Batboard

I have a R2001A. When I received this, there was a problem with the intensity and I could not adjust it. Everything else seemed to work properly. Per a post on this forum, I replaced the 87 volt zener and that cured the problem. Some time later (same day) I changed the function to the spectrum analyzer. Now I have no spectrum display. I see the letters/numbers across the top and can change frequency. With 10mc entered and antenna connected I can see in the lower left, what appears to be a vertical only display. A horz. amp problem?? I can hear WWV in the other modes. Also, I have no audio in this position. The letters/numbers across the top are jittery and not solid as on other functions. As a side note, in the scope mode, the line is very sharp on the left side and trails off and gets thinner the farther to the right it goes and fades out. The voltages seem to be good on the LVPS. I checked on pin 6 of the RF Synthesizer module and do have a 50 hz square wave. I don't know if I have caused a problem or not?? On the scope amp board A2 at TP1, the horz amp input of A2 board(scope amp) I have 1.0 vdc with a Fluke DVM. On my antique 453 Tek scope I have a sawtooth display of .5 v and some type of information on the vertical sides of the sawtooth. I don't know what that display should look like. At TP 6 and 7 (vertical deflection plate) with the 453 scope I see what looks like a spectrum display. I have decided that I have a switching problem in A3 scope/DVM control board?? Any and all suggestions are welcome.
Thanks
Lynn

Hello Lynn and welcome to the board. M name is Dave and I used to service the R2000 series for Motorola's test equipment depot. As for your spectrum analyzer problem, I think you are correct with your diagnosis, keep looking at the scope/dvm board. As for the rest of the problems, I think most of them will be eliminated by doing a basic alignment. I have a copy of the R2001A service manual on a CD (someplace). If you would like to borrow it send me a PM with your address and I'll send it to you. It's in a PDF file that you can then copy and keep. I'd email it but the file is too large.

Hi Dave, thanks for the quick reply. Yes, I would like to have a good copy of a "A" service manual. I will proceed by pulling scope/dvm board and look for problems there. I will send you a PM. Thanks again Dave.
Lynn

I had a similar trace "fading" problem on my R2001B. A touch-up of the Intensity Limit and Intensity Balance pots on the A2 card fixed it right up.

Unfortunately my unit is still suffering from almost unreadable (extremely dim) text but quite decent (bright and clear) swept traces. All controls work as they should and alignment hasn't helped this situation.

Bob M.

Hi Bob, thanks for the reply. I will check that. Can I get any voltage or scope measurements for you?? Wonder what the waveform looks like at the input to the A2 board (scope amp)?? I am not sure what I should see there?? Dave suggested looking at the A3 board but I have not got a chance to do that yet.
Thanks
Lynn kb5by

one of the things that plague CRT /high voltage boards of this vintage across a lot of equipment is the resistors aging and getting much higher in value throwing off the bias voltages.

Never really dug into why by it seems as most of the typical carbon film resistors age the value drift can be quite high. May be due to the material loosening up with age. Metal film or other types may not have these issues.

It's not the typical thing you look for when troubleshooting but now i routinely check the CRT bias resistors and usually end up replacing at least one in most cases.

Hi jry. I have been looking at the A3 board this evening. I see several of the 10mfd@35v filter caps are leaking although the ESR checks ok. I will order 15 from Mouser. Also many of the resistors are high in value so will replace those. I am over my head with this R2001A but maybe I can get lucky with the caps and resistors. At least I will know those are good. It looks like U12,51 and 59 handle the switching for the spectrum display. I am going to look to see if those are still available. I think while I am waiting for parts I will try to figure out why I am loosing the audio?? Don't know if that is related or a different issue?? I wish I knew what sort of scope display I should see at TP1(?) the input to A2 board from the A3
Thanks,
Lynn

Here are some rough readings I got a couple of months ago.

Basically, TP1 is about the same in both text and swept trace displays as it has to cause full left-to-right deflection, especially for part of the spectrum analyzer display. If you're getting text but not the spectrum sweep, something is holding off the sweep for the spectrum analyzer. It must obviously be synchronized with the frequency sweep so things appear in the right location. The A2 card merely amplifies what comes into it; if you aren't getting sweep in one mode, some other card is not generating it.

I was switching between the main monitor screen and the AC or DC scope screen, hence no vertical deflection in Scope mode.
Bob M.

kcbooboo wrote:I had a similar trace "fading" problem on my R2001B. A touch-up of the Intensity Limit and Intensity Balance pots on the A2 card fixed it right up.

Unfortunately my unit is still suffering from almost unreadable (extremely dim) text but quite decent (bright and clear) swept traces. All controls work as they should and alignment hasn't helped this situation.

Bob M.

This is USUALLY an indication of a CRT that is ending it's life, HOWEVER, the readability of the characters also depends on the CRT manufacturer. The Telefunken tubes had much clearer and brighter characters and focus control. The characters on the Magnivox tubes always appeared "muddy".

Lynn, just so you aren't chasing ghosts, there is no audio in the spectrum analyzer function in the R2000 series.

Hi Dave, Thanks for the info, I have not spent much time looking for the audio in the spectrum mode. But, I had just about come to that conclusion. I could not see any place they were detecting the audio from the spect vert. The block diagram does show Log amp and detector, but apparently not audio.

Hi Bob, thanks for the voltage and waveform chart. I still need to check the alignment. I will try to look at the voltage and waveforms this evening. Anxious to get this working properly. Thanks again fellows!!
Lynn

My tube is an AEG, which I believe is Telefunken. There's not a burnt spot on it and physically it looks like a brand new tube. The CRT traces are nice and bright and clear; it's just the text that can barely be seen. The Z-Axis signals are the same 0-30V square waves or pulsed regardless of text or swept trace modes. It's as if there's a huge capacitor hanging across the control grid to cathode that is acting as a low-pass filter and letting the scope square waves come through but rejecting the text intensity pulses. I wonder if CRT rejuvenation would help it at all?

Bob M.

Hi Bob, do you have a CRT tester?? I have a BK tester that used to work good on TV CRTs. I did get a chance to look at some voltages and waveforms. Noted differences as follows: TP2 text +12.6v vs -1.72, TP3 text -17.6 vs +5.45, TP7 text +5.0 vs -6.5 and in the swept mode TP6 +20. vs +8.55 and TP8 +32. vs +14.6. Also TP2 and 3, my waveforms are running 120 PP?? I have not looked at the schematic yet to see what may be or not be happening in the horz deflection circuits. Also I took some measurements in the spectrum mode At TP1 in the spectrum mode waveform is 4 vpp@1.6 khz, TP2 & TP3 120 vpp@1.6khz w/retrace lines. TP3 erratic on DVM, TP4 4.0 vpp square wave TP6&7 15 vpp sawtooth TP 9 20 mv sawtooth and TP10 6.0 vpp sawtooth. Thanks again
Lynn

Good morning Bob and Dave. I will try to send a attachment that is the scope display of the horz input (TP1) on the A2 board and pin 72 the output of A3 board. This is in the spectrum mode. In the if, scope DC and AC mode I have a saw tooth wave form. The waveform is pretty much the same in all three modes but different in the spectrum mode that I am having troubles with. Don't know if I can figure out how to post a pix but will try.
[img]/home/lynn/Pictures/20161031_220003.jpg[/img]

Thanks
Lynn

The values on the deflection plates really depend on where the trace is and what's being displayed on the screen. For example, I had already performed the (limited) alignment procedure on the unit and set the vertical position to dead center. I don't recall what the sweep speed was but there was no flickering, so it was fast enough for a solid straight line. There was no other equipment connected so no vertical deflection in either AC Scope or DC Scope modes, and I kept switching between that (lowest mode) and the normal modulation (highest mode) setting. As they always say, your mileage may vary.

The spectrum analyzer display is the only one that has text at the top and a swept scope trace at the bottom. All the others are either all text or all swept scope traces. Those sawtooth waveforms won't read correctly on anything but a scope, and I only had a 1X probe handy, and the scope only goes up to 20V/div and I had to uncalibrate the vernier too; that's why my deflection test point readings say >60V, so if they really are 120Vp-p, that seems fine.

I had also set the high voltage on the cathode to -2,100VDC which gave me around +4,200VDC on the 2nd anode.

I don't have a CRT tester but I would be interested in trying one that has a rejuvenation function in it.

If you're getting several sawtooth sweeps on the horizontal deflection plates in spectrum analyzer mode, then I suspect your intensity balance needs adjusting to get the left side dimmer so you can raise the overall intensity to see the trace.

Bob M.

Lynn,

This should make things easier.

http://www.repeater-builder.com/test-eq ... 9e84-o.pdf

Hi Dave, that is by far the best copy that I have seen. Thanks for taking the time to post it!!
Lynn

Hi Bob, You are exactly right!! I went through the basic alignment and my horz display is back!! In the spectrum display, the display is quite bright compared to the Character display. I can control that with the intensity control. That may still be an alignment issue?? Also the trace rotation pot does not have any effect.??. I did pull the CRT to pull the HV supply and later seen that was not needed. I did find the B&K. I do have the picture tube chart that was current in 1971 and the only 5" tube they show is a 5AXP4. I also have the schematic. Here is a link to the owners manual that I do not have. It is listed as a rejuvenator and in a past life I have used it as such. http://www.oldtubes.net/library/free_ma ... 1-Data.pdf It would be my pleasure to send it to you. As I recall, they used to sell a brightner for CRTs and I suppose it consisted of a transformer to increase the filament voltage??
Thanks again
Lynn

Good afternoon Dave and Bob, The trace rotation problem is cured. I did not have a good connection on J2, pin 1 which delivers the voltage to the coil on the neck of the CRT. I need to put the cage back on the LVPS and take some voltages for future reference. I think, I will still replace the 15, 10mfd @ 25 v caps on the A3 board as several were leaking and deformed on the bottom of the cap. Bob, let me know about B&K. Will keep you posted.

Thanks again
Lynn

Lynn: thanks for the offer, but hold on that for a while. I acquired an R2001D and will swap CRTs to see if that helps my R2001B brightness issue, and if so, I'll stick with the "D" tube, so I won't need to try to fix my CRT, although it looks brand new. If I hadn't acquired the "D" I'd take you up on the offer.

I have no idea what the tube number is either. The only sticker on it doesn't show any industry-standard part numbers so I'm at a loss to figure out what it really is. Shouldn't be a problem though as the rejuvenator should only need the filament, cathode, and control grid connections, and those can be made with alligator clips.

On my unit, someone had chopped the two wires coming from the trace rotation coil. I installed a 2-pin 0.068" Molex connector so I can easily disconnect it and get anything else out when required.

There's a guy on ebay selling extender boards and he made me a 100-pin and a 72-pin board with extended height so you can get to the entire board. They weren't inexpensive but I found I needed them to get to some of the adjustment pots, such as for the SINAD, which on my unit would read 15dB on its own pure sine wave. After adjustment it got to 40dB and I think that's as good as it could ever get.

You might end up replacing a LOT of capacitors, especially any that are leaking or deformed. Also the two power supplies could probably use it too. I wrote an article about doing this for the "B" and "C" as the "A" is quite different but it still could be done.

Bob M.

Very good Bob. I was surprised as the HVPS does not have any electrolytic caps in it. I did find two in the LVPS that the ESR was high and replaced those. I will use this for a while and see if all works well, I have a buddy who has a IFR 1200 as well as a R2660 (I think) and we can calibrate this one as needed. The IFR has been recently calibrated. I don't work on anything but ham and shortwave equipment so does not have to be perfect. Just curious what the "D"s are going for since the "A" is such an "odd ball"??
Lynn kb5by

Guys, you won't find a commercial # for the CRT as Motorola had it manufactured specifically for the R2000 series. No other piece of equipment uses that CRT. Also those "chopped" rotation coil wires you have, came from the factory on the "A", "B" and "C" series analyzers.

Good evening Dave, thanks for that info...I wonder if anyone has given any thought to having audio in spectrum display position. I do see a couple of 455kc filters on the receiver. I wonder if it would be possible to use a small disc cap and bring out the 455kc. Then amplify and detect the AM audio. Maybe using a regular AM radio to perform the duties??
Lynn

Does anyone have a RTL-4055A external in line wattmeter?? Thought it might be nice to have and play with. Maybe a schematic?? I am not sure what all will work on the R2001A.
Thanks,
Lynn

Lynn: I realize it's been a while, but things go slow here. My CRT is still quite dim. A friend had one in the same condition so he bought a rather used (and needing repair) Sencore CR70 CRT tester/rejuvenator. He ran his CRT on that and after a few rejuv cycles, he said it looks like a brand new tube. I was still quite hesitant to ship my CRT, and the cost of shipping his CR70 both ways was getting up there, so I ended up buying my own CR70 that was in excellent condition. I ran it through its field tests and everything seems to be OK. I'm just waiting to clear my bench so I can pull my CRT out and rejuvenate it. Don't hold your breath waiting for this to happen; might be another month the way things go.

Bob M.

Very good Bob M, My R2001A seems to still be working fine. When in the Spectrum display mode, my baseline is not at the bottom but up at the 100db rather than the 120db line. I thought at one time I had adjusted that, but now I can't find the instruction or pot. Do you remember if and how that is adjusted??
Thanks
Lynn

There are vertical and horizontal gain pots on the A2 card that control the overall CRT display. These are separate from the vertical and horizontal calibration pots that are on the A3 or front panel cards. Obviously noise coming through the RF section will raise the baseline. You might have to disconnect something to get the baseline to rest at the bottom of the screen.

There is a spectrum analyzer horizontal (frequency) "centering" adjustment on the front panel card but I don't recall a vertical one.

Also, the vertical deflection circuit on the A2 card could be defective, or the +/- 100V supplies that drive the deflection plates could be low. That's all that immediately comes to mind.

Bob M.

Good morning Bob M. I went though the basic alignment and all of that seemed to be ok. I did see the the horz. adj. and set that correctly. I thought if that was a simple adj. I would do so. I want to thank you again as well as the rest of the fellows for your help.
Lynn

LCB091 wrote:Does anyone have a RTL-4055A external in line wattmeter?? Thought it might be nice to have and play with. Maybe a schematic?? I am not sure what all will work on the R2001A.
Thanks,
Lynn

I think I actually have a couple of them, and likely only need one. Talk to me... In the meantime I'll check it out. Not sure if they have any elements in them though.

One more quick question. I know the CRT pins for filament, cathode, and control grid, but I'm not sure which is the correct pin or element to use as the second grid, or G2. The Sencore CR70 setup manual says pin 4 which is the Focus grid, but other research has indicated that the Focus, Geometry, and Astigmatism grids are further towards the front, and the Accelerator (pin 7) is the actual second grid. So I'd be interested to know which one you used to test and/or rejuvenate these CRTs.

It may be that it only matters for the emission/gain test and the rejuvenation function only uses the cathode and control grid.

Bob M.

I connected the CRT to the CR70 tester per the book, using pin 4 (focus) as G2. I got ZERO emission. I then tried it with pin 7 (accelerator) as G2; still zero emission. I went through the rejuvenate, auto restore, and both manual restore procedures. Still had zero emission using pin 4, but when I hooked it back to pin 7, lo and behold I had almost full scale on the emission test.

I put the CRT back into the R2001B and WHAT A DIFFERENCE. I can read everything. The tube is nice and bright and quite well focused. The intensity pot causes the brightness to increase throughout its entire range, getting brighter as I rotate it CW, just as expected. I made no other adjustments but it will now get a thorough alignment. The only issue I have is that the middle of the display is brighter than the top and bottom, especially in display modes that have lists of data. I can turn the brightness up to compensate but then it's way too bright for things like swept scope traces. But it's definitely usable now.

Bob M.

Does DPJ126 or Jry or anyone else know what type of RF connectors were used on the RF boards and motherboard? I'd like to make some RF extender cables so I can align the boards above the chassis. I already have 72-pin and 100-pin extender cards. They look like SMA without the threaded outer part or SMB or something inbetween. Any clues?

Bob M.

would try an SMB jumper.

I do have the R2001A extender kit ...will look to see what they had in there.

Thanks. It looks bigger than SMB but smaller than SMA. Also could be reverse-polarity.

I presume they used the same extender kit on the entire R2001 line, however it's not inconceivable that they used something else on the "D", where so much changed.

Bob M.

D series only used the PCB extender IIRC

Bernie found some letters on one connector. They appear to be Omni-Spectra "OMQ" series, which have not been made since the late 70s, early 80s. There may not be anything that will actually fit properly these days.

Bob M.