FOCUS THREAD: CDV-700 ENi brand HV Transformer info
A place to measure, Eni HV transformers and share that information.
It's?a FOCUS THREAD, so stay focused on this subject within this thread.
Geo
|
will do and I will report back..
and to make sure I check the correct wire pairs:? ?according to schematic,? ?pins 1 and 2 together;? pins 3 and 4 together;? and pins 5 and? 6 together.? ?correct??
|
?Michael C Can you measure the resistance of the 3 windings, and check each for a short to ground?? You may have to suck the solder out of the hole to get to the wires alone.
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Thursday, April 28, 2022 3:31:51 PM Subject: Re: [CDV700CLUB] Leni conversion #3
nope, wasn't that.? hardwired batteries to board no spring clips... no difference.? ?Replaced CR4 for grins, no difference.? ? Replaced all three transistors with new russians, no difference.? ?I suspect a bad transformer.? ?Not getting the expected voltage out.??
|
nope, wasn't that.? hardwired batteries to board no spring clips... no difference.? ?Replaced CR4 for grins, no difference.? ? Replaced all three transistors with new russians, no difference.? ?I suspect a bad transformer.? ?Not getting the expected voltage out.??
|
I wonder if crappy battery tray connections (there are 8 of them) are part of my problem.? ?I think I may hard wire to the board and use battery boxes while I am debugging to remove that as a variable.??
|
I've not ever had to replace that diode. Test it before jumping.
Battery tray, still with spring attachments, those are terrible when they are working right! that problem completely eliminated in the LENi upgrade and only 2 D cells used.
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Wednesday, April 27, 2022 6:03:29 PM Subject: Re: [CDV700CLUB] Leni conversion #3
it is hard to access anything with the ENI battery tray attached.? I was able to get a probe in on a couple of points and where I should measure 15 v I measure 7v.? ?ENI manual says if this measures low, replace rectifier CR4.?
|
it is hard to access anything with the ENI battery tray attached.? I was able to get a probe in on a couple of points and where I should measure 15 v I measure 7v.? ?ENI manual says if this measures low, replace rectifier CR4.?
|
PS this repair, when finished, will make a great repair story for GeigerCounterEnthusisatsGroup,? especially with you great pictures. My cameras are 20 and 27 year old technology.
George?
From: "geoelectronics at rallstech.net" <GEOelectronics@...> To: "CDV700CLUB" < [email protected]> Sent: Wednesday, April 27, 2022 5:27:18 PM Subject: Re: [CDV700CLUB] Leni conversion #3
All readers, I second what Perter said: "Even if 900V is not present, it might be intermittent, so exercise caution. It might appear while probing if there is a cold solder joint or a cracked trace ?"
Geo
From: "peter via groups.io" <epkoncept@...> To: "CDV700CLUB" < [email protected]> Sent: Wednesday, April 27, 2022 4:43:34 PM Subject: Re: [CDV700CLUB] Leni conversion #3 In the manual, the schematic pages usually show the nominal voltages. Perhaps, after the visual check you can probe the board for voltages.
If -15V is not there, that's a hint. osc tr, or transformer is dead ?
Even if 900V is not present, it might be intermittent, so exercise caution. It might appear while probing if there is a cold solder joint or a cracked trace ?
Do you have any liquid flux ? I find that the easiest way to fix cold solder joints is to reheat the joint after applying flux. If you don't have flux, just add a little solder to each joint as you touch them up.
P
|
All readers, I second what Perter said: "Even if 900V is not present, it might be intermittent, so exercise caution. It might appear while probing if there is a cold solder joint or a cracked trace ?"
Geo
From: "peter via groups.io" <epkoncept@...> To: "CDV700CLUB" < [email protected]> Sent: Wednesday, April 27, 2022 4:43:34 PM Subject: Re: [CDV700CLUB] Leni conversion #3
In the manual, the schematic pages usually show the nominal voltages. Perhaps, after the visual check you can probe the board for voltages.
If -15V is not there, that's a hint. osc tr, or transformer is dead ?
Even if 900V is not present, it might be intermittent, so exercise caution. It might appear while probing if there is a cold solder joint or a cracked trace ?
Do you have any liquid flux ? I find that the easiest way to fix cold solder joints is to reheat the joint after applying flux. If you don't have flux, just add a little solder to each joint as you touch them up.
P
|
In the manual, the schematic pages usually show the nominal voltages. Perhaps, after the visual check you can probe the board for voltages.
If -15V is not there, that's a hint. osc tr, or transformer is dead ?
Even if 900V is not present, it might be intermittent, so exercise caution. It might appear while probing if there is a cold solder joint or a cracked trace ?
Do you have any liquid flux ? I find that the easiest way to fix cold solder joints is to reheat the joint after applying flux. If you don't have flux, just add a little solder to each joint as you touch them up.
P
|
OK, Michael C., yes what you did are the logical first steps. Next, check the -15.5V test point it's located at the end of one of those electrolytic and is featured in the manual on the schematic there. If that is NOT there, then the transformer or the HV transistor are suspected as being the fault.
I'm not in front of a manual but can print one out if needed to help. ENi CDV-700 is POSITIVE ground, all transistor circuits were in the beginning because we only had PNP transistors at first. So expect the operationg Voltages to be NEGATIVE with respect to ground. Might be confusing for newcomers to these vintage circuits.
When old-timers like me got into electronics, we had no idea where solid-state would lead to after all these years. We knew no silicon transistors, or diodes yet, certainly nothing solid state was high power at all and severely limited in frequency, usually audio, then i.f. then eventually 1Mc/s (Megacycle/s)*..
Attached is a link to charts to covert Megacycles/s? to MHz for the younger readers. Used the LINEAR chart if you are a beginner, or the LOG chart if your are more proficient with math.
Geo
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Wednesday, April 27, 2022 3:36:02 PM Subject: Re: [CDV700CLUB] Leni conversion #3
I haven't started converting yet.. still checking out the original unit to see if worth pursuing.??
checked the board for cracks. didn't see any.? the traces are good.??
I am not getting 900V to the probe.??
and on second thought,? I guess I can't hear a hum from the transformer.? Not like my other ENI/Leni's you can hear them clearly.??
so, turn it on,? the needle moves to position on the dial and sits there. you can move it with the calibration knob.? ?no sound.? ?X10 it moves to about 2 mR/hr;? X1 full scale right;? X100 sits where X10 sits.? ?
Replaced the HV diode and the 2 electrolytic caps.? no effect.? ?
|
I haven't started converting yet.. still checking out the original unit to see if worth pursuing.??
checked the board for cracks. didn't see any.? the traces are good.??
I am not getting 900V to the probe.??
and on second thought,? I guess I can't hear a hum from the transformer.? Not like my other ENI/Leni's you can hear them clearly.??
so, turn it on,? the needle moves to position on the dial and sits there. you can move it with the calibration knob.? ?no sound.? ?X10 it moves to about 2 mR/hr;? X1 full scale right;? X100 sits where X10 sits.? ?
Replaced the HV diode and the 2 electrolytic caps.? no effect.? ?
|
thanks for the tips and help.? ?and I found an outfit in England that sells CDV 700 parts.? I got a new ENI rotary switch and Mod-A from them. I bought them for the spares kit, maybe i will put them to use.??
|
Good, drop by anytime. I've seen several different transformers, all original and from many different manufacturers, the groddy looking ones are the best, the nice new looking ones with no gunk have super fine wires exposed and those ALWAYS break. If a transformer is bad, 1) it won't sing, 2) you can hear it arc inside, sounds like a hiss, or 3) the secondary HV side winding already burned open from arcing. Much more likely a transistor got zapped, remember when changing the 2 metering transistors, change them both at once. We've all chased our tails putting just the tested bad one in, just to have the other one pop instantly.
Definitely figure on the 2 electrolytic capacitors and the HV diode need swapped out for new.
Besides visual, you can follow the traces from end to end with an Ohmmeter, those thin ones that run a longs way are susceptible to breaking or pitting, easy to find by checking end-to-end resistance.
Of all the ENi's I've personally refurbished with the LENi mods, we got a good 80% of them back just like new. The other 20% we scrapped for spare parts etc.With enough board swapping, case parts swapping probably could have gotten 1/2 of those going too, but it worked out in the end.
The ENi in particular is a really good mechanical platform to put some work into, once updated, it might go another 50 years.
Even those nasty looking range switches, which must be silvered, can be completely stripped and polished, works like new and looks like jewelry, guessing the gunk is some kind? ?of buildup from the chemicals we still smell in there out-gass, and the oil they used on the O-ring on the switch shaft to make it waterproof. Super well built.
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Tuesday, April 26, 2022 9:38:00 PM Subject: Re: [CDV700CLUB] Leni conversion #3
yes, the hex head screw and star washer are tight.? ?where the coax probe cable solders to the board by R12, the cable shield is grounded to the chassis mounting post right there at the screw down also.? ??
will do the bright light inspection.? ?since these are single sided boards, I can bridge broken traces with solder - actually glad these aren't multilayered and plated through hole.? ?
I don't smell anything too odd - has that typical 1960s (my birth year) CDV 700 smell..? ?my wife says I have a smell too.? ? the transformer looks grody -? like somebody shellaced it, or, it boiled over.? ?
will also check the HV the proper way.? see what I get.??
Michael
|
yes, the hex head screw and star washer are tight.? ?where the coax probe cable solders to the board by R12, the cable shield is grounded to the chassis mounting post right there at the screw down also.? ??
will do the bright light inspection.? ?since these are single sided boards, I can bridge broken traces with solder - actually glad these aren't multilayered and plated through hole.? ?
I don't smell anything too odd - has that typical 1960s (my birth year) CDV 700 smell..? ?my wife says I have a smell too.? ? the transformer looks grody -? like somebody shellaced it, or, it boiled over.? ?
will also check the HV the proper way.? see what I get.??
Michael
|
WAIT!
I forgot first step-- important. There is a 1/4" hex head going through the PCB near the transformer, that one screw is the only one that grounds the PCB to the case. If that is not there, it won't work. Also check PCB VERY closely around that screw, because of the weight of the transformer that large conductor trace that the transformer is soldered to can crack, separating the ground connector from the back of the PCB to the front of the PCB where the meter is.
Next step after all this is change the HV diode and the two electrolytic capacitors.
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Tuesday, April 26, 2022 7:06:23 PM Subject: Re: [CDV700CLUB] Leni conversion #3
got around to pulling the ENI I got off epay out of the box and checking it out.? A problem child - but it is an ENI.? Could use suggestions from the smart people in the room -? the ENI turns on but doesn't do anything. Turn it X10, the needle goes right to about 2 mR/s and sits there.? Turn it to X1, it goes full right.? You can move the needle around with the calibration knob on the ceramic component module (MOD A).? There is no sound. No clicky.? and no response to the check source. You just turn it on and the needle moves to position depending on the range setting.? ?From what I can tell, this ENI seems original - no evidence of any previous soldering.? ?
I suppose I should start with the basic checks outlined in the manual.??
|
Good Michael, you are equipped!
Every trouble shooting experience always starts with a smell (sniff)n test and a really good visual looking over under bright lighting, in that order. We'll walk you through it. Like P. said, check all the components for looseness etc.
if nothing smells or looks bad, next step would be turn it on, check for high voltage with an HVM like you have or just a regular VOM set on 500 or 1000V. It will read 300-400V if there is HV at 900V. No good for calibrating but just a rough (very rough indicator).
Do you have a neon bulb like Ne2 or a neon bulb ac socket tester?
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Tuesday, April 26, 2022 7:25:37 PM Subject: Re: [CDV700CLUB] Leni conversion #3
I have a high voltage meter I bought from you.? I have the pulse calibrator I bought from you.? I have a standard volt meter.? I have no electrical background (chem E) but can solder and read.? ?
Good idea to check the circuit board - will do that!?
Yes, I can hear humming through the case when I turn it on.??
Michael
|
I have a high voltage meter I bought from you.? I have the pulse calibrator I bought from you.? I have a standard volt meter.? I have no electrical background (chem E) but can solder and read.? ?
Good idea to check the circuit board - will do that!?
Yes, I can hear humming through the case when I turn it on.??
Michael
|
Michael C
Can you hear the HV singing?
Tell me about any electronics test meters etc. you have access to....
Turn it off and examine the PCB under a strong light, even a minute crack can interrupt a circuit trace, a very common problem! We'll give next steps to test when you reply..
Geo
From: "Michael C" <mtcooper01@...> To: "CDV700CLUB" < [email protected]> Sent: Tuesday, April 26, 2022 7:06:23 PM Subject: Re: [CDV700CLUB] Leni conversion #3
got around to pulling the ENI I got off epay out of the box and checking it out.? A problem child - but it is an ENI.? Could use suggestions from the smart people in the room -? the ENI turns on but doesn't do anything. Turn it X10, the needle goes right to about 2 mR/s and sits there.? Turn it to X1, it goes full right.? You can move the needle around with the calibration knob on the ceramic component module (MOD A).? There is no sound. No clicky.? and no response to the check source. You just turn it on and the needle moves to position depending on the range setting.? ?From what I can tell, this ENI seems original - no evidence of any previous soldering.? ?
I suppose I should start with the basic checks outlined in the manual.??
|
well,I would start by looking at anything that has a DC path to the meter. Check the diodes and transistors that are connected to the meter.
P
|
Michael C