Wanted: ICD RAMBO XL Schematic

[+mytek]

5 hours ago, ClausB said:

The original article linked upthread has a BOM. Just add some jumper headers.

Thanks

 

Pretty much all you have to do is enter the chip numbers into the search box on an electronic vendor's site and it'll pop up with a suggestion. As for the headers and shorting blocks that's a bit trickier since I just pulled those from existing stock that I bought years ago from who knows where. If you go with the stock 74LS chips I think Jameco would be a good possibility to get all that you need, including the headers and the single capacitor. However they do have a $20 minimum order, so it would be best if you are planning on building more than just one board.

 

I just did a quick search at Jameco and spotted these which should work (cut it down to the sizes needed).

• Jameco Part no.: 207686

• Jameco Part no.: 109576

• Jameco Part no.: 19141

• Jameco Part no.: 2296367

 

• Jameco Part no.: 2245538

 

And then in the search box on Jameco's website - search for 74LS139, 74LS153, 74LS158, 74LS393.

 

There's your BOM

 

[+DrVenkman]

1 hour ago, mytek said:

There's your BOM

And for the absolute neophytes, add in some 256 kilobit DRAMs, quantity 8. 

[Ricky Spanish]

1 hour ago, mytek said:

There's your BOM

Thanks. got everything in the cart(s) but a couple question: you list 4 chips, but 5 are on your board, what's the 5th? And;

I uploaded your file 2 the PCB order (but in blue) they want the dimensions of the board. That's the only thing holding me

up at checkout. Thanks !

[+DrVenkman]

10 minutes ago, Ricky Spanish said:

you list 4 chips, but 5 are on your board, what's the 5th?

There are two (2) of one of the logic chips - take a look at the photos.

[Ricky Spanish]

3 minutes ago, DrVenkman said:

There are two (2) of one of the logic chips - take a look at the photos.

Yes, CD74HTC158. So would that be 74LS158 as he listed above ? Thanks.

[+DrVenkman]

3 minutes ago, Ricky Spanish said:

Yes, CD74HTC158. So would that be 74LS158 as he listed above ? Thanks.

Yes, they are interchangeable in most (but not all) retrocomputing applications - same goes for pretty much all 74-series logic. The LS, HTC, F, etc are different speed/response ratings. LS are the slowest and oldest technology. Some modern enhancements and upgrades benefit from using faster logic chips to keep signals synchronized, but the RAMBO256K upgrade has been around for decades and doesn't really need faster chips. 

[Ricky Spanish]

1 minute ago, DrVenkman said:

Yes

Ok I'll double up on all the chips and proceed to the checkout. now just waiting on that PCB board dimensions. Thanks !

[+LarryL]

16 minutes ago, Ricky Spanish said:

Ok I'll double up on all the chips and proceed to the checkout. now just waiting on that PCB board dimensions. Thanks !

PCBWAY.COM did detect the dimensions whilst uploading the gerbers

Detected 2 layers board of 40 x 54mm(1.57 x 2.13 inches).

[Ricky Spanish]

19 minutes ago, LarryL said:

PCBWAY.COM did detect the dimensions whilst uploading the gerbers

Detected 2 layers board of 40 x 54mm(1.57 x 2.13 inches).

Sorry not in my case. Guess I'll add 40x54 mm, thanks.

[+mytek]

25 minutes ago, LarryL said:

PCBWAY.COM did detect the dimensions whilst uploading the gerbers

Detected 2 layers board of 40 x 54mm(1.57 x 2.13 inches).

Those are the correct dimensions. JLCPCB would have figured it out without them, but it does streamline the order process.

 

51 minutes ago, Ricky Spanish said:

Yes, CD74HTC158. So would that be 74LS158 as he listed above ? Thanks.

You will get a freebie when you remove the one currently on your motherboard where the RAMBO board plugs in.

 

1 hour ago, DrVenkman said:

And for the absolute neophytes, add in some 256 kilobit DRAMs, quantity 8. 

Opps I forgot that part. Wouldn't be much of a memory upgrade if you left the original 6Kbit chips in place

 

[Ricky Spanish]

27 minutes ago, mytek said:

You will get a freebie when you remove the one currently on your motherboard where the RAMBO board plugs in.

That's ok. Bought the mandatory minimum of 5 boards, so bought everything to complete 5 boards. 

[Mathy]

Hello guys

 

Wasn't there a company in Bulgaria or somewhere close to it that made PCBs?  I don't like China for a couple of reasons.  And shipping from the US is way too expensive at the moment.

 

Sincerely

 

Mathy

 

 

[HiassofT]

2 hours ago, Mathy said:

Wasn't there a company in Bulgaria or somewhere close to it that made PCBs?  I don't like China for a couple of reasons.  And shipping from the US is way too expensive at the moment.

Yes, there was, but I forgot their name. But I remember they shipped terrible quality, nothing but issues with their boards and they weren't too cheap either.

 

Better stick with above mentioned PCB manufacturers.

 

so long,

 

Hias

[ClausB]

6 hours ago, DrVenkman said:

There are two (2) of one of the logic chips - take a look at the photos.

But U1 is the chip you pull from your XL board, so you don't have to buy it.

[ivop]

20 hours ago, HiassofT said:

Yes, there was, but I forgot their name. But I remember they shipped terrible quality, nothing but issues with their boards and they weren't too cheap either.

You mean Olimex? (https://www.olimex.com/PCB/)

 

 

[HiassofT]

1 hour ago, ivop said:

You mean Olimex? (https://www.olimex.com/PCB/)

No, Olimex also came to my mind but it wasn't them (and they have rather good reputation eg for their JTAG adapters).

 

I couldn't let go and went through my email archive and finally found the name: it was Bilex. Google  turned up a website but it looks quite orphaned so could well be they're out of business by now.

 

so long,

 

Hias

[ivop]

1 hour ago, HiassofT said:

No, Olimex also came to my mind but it wasn't them (and they have rather good reputation eg for their JTAG adapters).

I was always under the impression that Olimex was pretty good, albeit more expensive than Chinese options these days. Good to hear that's still true, and the "bad guy" was Bilex.

Edited June 13, 2022 by ivop

[manterola]

Regarding the BOM, one "component" I always struggle to find or know how to order is the DIP headers (the two rows of pins that actually goes to the Atari socket, in this case goes to the location of the ls158).

Regular pin headers are too thick, but kind of work for cheap spring IC sockets (but are too thick for machined sockets). Also sometimes are too short to give enough clearance for proper insertion.

On the other hand, the round machined pin headers are too thin, and I have had connection problems when they go on top of both machined and spring IC sockets.

Not sure if Jameco Part no.: 109576 is really what is needed. mytek mentioned the machined ones previously in this topic, but I had bad experiences as mentioned before.

Any recommendation, opinions? 

 

Regular Header:

Machined:

 

 

 

 

[ClausB]

5 hours ago, manterola said:

one "component" I always struggle to find or know how to order is the DIP headers (the two rows of pins that actually goes to the Atari socket, in this case goes to the location of the ls158).

 

Something like this is just right.

[+mytek]

Although not the same as what ICD was using, this is what I used, and linked to earlier.

 

 

This is the same thing I used on my TK-II-STEREO board, and on some of the older TransKey boards. Never had any problems with them myself. Although @manterola mentioned he did.

 

The regular rectangular pin header will not fit the holes on my board which were intended for the piggyback, and they would be destructive to the socket on the Atari board anyway.

 

ICD used a rather interesting dual row 16-pin header which I have been unable to source. If I could find them they would be ideal since they have legs very much like an IC on one side, and skinny round pins on the other side that get soldered into the RAMBO board.

 

EDIT: Hold your horses I think I just found something that might work, and is similar to what ICD used.

 

Digi-Key P/N: 1175-1521-5-ND

Price: $1.47 (over 2,000 in stock)

 

 

Edited June 14, 2022 by mytek

[ClausB]

Oh I see, so the board plugs right into the socket. On my prototype I cut a ribbon cable in half and soldered the wires to the board. I'll post a picture later.

[+mytek]

3 hours ago, ClausB said:

Oh I see, so the board plugs right into the socket.

Yep that is correct.

 

3 hours ago, ClausB said:

On my prototype I cut a ribbon cable in half and soldered the wires to the board.

I usually try to avoid this, because I always find that soldering wires or building harnesses is very time consuming. Any place I can circumvent this the better. That is also why I changed from individually soldered wires on the board to a pin header. Now days it's pretty easy to find already terminated wire kits that'll plug straight into this header style. The original RAMBO XL board didn't do this, and used soldered wires instead, although they did use the chip piggyback idea same as I have done.

 

[BillC]

15 hours ago, ClausB said:

Something like this is just right.

For those looking for these male IDC connectors they are also known as "transition plugs".

https://www.peconnectors.com/male-idc-headers-plugs-.100/

[ivop]

16 hours ago, ClausB said:

You'd think they would take pictures without bent pins

[ClausB]

Here it is. The Original!