TID12-01 TCI board schematic and extra info

sleddog83

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I have been collecting this information for a while. Finally getting around to posting it. I don't think this stuff is stored in the tech section. The picture of the bottom of the circuit board was done when I was reverse-engineering the board. I thought it might be useful for anyone who is doing some troubleshooting. The board works similar to the 12-03 board in that it creates a couple integrator waveforms that it compares for the advance timing. I have changed the resistors at R22/R23 and R14/R51 to correct the advance curve on my board, but the values listed on the schematic were what it came with. Other boards may be different. I suspect they were "fine tuned" at the factory. I also replaced C5. I am not sure what the factory value should be, but I have a 10uF on the board right now. This was an oops on my part. I missed the cap during the reverse-engineering process then subsequently removed and lost it when I was doing some bench testing of the board. The 10 uF seems to work, but if anyone knows what should be in there let me know.
The board I have is my backup board as well as bench test board that I try out different stuff on, so it is a little hacked up. A note of caution with this version of board. The circuit board traces are quite delicate. It doesn't take much heat to rip the traces right off the board. Takes a good soldering iron and a delicate touch.
A couple of other things to note. I have successfully used the ST901A as a substitute for the output transistor(PTR1) on this board. I have been unable to find original replacement transistors for T1 and T2. I have found a substitute KSC1845 that I think will work okay, but haven't tested them on this board yet.
 

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xjwmx

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I popped my spare open to find C5 for you, but it's a different design, that uses about half as many parts...maybe the difference between a -01a and -01b versions, just guessing?

For substitute transistors you might try 2N2222 and TIP120, both should be at Radio Shacks. MJE5742 would be good too, and slightly more robust (note EC and B might be different pins)
 
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Jan_P

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Nice Work
Some abbreviations perhaps everyone except me understands
SHT 2 XXX
TXC
 

sleddog83

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10 uF... good. I guessed correctly.

The abbreviations I used such as T1C, refers to connecting to the collector of transistor T1. Some of those signals go all over the place. It easier just to reference it one place, rather than draw schematic lines all over the place. On the oscilloscope captures, I also refer to the cathode of specific diodes. For example, D3C refers to the cathode of diode D3.

Those transistors you suggested are OK general purpose transistors. But I suspect some of the parameters such as the beta are not the same. I am not an engineer and my training in that theory disappeared many beers ago. My thinking is that the original design with that particular biasing created a mode where the transistors are just barely switched on, just on the edge of saturation. When a negative pulse comes in, the transistors switch off. On an original board, a pulse of -0.7 v will cause the transistor to switch off. It is very sensitive. My first design with the 2n3904 required a pulse of -2 v. I tried different biasing and the sensitivity improved but the pulse shape and delay changed a little. I tried reading up on transistor theory and design, but ended up going with a transistor that closely matches the original. The substitute is KSC1845FTA Testing on the breadboard with this transistor showed it switching at the same levels as the original board.
 

xjwmx

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^Could be. I was assuming it wasn't balanced on a knife edge. Are you going to make one from scratch on a perfboard? That would be fun.
 

Jan_P

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Thinking out loud
I know that HiFi service manuals have Voltage specs on the Schematic that makes it Simpler / Possible ? to fault find
Depending on what type of fault .
So if this is a work in progress some digits on the schematic i believe would help should someone try to repair.

Furthermore it is often so that the same fault is common on certain designs.
The same component transistor and resistor can be a typical fault .
Which can be difficult to find if an intermittent problem. ( Heat dependent )

If the knowledge gets to that point .The fault finding step can be left out .
And directly replace those couple of components that is the common fault
Typically not expensive components say $ 5 in comparison to the $ 200 for a new ignition.
Should it solve it --- fine --- if not take it to the next step.
 

xjwmx

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Thinking out loud
I know that HiFi service manuals have Voltage specs on the Schematic that makes it Simpler / Possible ? to fault find
Depending on what type of fault .
So if this is a work in progress some digits on the schematic i believe would help should someone try to repair.

Furthermore it is often so that the same fault is common on certain designs.
The same component transistor and resistor can be a typical fault .
Which can be difficult to find if an intermittent problem. ( Heat dependent )

If the knowledge gets to that point .The fault finding step can be left out .
And directly replace those couple of components that is the common fault
Typically not expensive components say $ 5 in comparison to the $ 200 for a new ignition.
Should it solve it --- fine --- if not take it to the next step.
What fails on them is the solder joints. A typical symptom is the engine randomly stops but will start right up again. The best fix/preventative measure is to re-solder every joint on the board. It's not as bad as it sounds -- it can be done through the coating and it takes maybe 15 min.

However -- my only personal experience is with the brown board, and the experiences I've read that confirm the typical symptom may be the brown board too. I don't know. Brown circuit looks very different from the other.
 

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Jan_P

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I am no expert ..but have looked a little on Hifi Boards and other
Not so many components in there and surprisingly printed codes on the IC circuits not always so.
Would not surprise if those can be found Hitachi is still around. Can of course be sold out. .
End / Output transistor is a common problem on HiFi
Also with code on them here
Plenty of space to measure on components .. Unusually large spacing
 
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