DSE FP-200 Telephone Repair - Part 2
Following on from the previous video, I continue the saga of the DSE FP-200 telephone, diving deeper into the circuitry in an attempt to understand and fix the non-ringing ringer...
Part 1: • DSE FP-200 Telephone Repair
Errata: At 17:55 I identify R48 (blue-grey-yellow) as 68k, when the correct value is 680k.
0:00 - Introduction
1:08 - Research on ICs
2:10 - Holtek HT9215 dialer
5:02 - Motorola MC33215 line/audio chip
7:22 - ROHM BA8205 ringer IC
8:02 - Is this the fault location?
9:30 - The ringer circuit itself
10:54 - Speculating on the fault
15:34 - Circuit observations
20:20 - A mysterious voltage drop
22:33 - Catching the red LED herring
23:56 - More speculations and measurements
27:02 - Off-line testing results
29:34 - Narrowing in on the issue
29:50 - The prime suspect
31:33 - Questionable bending
32:10 - A guilty verdict?
34:43 - Replacement options
37:00 - Decisions...
40:00 - ...and distractions
42:16 - Lead forming & fitting
47:14 - Out! Damned glue!
47:40 - On the home stretch
49:33 - Reassembly
50:39 - The moment of truth
53:13 - Conclusion