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martin1b

My first ADAM - no video

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I recently bought my first ADAM. Turning it on, printer does it's start up, keyboard light comes on, but I get no video. I see no video signal out of the 'monitor' output. After doing some checking, on the processor, NMI (17) is low, but HALT, INT and WAIT are all high. To confirm, these are inverted, so NMI is active, correct? I have clock signal on pin 6. 

 

Looks like one of the places NMI connects to is U9 (TMS9928A) - video display processor.

 

Thoughts on next steps? 

 

 

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One of the more technically inclined will have to help with you questions...

 

Do you get the ColecoVision BIOS screen when you press the Cartridge Reset switch... I’m assuming you have the Stand-Alone Memory Console with CV built-in?

 

Do you hear any audio either on the Adam side or on the CV side if you have a cartridge?

 

As soon as you turn it on, press some letter keys to see if the printer does anything seeing as the Adam starts up in Typewriter mode and you have to press Escape/WP to enter word processing mode.

 

Check the contact switch for the print head on the left side/inside of the Printer to make sure it’s not bent or dirty. This is needed for the ADAMnet to complete initialization and for the Typewriter screen to display.

 

Check all socketed chips, especially the U## chips on the Adam PCB and also check the large connector that joins the ADAM and CV PCBs.

 

if you have a SmartBasic DDP, insert it into the drive and turn on the system to see if it will load. I don’t like doing this, but sometimes you have to roll the dice and hope it won’t damage the DDP.

 

What video connection are you using... RF, Monitor or Auxillary?

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13 hours ago, martin1b said:

I recently bought my first ADAM. Turning it on, printer does it's start up, keyboard light comes on, but I get no video. I see no video signal out of the 'monitor' output. After doing some checking, on the processor, NMI (17) is low, but HALT, INT and WAIT are all high. To confirm, these are inverted, so NMI is active, correct? I have clock signal on pin 6. 

 

Looks like one of the places NMI connects to is U9 (TMS9928A) - video display processor.

 

Thoughts on next steps? 

By "no signal" do you mean black screen, or do you mean that there is no electrical signal?

 

Did you verify which output you're using?  It has both composite and TV outputs.  The TV output is made to connect to the tuner input and uses channel 3 or 4.

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Posted (edited)

When I turn the computer on, nothing changed on the screen (static) as if there is no video signal being sent. No BIOS screen, no sound     or anything.  I measured for video signal on the 'Monitor' output looking for video signal and there is none. I've hooked it up from 'TV' (RF output) through a VCR. Same issue. Then, from 'Monitor' (composite output) to composite in to my monitor. Also no signal. To confirm my video set up, I brought in another computer (TRS80 CC1 with RF out). I could only test RF output through the VCR and it worked fine. I would expect to see video signal on 'Monitor' but saw nothing. 

 

Notes: This had 2 data drives. To take it apart, I disconnected both of them and only installed one. It will still work, right?

 

Other tests : I tried typing, nothing from the printer. I typed more, pressed 'Print', 'IV', 'V' (read that in the tech manual) and still no printing.  I put a data pack in and I heard something very faint but but no actual tape movement. It must have moved some as there was a bit of tape out of the data pack when I removed it. On the printer startup, the carriage adjusts left, then the daisy wheel rotates for about 2 seconds. Assuming that's correct?

 

I'm pretty new to the ADAM so don't know what you mean regarding 'Stand-Alone Memory Console with CV built-in'. The 2 green wires connecting to the print head look connected properly. Didn't see any socketed chips, but I'm only looking at the processor board. 

 

 

IMG_20210603_143413719.jpg

IMG_20210603_143435367.jpg

 

IMG_20210603_143801088.jpg

Edited by martin1b
Add picture

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The board you took a picture of is the Colecovision board.  The system has 2 reset buttons, one for booting the Colecovision half, and one for booting the computer.  You see them on either side of the cartridge port.  The computer expands on the Colecovision, so if the Colecovision board isn't working, then the rest of the system doesn't either.

 

Again, how do you define "no signal" on the composite out?  Black screen?  Or does the TV tell you there is no signal?  The antenna output will be only a few millivolts, so don't expect to be able to measure that.  Composite output should be measurable on the AC setting.

 

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I'm feeding it into a vcr, then composite output into a video capture device.

Here is the VCR with no input (to confirm we see video): 

vcr.PNG.6dd4a32d67bebd09b81d31a9ca197762.PNG

 

Here is from the RF output of the ADAM through my setup:

fromRF.PNG.ed1c3ab5df1c966983f689afd564b9d7.PNG

 

Here is from composite

fromcomposite.PNG.e908265e4f32b6a0479f4d4a7b310884.PNG

 

I had a composite monitor laying around and confirmed I could see the VCR picture on it. When hooking up to the ADAM's composite out, this is what I get

 

IMG_20210603_215953132.thumb.jpg.ac3978662e4ffabe87c35f2958bb06a7.jpg

 

I did notice a flicker when I turn it on. However, overall, it's the same. FWIW: I see scan lines when the ADAM is on. They disappear when it's off, so something is coming out 

IMG_20210603_220426450.thumb.jpg.e80e08e1428ff0ee3318059cc682b4f6.jpg

 

As I cycle the power, after about 6 or 7 times, they monitor goes dark on startup (not sure if that's my monitor. Likely not as it only happens when turning on the ADAM)

IMG_20210603_221255150.thumb.jpg.cbe39180aa446a39181e49695047d813.jpg

 

 

Hope this explains what I'm seeing. Is there a special startup sequence, or buttons I need to push?

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Check the DC voltage at this pin on any of these chips.  You can use the RF box as the ground for your black probe.

IMG_20210603_143413719.thumb.jpg.53b3a19339dc2c59f40bd6dc0f2268af.jpg.a6e984a97d84d6c08304e2d8b6ee64c1.jpg

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I didn't see an answer to NIADs question.  If you power on the ADAM, after you get the black screen, if you pull the right hand cartridge reset does the picture change at all or still just a black screen?  Also do you have the sound channels from the ADAM going to the monitor?  I was wondering if you get any sound when you turn on the ADAM.

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Good catch on NIAD's question. Yes, the picture doesn't change when pulling the right hand reset. I took the top board off and pushed on the socketed ICs on the lower board.  After assembly,  I noticed what appears to be a video reset when I power it on, using the composite monitor. You can see it and what happens when I use the reset button in the attached video. 

 

Does the ADAM have sound output other than from RF other than the DIN connector? When running RF, all I hear is a quick bit of static when turning it on (attached). 

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The audio goes to 1) the RF output, 2) the DIN plug (you see a bundled set of wires connected to E1 and E2 on the board, and follow it to its output), or 3) the expansion port, pin 56.

 

E3 is the composite video.

 

Q9 (the transistor near the RF box and the video chip) is the final drive output for composite out.  One pin will be 12V.  The middle pin should be signal input, and the 3rd pin should be signal output.  You can check continuity from the composite out to that pin.

 

If you can find Q6 and R76, that's the first amplifier for the B/W composite signal. You could patch that into a composite output cable just to test if there is a signal almost directly from the video controller.

 

Do you happen to have an oscilloscope?

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Q9 : one pin is 11.98, one pin is 5.59 v, other is 4.89. Resistance from E3 to the emitter of Q9 is 385 ohms. Looked all over and couldn't find Q6. Yes, I have an oscilloscope. Using it, I could not find a video signal on Q9 or E3.

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Okay, look at pin 36 of the video chip (U9).  That would be the B/W composite signal straight from the chip.  If that's dead too, check that pin 40 has a 10MHz clock signal (actually closer to 10.5, but anyway...).

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Pin 33 and 34 should be 5V, pin 12 should be grounded.

 

If all of that is in order, it's likely that the 9928 is dead.

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Posted (edited)

Yes, 33, 34 are 5v and 12 is gnd. Ok, going to replace the VDP.  Will let you know.

Edited by martin1b

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Trying to get the IC out and it's not easy. Doesn't budge. I would think the pins would move some.

 

Are these glued down?

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I don't think so.  The biggest issue is removing all the solder.  There will usually be a tiny amount that still welds the pin to each hole.  If you've removed enough of it, a little wiggle of each individual pin with your finger will break it loose.  If not, then you need to try all the usual tricks, including soldering some back and then removing it again.  Solder braid and a desoldering pump are your best bets.

 

An alternative is low-temperature solder that you can apply over the pins.  Then when you're ready to wrestle with one side's pins, heat up the entire row and then attempt to work the pins out of their holes.

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I wish the inline video player worked :S

 

That's a definite improvement over nothing, at least.  Make sure the memory chips have continuity with the video chip.  You have the Adam schematic, right?  Many of the pins will connect in parallel to every memory chip.  Some will uniquely connect to a pin on the video chip, and the address lines will also carry data so each chip will be connected to a different address line.

 

But the noise likely means that the system has not silenced the sound chip yet, meaning that it hasn't run the BIOS code.  That may explain why reset has no effect either.  So after verifying that the memory chips are all still connected to the video chip, the CPU will likely be the next focus of attention.

 

Make sure that when you pull reset, the reset line on the CPU goes low.  See if the MREQ line ever pulses after reset.  Same for RD.  When MREQ and RD are active, WAIT should also pulse.

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Posted (edited)
On 6/3/2021 at 2:35 PM, martin1b said:

When I turn the computer on, nothing changed on the screen (static) as if there is no video signal being sent. No BIOS screen, no sound     or anything.  I measured for video signal on the 'Monitor' output looking for video signal and there is none. I've hooked it up from 'TV' (RF output) through a VCR. Same issue. Then, from 'Monitor' (composite output) to composite in to my monitor. Also no signal. To confirm my video set up, I brought in another computer (TRS80 CC1 with RF out). I could only test RF output through the VCR and it worked fine. I would expect to see video signal on 'Monitor' but saw nothing. 

 

Notes: This had 2 data drives. To take it apart, I disconnected both of them and only installed one. It will still work, right?

 

Other tests : I tried typing, nothing from the printer. I typed more, pressed 'Print', 'IV', 'V' (read that in the tech manual) and still no printing.  I put a data pack in and I heard something very faint but but no actual tape movement. It must have moved some as there was a bit of tape out of the data pack when I removed it. On the printer startup, the carriage adjusts left, then the daisy wheel rotates for about 2 seconds. Assuming that's correct?

 

I'm pretty new to the ADAM so don't know what you mean regarding 'Stand-Alone Memory Console with CV built-in'. The 2 green wires connecting to the print head look connected properly. Didn't see any socketed chips, but I'm only looking at the processor board.

You are in great hands with ChildOfCV on the case!!!

 

Referring back to Post #4, sorry... busy days!

 

Two versions of the ADAM Computer were made:

- Expansion Module #3 ADAM that connects to a ColecoVision Game System

- Stand-Alone ADAM which has the ColecoVision PCB built-in to the Memory Console. The ADAM PCB in this has a number of small differences, but for the most part is the same that comes in the EM#3 Memory Console.

 

RF = Video and Sound

Monitor = Composite Video only

Auxillary = Composite Video with Audio

 

You can have 0, 1 or 2 Digital Data Drives installed in the system. The system will work just the same, but of course, that will determine what drives are available to load or save to.

 

If the ADAM PCB is working properly of partially working, the data pack that you inserted in the Data Drive should have began seeking as soon as you pressed the Computer Reset. That the tape only moved slightly is not a good sign as far as the ADAM PCB is concerned... but this does not rule out the ColecoVsion PCB as you have been finding out.

 

The Printer startup or on pressing the Computer Reset is as follow:

- Print Head moves all the way to the left and make contact with a contact switch so that the system knows exactly where the print head is

- The Daisy Wheel spins for a couple seconds to position itself

- The Print Head moves a couple inches to the right... it's Home position

 

The U## sockets are located on the ADAM PCB (the bottom board in the Stand-Alone ADAM or the only board in the EM#3 ADAM) and contain the SmaWriter roms (could be 2 or 3 roms... 3 for earlier released systems, 2 for later). Pictured attached for reference.

 

When you turn on the ADAM, it starts in Electronic Typewriter Mode where anything you type is sent to the Printer... just like a real typewriter. Pressing the Escape/WP key switches to the full word processor... SmartWriter. Pressing the COMPUTER RESET attempts to load a disk or data pack that may be inserted... no  load commands needed for most ADAM software compared to say a C=64. Pressing the CARTRIDGE RESET switches to ColecoVision mode... with no cartridge inserted just the CV BIOS screen displays.

 

Good luck with the repair. If all else fails, a longtime ADAMite and former Coleco employee has started to sell a lot of ADAM gear on eBay.... moonxpl.

 

Exp. Mod. #3 Adam PCB (top) vs. Stand-Alone Adam PCB (bottom) - #1.jpg

ADAM Logic Board - #01.jpg

Edited by NIAD

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@NIAD - Great info. It really helps. Thank you! Yes, ChildofCV is VERY helpful!

 

@ChildOfCv I've confirmed continuity between U9 and the memory ICs. I also confirmed RESET goes low when the reset switch is pulled. MREQ and RD do NOT pulse on reset (at least I didn't see anything on the o-scope). MREQ (19) is at 1.25V and RD (21) is at 1.68. WAIT (24) is at 5V. 

 

Is that normal?

 

I as able to get it hood up to a monitor, using composite out (FWIW). See below:

 

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16 minutes ago, martin1b said:

Is that normal?

One more thing:  Make sure BUSRQ is at +5V.  And you already said you verified clock input, right?  The CPU is supposed to begin its life by reading memory starting at 0000.  So there should be an immediate series of RDs and MREQs after reset goes inactive.  BUSRQ will put the CPU on hold, as will WAIT.  Both should be +5V normally, with WAIT pulsing low for a clock on memory reads.  If all of that is in order but the CPU is not reading memory, then it's dead too.  Note about buying Z80 replacements:  Z80 is an entire line of chips with various functions that can work together to make a complete computer.  Make sure your replacement Z80 is a CPU chip, not a PIO or DART or ...

 

It makes me wonder if there was an over-voltage event due to a bad regulator.  Also makes me wonder how many more dead chips there are.  A couple of them are ADAM-specific, so replacements may be expensive if you can find them at all, separate from another ADAM.

Edited by ChildOfCv

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BUSRQ (25) is at 5v. Yes, confirmed clock signal on pin 6. WAIT is not pulsing, but holding at 5v.

 

Interesting, I always thought Z80 was only a CPU. So, would you agree the next step is a new Z80 CPU?

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30 minutes ago, martin1b said:

BUSRQ (25) is at 5v. Yes, confirmed clock signal on pin 6. WAIT is not pulsing, but holding at 5v.

 

Interesting, I always thought Z80 was only a CPU. So, would you agree the next step is a new Z80 CPU?

Yeah it sounds like that one is dead.  Oh, and make sure you get one that can handle 4MHz.  There's a 2MHz-rated one that you definitely do not want.  There are also 6 and 8MHz capable models.  I think they will work at 4MHz also.

 

There are also many clones, such as NEC and Sharp.  Some CV's use the NEC one, so don't be afraid to buy a uPD80-1 if you see one.

Edited by ChildOfCv

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