Wanted : schematics Datron/Wavetek 4600 - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: April 17, 2017, 11:37:43 am
content: Hello,I am looking for the schematics of the Datron/Wavetek 4600A transconductance amplifier. Thank you

author: perdrix
author_rank: Frequent Contributor
timestamp: July 10, 2017, 05:29:37 pm
content: I too am hunting for the service manual for the 4600.ThanksDave

author: lukier
author_rank: Unknown
timestamp: July 10, 2017, 07:38:23 pm
content: I might need that manual soon as well. Unfortunately, it seems it didn't make it to the Internet.Possible sources:Some ancient website:http://www.tennesseequipment.com/East-Cost-/New-Jersey-/Publications-/Datron-4600-user-s-handbook-5-shipping.plThis seller offered one with the equipment:http://www.ebay.de/itm/231823520029I wonder if user manuals are considered books. If yes then maybe British Library has the legal deposit.Bummer

author: alm
author_rank: Super Contributor
timestamp: July 10, 2017, 07:46:40 pm
content: I have never ever seen a user's manual with an ISBN, so I would not to find them at a public library. If instruments were purchased by the military, then you can sometimes find military manuals in archives likeLOGSA.Does Fluke (who bought Wavetek after Wavetek bought Datron) provide any support?

author: MK
author_rank: Regular Contributor
timestamp: July 10, 2017, 09:34:13 pm
content: Fluke has put all its obsloete product manuals in the public domain, so there is hope it will appear sometime.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 11, 2017, 09:41:00 am
content: More in hope than expectation, I've emailed Fluke to ask about these manuals. Sadly I'm not optimistic.Dave

author: pelule
author_rank: Frequent Contributor
timestamp: July 11, 2017, 07:25:01 pm
content: I am looking for it a while also.Have even tried to buy a 4600 service manual. But could not find any offer yet./PeLuLe

author: lukier
author_rank: Unknown
timestamp: July 13, 2017, 10:57:39 pm
content: I hope nobody minds me hijacking this thread.So the Wavetek 4600 arrived today and I'm afraid the manual would be super useful. I didn't pay much, probably the low thermal binding posts + 11 S102 Vishay resistors are worth more, but I would rather have the amplifier.The unit consists of a small transformer - I'm guessing for linear supplies for the precision section and a big switching supply that seems to be described in the US4910653 patent, taking mains on the input, via bridge rectifier, caps and other typical bits and bobs through two IXTH12N50A with gates driven by small inductors (it looks so), these transistors drive this strange dual transformer arrangement (described in the patent) and the secondary side is pretty much just four USD945 and a lot of caps. That is the main board of this PSU, auxillary board has the control for both sides and AFAIR some form of feedback.This switcher produces high amp +- 7.5V that goes via bus bars to the power output stage. Here it looks like a NPN/PNP push-pull output, with 9 x MJE15028 (NPN), 3 x BD139 (NPN), 9 x MJE15029 (PNP) , 3 x BD140 (PNP), lonely OP27 and 18 W21 R47 5% resistors (I guess to balance the currents) + misc components. This is controlled via IDC cable from the precision section. Busbar output from this stage enters the precision section of the device, goes through a precision selected shunt resistor and via relay ends on the output binding posts.The precision board is complex, full of analog wizardry, precision resistors and opamps + some digital stuff related to the remote control from the 4800 series calibrator (i.e. non-solo mode).The problem is that there is no output. After connecting a valid load (either L&N 4385 shunts or a DMM on amps) it allows to enable the output (no Overdrive), no other errors on the front panel, but the output isn't what it should be (1A/V). However, there is some faint transimpedance action:VoltsAmps0.19 V0.0 mA1.0 V1.15 mA5.0 V6.90 mA10.0 V14.20 mAand Overdrive cut-off at around 12.5V. The gain is ~1000x less than it should be.The switcher produces this +-7.5V voltage, I don't know if this is correct but seems sensible. Next week I'll try loading these rails to 11A with a DC load. The unit is full of the nasty old drop-shaped tantalums, but I didn't find any obvious shorts or explosions. The precision feedback control board will require complex study.My first suspect is the power output stage. It runs extremely hot, too hot to touch in a mater of minutes - without even producing a single amp (and the fan running). I know this is bipolar, but still doesn't feel right. And the whole unit consumes the nameplate power (~200W) constantly. One would guess that Overtemperature/Overload indicator would work or any of a dozen of fuses inside would be blown, but sadly noIf anyone has any hints that would be more than welcome. Next week I can post more detailed photos from the internals.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 14, 2017, 12:51:43 am
content: Quote from: lukier on July 13, 2017, 10:57:39 pmThat's most interesting as mine does *exactly* the same. Clearly a "common" issue.PS how did you get inside that switch-mode supply - I couldn't work out how to dis-assemble that part!Dave

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: July 14, 2017, 02:40:44 am
content: My 4600 came in at the end of last week and I plugged it in tonight. The initial indications are that it is operational. I used it in solo mode and the output agreed close enough to tell me it is not dead.Short of getting the service manual at the last minute, hi-res photos will be needed including test points. Afterwards, a measurement of the power supply and different test points might help guide everyone through finding the source of your problems.Perhaps a collection of photos from different units could show and minor revs to the hardware?

author: perdrix
author_rank: Frequent Contributor
timestamp: July 14, 2017, 05:24:39 am
content: Quote from: perdrix on July 11, 2017, 09:41:00 amIndications from Fluke Norwich are not sounding good, and without a highish level management contact to prod the system, I don't think the worker bees are going to look very hard.Dave

author: lukier
author_rank: Unknown
timestamp: July 14, 2017, 05:44:17 am
content: Quote from: perdrix on July 14, 2017, 12:51:43 amInteresting.Quote from: perdrix on July 14, 2017, 12:51:43 amFirst remove the power amplifier board, I keep the busbars with this board, so I unscrew the busbar from the switcher (don't loose metal pipe like stand-offs) and the precision board. Then disconnect the cables that connect the switcher to mains, transformer input-output and control (front panel board). This PSU is held to the frame with 4 screws.With the PSU out just unscrew every screw there, noting which goes where. Including the heatsink, ducting that directs part of the airflow to the PSU, side screws and the main ones holding the PCB. The side with the cables might have some aluminium tape (shielding), but should come out, releasing the cables and then the PSU internals can slide out of the case.In my case two screws on the bottom, holding the PCB, had striped heads - somebody must have been there beforeSo remember to use the correct phillips screwdriver, some of the screws might be seized with oxidation.So I had to drill through these screws (I'll need to add screw extractors to my shopping list). This is also one of these moments where having a small box with totally random fasteners, collected from various teardowns over the years, comes handyas I quickly found replacement screws.Picture of the switcher main PCB (and part of the control PCB that goes into vertical slot) attached.

author: lukier
author_rank: Unknown
timestamp: July 14, 2017, 05:54:03 am
content: Quote from: ManateeMafia on July 14, 2017, 02:40:44 amNext week when I'll be back I can create a high-res stitched photo of the precision board, number the dozens of the test points, and if you don't might we could share measurements. Let's assume the same conditions, output on, 1V on the input, solo mode. That could be very helpful.BTW How does your power amplifier output stage behave, under no load (0V input) or with the output off. Also running very hot? I still think maybe some of the bipolars went bad and short the rails, but because of the emitter ballast resistors (I guess that's their purpose) it doesn't blow fuses.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: July 14, 2017, 11:29:56 pm
content: The rear vent is blowing out a lot of heat even with the output off. It heats up almost immediately.I tested the overload by disconnecting one of the output cables while it was on and the Overload LED came on briefly before the output turned off.Could there be an internal shunt that is connected when the output is off? This would keep the overload led from turning on with the output off.

author: Testtech
author_rank: Regular Contributor
timestamp: July 18, 2017, 09:10:08 pm
content: The amplifier runs hot all the time, with or without an input or output. This is normal, and the rubber air baffling pieces are critical to be in the proper places! Also, special heatsink interface material was used on the amplifier power transistors.I have the complete 4600 service manual, and will upload to KO4BB' site.As for no output, mine did this. It was a failed signal MOSFET in the input signal attenuator/switch, essentially clamping the input.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 18, 2017, 09:53:59 pm
content: I hope to receive a full set of paper manuals soon. Once I've got all my stuff working, they will be scanned.Manuals include User, Reference, and Service for 4808, User and Service for 4600 (Option 60), User and Service for Option 70 (Wideband Source).As you can understand, this will take time, so please bear with me. I will liaise with Testtech over whose scan of the 4600 Service manual finally ends up on Didier's site (I have no axe to grind here, I just want to ensure we all get the best possible scan).CheersDave

author: lukier
author_rank: Unknown
timestamp: July 18, 2017, 10:24:33 pm
content: Quote from: Testtech on July 18, 2017, 09:10:08 pmI've noticed unusual "silpad" between the transistors and the heatsink. I wondered what that was.Quote from: Testtech on July 18, 2017, 09:10:08 pmQuote from: Testtech on July 18, 2017, 09:10:08 pmOne of these little TO-92 JFETs, J108 and J304, surrounding the input (front/rear) connectors?

author: Testtech
author_rank: Regular Contributor
timestamp: July 19, 2017, 05:08:17 pm
content: Lukier,It was Q402, shown on the Sense PCB Sht.4 schematic.

author: lukier
author_rank: Unknown
timestamp: July 19, 2017, 05:18:11 pm
content: Quote from: Testtech on July 19, 2017, 05:08:17 pmOK, I'll wait for the scans as the PCB doesn't have any designators

author: Testtech
author_rank: Regular Contributor
timestamp: July 21, 2017, 02:10:46 pm
content: I uploaded the file to KO4BB, but I don't know how long it takes for the file to be moved to the public area.

author: 2N3055
author_rank: Super Contributor
timestamp: July 21, 2017, 02:55:57 pm
content: Quote from: Testtech on July 21, 2017, 02:10:46 pmIt is ready for download... Thanks a lot!!

author: lukier
author_rank: Unknown
timestamp: July 21, 2017, 03:38:07 pm
content: Thanks Testtech!These manuals are a thing of beauty, from detailed theory of operation, via neat schematics down to the cable assembly drawings. They don't make them as they used to (or don't make them at all).

author: jfphp
author_rank: Regular Contributor
timestamp: July 21, 2017, 05:40:40 pm
content: Thank you very much !

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: July 21, 2017, 05:45:01 pm
content: Thanks for the upload.

author: Echo88
author_rank: Frequent Contributor
timestamp: July 21, 2017, 07:31:51 pm
content: It seems im too blind to find it.Can someone please provide a link?

author: alm
author_rank: Super Contributor
timestamp: July 21, 2017, 08:22:56 pm
content: It is in this folder:http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/Datron

author: perdrix
author_rank: Frequent Contributor
timestamp: July 21, 2017, 08:30:26 pm
content: I suspect it's been uploaded to ko4bb.com but not yet processed by Didier.Ping him an email asking it he can process it ...Dave

author: lukier
author_rank: Unknown
timestamp: July 23, 2017, 09:29:23 am
content: Quote from: Testtech on July 19, 2017, 05:08:17 pmSpot on! I decided that your hint would be the first place to start troubleshooting and yes, it was failed Q402 too.At a closer look I've noticed somebody already replaced this MOSFET (flux residue) and with 2N7000 instead of BS170 that is specified in the service manual (remember to flip the transistor around - different pinouts). Fortunately, I had some spare 2N7000 and the amplifier works now.Now need to calibrate that. For DC I can use the L&N 4385 shunts. For AC I don't have a thermal transfer standard, so Keithley 2001 will be the next best thing I guess.