IBM 5150 w/Expansion Unit 1801 post on Boot

[Silvio2117]

Tested the p10 orange connector again and now I'm getting 63.2 mV.

One more note: when I did the test of all connectors with the psu open, I had removed the FAN. Could the FAN be bad?

 

[modem7]

I have not seen that tester before but the one i have for ATX PSU's is nothing more than a glorified DMM, eg: It shows all the output voltages and PG on one screen, It's handy for that but nowt else.

Isn't it good for independent loading as well, i.e. unit contains load resistors ?

I tested all connectors with the following results:

POWER GOOD is a TTL level signal, not a supply voltage. And so expected is a voltage at roughly +5V.

So now P10 orange is looking good. Not sure what happened. I did two test that with both at .45V.

It is important that the PSU be adequately loaded, otherwise a lot of PSU's of this vintage will shut down.
So maybe when you saw 0.45V, you had the hard drive disconnected at the time ?

 

[Silvio2117]

Isn't it good for independent loading as well, i.e. unit contains load resistors ?


POWER GOOD is a TTL level signal, not a supply voltage. And so expected is a voltage at roughly +5V.


It is important that the PSU be adequately loaded, otherwise a lot of PSU's of this vintage will shut down.
So maybe when you saw 0.45V, you had the hard drive disconnected at the time ?

When I got the .45 V on the p10 connector the drive was connected.
After I opened the PSU removed the fan and tested all connectors results looked fine (Noting was connected at the time).
I put the fan back and closed up the PSU. Went back and tested the p10 Orange wire again. It came up way short with a reading of +63.2mV.
At that time the drive was connected. So with the PSU open and the FAN disconnected all tested of the connectors were good. Nothing was connected at the time.

I re-connected the fan closed up PSU, plugged in all connectors (2 to the Motherboard and 1 to the drive / P10 was for additional drive that was not installed). Re-tested the orange wire on P10. The results were +63.2mV. I think this is way low. Expecting +12V. Could the FAN cause this?

 

[Cyberstein]

Just thought I'd put in my 2 cents. I would narrow things down myself. As in remove all cards except for essentials in both the 5150 and the 5161. Sometimes one card can take down or interfere with others. I would also reseat the extender and receiver cards, maybe even try them both in different slots. While doing this I would perform cleaning on the gold fingers with alcohol or contact cleaner just to be sure. And as Modem7 suggested, perform pin-pin continuity checks on the cable. Although I suggest plugging it into the receiver/extender cards when you do this. This will allow you to test your mating connections as well and might make it easier. Continuity checks on cables are tedious, I know, but sometimes necessary to avoid chasing ghosts. You might also want to move the cable around while your testing to look for intermittent failures. I also have an IBM 5150/5161. The 5161 in my opinion is more rare than the 5162, took me forever to find one. Good luck sir!

 

[modem7]

I re-connected the fan closed up PSU, plugged in all connectors (2 to the Motherboard and 1 to the drive / P10 was for additional drive that was not installed). Re-tested the orange wire on P10. The results were +63.2mV. I think this is way low.

The circuit diagram of the receiver card shows that it uses +5V only. Earlier, it appeared that your PSU was not producing +5V, but you have subsequently found that +5V is being produced, and on P9. So, at this point, the low +12V voltage on the P10 connector is a distraction to finding the cause of the 1801 error.

It is a extremely good bet that the +5V from P9 is reaching the receiver card (via two of the +5 lines running from P9 to the ISA slots). So it is back to stuff like what is written in the previous post.

 

[Silvio2117]

Modem7 thank you for your latest post. Right now I have the PSU back in the unit with all connectors attached. I tested the P10 that is reading -.446V. I never tested any other connectors while the unit was hooked. But, this is telling me that neither the 12 or 5 v rails are ok. Again, they tested ok with no load, no fan and the PSU open.

 

[Malc]

Isn't it good for independent loading as well, i.e. unit contains load resistors ?

It does load the PSU yes, But not enough,, I have deliberately connected up known faulty PSU's and at first look all appears good on screen until more loads added, Even then depending on the fault the on screen readings may not change. I certainly don't trust it, It's just a glorified DMM to me.

 

[Malc]

I had removed the FAN. Could the FAN be bad?

A faulty 12v DC fan could drag down the voltage rail, Am i right in thinking when you had the PSU on the bench you used the Hard drive etc from the 5161 expansion unit as loads ??, It's best to use known good working loads, One of those loads you used could be faulty ?. Of course the PSU may be faulty but prove it is or is not first on the bench.

 

[modem7]

In post #20, all voltage measurements were as expected (except for POWER GOOD, way exceeding the expected +5V, roughly).
So what has changed between post #20 and now !

 

[Silvio2117]

A faulty 12v DC fan could drag down the voltage rail, Am i right in thinking when you had the PSU on the bench you used the Hard drive etc from the 5161 expansion unit as loads ??, It's best to use known good working loads, One of those loads you used could be faulty ?. Of course the PSU may be faulty but prove it is or is not first on the bench.

Thank you for the suggestion. I did try to remove each connector (thus removing each potential bad load) and retested. I continued to get bad reading on all tests. So I don't think my problem is a bad load.

 

[Silvio2117]

In post #20, all voltage measurements were as expected (except for POWER GOOD, way exceeding the expected +5V, roughly).
So what has changed between post #20 and now !

The tests done in post #20 were done with no load, the PSU open, and the fan removed. Next, I plan on re-opening the PSU and testing with the fan hooked up. I'll also do some tests with with various loads.

 

[Silvio2117]

So I retested before doing anything and the unit continued to test bad. Opened it, removed the fan (it was running on the last test) and did another test. This time it tested bad -12.38 and -.447v on the p10 connector. Nothing hooked up at the time of these tests. I have no idea what's happening. It doesn't appear to be a fan issue. The unit does appear to be bad. I plan on going through the tests again tomorrow. I'll try and include more pictures.

 

[modem7]

This time it tested bad -12.38 and -.447v on the p10 connector.

That is actually +12.38V.
Why?
The red and black wires cables are connected to the wrong sockets on the meter.

 

[Silvio2117]

That is actually +12.38V.
Why?
The red and black wires cables are connected to the wrong sockets on the meter.

Good catch Thank you. I must have check the leads three or 4 times, but, never checked the plugs into the DMM. I feel like a big dummy. You given me hope. I'll retest and provide an update later in the day.

 

[modem7]

You given me hope. I'll retest and provide an update later in the day.

Remember to keep an open mind. There could be multiple problems. For example:
- A fault resulting in no +5V on the +5V connector of P10. But there is +5V on the three +5V pins of P9. Never noticed before because P10 has never been used.
- A fault, having nothing at all to do with supply voltages, causing the 1801 error.

 

[Silvio2117]

With all cables disconnected (fan reconnected) no issues. All power was within spec. With P8, P9 and P11 connected, voltage way below normal 63.4 mV on the P10 orange. I tried removing the Drive control card (still too low), then the expansion card still too low. I then removed the p8 still ng. Put p8 back in and removed p9, still NG. But, after removing both the P8 and P9 the readings on the P10 when back to normal. I'm thinking the PSU is OK and the problem is related to the expansion unit's mother board.

This is the test on P10 orange with P8 and p9 disconnected.
Same test of P10 with P8 connected to the mother board. I get the same results with all cards removed and just p9 or both p8 and p9 connected to the Mboard.

 

[Malc]

I'm thinking the PSU is OK and the problem is related to the expansion unit's mother board.

What is the Power Good reading now ?, With nothing connected to the PSU, Previously it was way too high,

 

[Silvio2117]

13.6 mV

 

[Malc]

13.6 mV

And with just the hard drive plugged in ? and does it spin up fully

 

[Silvio2117]

Yes the hard drive was plugged in and it does sound like it spins up completely.