From eenriquez at snf.stanford.edu Mon Aug 4 15:15:15 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Mon, 4 Aug 2008 15:15:15 -0700 Subject: Comment pquest SNF 2008-08-04 15:15:15: Update Message-ID: Chamber vented. Installed 40 durometer o-ring. Installed fingered clamp. Aligned clamp support post. Need to adjust clamp level and force. From eenriquez at snf.stanford.edu Tue Aug 5 15:04:11 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:04:11 -0700 Subject: Shutdown pquest SNF 2008-07-25 14:36:39: system left "offline" Message-ID: Installed 40 durometer o-ring, full wafer clamp and new stiffer clamp springs. Leveled clamp by using a feeler gauge. Cycled wafer in and out of the chamber with no problems. From eenriquez at snf.stanford.edu Tue Aug 5 15:04:26 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:04:26 -0700 Subject: Shutdown pquest SNF 2008-07-25 14:34:01: wafer recovered but system left "offline" Message-ID: Installed 40 durometer o-ring, full wafer clamp and new stiffer clamp springs. Leveled clamp by using a feeler gauge. Cycled wafer in and out of the chamber with no problems. From eenriquez at snf.stanford.edu Tue Aug 5 15:04:37 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:04:37 -0700 Subject: Comment pquest SNF 2008-08-04 15:15:15: Update Message-ID: Archived From eenriquez at snf.stanford.edu Tue Aug 5 15:04:49 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:04:49 -0700 Subject: Comment pquest SNF 2008-07-28 04:58:59: Wafer transfer Message-ID: Archived From eenriquez at snf.stanford.edu Tue Aug 5 15:05:04 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:05:04 -0700 Subject: Comment pquest SNF 2008-07-29 23:33:48: Clamp Message-ID: Archived From eenriquez at snf.stanford.edu Tue Aug 5 15:05:13 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:05:13 -0700 Subject: Comment pquest SNF 2008-07-31 02:02:32: Clamping Message-ID: Archived From eenriquez at snf.stanford.edu Tue Aug 5 15:05:23 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:05:23 -0700 Subject: Comment pquest SNF 2008-07-25 11:59:58: Update Message-ID: Archived From eenriquez at snf.stanford.edu Tue Aug 5 15:06:03 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:06:03 -0700 Subject: Comment pquest SNF 2008-05-27 10:41:59: RF tuning update Message-ID: Archived From eenriquez at snf.stanford.edu Tue Aug 5 15:11:30 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 5 Aug 2008 15:11:30 -0700 Subject: Comment pquest SNF 2008-08-05 15:11:30: Update Message-ID: New hardware installed. Full wafer clamp, stiffer clamp springs. Also reduced clamping force. Please run a test run a test wafer before comitting your actual samples. From bashar at snf.stanford.edu Wed Aug 6 19:18:57 2008 From: bashar at snf.stanford.edu (bashar at snf.stanford.edu) Date: Wed, 6 Aug 2008 19:18:57 -0700 Subject: Problem pquest SNF 2008-08-06 19:18:56: Wafer Unload Issues Persists! Message-ID: 4" Si carrier wafer was thrown off the three prongs by spring action during unload - this was BEFORE the robot arm came into the chamber to unload the wafer. From bashar at snf.stanford.edu Wed Aug 6 21:07:55 2008 From: bashar at snf.stanford.edu (bashar at snf.stanford.edu) Date: Wed, 6 Aug 2008 21:07:55 -0700 Subject: Shutdown pquest SNF 2008-08-06 21:07:54: Swallowed Wafer ... during unload Message-ID: Per Dr Baxter's orders, I am shutting down the tool. From shott at snf.stanford.edu Thu Aug 7 19:04:40 2008 From: shott at snf.stanford.edu (shott at snf.stanford.edu) Date: Thu, 7 Aug 2008 19:04:40 -0700 Subject: Shutdown pquest SNF 2008-08-06 21:07:54: Swallowed Wafer ... during unload Message-ID: Elmer did some more fine tuning of the clamp assembly. In particular, he did 2 key things: 1. He discovered and adjusted the "holding wedge" underneath the up/down mechanism at the left of the chamber. Proper adjustment of this seems to prevent the clamp from sliding to the left under higher clamping loads. 2. He also recuced the clamping force by reducing the spring preload at each corner of the clamp assembly by loosening the allen scred by 2 1/2 turns on each corner. 3. Final adjustment of up/middle/down clamping positions completed the work. Testing under Jim Kruger's oxygen3 program showed a helium "blow by" of roughly 4.0-5.5 sccm to maintain the 10 Torr backside pressure and 600 watts of power (I think) resulted in a backside bias of about 67-68 volts. Releasing for cautious use, John From shott at snf.stanford.edu Thu Aug 7 19:04:57 2008 From: shott at snf.stanford.edu (shott at snf.stanford.edu) Date: Thu, 7 Aug 2008 19:04:57 -0700 Subject: Problem pquest SNF 2008-08-06 19:18:56: Wafer Unload Issues Persists! Message-ID: Elmer did some more fine tuning of the clamp assembly. In particular, he did 2 key things: 1. He discovered and adjusted the "holding wedge" underneath the up/down mechanism at the left of the chamber. Proper adjustment of this seems to prevent the clamp from sliding to the left under higher clamping loads. 2. He also recuced the clamping force by reducing the spring preload at each corner of the clamp assembly by loosening the allen scred by 2 1/2 turns on each corner. 3. Final adjustment of up/middle/down clamping positions completed the work. Testing under Jim Kruger's oxygen3 program showed a helium "blow by" of roughly 4.0-5.5 sccm to maintain the 10 Torr backside pressure and 600 watts of power (I think) resulted in a backside bias of about 67-68 volts. Releasing for cautious use, John From lwchang at snf.stanford.edu Fri Aug 8 15:25:17 2008 From: lwchang at snf.stanford.edu (lwchang at snf.stanford.edu) Date: Fri, 8 Aug 2008 15:25:17 -0700 Subject: Shutdown pquest SNF 2008-08-08 15:25:14: broken wafer Message-ID: wafer was sitting on the 3 pings when robot came in...when arm reached the wafer it crashed the wafer. Not sure what happened. Broken wafer in the chamber. From cbaxter at snf.stanford.edu Sat Aug 9 09:29:25 2008 From: cbaxter at snf.stanford.edu (cbaxter at snf.stanford.edu) Date: Sat, 9 Aug 2008 09:29:25 -0700 Subject: Shutdown pquest SNF 2008-08-08 15:25:14: broken wafer Message-ID: Vacuumed broken wafer inside the chamber and adjusted optic sensor for clamp at up position. John installed a coupling on the drive shaft to prevent the shaft from moving up and causing the clamp to over travel. Ran 20mins o2 plasma. From lwchang at snf.stanford.edu Sat Aug 9 13:45:26 2008 From: lwchang at snf.stanford.edu (lwchang at snf.stanford.edu) Date: Sat, 9 Aug 2008 13:45:26 -0700 Subject: Shutdown pquest SNF 2008-08-09 13:45:25: 1st wafer was off the pings during unloading Message-ID: hit esc to stop robot arm....wafer still in chamber. Backside He around 7sccm with wafer. Also noticed possible N2 leak (pink plasma) during low O2 flow/low pressure etching. From shott at snf.stanford.edu Sun Aug 10 11:38:01 2008 From: shott at snf.stanford.edu (shott at snf.stanford.edu) Date: Sun, 10 Aug 2008 11:38:01 -0700 Subject: Shutdown pquest SNF 2008-08-09 13:45:25: 1st wafer was off the pings during unloading Message-ID: I cleared the wafer and reset the system. When the clamp comues up, the wafer "jumps" just a bit. It still appears as if the wafer is catching slightly on he 45 degree bevel at thte side of the chuck although I don't see any rough edges there. One possiblity, I think, might be to slow down the clamp motor sliglhtly by getting a smaller gear and a slightly smaller belt for the motor while leaving the gears on the sensor and clamp assembly shafts the same. John From lwchang at snf.stanford.edu Sun Aug 10 17:26:39 2008 From: lwchang at snf.stanford.edu (lwchang at snf.stanford.edu) Date: Sun, 10 Aug 2008 17:26:39 -0700 Subject: Shutdown pquest SNF 2008-08-10 17:26:38: wafer off the pings during unloading Message-ID: hit esc... From eenriquez at snf.stanford.edu Mon Aug 11 14:48:40 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Mon, 11 Aug 2008 14:48:40 -0700 Subject: Shutdown pquest SNF 2008-08-10 17:26:38: wafer off the pings during unloading Message-ID: Recovered the user's wafer. Adjusted the the wafer clamp stop to eliminate the clamp's side to side movement. Also adjusted the lift pins so that they are slightly at different levels in order to minimize wafer movement during the unload. If it still fails, we'll adjust the wafer lift speed. Ran O2 plasma. Backside He flow is ~ 6 sccm. From lwchang at snf.stanford.edu Mon Aug 11 20:36:51 2008 From: lwchang at snf.stanford.edu (lwchang at snf.stanford.edu) Date: Mon, 11 Aug 2008 20:36:51 -0700 Subject: Problem pquest SNF 2008-08-11 20:36:50: clamp did not go dw Message-ID: sys is still waiting for clamp dw sensor. wafer in chamber. From eenriquez at snf.stanford.edu Tue Aug 12 08:37:00 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 12 Aug 2008 08:37:00 -0700 Subject: Problem pquest SNF 2008-08-11 20:36:50: clamp did not go dw Message-ID: Recovered user's wafer. Adjusted clamp down sensor sensitivity. Reduced the speed of the wafer lift motor. From eenriquez at snf.stanford.edu Tue Aug 12 08:37:13 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Tue, 12 Aug 2008 08:37:13 -0700 Subject: Comment pquest SNF 2008-08-05 15:11:30: Update Message-ID: Archived From kaimeifu at snf.stanford.edu Tue Aug 12 13:09:37 2008 From: kaimeifu at snf.stanford.edu (kaimeifu at snf.stanford.edu) Date: Tue, 12 Aug 2008 13:09:37 -0700 Subject: Comment pquest SNF 2008-08-12 13:09:37: trouble striking Message-ID: I had trouble with the plasma igniting for my GaP etch. From lwchang at snf.stanford.edu Tue Aug 12 17:45:59 2008 From: lwchang at snf.stanford.edu (lwchang at snf.stanford.edu) Date: Tue, 12 Aug 2008 17:45:59 -0700 Subject: Shutdown pquest SNF 2008-08-12 17:45:57: wafer off pings Message-ID: From eenriquez at snf.stanford.edu Wed Aug 13 19:00:07 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Wed, 13 Aug 2008 19:00:07 -0700 Subject: Comment pquest SNF 2008-08-13 19:00:06: Update Message-ID: Handling problem- Realigned the lift pins Found two of the pins were slightly turned so that during wafer lift from the electrode, the high side of the two pins would initially lift the wafer before dropping to the low side. This drop sometimes causes the wafer to come off one or two of the lift pins. Turbo pump does not start - Currently installing a new turbo. Turbo is in place and the sytem is pumped down. Still need to connect the water lines and nitrogen purge. New turbo did not ship with a nitrogen purge port. If the purge port is available from our local pump vendors, the system should be ready by 3 pm tomorrow. From eenriquez at snf.stanford.edu Thu Aug 14 15:09:28 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Thu, 14 Aug 2008 15:09:28 -0700 Subject: Comment pquest SNF 2008-08-14 15:09:27: Update Message-ID: Ordered the Turbo pump N2 purge sealing gas valve. It should be here early next week. From emyers at snf.stanford.edu Tue Aug 19 03:28:11 2008 From: emyers at snf.stanford.edu (emyers at snf.stanford.edu) Date: Tue, 19 Aug 2008 03:28:11 -0700 Subject: Shutdown pquest SNF 2008-08-19 03:28:11: Cl and HBr are off Message-ID: Chlorine and HBR gas cabinet is off following toxic gas alarm. Alarm showed Cl in the P5000 exhaust monitor. Since the etch tools have not recovered from the power outage, I did not turn on the gases. From emyers at snf.stanford.edu Tue Aug 19 10:52:05 2008 From: emyers at snf.stanford.edu (emyers at snf.stanford.edu) Date: Tue, 19 Aug 2008 10:52:05 -0700 Subject: Shutdown pquest SNF 2008-08-19 03:28:11: Cl and HBr are off Message-ID: Cl and HBr gas cabinets were reset at 9am. From eenriquez at snf.stanford.edu Wed Aug 20 14:59:33 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Wed, 20 Aug 2008 14:59:33 -0700 Subject: Shutdown pquest SNF 2008-08-12 17:45:57: wafer off pings Message-ID: Realigned the pins. Replaced the turbo pump. Installed a metal screen on the bottom of the chamber to protect the gate valve and turbo from ingesting pieces of wafers. Ran O2 plasma clean for 2 hours. Backside He flow is ~ 3 sccm. Bias voltage is about 50% of normal. Loaded and unloaded wafers several times with no problems. Chamber leak rate looks normal about 1.3 mT/min. Gate valve does not appear to be leaking anymore. System is OK to use but please verify your process before committing your samples. From eenriquez at snf.stanford.edu Wed Aug 20 14:59:55 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Wed, 20 Aug 2008 14:59:55 -0700 Subject: Comment pquest SNF 2008-08-13 19:00:06: Update Message-ID: Archive From eenriquez at snf.stanford.edu Wed Aug 20 15:00:06 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Wed, 20 Aug 2008 15:00:06 -0700 Subject: Comment pquest SNF 2008-08-14 15:09:27: Update Message-ID: Verify From eenriquez at snf.stanford.edu Wed Aug 20 15:05:39 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Wed, 20 Aug 2008 15:05:39 -0700 Subject: Problem pquest SNF 2008-07-07 11:16:36: PQ Still leaks? Message-ID: Cleaned gate valve and sealing surfaces. Now able to vent the chamber without venting the turbo pump. From tdo at snf.stanford.edu Thu Aug 21 13:21:56 2008 From: tdo at snf.stanford.edu (tdo at snf.stanford.edu) Date: Thu, 21 Aug 2008 13:21:56 -0700 Subject: Problem pquest SNF 2008-08-21 13:21:55: minor glitches Message-ID: Was able to do 2 successful runs (plus 1 dummy), but noticed 2 minor glitches: 1) After the first clampdown, the sensor did not sense the clamp was down 2) When unloading every wafer, it still "pops" out of the groove, but fortunately, not enough to push it off the pins. Suggest users watch every unloading process carefully because the wafer could still fall off the pins From kaimeifu at snf.stanford.edu Fri Aug 22 09:40:48 2008 From: kaimeifu at snf.stanford.edu (kaimeifu at snf.stanford.edu) Date: Fri, 22 Aug 2008 09:40:48 -0700 Subject: Problem pquest SNF 2008-08-22 09:40:47: dc bias very low Message-ID: I tried doing a run today but the dc bias was -17 instead of the usual -54V. The backside helium flow was 11 sccm. From kaimeifu at snf.stanford.edu Fri Aug 22 23:29:07 2008 From: kaimeifu at snf.stanford.edu (kaimeifu at snf.stanford.edu) Date: Fri, 22 Aug 2008 23:29:07 -0700 Subject: Comment pquest SNF 2008-08-22 23:29:07: tonight's run Message-ID: Back side He was good < 3 sccm for all 4 runs. Clamp sensor did not detect clamp down in 3 out of 4 runs- I pressed escape after waiting a while and still did the runs. Back side bias was 47V which is close to the normal 53-54V. From krivoire at snf.stanford.edu Sat Aug 23 17:29:58 2008 From: krivoire at snf.stanford.edu (krivoire at snf.stanford.edu) Date: Sat, 23 Aug 2008 17:29:58 -0700 Subject: Shutdown pquest SNF 2008-08-23 17:29:57: wafer slipping off the pins during unloading Message-ID: wafer slipped off pins during unload. currently, robot arm is between chamber and home position, and wafer is inside chamber. From shott at snf.stanford.edu Sun Aug 24 10:09:01 2008 From: shott at snf.stanford.edu (shott at snf.stanford.edu) Date: Sun, 24 Aug 2008 10:09:01 -0700 Subject: Shutdown pquest SNF 2008-08-23 17:29:57: wafer slipping off the pins during unloading Message-ID: well, I've cleared the wafer and put in a special Elmer bead-blasted O-ring. I also did a bunch of load/unloads to try to make sure that sticking is OK. While I think that is a bit better, helium blowby seems worse. So, I'm a bit confused as to what I did. John From shott at snf.stanford.edu Mon Aug 25 06:17:17 2008 From: shott at snf.stanford.edu (shott at snf.stanford.edu) Date: Mon, 25 Aug 2008 06:17:17 -0700 Subject: Shutdown pquest SNF 2008-08-25 06:17:16: Checking O-ring flatness ... Message-ID: I'm shutting this down briefly to check the flatness of the O-ring and the clamp ring with a quartz wafer ... John From shott at snf.stanford.edu Mon Aug 25 13:26:21 2008 From: shott at snf.stanford.edu (shott at snf.stanford.edu) Date: Mon, 25 Aug 2008 13:26:21 -0700 Subject: Shutdown pquest SNF 2008-08-25 06:17:16: Checking O-ring flatness ... Message-ID: Tried to check O-rimg flatness with limited success and also flattened the teflon portion of the clamp ring with some 600 grit emery paper. From lwchang at snf.stanford.edu Wed Aug 27 12:15:59 2008 From: lwchang at snf.stanford.edu (lwchang at snf.stanford.edu) Date: Wed, 27 Aug 2008 12:15:59 -0700 Subject: Shutdown pquest SNF 2008-08-27 12:15:55: dummy wafer off pings during unloading Message-ID: still observed wafer popped out the pings then went off the pings. Now sitting on 2 pings...hit esc From eenriquez at snf.stanford.edu Wed Aug 27 19:07:03 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Wed, 27 Aug 2008 19:07:03 -0700 Subject: Shutdown pquest SNF 2008-08-27 12:15:55: dummy wafer off pings during unloading Message-ID: Recovered the wafer and replaced the helium cooling o-ring. From jimkruger at snf.stanford.edu Thu Aug 28 11:42:55 2008 From: jimkruger at snf.stanford.edu (jimkruger at snf.stanford.edu) Date: Thu, 28 Aug 2008 11:42:55 -0700 Subject: Shutdown pquest SNF 2008-08-28 11:42:55: broken wafer (on unload) in system Message-ID: From eenriquez at snf.stanford.edu Thu Aug 28 13:43:06 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Thu, 28 Aug 2008 13:43:06 -0700 Subject: Shutdown pquest SNF 2008-08-28 11:42:55: broken wafer (on unload) in system Message-ID: No wafer pieces on the chuck. Reduced clamping force and ran O2 plasma. From jimkruger at snf.stanford.edu Fri Aug 29 12:47:56 2008 From: jimkruger at snf.stanford.edu (jimkruger at snf.stanford.edu) Date: Fri, 29 Aug 2008 12:47:56 -0700 Subject: Problem pquest SNF 2008-08-29 12:47:55: No bias voltage indicated Message-ID: RF seems to tune, but no voltage indicated on screen or on RF supply. Etches may not be working normally. From eenriquez at snf.stanford.edu Fri Aug 29 14:55:35 2008 From: eenriquez at snf.stanford.edu (eenriquez at snf.stanford.edu) Date: Fri, 29 Aug 2008 14:55:35 -0700 Subject: Shutdown pquest SNF 2008-08-29 14:55:35: No bias voltage Message-ID: Unable to generate any bias voltage (there is a - 6V offset) . RF generator checked OK ( used a bird watt meter and dummy load). Matching network seems to be working OK. Suspect a bad connection or component in the matching network- electrode assembly. Need to troubleshoot further. From shott at stanford.edu Sun Aug 31 09:35:12 2008 From: shott at stanford.edu (John Shott) Date: Sun, 31 Aug 2008 09:35:12 -0700 Subject: Shutdown pquest SNF 2008-08-29 14:55:35: No bias voltage In-Reply-To: <20080829215535.F331A60E6A9@smtp3.stanford.edu> References: <20080829215535.F331A60E6A9@smtp3.stanford.edu> Message-ID: <48BAC840.9050805@stanford.edu> Elmer, Jim, and Jim: While I haven't actually measured any voltages, I see from the manual for the matching network that it generates a "DC sample" signal that is the measured DC bias that it measures that is attenuated by -200. In other words, a DC bias of -100 V would generated a +0.5V signal on the DB9 connector that comes out the back of the matching network. The DC output should be on both pins 8 and 9 of the DB9 and ground is on pin 3. (Note: +15 V and -15V should be on pins 1 and 2, respectively and, I think, powers this circuit so if we are reading -6V, it's also possible that the +15 V DC supply is missing). My guess is that putting in a "breakout box" for the DB9 would be the first step towards determining whether the problem reading the DC bias is either in the electrode or the matching network or whether it is in the readout circuit of the power supply. Note: I have full schematics of the matching network and have the user manual for the power supply .... but not the circuit schematics. Now that I know the Advanced Energy part number, I will contact Advanced Energy on Tuesday morning to see if they can send me the schematics and maintenance manual for the supply itself. Have a good weekend, John From mcvittie at cis.Stanford.EDU Sun Aug 31 17:19:50 2008 From: mcvittie at cis.Stanford.EDU (Jim McVittie) Date: Sun, 31 Aug 2008 17:19:50 -0700 (PDT) Subject: Shutdown pquest SNF 2008-08-29 14:55:35: No bias voltage In-Reply-To: <48BAC840.9050805@stanford.edu> Message-ID: John, A 200x reduction in the dc bias in the match box is pretty common. THe reduction helps with the rf filtering and you want a small voltage at this point. Typicially, this reduced voltage can be feed into a A2D which goes to the computer, or the A2D conversion can be done in the match controller box. I would expect a -100V bias to yield a -0.5 v bias out of the match box. To test the bias measurement circuit, one can apply a large neg voltage, such as -100V to the wafer electrode with the chamber open. Or if you get at the output side of the match box, you can apply the voltage there. I have a high voltage Dc supply which I use for the purpose. Sometimes, it is useful to look at the rf voltage with an oscilloscope at the output of the match box. You measure the bias voltage and look for usual distortion in the rf caused by a faulty rf supply. Note that there is always some distortion since the plasma has some nonlinearity. Jim On Sun, 31 Aug 2008, John Shott wrote: > Elmer, Jim, and Jim: > > While I haven't actually measured any voltages, I see from the manual > for the matching network that it generates a "DC sample" signal that is > the measured DC bias that it measures that is attenuated by -200. > In other words, a DC bias of -100 V would generated a +0.5V signal on > the DB9 connector that comes out the back of the matching network. The > DC output should be on both pins 8 and 9 of the DB9 and ground is on pin > 3. (Note: +15 V and -15V should be on pins 1 and 2, respectively and, I > think, powers this circuit so if we are reading -6V, it's also possible > that the +15 V DC supply is missing). > > My guess is that putting in a "breakout box" for the DB9 would be the > first step towards determining whether the problem reading the DC bias > is either in the electrode or the matching network or whether it is in > the readout circuit of the power supply. > > Note: I have full schematics of the matching network and have the user > manual for the power supply .... but not the circuit schematics. Now > that I know the Advanced Energy part number, I will contact Advanced > Energy on Tuesday morning to see if they can send me the schematics and > maintenance manual for the supply itself. > > Have a good weekend, > > John > > > > -- -------------------------------------------------------------- Jim McVittie, Ph.D. Senior Research Scientist Allen Center for Integrated Systems Electrical Engineering Stanford University jmcvittie at stanford.edu Rm. 336, 330 Serra Mall Fax: (650) 723-4659 Stanford, CA 94305-4075 Tel: (650) 725-3640