might want to reconsider your priorities!

 

While there's still time...friend.

[GDMike]

I played with my bad Transformer and shorted out a few things across it like pliers that fell on it, a screwdriver and got a bite here and there, I lived! I have this awkward walk..but seriously, I lived!

[HOME AUTOMATION]

That'll probably clear-up after a few years or so ...trust me!

[HOME AUTOMATION]

28 minutes ago, GDMike said:

I played with my bad Transformer and shorted out a few things across it like pliers that fell on it, a screwdriver and got a bite here and there, I lived! I have this awkward walk..but seriously, I lived!

Good thing! Not everyone does...

 

Demon core(link)

 

[HOME AUTOMATION]

So, that internal fuse-link, jobby, is probably meant mainly to protect against ...enough smoke to fill the Empire State Building, should a winding or two short-out. It's installed in the COMMON's path, so that it will function with all supply-voltage taps.

 

One way around this, assuming there is no serious internal fault condition. Would be to permanently affix a thermal fuse or two, to the core, in series with the supply line, and connected to the transformer's 100vac and 220vac taps.