I recently purchased a broken D4708 with all options. It arrived in good condition but I sadly discovered someone had swapped the LTZ ref for the 4000 diode ref.
I have since repaired the 4708 and it is working well but I'd really like the proper LTZ1000 ref - does anyone have one they would consider selling?
I only need the ref module itself, the divider board is the proper 4708 model.
For reference here are the parts that my D4708 required changing:
All 10 uF 25 volt tantalums - several where shorted on the + and - 15 volts rails on several boards. They must all be changed. Replace with 10 uF 35 volt(minimum).
D29 (ZN458) on the power amplifier board - this is a precision 2.45 volt zener used as part of the + and - 15 volt supply rail check, it was shorted, discontinued but available on ebay.
C26 on the power amplifier board - 100 uF 40 volt electrolytic, it had leaked, thankfully it wasn't acidic, no PCB damage.
Q1 on the in guard supply - this is a TIP141 transistor operating as a pre-regulator for the + 15 volt rail, it was shorted C to E.
M1 on the in guard supply - this is a 7815 regulator that had been tortured when Q1 shorted.
That was it to get it running. While I had it on the bench I also replaced nearly every electrolytic in the power supplies and all of the 22uF and 33uF 25 volt tantalums. They all test fine but are 30 years old. Hopefully it is good for another 30 years.
As you can see it is badly in need of a calibration as the swapped ref isn't even close to correct. For now I'll see how the diode ref behaves but am sad about the missing LTZ, paypal is ready, anyone?


