Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
old fashioned 535 - first start after 35 years
|
Michael Petereit
Hi,
now I finished the repair of this pretty old scope. I switched on and was afraid of getting "flames" out of it. This didn't happen but even after 10 minutes running no beam appeared on the tube. Since the servicemanual describe resistors and capacitors with it's number within the system the reality looks different. I cannot measure neither 9kv voltage nor I can find the correct part cause the scope is pretty dirty inside. Any hints where to look first ? Thanks, Michael |
|
Artek Media
Michael
For starters , do a search in the Tekscopes archives for a a long email thread on washing and baking old scopes to get the grime out . It may be as far back as two years ago but there was a lot of discussion. Next I would carefully remove and mark the locations of all the tubes, find a friend with a tube tester and test all the tubes ... Once you have a clean dry scope and a good set of tubes time to start tracing the circuits for bad electrolytic.. Many will suggest that you just replace them all :-) Does the filament on the CRT glow ? If that is dead ...you may be out of business till you find a doaner scope Good luck and HAVE FUN Dave At 02:02 PM 2/4/2007, Michael Petereit wrote: Hi,Dave & Lynn Henderson ArtekMedia Digitally remastered "out of print" test equipment manuals www.ArtekMedia.com manuals@... 952-807-5484 |
|
Before you go too far with the chassis cleaning and wholesale tube
testing, check and repair the low voltage power supplies first (be especially wary of the bypass capacitors across the precision voltage divider resistors). If the voltages are all in tolerance, look at the high voltage rectifier tubes under the top HV cover to see if their filaments are glowing. This will tell you if the HV oscillator is working. If they are glowing, the CRT filament should also be glowing. You won't be able to fix anything else until the power supplies are working. BAMA has a 535_545 manual listed for free download if you are in for some troubleshooting. Good luck. --- In TekScopes@..., Artek Media <manuals@...> wrote: discussion.
|
|
Petrosilius Zwackelmann
Well, all tubes below the CRT are working. I didn't checked the CRT so far but try what you suggested.
toggle quoted message
Show quoted text
Btw: The startup behaviour of the scope is strange. On the first start after around 1 minute a relais was working i the back, below the big fan. After another 30 sec the relais release with a big spark. Now the startup is different. The relais is working after 30 seconds but do not relase the contact any more. I assume some capacitors might be charged to high and keep voltage. I'll try agai once I'm back home tonight. BR, Michael -------- Original-Nachricht -------- Datum: Mon, 05 Feb 2007 02:35:04 -0000 Von: "m38a1_1962" <m38a1_1962@...> An: TekScopes@... CC: Betreff: [TekScopes] Re: old fashioned 535 - first start after 35 years Before you go too far with the chassis cleaning and wholesale tube --
"Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ... Jetzt GMX TopMail testen: |
|
Dave,
toggle quoted message
Show quoted text
I fond that thread but it didn't gave that conclusion. I used alcohol for slight mud, this scope was placed in a dirty an humid cellar for years without it's coverage. The aluminium is best cleaned by caustic potash but it will eat up tin too. Thus I tried with a industrial cleaner which worked pretty good. In the area of the high voltage transformator I didn't used anything else than alcohol. I was afraid of getting shorts by using chemical stuff. I try to build up ths voltage divider to measure the high voltage. BR, Michael -------- Original-Nachricht -------- Datum: Sun, 04 Feb 2007 14:27:26 -0600 Von: Artek Media <manuals@...> An: Michael Petereit <michael.petereit@...>, TekScopes@... CC: Betreff: Re: [Tekscopes] old fashioned 535 - first start after 35 years Michael --
"Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ... Jetzt GMX TopMail testen: |
|
faustian.spirit
--- In TekScopes@..., "Petrosilius Zwackelmann"
<michael.petereit@...> wrote: so far but try what you suggested. start after around 1 minute a relais was working i the back, below the big fan. After another 30 sec the relais release with a big spark. I don't think it should release until you switch off the power. This must be the relay which switches on the anode voltages after the tubes are at working temperature. BTW does somebody know how many different thermal delay tubes there are? but do not relase the contact any more. I assume some capacitors might be charged to high and keep voltage. out . startIt may be as far back as two years ago but there was a lot ofdiscussion. be outtracing the circuits for bad electrolytic.. Many will suggest that --of business till you find a doaner scope |
|
As far as I know there is only one delay relay. It kicks in after
the tubes have had a chance to warm. The only time mine ever kicked out was when the thermal protection tripped, which it will do fairly quickly without the fan, with the cover off. Check the regulated voltages of the low voltage power supply. That is very important. Everything is referenced off the -150v supply. There are some .01 capacitors across the precision voltage dividers that probably leak badly. And speaking of capacitors, these scopes were originally full of Sprague "black beauty" paper capacitors. They will be black plastic things with a solder blob at one end. All of them should be replaced. The 535 uses a high voltage tripler made of 3 tubes. The capacitors which charge to make the high voltage were probably originally black beauties. If they are still there they are surely bad. John |
|
Richard Aston
The delay relay closes its contacts which energises the coil of a conventional relay which a: shunts the contacts of the delay relay, thus maintaining itself closed and b: disconnects the heater supply to the delay relay which allows it to cool so that it may be ready to provide another delay if the power is interrupted.
toggle quoted message
Show quoted text
The delay relay therefore drops out of circuit immediately it closes. It should not drop out with a 'big spark' thirty seconds later. Richard. casej451 wrote: As far as I know there is only one delay relay. It kicks in after |
|
Michael Petereit
I tried again. Since the CRT is completely covered I cannot see any
toggle quoted message
Show quoted text
filament working. Shortly before the tube's diameter gets wider some connectors for deflection I guess. Even there some color avoid having a look onto any filament. Is it really colour or might it be dirt ? The tube is such long you can't have a look from the back unless you remove the backcover. But I would like to avoid as much disassembling as possible unless it worked once. Then any other cleaning will happen and I try to "renovate" the item. I'll try to get a high voltage adapter for my Gossen multimeter. Then I'll check the -1350V and the 8960V. br, Michael m38a1_1962 said the following on 05.02.2007 03:35:
|
|
aobp11
Be careful, the CRT heater gets its supply directly from the big
mains power transformer, *not* from the HV transformer. When the isolation is bad then the HV won't start. See many earlier posts about CRT filament or heater problems. Albert --- In TekScopes@..., Michael Petereit <michael.petereit@...> wrote: any filament.you remove the backcover. But I would like to avoid as muchdisassembling as possible unless it worked once. Then any other cleaning willhappen and I try to "renovate" the item.Then I'll check the -1350V and the 8960V.---- If the voltages are all in tolerance, look at the theirhigh voltage rectifier tubes under the top HV cover to see if glowing.filaments are glowing. This will tell you if the HV oscillator is ----- No, according to 535-545 manual the CRT filament gets 6.3V from the mains transformer. Albert |
|
Stan and Patricia Griffiths
Hi Michael,
If the relay is opening again after closing, it is not getting coil voltage from its own contacts. If you burnish (clean) the relay contacts, it will probably hold in until the power switch is turned off. It is not usually necessary to check the +8650 volts on the CRT anode. If the -1350 is present, then the +8650 will be OK. All of the other power supplies must be working properly before you bother to measure the -1350. The other supplies are: -150, +100, +225, +350, and +500. Stan _____ From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Michael Petereit Sent: Monday, February 05, 2007 8:19 AM To: m38a1_1962 Cc: TekScopes@... Subject: Re: [TekScopes] Re: old fashioned 535 - first start after 35 years I tried again. Since the CRT is completely covered I cannot see any filament working. Shortly before the tube's diameter gets wider some connectors for deflection I guess. Even there some color avoid having a look onto any filament. Is it really colour or might it be dirt ? The tube is such long you can't have a look from the back unless you remove the backcover. But I would like to avoid as much disassembling as possible unless it worked once. Then any other cleaning will happen and I try to "renovate" the item. I'll try to get a high voltage adapter for my Gossen multimeter. Then I'll check the -1350V and the 8960V. br, Michael m38a1_1962 said the following on 05.02.2007 03:35: <mailto:TekScopes%40yahoogroups.com>, Artek Media <manuals@...> wrote: |
|
Michael Petereit
Stan,
toggle quoted message
Show quoted text
I checked the voltages: +100V = 124V +225V = 203V +350V = 306V +500V = 464V -150V = -144V A lot voltage is below the limits. The main supply is switched to 234V, the current standard voltage is 235V on the power line. I assume the rectifier might be broken. Since the hartley oscillator is powered by the +350V line and coupled with the +340V line according schematics the tube might not run as expected. The frequency must be aroung 50kHz but I do not have a AM receiver to check ans again the dirt inside the scope is expecially around the HV and this oscillator horrible. Any other ideas about the lower voltages ? BR, Michael Stan and Patricia Griffiths said the following on 05.02.2007 22:02:
|
|
aobp11
Hello Michael,
Also measure the unregulated voltages at the filter caps. (Values on the schematics are only crude indications). Low values might indicate bridge faults or open filter caps or a very high load somewhere. I suppose you can first of all set -150V to the correct value? (Does no harm to try this.) I would start with the deviating +124V since this fault has the best isolated cause: +100V is not stacked upon one of the other supplies, the *positive* deviation cannot be due to a wrong unreg. voltage, or a leaky bypass cap C750 or a bad regulator tube V7488. Also no load at the +100V output seems unlikely(?). Remains specifically (I hope to make no mistake!) the divider resistors R750/R751 and a bad V742. The grid of V742 should be several volts negative. Also check the voltages at the ends of these resistors are indeed the same as on the "-150V" and "+100V" test points. When suspect, you might exchange the 6AU6 with one of the other (say +225V) supplies. Albert --- In TekScopes@..., Michael Petereit <michael.petereit@...> wrote: 234V, the current standard voltage is 235V on the power line.oscillator is powered by the +350V line and coupled with the +340V line accordingbe aroung 50kHz but I do not have a AM receiver to check ans againthe dirt inside the scope is expecially around the HV and this oscillatorhorrible. coil turned off.voltage from its own contacts. If you burnish (clean) the relay of bother tothe other power supplies must be working properly before you +350,measure the -1350. The other supplies are: -150, +100, +225, -------and +500. |
|
Stan and Patricia Griffiths
Hi Michael,
toggle quoted message
Show quoted text
Something I forgot to mention that you may not know is that for the power supplies in a 535 to work, it MUST have a plugin installed, otherwise, the load on the power supplies will be too light and they will not regulate. Stan -----Original Message-----
From: Michael Petereit [mailto:Michael.Petereit@...] Sent: Tuesday, February 06, 2007 9:10 AM To: TekScopes; Stan and Patricia Griffiths Subject: Re: [TekScopes] Re: old fashioned 535 - first start after 35 years Stan, I checked the voltages: +100V = 124V +225V = 203V +350V = 306V +500V = 464V -150V = -144V A lot voltage is below the limits. The main supply is switched to 234V, the current standard voltage is 235V on the power line. I assume the rectifier might be broken. Since the hartley oscillator is powered by the +350V line and coupled with the +340V line according schematics the tube might not run as expected. The frequency must be aroung 50kHz but I do not have a AM receiver to check ans again the dirt inside the scope is expecially around the HV and this oscillator horrible. Any other ideas about the lower voltages ? BR, Michael Stan and Patricia Griffiths said the following on 05.02.2007 22:02:
|
|
Stan and Patricia Griffiths
Hi Michael,
toggle quoted message
Show quoted text
All of the low voltages in your chart must be within 2% of nominal value before you even try to measure the -1350. The first two supplies to work on are the -150 and the +100 which are interconnected and must BOTH work at the same time. It is not easy to tell which of the two supplies is the bad one. Try rotating the -150 adjustment pot back and forth as I have seen a noisy pot cause this sort of problem. Rotating the -150 adjustment a few times may clean up any noise it has. Once you get the -150 and +100 working, then check the +225 and you may find it too is now working. Same with +350 and +500. When all of those are working, then check the -1350 and you might find it is OK, too. I think you said this was a 535 (not a 535A). There are about 7 black capacitors with colored stripes on them in the power supplies that are real problems in 535 and other scopes of this vintage. These caps are called "Black Beauties" and are famous for getting leaky with age. Most of these caps are 0.01uf at 400 volts, but one is 0.01uf at 600 volts. You should change all of these capacitors to new ones. After you do this, check the power supplies again and let me know if they are now working and we can go from there. If the power supplies are still not correct, I have some more suggestions. Stan -----Original Message-----
From: Michael Petereit [mailto:Michael.Petereit@...] Sent: Tuesday, February 06, 2007 9:10 AM To: TekScopes; Stan and Patricia Griffiths Subject: Re: [TekScopes] Re: old fashioned 535 - first start after 35 years Stan, I checked the voltages: +100V = 124V +225V = 203V +350V = 306V +500V = 464V -150V = -144V A lot voltage is below the limits. The main supply is switched to 234V, the current standard voltage is 235V on the power line. I assume the rectifier might be broken. Since the hartley oscillator is powered by the +350V line and coupled with the +340V line according schematics the tube might not run as expected. The frequency must be aroung 50kHz but I do not have a AM receiver to check ans again the dirt inside the scope is expecially around the HV and this oscillator horrible. Any other ideas about the lower voltages ? BR, Michael |
|
Stan and Patricia Griffiths
Hi Michael,
toggle quoted message
Show quoted text
The black capacitors I am talking about are located in the -150, +100, +225, +350, and +500 power supplies and not in the high voltage area. You should be able to remove and replace these capacitors without removing any other parts. If one of the precision resistors in the power supply gets damaged, I have some spares from scrapped old scopes. Stan -----Original Message-----
From: Michael Petereit [mailto:Michael.Petereit@...] Sent: Friday, February 09, 2007 8:57 AM To: Stan and Patricia Griffiths Subject: Re: [TekScopes] Re: old fashioned 535 - first start after 35 years Hi Stan, the plugin is available and installed. Unfortunately one channel will not work for sure since the wire of one coil is broken.... But this won't prevent the startup of the complete "vehicle". For checking the black old capacitors I have to unsold all other resistors above. For cleaning purpose this is the best choice but a little bit risky too. Thanks, Michael Stan and Patricia Griffiths said the following on 09.02.2007 08:00: Hi Michael, |
|
Stan and Patricia Griffiths
Hi Michel,
toggle quoted message
Show quoted text
The only part that I know of in that scope that can be damaged by water is the power transformer and then usually only if you submerge it in water or use water with a lot of metal ions in it. You could always remove the power transformer to keep it away from the water and wash the rest of the scope with detergent and water. Warm water works best. I have never heard of using caustic potash to clean a scope so I am not sure how this will work. I would not do it. Stan -----Original Message-----
From: Michael Petereit [mailto:Michael.Petereit@...] Sent: Friday, February 09, 2007 9:05 AM To: Stan and Patricia Griffiths Subject: Re: [TekScopes] Re: old fashioned 535 - first start after 35 years Hi Stan, well, I had really doubts thinking about changing the capacitor of this scope. The one I bought from you seems working fine. There are a lot more capacitor rolled in paper and with no printed value on it. In general it's pretty hard to find any resistor or capacitor on the scope accord to the schematics. There is no part definition printed like on modern pcbs. And the dirt covers really everything, especially the wiring with it's colour scheme. Maybe it's best first to clean this device but all post from the past concerning this issue are not really usefull. From outting it into the dishwasher to placing it into the bath tube and showering it... Hmmm, it don't want to try this. The easiest way to get rid of this dirt is caustic potash. It nags the aluminium and the dirt very good. But without unmounting nearly every part the cleaning won't be succesful. I thought about changing all electircal part except of tubes and coils and special parts at all. What do you thin about that ? Regards, Michael |
|
Bill R
Hi, Michael:
toggle quoted message
Show quoted text
The aluminum chassis in Tek scopes has been Alodized or Anodized (I can't remember which process is used). This process cleans the surface and hardens it. I'm no chemist, but I think part of that process uses potash. If you use potash to clean it I think your chassis surface will be changed (will not look good). Any chem heads correct me please. Bill Roberts michael.petereit@... wrote: Dave, |
|
faustian.spirit
--- In TekScopes@..., "Stan and Patricia Griffiths"
<w7ni@...> wrote: water is the power transformer and then usually only if you submerge it inwater or use water with a lot of metal ions in it. You could always removethe power transformer to keep it away from the water and wash the rest of thescope with detergent and water. Warm water works best.not sure how this will work. I would not do it.35 years
Hmm? There is quite a lot of reading material printed on the chassis. Probably just concealed beneath all the dirt :) BTW, does your unit still have the original solder spool inside? (Do read the old discussions on this forum regarding solder types to use and not use on the ceramic strips). And the dirt covers really everything, especially the wiring with it's |
|
-------------------snip-----------------------
I followed the advice to "wash" the scope what I did two days ago. Now it's drying in a warm room. There is some solder spooled in the back and I read about some advices not to use solder without silver. Let me wait some more days until it's really dry. Then I'll have a look at all parts and after remounting the tubes I try a first start... Michael -- "Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ... Jetzt GMX TopMail testen: www.gmx.net/de/go/mailfooter/topmail-out |
to navigate to use esc to dismiss