INOVA600 Amplifier Repair
Symptom: No decoupling, proton experiment OK. XMT I and II board OK, XMT I (H1) outpu 1.80V, XMT I (C13) 3.20V; XMT II (DEC) 1.96V.
XMTI and II send the pulses to the Attn board (I and II), The output CH1(OBS---HB or LB) and CH2 is for (DEC--H1 only). The CH1 to HB AMP and CH2 outpu to LB AMT. The output is 0 - 1 Volts (Controled by dpwr or tpwr).
When it sets to C13, the CH1 is OK, but the CH2 output was no change when the dpwr changed. The output is very small only few mV. Here is the data when it is working correctly:
When set up for H1 OBS: | |||||
TPWR | 42 | 48 | 54 | 60 | |
XMT I output | 1.8V | 1.8V | 1.8V | 1.8V | |
Attn CHI output | 46.8mv | 96mv | 192 | 384mv | |
When set up for C13 OBS: | |||||
TPWR | 42 | 48 | 54 | 60 | |
XMT I output | 3.02V | 3.02V | 3.02V | 3.02V | |
Attn CH2 output | 72mv | 135mv | 270mv | 540mv | |
DPWR | 30 | 36 | 42 | 44 | |
Attn CH1 output | 20.4 | 32.4 | 56.8 | 68.4mv |
Troubleshoot:
1. Exchange the Attn/SW (This board exchangeable with unity, inova at different field (400, 500 or 600). In this case, there is still no decoupling.
2. Exchange the Amp & Routing borad. This board is control the routing (switch between H1 and C13, as well as control the setting for dpwr and tpwr). This board fixed the problem. Varian Draw # 87-195843 Part Number992312.
Spin Rate Control:
Symptom: You can not control the spin rate, It could go to 50Hz or more depends on the air supply presure or flow.
Problem: The steel spider in the control valve is broken.
Fix: a. Turn air supply off. Unscrew the valve cap. replace the spider and shim kit.You could order the kit from Clippard.