5160 - unknown component?

[VERAULT]

@lordhailsham So what did you end up doing to fix this?

Come on dont leave us hanging! Never abandon a thread! EVER! Just reply to ones you left hanging many months later like I do.

 

[sergey]

I guess it depends on how it is broken. Not adjustable is probably fine. But the cap is in series with the crystal so if it is non conductive the oscillator may not work at all.

Correct, it assumes that the broken cap still has some capacitance (and also that it doesn't have a short-circuit)

 

[lordhailsham]

@lordhailsham So what did you end up doing to fix this?

Come on dont leave us hanging! Never abandon a thread! EVER! Just reply to ones you left hanging many months later like I do.

Hey - i ordered the variable caps on ebay... TICK TOCK!

 

[lordhailsham]

so to re-cap (no pun intended, sigh) I will be replacing the two tantalums (following the minuszero diagnostics) and the variable capacitor.

Also have a lovely "new" VGA card on the way as well (other thread)

Fingers crossed!

 

[VERAULT]

I cant get past people throwing the word "lovely" around on old hardware..... I just cant.

 

[lordhailsham]

Evenin' folks....soo... by way of an update his is what's going on:

1. replaced The Two Troublesome Tantalums (c58 and c56)
2. replaced that variable ceramic cap
3. Re-applied power. SUCCESS!!
4. Added cards in one-by-one:

CGA card (running through composite, 40 lines)​

Keyboard​

AST Six Pak​

HD controller​

Floppy controller​

5. As I added cards I got more errors. I also believe my PS2->XT converter keyboard is not gonna cut it. Here's the current list

301 - keyboard (same error with or without keyboard attached)​

20000 201 - memory problem at 20000​

1701 some general HDD or Controller problem​

601 Floppy (well in fairness the floppy isn't even there)​

6. I just received my ISA Cirrus Logic VGA card from ebay and interestingly IT WORKS - but only if I configure the switches for MDA, not VGA. Weird huh?

Special note: I believe my final step to add floppy drive caused a sharp, burning component smell. I immediately powered down, but despite frantic sniffing I couldn't locate the source.

Anyway, HDD and Floppy seem to be toast right now. And the keyboard. Oh, and memory location 20000..... apart from that we doing great!

cheers! Andy

 

[modem7]

301 - keyboard (same error with or without keyboard attached)

... And the keyboard.

Allow for the fact that the symptom cause could also be faulty keyboard interface circuitry on the motherboard.

 

[modem7]

20000 201 - memory problem at 20000

If we assume that the cause is a faulty RAM chip, then [this] points to the parity chip in the bank at address 128 KB.

 

[modem7]

6. I just received my ISA Cirrus Logic VGA card from ebay and interestingly IT WORKS - but only if I configure the switches for MDA, not VGA. Weird huh?

MDA, or monochrome VGA ?

 

[modem7]

1701 some general HDD or Controller problem

Yep. Lots of possibilities. See [here].

 

[modem7]

1. replaced The Two Troublesome Tantalums (c58 and c56)

I added that to the list at [here].

One of these day, I will stop updating the list. It finished 'serving its purpose' long ago.

 

[lordhailsham]

I added that to the list at [here].

One of these day, I will stop updating the list. It finished 'serving its purpose' long ago.

naaah.... keep doing it for posterity!

 

[lordhailsham]

MDA, or monochrome VGA ?

well... my screen is a regular VGA and seems to bein black an white, but maybe that's just because the POST stuff and the VGA BIOS messages are only in monochrome?
OTOH my VGA monitor is old, and somtimes the color goes a bit wonky (bad cable I think)

And just to be precise I tried setting the switches to VGA (5=ON , 6=ON) but only the MDA switch setting worked:
5=OFF, 6=OFF

 

[lordhailsham]

Allow for the fact that the symptom cause could also be faulty keyboard interface circuitry on the motherboard.

yikes!

 

[modem7]

And just to be precise I tried setting the switches to VGA (5=ON , 6=ON) but only the MDA switch setting worked:
5=OFF, 6=OFF

Ah, motherboard switches (rather than switches on card).

Are you really sure that your switches are set to OFF/OFF, rather than ON/ON ?
Periodically, we see people who get it wrong (which isn't hard to do).
See [here].
Perhaps post a photo of switch block SW1.

 

[modem7]

Allow for the fact that the symptom cause could also be faulty keyboard interface circuitry on the motherboard.

yikes!

And might the problem be your "PS2->XT converter" !
Confirm for us that it is an active device like [here], not just a cable with different connectors at the ends.

 

[lordhailsham]

Ah, motherboard switches (rather than switches on card).

Are you really sure that your switches are set to OFF/OFF, rather than ON/ON ?
Periodically, we see people who get it wrong (which isn't hard to do).
See [here].
Perhaps post a photo of switch block SW1.

it would not be the first time that I have embarrassed myself publicly.. let me check!

 

[modem7]

it would not be the first time that I have embarrassed myself publicly..

You're talking to someone who once filled all RAM banks of an IBM 5170 motherboard with chips put in the wrong orientation. 36 chips. An expensive mistake.

 

[lordhailsham]

And might the problem be your "PS2->XT converter" !
Confirm for us that it is an active device like [here], not just a cable with different connectors at the ends.

According to my cheap multimeter I am going to make the assumption that my xt-ps2 dongle is just a few wires connected ... without any circutry.

 

[tom.storey]

You may have made the same mistake that I made, and that was assuming that a PS/2 keyboard would work on an XT with a PS/2 to DIN adapter. But the protocols used by the two standards are different enough to not be compatible.

I built an AT2XT keyboard adapter on some strip board and that has been serving me well so far.