HP-41 82161A HP-IL Tape Reader - Doesn't work anymore - Help Needed

[albertofenini]

(04-14-2019 05:17 PM)Dave Frederickson Wrote:  I'm not sure which contacts you're referring to. The schematic does show a 5.6 ohm resistor connected between two of the contacts (R1).

I suggest you start with the troubleshooting procedure in Table 4-4, Improper Turn-On.

Dave

Hi Dave, hi Everyone, we started some troubleshooting this morning and this is what we have found out so far.

The test situation is this :
- AC charger connected
- A charged battery in place
- No tape inside the units
- No HP-IL connection to the HP-41 calculator
- Logic PCA and Drive PCA connected together

Table 4-4

We turned the switch ON even if it is not specified in the manual
step 1: measure voltage at the left side of W1 value is 1,6 (exptected 4.9 -5.1)
Manual suggests to go to table 4-11 Power Supply Circuit

Before we moved to table 4-11 we also took the other steps described in table 4-4 and these are the values :

step 2: measure A1U2-8, the value was 1,6 (expected 4.9 to 5.1)
step 3: measure A1DS3 anode, the value was 1,6 (expected 4.9 to 5.1)
step 4: measure A1U2-9 the value was 5,27 (expected 4.7 to 4.8)
step 5: measure A1U2-14 the value was 5,26 (expected 0 to 0,5)
step 6: measure A1Ds3 chathode, the value was 5,25 (exptected less than 3,2)

Is it correct that looking at these values the action suggested is to replace A1U2 and then A1U7 ?
Or it is more wise after step1 jump to table 4-11 ?

Table 4-11

step 1 : Turned the switch on
step 2 measure A1U2-4 and it was 1,6 (should be 4.9 to 5.1)
measure A1U2-8 and it was 1,6 (should be 4.9 to 5.1)

At this point the manual does not give a clear indication of what to do if BOTH values are out of range,
it says what to do if pin 4 is in the range and pin 8 is not in the range but not if both are out of range.

Nevertheless we proceded as described in the manual and we de-soldered left side of A1W1

Something weird started to happen, the left motor (the left one looking at the drive board from the trace side,
in working position that would be the right motor, the one that make the tape advance) started to run.
We left however the two PCA connected and we proceeded as follow

Step 4 : measure A1U2-4 and the value was 5.076 which is in range (expteced 4.9 to 5.1)

Following the manual we separeted the logic PCA from the drive PCA we reconnected W1 but the values
measured before remained all wrong, which for the manual means that the problem is on the logic PCA

We disconnected again W1, reconnected the two logic boards, left the motor run and took the following steps :

Step 5 : measure A1U7-7 and was 6V (expected 16 to 19)
Step 6 : measure A1U2-5 5.2 (expected 4.9 to 5.2)
Step 7 : measure A1U2-2 was almost 0V

However, then in the action it says often if 5V supply is above range... or if 5V supply is below range
How can we exactly find out if 5V supply is above or below range ?

thanks everyone for the support !!!