AM-FM Zenith Y832

3/4/2008 2:43:04 PMSteve

:Hi Mark,
: I had a similar problem here. It was an IF with silver mica. The problem only affected AM, though.
: Yours sounds like it is in the audio section. If you haven't dug into the audio section, suspect the capacitors on the input of the audio transformer.
: I also notice that you said that you replaced the electrolytics. Have you done all the paper capacitors, too?
:
: By the way, AES sells schematics. They have yours, I am sure.
:Best Regards,
:
:Bill Grimm
:
:Mark,

Check the speaker, it might be bad. Swap it with another one to compare.

Steve

3/4/2008 2:44:35 PMSteve

::Hi Mark,
:: I had a similar problem here. It was an IF with silver mica. The problem only affected AM, though.
:: Yours sounds like it is in the audio section. If you haven't dug into the audio section, suspect the capacitors on the input of the audio transformer.
:: I also notice that you said that you replaced the electrolytics. Have you done all the paper capacitors, too?
::
:: By the way, AES sells schematics. They have yours, I am sure.
::Best Regards,
::
::Bill Grimm
::
::Mark,
:
:Check the speaker, it might be bad. Swap it with another one to compare.
:
:Steve
Strike that. DUH. I went back and reread your post.

Nevermind
Steve

3/4/2008 2:46:07 PMsteve

:::Hi Mark,
::: I had a similar problem here. It was an IF with silver mica. The problem only affected AM, though.
::: Yours sounds like it is in the audio section. If you haven't dug into the audio section, suspect the capacitors on the input of the audio transformer.
::: I also notice that you said that you replaced the electrolytics. Have you done all the paper capacitors, too?
:::
::: By the way, AES sells schematics. They have yours, I am sure.
:::Best Regards,
:::
:::Bill Grimm
:::
:::Mark,
::
::Check the speaker, it might be bad. Swap it with another one to compare.
::
::Steve
:Strike that. DUH. I went back and reread your post.
:
:Nevermind
:Steve

3/4/2008 2:46:07 PMsteve

3/4/2008 2:52:49 PMSteve

::::Hi Mark,
:::: I had a similar problem here. It was an IF with silver mica. The problem only affected AM, though.
:::: Yours sounds like it is in the audio section. If you haven't dug into the audio section, suspect the capacitors on the input of the audio transformer.
:::: I also notice that you said that you replaced the electrolytics. Have you done all the paper capacitors, too?
::::
:::: By the way, AES sells schematics. They have yours, I am sure.
::::Best Regards,
::::
::::Bill Grimm
::::
::::Mark,
:::
:::Check the speaker, it might be bad. Swap it with another one to compare.
:::
:::Steve
::Strike that. DUH. I went back and reread your post.
::
::Nevermind
::Steve

Mark,
I'm back and gathered my thoughts. Yes I'm in a closed room with solvents. But I digress, sometimes these old units i.e.hifis' need a proper impedance matched speaker. I don't have acess to your schematics but impedance matching I've learned is uber important

3/4/2008 8:18:40 PMMmakazoo

Bill and Steve: I agree, it seems that the audio stage would be the place to concentrate. I will try to spend some time on this over the weekend. Yes, I have replaced all paper caps. Now I am wondering about the flat, round caps (ceramic?). How well do those hold up? Do folks typically replace those like they would the paper ones? I will test them, at any rate. Also, there appear to be several resistor/capacitor combinations. How does one test these? Lastly, I do have a schematic that I ordered from AES. I mentioned that this site doesn't have one for my set in case folks weren't responding to my posting because they weren't sure what radio I had. Thanks for your help. Mark from Kalamazoo

3/4/2008 8:42:16 PMBill G.

:Bill and Steve: I agree, it seems that the audio stage would be the place to concentrate. I will try to spend some time on this over the weekend. Yes, I have replaced all paper caps. Now I am wondering about the flat, round caps (ceramic?). How well do those hold up? Do folks typically replace those like they would the paper ones? I will test them, at any rate. Also, there appear to be several resistor/capacitor combinations. How does one test these? Lastly, I do have a schematic that I ordered from AES. I mentioned that this site doesn't have one for my set in case folks weren't responding to my posting because they weren't sure what radio I had. Thanks for your help. Mark from Kalamazoo

Hi Mark,
Sometimes flat capacitors that look like silver mica are really paper wax in a delux case. I tend to go by appearance and value. If it is flat and round, it is silver mica and I leave it alone. Your radio probably has a lot of them. If it is tubular, looks like a large rectangular silver mica, or black with stipes, it goes. These will typically have values between 0.001 uF and 0.5 uF.
The first capacitor to replace if it is not silver mica goes between the plate of the 19T8 triode and the grid of the 35C5. Second are any capacitors conenctec to teh output transformer. Third is the one connected to the center tap of the volume control. These are all in the audio section.

Best Regards,

Bill Grimm

3/5/2008 12:27:25 PMEdd

Heh..heh…heh…I think that this schematic is certainly close enough to work with, on that set of yours…. if not exactly the same.
For the audio, be sure that the 470 k that I marked up has not drifted up appreciably in value. As well as the electrolytic caps that are associated with the output stage and its B+ bypassing . Possibly, a gassy AF output tube could be involved. After a chassis photo examination, I certainly believe that your coupling capacitors feeding into the AF output tube 1st grid, as well as the vol-you-me control are the round tubular paper type capacitors and not the trouble free, flat disc ceramic units with the Zenith yellow markings upon them. Those last units seem to be decidedly reserved for RF decoupling use in Zenith sets.

Sooooo check out those two caps by leaving the B+ side connected and take the grid side connecting wire out of circuit and then power up and temporarily ground that lead and then DC monitor it to then confirm that there is nothing more than the typical couple decades of millivolts of leakage of a premium capacitor.

For a more exacting audio evaluation…pump one channel of a CD / DVD players audio into the phono input, or tie into the top of the vol-you-me control, should it not have the phono input as shown on the back, but with this being the deluxe version, I think that it will.

Working Schematic:

73's de Edd

3/8/2008 8:35:30 PMMmakazoo

Edd: I checked that 470k resistor and it had gone way up to about 600k. So, I replaced it. No change in the problem. I did find that resister (R29) 4.7meg ohm was open and replaced with 5meg ohm. This decreased the problem a little and improved the high frequencies a lot. All paper caps have been replaced. All the rest in the AF stage are flat disc type. Values are way too high to test. Do you just check for leakage and assume they are okay? I don't have any that small to swap out for testing. Mark from Kalamazoo
:
:

:
:
:
:Heh..heh…heh…I think that this schematic is certainly close enough to work with, on that set of yours…. if not exactly the same.
:For the audio, be sure that the 470 k that I marked up has not drifted up appreciably in value. As well as the electrolytic caps that are associated with the output stage and its B+ bypassing . Possibly, a gassy AF output tube could be involved. After a chassis photo examination, I certainly believe that your coupling capacitors feeding into the AF output tube 1st grid, as well as the vol-you-me control are the round tubular paper type capacitors and not the trouble free, flat disc ceramic units with the Zenith yellow markings upon them. Those last units seem to be decidedly reserved for RF decoupling use in Zenith sets.
:
:
:Sooooo check out those two caps by leaving the B+ side connected and take the grid side connecting wire out of circuit and then power up and temporarily ground that lead and then DC monitor it to then confirm that there is nothing more than the typical couple decades of millivolts of leakage of a premium capacitor.
:
:
:For a more exacting audio evaluation…pump one channel of a CD / DVD players audio into the phono input, or tie into the top of the vol-you-me control, should it not have the phono input as shown on the back, but with this being the deluxe version, I think that it will.
:
:
:Working Schematic:
:
:
:

:
:
:73's de Edd
:

:
:
:
:

3/10/2008 3:13:46 PMEdd

As I had previously mentioned,I really think the next logical step now would be to really give the units two audio portions a real shake down by the utilization of the mentioned CD or DVD audio sourcing into the unit , and see if it also sounds squirrelly.

That thought of the audio sent me looking back to your work on your Zee-nuts T825…which I have yet to find my spiral notebook on its info, but I have added onto its post for you to give me additional info.

73's de Edd

:Edd: I checked that 470k resistor and it had gone way up to about 600k. So, I replaced it. No change in the problem. I did find that resister (R29) 4.7meg ohm was open and replaced with 5meg ohm. This decreased the problem a little and improved the high frequencies a lot. All paper caps have been replaced. All the rest in the AF stage are flat disc type. Values are way too high to test. Do you just check for leakage and assume they are okay? I don't have any that small to swap out for testing. Mark from Kalamazoo
::

3/10/2008 7:41:14 PMMmakazoo

Edd: That's a different Mark with the T825! :) I will do the test you suggest and report back with the results. Mark from Kalamazoo

3/22/2008 2:26:15 PMMmakazoo

Edd: I got side tracked, but had some time today to perform the test you suggested. I fed in audio to the phono input. Here's what I found: Strong hum, but the audio did play (though the audio was not as loud as radio station) and the annoying distortion was still there. So, I have replaced all paper caps, electrolytics, out-of-tolerance resisters, swapped tubes, and tested with another speaker. Where should I look next? Mark from Kalamazoo.

3/10/2008 4:22:38 PMBill G.

Hi Mark,
Edd's suggestions are good. It may be easier to wire in a known good speaker for a test. If you have a known good speaker you can use it to test the speaker in the set. The speaker should be 4 ohm. Disconnect the one in there and connect the test speaker to the output transformer. You will only need to dicinnect one conneciton between speaker and transformer.

Best Regards,

Bill Grimm

3/10/2008 7:44:51 PMMmakazoo

Bill: I already tried another speaker and had the same results. I was thinking of another way to describe the distortion that maybe would give folks a better idea of what it sounds like. Just the deep bass notes are distorted. It's a lot like when you pull up next to a teenager at a stop light and all you can hear from his car are the deep rattles from his subwoofer! I will perform the test Edd suggested later this week - I'm taking a couple days off work for a little R & R. Mark from Kalamazoo

3/24/2008 11:31:29 AMEdd

In all probability, the small hum that you did pick up via the injection of Audio / music into the phono input was attributable to its experiencing a slight degree of a ground loop in the incoming signal between their interconnects.

My next question would be the status of the main electrolytic filters of that unit, as the first thing that usually happens on power supply degradation via the degree of decoupling provided by those components is a slight modulation of the bass response of the Audio section, before the readily apparent HUMMMMM…chum …..gradually fully onsets.

If you were unsuccessful in the troubleshooting via the parts subbing and testing that you have done to date, let’s go at it via a different mode.

That would be the utilization of an amplified speaker system that you might already be utilizing on your current computer system, or can borrow one from a source long enough on enact your testing.

The design of the desired unit would consist of a speaker housing with its internally contained stereo power amplifier , along with a feed to an adjunct slave speaker which is hard wire connected and is receiving its AF power from the main unit just mentioned.

Now the good part, they typically are powered from an wall mounted AC wall wart, so that goes a long ways toward knocking that interconnect possibility of ground induced hummmmm.

Additionally, the AF sensitivity of the input is geared towards the ~500mv- 1VAC output level of an audio card. You additionally should find your self having the capability of adjusting the volume via a case mounted volume control…bass and treble also, on the step up versions.

Plus+s+s+s+s…those heavy magnet , deep throw / excursion speakers, along with the tuned baffling found in those units ….give quite a sound experience for their small sizing…..JB Lansing comes to mind.

Just use one main unit, as the slave will not be needed and you connect a shielded line to the input plug that feeds that channel in the main unit and have the other end of the shielded wire be the point where you can sample the AF from the Zenith.

If that end happens to have an RCA plug at its end, you could solder tack a short leaded ~.05--.1 ufd “paper” cap onto its center conductor for the DC isolated AF sampling input and use a test lead clipped onto its ground shell to make the companion ground connection to the Zenith in the AF area.

Initially just connect up the ground interconnect and power up both units and up the volume on the amplified speaker to its max and confirm no hum being present with no signal input as of yet. Reverse the AC power plug possibilities to find the least hum IF any was even heard.

Start your initial probe of the AF at its derivation point at the FM detector section and walk on up the AF amplification chain....1st grid to plate....and aurally evaluating each point to see where the problem onset is.

Standing by…..

73's de Edd

4/29/2008 5:08:50 PMMark Johansson

Hi Mark from Kalamazoo, this is Mark from Sunnyvale (CA),

I was wondering if you had any luck tracking down the distortion in your Zenith. I have a T825 that is having the exact same problem with the distorted bass. Our radios look to be the same schematic/tube layout except mine doesn't have the 2 tweeters. When I set the tone control to about the middle it really overdrives the bass.

Thanks,

Mark

:Bill: I already tried another speaker and had the same results. I was thinking of another way to describe the distortion that maybe would give folks a better idea of what it sounds like. Just the deep bass notes are distorted. It's a lot like when you pull up next to a teenager at a stop light and all you can hear from his car are the deep rattles from his subwoofer! I will perform the test Edd suggested later this week - I'm taking a couple days off work for a little R & R. Mark from Kalamazoo

4/29/2008 9:19:09 PMMmakazoo

Hello, Mark from CA: No, I have not tracked down the problem and have set it aside for a while hoping that the inspiration to try again will return. However, I did note a few other observations. If I set my signal generator to an unmodulated frequency in the FM range and turn up the volume on the radio, it starts to oscillate. I haven't tracked down what part might be causing this (swapped out tubes one by one with no luck). I assume that it should not do this because it is part of the alignment procedure described in the sam's info I have on the radio. Makes me wonder if my distortion is caused by feedback, possibly due to vibration from the deeper bass notes. Maybe someone on this forum can tell me how far off I am in my thinking! At any rate, I can't seem to replicate it by tapping on tubes, coils, and other parts of the radio, so I could be wrong. Mark from Kalamazoo

4/30/2008 10:26:13 AMBill G.

Hi Mark from Kalamazoo, and Mark from Sunnyvale,

Seems I sense interest in getting the 832 and 825 in shape. Your chances are better now that there are two looking for the problem.
I have gone over the postings. All the paper wax and electrolytic capacitors have been replaced. The speaker has been checked on the radio from Kalamazoo, but not Sunnyvale.
I think it may be time to look at the silver mica disk capacitors. Only in the audio section, though. As I mentioned before, these rarely are a problem, but they are 50 years old. A failure of one of these has to be considered. Start with the capacitors around that open 4.7meg resistor that was replaced.

We had an interesting posting a few days ago. Someone had distortion on a 1950's radio. He had swapped out the 50C5 with two others he had. there was no difference. Despite this some of the guys kept coming back to the audio output tube as the problem. The person happened to find an NOS 50C5 in his attic stash, and low and behold that cleared the problem. He had three bad 50C5s, all of which tested good on the tube tester.
The thing that made the difference is that in his case the audio started good, but then deteriorated as the set warmed up. I didn't see this mentioned about these sets.

Best Regards,

Bill Grimm

4/30/2008 5:34:41 PMMmakazoo

Bill: Yes, I am encouraged that someone else is experiencing a similar problem and that this might generate more interest in solving the problem. It will likely be a month before I get the time to sit down and work on this again,but I will take your suggestions. Edd had a good idea about how to check out the audio section, but I don't know if my skills up to that level. As a side note, one of my weekends will be spent traveling back home for the memorial funeral for my uncle, Raymond Kaiser, who was a radio and tv repairman of incredible talent. He gave me his signal generator the last time I saw him and I will treasure this. I was in awe of him as a child due to his ability to diagnose and solve any electronics problem. I bet he would have had my Zenith solved in no time. Mark from Kalamazoo

4/30/2008 7:12:17 PMRobert Blakeley

:Bill: Yes, I am encouraged that someone else is experiencing a similar problem and that this might generate more interest in solving the problem. It will likely be a month before I get the time to sit down and work on this again,but I will take your suggestions. Edd had a good idea about how to check out the audio section, but I don't know if my skills up to that level. As a side note, one of my weekends will be spent traveling back home for the memorial funeral for my uncle, Raymond Kaiser, who was a radio and tv repairman of incredible talent. He gave me his signal generator the last time I saw him and I will treasure this. I was in awe of him as a child due to his ability to diagnose and solve any electronics problem. I bet he would have had my Zenith solved in no time. Mark from Kalamazoo

Fixed one of these today.After recapped it had the exact symptoms you describe. It was C 37 on Edd's Schematic.

5/1/2008 2:28:44 PMMArk Johansson

I've replaced all the paper caps in the radio & micas in the audio stages, tried a 35C5 from a known good radio & the 19T8 disc/1st audio with a NOS tube. Hooked up my ipod @ the phono input to eliminate RF/IF. discriminator stages. still getting distorted bass. Have not tried another speaker or the electrolytics, though I have replacements, will probably try those this weekend.

Mark in CA

:Fixed one of these today.After recapped it had the exact symptoms you describe. It was C 37 on Edd's Schematic.

5/1/2008 4:37:09 PMBill G.

:Fixed one of these today.After recapped it had the exact symptoms you describe. It was C 37 on Edd's Schematic.

Hi Robert,
Was C37 a paper wax capacitor or silver Mica? If it is Silver Mica, the guys are missing it.

Best Regards,

Bill Grimm

5/1/2008 5:53:59 PMEdd

In the cases I have run into on that problem, one potential problem tends to be the 470K plate resistor drifting on up into the meg range.( Its brother …R33 in the grid circuit of the ‘C5 output tube is not above reproach also).
A units audio seems to be loosing its punch and sounding a bit mushy on higher volume demands.

Of course the ‘C5 output tube having a gassy condition or the onset of grid emission would be categorized in a like effect.

I was experiencing some neural memory synapses on the coupling capacitors type but the supplied referencing shows cap C-37 (yellow), to be a disc ceramic capacitor unit, with its typical conformal coating along with the 22-xx white-grey or yellow symbolization of a Zenith capacitor….having been placed upon it.

Those disc ceramics usually are very leakage free…..but ceramic substrate contaminants could prove different with time passage.

The referencing shows two other caps nearby of the “paper” category…C-36 and C-35 (magentas), as well as the similar construction on the Zenith special C-32 (orange) low level audio coupling capacitor, but, with its external peripheral shielding.

If that was my unit to evaluate, I would be snipping the C-37 cap right at its furtherest end that is NOT making connection to the AF plate circuitry…Why snip ?.....because latent heat from a soldering iron heat oftimes has some mysterious and curative and healing effects upon components. NOT a condition that you would want to occur BEFORE you had evaluated a component.

Then I would hook up a digital or VTVM to that lead with clip leads such that the metering negative lead goes to ground and the
positive metering lead gets clipped onto the free lead of the capacitor. The set is then turned an and placed off station and then a jumper lead is run from ground to the meter positive lead to let the cap take on its initial charge, almost instantly. Then after the jumper is removed you watch the metering to see if any DC leakage comes thru. I expect no more than low decade ranges of millivolts of leakage. If that unit starts rising up to the 100-200-500-1000 mv of leakage. RE-place it.

"Unner" 'da hood referencing:

73's de Edd

5/1/2008 9:50:03 PMRobert Blakeley(61925:61908)

::Fixed one of these today.After recapped it had the exact symptoms you describe. It was C 37 on Edd's Schematic.
:
:Hi Robert,
: Was C37 a paper wax capacitor or silver Mica? If it is Silver Mica, the guys are missing it.
:
:Best Regards,
:
:Bill Grimm
Bill: My set had a "square box" type like an old mica mold cap. I think times a wastin', just replace the darn thing! All else seems to have been tried. I would first look however, at the DC voltage on the 35C5 grid. If it is 20% or more positive, the cap is likey leaky. We often tend to think that ceramic and mica caps don't fail. But they do. Just not as often as paper dielectrics.
Have a great day!
Robert Blakeley

5/1/2008 9:56:54 PMRobert Blakeley(61926:61925)

:::Fixed one of these today.After recapped it had the exact symptoms you describe. It was C 37 on Edd's Schematic.
::
::Hi Robert,
:: Was C37 a paper wax capacitor or silver Mica? If it is Silver Mica, the guys are missing it.
::
::Best Regards,
::
::Bill Grimm
:
:
:
:Bill: My set had a "square box" type like an old mica mold cap. I think times a wastin', just replace the darn thing! All else seems to have been tried. I would first look however, at the DC voltage on the 35C5 grid. If it is 20% or more positive, the cap is likey leaky. We often tend to think that ceramic and mica caps don't fail. But they do. Just not as often as paper dielectrics.
:Have a great day!
:Robert Blakeley

BTW: Just figured out our friend "A Valid Name". As I entered my reply, I forgot to but my name in the box. When I submitted my follow up, I got an error message which said: must enter a valid name. Maybe I am a little slower than the rest of you guys but just give me a little time...and I'll catch on!

5/2/2008 8:16:15 AMBill G.(61935:61925)

Hi Robert,
Thanks to Edd. He always has the good information and presents it well.
Best Regards,
Bill

6/7/2008 4:52:47 PMMmakazoo(62884:61935)

Well, I finally got some time to look into this. I replace the capacitor C37 with an orange drop rated at .022mf. The radio played for just a short while and then went dead. While it played, the distortion was still there. Put the old cap back in and radio works again, but with the same distortion. I have a question: the Sam's photofact schematic and part list I have says that the capacities given are in mf for paper caps and mmfd for ceramic caps. That doesn't seem possible to me that it would be .022mmfd. Am I reading this wrong? The C37 capacitor in my radio is the round disc type, not a paper. It has a zenith number of 22-16 on one side and 0022 on the other. I want to make sure that I am using the correct cap. Can someone help me make sense of this? The old cap checks out at .001 on my capacitor checker. Mark from Kalamazoo

6/9/2008 10:22:34 AMBill G.(62955:62884)

:Well, I finally got some time to look into this. I replace the capacitor C37 with an orange drop rated at .022mf. The radio played for just a short while and then went dead. While it played, the distortion was still there. Put the old cap back in and radio works again, but with the same distortion. I have a question: the Sam's photofact schematic and part list I have says that the capacities given are in mf for paper caps and mmfd for ceramic caps. That doesn't seem possible to me that it would be .022mmfd. Am I reading this wrong? The C37 capacitor in my radio is the round disc type, not a paper. It has a zenith number of 22-16 on one side and 0022 on the other. I want to make sure that I am using the correct cap. Can someone help me make sense of this? The old cap checks out at .001 on my capacitor checker. Mark from Kalamazoo
Hi Mark,
There is no such thing as a dliberate 0.022mmf capacitor. They happen all the time by accident when wires come close to each other. The capacitor's real value is 0.022mf.
I think you have proven that the capacitor is not the problem, however, it indicates that you are close. Cosider the possibility of a bad tube socket. I used to say that I have encountered more bad tube sockets than bad tubes. I then got the radio with 5 bad tubes, and that went away, but nevertheless, I have noticed that the 9 pin sokets tend to be among the least reliable in vintage radio.
Best Regards,
Bill Grimm

6/9/2008 7:46:32 PMEdd(62978:62955)

Sir Mark:

The C37 capacitor in my radio is the round disc type, not a paper.

Certainly thought that would be the OEM device in the set and they rarely go bad…if you will check the last entry that I made…on my DTG 05/01/2008 17:53 …there is the photo of the said device and my textual referencing to the unit having the Zenith 22- (capacitor designator), but I was unsure of its specific dash series, but you specify it as being a -16 value.Which would be an .022 ufd value

The old cap checks out at .001 on my capacitor checker.

If your C37 cap is actually reading as now being / transitioned to an .001 value, I would certainly expect the audio to be somewhat tinny and void of any appreciable bass response…

Plus, that large oversize speaker that your unit contains is certainly capable of producing greater than average bass.
Therefore, I question the accuracy of the reading of your capacitance tester, considering that you have the cap totally pulled and is being tested out of circuit.

As a double check confirmation, try this procedure :
Requirements…. 1 meg resistor…wattage insignificant, AC DVM, 4 or so test leads, plus, the Cap to be evaluated.

In referencing my supplied chassis schematic ( http://www.nostalgiaair.org/Forums/Messages/163/M0060163.htm ), in tracing down the filament string, you will see that the 19T8 (V7) is at the very end of the filament string and then goes to ground. If you will then meter for AC voltage across its pin 5 while using its pin 4 as the meter ground you should find ~ 19-20 VAC being across those pins.

It then only takes about 4 test leads with end clips on them to temporarily lash up the test hookup shown in the schema below.
There is the blue lead that gets a 20 V RMS sample of 60~ AC from pin 5 and then there is the green lead that completes the ground loop connectivity and then the DVM set in its AC mode, which is shunted across a 1 meg loading resistor, the test capacitor then completes the circuit.

If that questioned capacitor actually IS of an ~.001 ufd value , then the capacitive reactance path to ground will only have minimally bypassed AC to ground only to the extent of having still left you with an ~18.75VAC reading across that resistor.
Now in plugging in the mathematics and interpolating to other values of capacitance being used in that test position.

If one had an:

.001 ufd capacitor____expect ~___18.75VAC

.01 ufd capacitor_____expect ~___ 5.5VAC

.02 ufd capacitor_____expect ~___ 2.8VAC

.022 ufd capacitor____expect ~___ 2.5VAC

.05 ufd capacitor_____expect ~___ 1.2VAC

That is giving you a capacitance range somewhat above and below that .022 value, and you could now see if that cap actually now IS .001 ufd, there is quite a day and night differential in the reading of an AC voltage of ~18.75 for an .001 ufd versus one of ~2.5 for the .022 ufd value.

Technical Referencing:

73's de Edd

6/9/2008 8:32:30 PMBill G.(62982:62978)

Edd, where do you get this stuff. It's great!
Best Regards,
Bill Grimm

6/10/2008 11:45:49 AM*** Schema Correction ***(62999:62978)

Mark…hoping that you have not acted upon the info, yet, what with the time delay to date in getting the initial .022 changed out.

Upon looking at the provided schematic for the test hookup below, it seems that I had placed the test cap and the load / isolation resistor turned ~ 90 degrees so a correction is shown below.

Also there was the possible difference of the 19-20 VAC sampling, so I have centered upon a 19.5 VAC value and computed the ~ voltages to be experienced….they are now amended in the voltage charts placed below.

If that questioned capacitor actually IS of an ~.001 ufd value , then the capacitive reactance path to ground will only have minimally bypassed AC to ground only to the extent of having still left you with an ~16.5VAC reading across that resistor.

Now in plugging in the mathematics and interpolating to other values of capacitance being used in that test position.

If one had an:
.001 ufd capacitor____expect ~___16.5VAC
.01 ufd capacitor_____expect ~___ 4.5VAC
.02 ufd capacitor_____expect ~___ 2.8VAC
.022 ufd capacitor____expect ~___ 2.3VAC
.05 ufd capacitor_____expect ~___ .9 VAC

That is giving you a capacitance range somewhat above and below that .022 value, and you could now see if that cap actually now IS .001 ufd, there is quite a day and night, spread out differential, in the reading of an AC voltage of ~16.5 for an .001 ufd versus one of ~2.3 for the .022 ufd value.

73's de Edd