Re: 11801 diagnostic help
I'm envious of your scores!? Some day I will get back into owning and operating 11000 series gear....Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: "Reginald Beardsley via Groups.Io" <pulaskite@...> Date: 3/15/19 3:48 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 11801 diagnostic help No one in the US will have the ST part in stock until June!? But someone in the UK has offered to get a couple for me there.? I bought the scope for $100 plus $85 shipping because I knew what the E5622 error was.? And I dealt with replacing the Dallas part in a Sun workstation.Reseating all the connectors a 2nd time seems to have done the trick and I can navigate around the extended diagnostics with the touch screen.? I got a pair of SD-22s for $150 and an extension cable for $100, so if the SD-22s are OK or are repairable I'll have it up and running for less than $500 which is pretty cool. The screen is clean and crisp.? No burn.I still want to get a complete set of manuals for the 11801, but so far the 11801A version is as close as I can get.? I do wish people would label things properly.? Once I get proper manuals I'll scan them and send them to all the archives.I'm really not sure what I have yet.? I've got 6 cards in the bay behind the CRT, but I was not able to learn anything about the memory expansion board from the diagnostic screen.Have Fun!Reg
|
Re: 11801 diagnostic help
No one in the US will have the ST part in stock until June! But someone in the UK has offered to get a couple for me there.
I bought the scope for $100 plus $85 shipping because I knew what the E5622 error was. And I dealt with replacing the Dallas part in a Sun workstation.
Reseating all the connectors a 2nd time seems to have done the trick and I can navigate around the extended diagnostics with the touch screen. I got a pair of SD-22s for $150 and an extension cable for $100, so if the SD-22s are OK or are repairable I'll have it up and running for less than $500 which is pretty cool. The screen is clean and crisp. No burn.
I still want to get a complete set of manuals for the 11801, but so far the 11801A version is as close as I can get. I do wish people would label things properly. Once I get proper manuals I'll scan them and send them to all the archives.
I'm really not sure what I have yet. I've got 6 cards in the bay behind the CRT, but I was not able to learn anything about the memory expansion board from the diagnostic screen.
Have Fun!
Reg
|
Tektronix 2465B Test 05 Fail 40 repair.
This seems to be a common problem so I thought I would report on my repair.
Summary:
Apparently fixed by replacing the U500 hybrid with a known good one.
Details:
This is my main scope. In 2015 it received new caps, repaired SMD A5, and new cal. memory. It worked flawless up until a few months ago. At that point it started failing the power on self test with ¡°Test 05 Fail 40¡± messages.
I set the scope aside dreading trying to find what I assumed would be another damaged trace on A5. After a while, I pulled it off the shelf and started testing it. Of course, it passed all self-tests.
So I put it back in service and waited for it to fail again. Eventually, it did.
This time I carefully measured the power supplies and checked that the DAC was basically functioning. Everything was okay. Before trying to troubleshoot the A5 sample-and-hold circuits I thought I would try an easy experiment. I swapped the U500 hybrid between a 2430A and this scope. Surprisingly, both scopes now work and pass self tests.
I don¡¯t have a good explanation as to why this worked (or indeed if it has ¡ª only time will tell). Perhaps the hybrid is marginal and the 2430A uses it under slightly different conditions. Perhaps an issue with contacts ¡ª although I had already tried cleaning the contacts and reseating it.
|
Re: 11801 diagnostic help
Tek 11801 Timebase Errors
Tektronix 11801, 11802, and CSA803 sampling scopes eventually fail with an
E5622 timebase error.
If you remove the bottom panel, you'll see a cluster of sram chips...
Two of them are plugged into Dallas "smart socket" battery backup things, which
in turn are plugged into the board. Likely the tiny batteries have died.
You can replace the Dallas things, which is the Dallas/Maxim (discontinued!) part
number DS1213. Or you can chuck the rams and the Dallas widgets and plug in
two ST Micro part number M48Z35-70PC1, which is a battery-backed SRAM
module. Digikey has them.
After you do this, you'll need to power cycle two or three times until it works.
There are coin-cell batteries on other boards in the main cardcage, but they
seem to last a long time.
Any other tips on 11801 or sampling head repair would be appreciated. Tek
never published schematics or other service info beyond board swapping.
The eeprom chips in the sampling heads seem to fail fairly often, and it would be
interesting to find a way to replace them.
John Larkin Highland Technology Inc jjlarkin@...
toggle quoted message
Show quoted text
On 3/15/2019 5:51 PM, Reginald Beardsley via Groups.Io wrote: I'm not sure I can identify the board. There are a couple of boards with no markings. I reseated the 4 boards on the left side while checking to see what they are. the left two are a memory board and a memory expansion board. The 3rd board is marked "property of and copyright Silicon Software". It and the other board next to it look very different and have no Tek markings.
I have gotten it to run the self test and it stops in the extended diagnostics with the E5622 error. I'm still hunting for a service manual. The BAMA has an 11801C manual listed as an 11801. There are a couple on eBay and I've asked the sellers to verify that they are for the 11801 and not a later variant. So far not replies.
|
Re: 11801 diagnostic help
I'm not sure I can identify the board. There are a couple of boards with no markings. I reseated the 4 boards on the left side while checking to see what they are. the left two are a memory board and a memory expansion board. The 3rd board is marked "property of and copyright Silicon Software". It and the other board next to it look very different and have no Tek markings.
I have gotten it to run the self test and it stops in the extended diagnostics with the E5622 error. I'm still hunting for a service manual. The BAMA has an 11801C manual listed as an 11801. There are a couple on eBay and I've asked the sellers to verify that they are for the 11801 and not a later variant. So far not replies.
|
Re: 11801 diagnostic help
What is the voltage on pin 28 of the two socketed rams on the timing and control board in the bottom of the unit?
toggle quoted message
Show quoted text
On 3/15/2019 4:07 PM, Reginald Beardsley via Groups.Io wrote: My 11801 arrived today. On power up it makes two beeps and puts up two lines of text on the screen:
Diagnostics in progress
Comm Test in progress
But does not go past that. The seller sent a picture showing an E5622 error, "passed" below that and ???? for the timebase, main acq, mcu a-d acq entries and a picture of the screen with "Self test in progress".
I have reseated all the boards and cables behind the CRT and the cables on the display board. The display board was missing the 4 corner screws. I have replaced those.
So does anyone recognize the issue? While I was pulling the boards I checked the 4 lithium cells and all were over 3 V despite 1988 date codes. That did not match the service manual for the 11801C which is a little disturbing. Is this really just a CSA803 with 4 extra ADC channels? Does anyone know of a manual for this unit? I think all the ROMs are marked 1989, but was not meticulous about that detail as I expected reseating the connectors to have an effect.
Thanks,
Reg
|
My 11801 arrived today. On power up it makes two beeps and puts up two lines of text on the screen:
Diagnostics in progress
Comm Test in progress
But does not go past that. The seller sent a picture showing an E5622 error, "passed" below that and ???? for the timebase, main acq, mcu a-d acq entries and a picture of the screen with "Self test in progress".
I have reseated all the boards and cables behind the CRT and the cables on the display board. The display board was missing the 4 corner screws. I have replaced those.
So does anyone recognize the issue? While I was pulling the boards I checked the 4 lithium cells and all were over 3 V despite 1988 date codes. That did not match the service manual for the 11801C which is a little disturbing. Is this really just a CSA803 with 4 extra ADC channels? Does anyone know of a manual for this unit? I think all the ROMs are marked 1989, but was not meticulous about that detail as I expected reseating the connectors to have an effect.
Thanks,
Reg
|
200/300 series scopes at stuff day
I have had several requests to list all the tek portables that will be at stuff day, so here's the info. We will be checking these next week, so status on every unit is still unknown as of today except where noted. all are in very good cosmetic condition, some look like new. I have always loved small scopes, so I keep accumulating these (and many others), but there's just too many now, and they have to go.
here's the 200/300 series list, we won't be testing these until next week:
4x Tek 321A portable (all different variations, one with factory leather travel case).
1 overhauled, rest as-is, have to re-test.
1x Tek 310A portable (needs repair, also have spare CRT).
1x Tek 308 logic analyzer complete with pouch and accessories. should be working, have to re-test.
2x Tek 336 digital portable, c/w top pouch and accessories, were working, have to re-test.
1x Tek 222PS digital power scout, needs repair, more unknown. Yellow/blackl color.
1x Tek 222 digital portable, c/w probes and pouch, but needs battery and power adaptor.
was working, have to re-test.
there's also many other Tek scopes, 2252, 2430, 2235, 561B system, and others.
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp
|
Re: 577 Curve tracer ringing CRT and noisy step generator
|
Re: M48Z35-70PC1 NVRAM for CSA803 & 11801 E5622 error
On Thu, Mar 14, 2019 at 09:28 PM, Maurice Smulders wrote: There might be a more elegant solution possible. The problem of battery ram
was discussed at length in the pinball forums, and people made other
solutions for it. Permanent ones. No battery to replace EVER.
For example:
Now, I couldn't find a 32Kx8 variant, but the RAMTRON chip you'd likely
need is the FM1808. Mouser seems to have it in stock, but at a pretty hefty
price, and you'd have to make the breakout board still (JLPCB maybe?)
There seems to be stock on eBay for lower prices from US sellers... I've done exactly this to my 2430A. I've replaced both of the dead Dallas NVRAM chips with Cirrus FM18W08 FRAMs in off-the-shelf SOIC to DIP converters (Aries LCQT-SOIC28), all bought from Farnell in the UK. The conversion works perfectly as far as I can tell, and the scope will never have dead batteries again. One day I might try the same trick on my CSA803A. Chris
|
Re: 2247A PSU Troubleshooting
On Thu, Mar 14, 2019 at 03:57 PM, tom jobe wrote: There are about 17 one amp ultra fast diodes that are used to rectify
the low voltages on the secondary side of the transformer. About a dozen
of them are in a row next to the transformer in the middle of the A18
board and they are known to fail especially if they are marked "ZS" or
one other marking which I can't remember. If they are marked ZM or ZS they are well known to get leaky. Replace these diodes with MUR160 600V 1Amp from Mouser/DK.
|
Re: Test input for an SD-32 sampling head
Hi, Reg.
Regarding fast pulses and such, there is a wealth of information at Jim
Andrews' page here: He founded
Picosecond Pulse Labs in 1980 and sold it to Tektronix in 2014. I used
PPL products with a CSA803 back in the mid 1990's at Lockheed. I think
the sampling head I used was an SD-24, but since it was about 25 years
ago, my memory is a bit fuzzy.
These days I have a 7904, a 7603, a 7S12, a 7S11, two S-4 sampling
heads, S-53 and S-51 triggering heads, etc in my garage lab. Oh, and a
couple of 10:1 probes I made out of board-edge SMA connectors, 450 ohm
(470 paralleled with 1.8k ohm) 0402 resistors, and 3-pin right-angle 0.1
inch spacing headers. I've not completely characterized the probes, but
at least they pass up to about 12-13 GHz without much attenuation above
the expected 20 dB. Planning to use them to probe some digital RF
boards I'm going to build for work (Raytheon). Too much trouble to try
to get a fast enough sampling scope at work :(
Enjoy the PPL app notes! I've referred to AN-2a through -2e often.
Thanks for the literature references. I'll have to check them out
(someday).
Jim Ford
toggle quoted message
Show quoted text
------ Original Message ------ From: "Reginald Beardsley via Groups.Io" <pulaskite@...> To: [email protected]Sent: 3/14/2019 6:03:56 PM Subject: Re: [TekScopes] Test input for an SD-32 sampling head I have one of Leo's 100 pS impulse units as a source for initial experiments. If I can narrow that to 10 -20 pS with discrete SMD parts I may be able to get the idea to work. There's a close connection to the Hilbert operator hiding in there somewhere.
I've been reading an excellent book on FPGA implementation of DSP by Roger Woods et al most of the afternoon. So I've not started on the dissertation yet. I can't really say much else until I understand the mathematics and physics of using the reverse biased diodes as capacitors. That should keep me entertained for a few weeks at least.
In any case, failure doesn't matter. It's a hobby project, not a client deliverable. I've been fascinated by the problem of getting a fast rise time edge for a long time. It's a bit of circular logic. My excuse for doing it is I bought an 11801 and my excuse for buying the 11801 is so I could try to do it. If I can narrow the 100 pS pulse by 5x I'll have an excuse to buy an SD-32.
I spent 3 years studying sparse L1 pursuits using "A Mathematical Introduction to Compressive Sensing" by Foucart and Rauhut as a text followed by reading the original papers by Donoho, Candes et al. Beats the hell out of watching television. I just wish I could find someone else who was interested in the subject to discuss it with. It's quite amazing what you can do with sparse L1 pursuits and really easy to do in practice. Understanding the math is not easy, but most people use FFTs without really understanding them.
Have Fun!
Reg
--- This email has been checked for viruses by AVG.
|
Re: Test input for an SD-32 sampling head
Picosecond pulse labs used to sell NLTL's for pulse sharpening amonst other applications.
NLTLs are still commercially available.
Bruce
toggle quoted message
Show quoted text
On 15 March 2019 at 14:03 "Reginald Beardsley via Groups.Io" <pulaskite@...> wrote:
I have one of Leo's 100 pS impulse units as a source for initial experiments. If I can narrow that to 10 -20 pS with discrete SMD parts I may be able to get the idea to work. There's a close connection to the Hilbert operator hiding in there somewhere.
I've been reading an excellent book on FPGA implementation of DSP by Roger Woods et al most of the afternoon. So I've not started on the dissertation yet. I can't really say much else until I understand the mathematics and physics of using the reverse biased diodes as capacitors. That should keep me entertained for a few weeks at least.
In any case, failure doesn't matter. It's a hobby project, not a client deliverable. I've been fascinated by the problem of getting a fast rise time edge for a long time. It's a bit of circular logic. My excuse for doing it is I bought an 11801 and my excuse for buying the 11801 is so I could try to do it. If I can narrow the 100 pS pulse by 5x I'll have an excuse to buy an SD-32.
I spent 3 years studying sparse L1 pursuits using "A Mathematical Introduction to Compressive Sensing" by Foucart and Rauhut as a text followed by reading the original papers by Donoho, Candes et al. Beats the hell out of watching television. I just wish I could find someone else who was interested in the subject to discuss it with. It's quite amazing what you can do with sparse L1 pursuits and really easy to do in practice. Understanding the math is not easy, but most people use FFTs without really understanding them.
Have Fun!
Reg
|
Re: M48Z35-70PC1 NVRAM for CSA803 & 11801 E5622 error
Reg,
There might be a more elegant solution possible. The problem of battery ram
was discussed at length in the pinball forums, and people made other
solutions for it. Permanent ones. No battery to replace EVER.
For example:
Now, I couldn't find a 32Kx8 variant, but the RAMTRON chip you'd likely
need is the FM1808. Mouser seems to have it in stock, but at a pretty hefty
price, and you'd have to make the breakout board still (JLPCB maybe?)
There seems to be stock on eBay for lower prices from US sellers...
Just a thought, make a breakout, put a SMD variant of the FM1808 plus
possibly some circuitry on it, and be done with it. No battery to deplete
anymore... You might even be able to find a DIP variant of it, and it looks
to be pin compatible...
There are some differences though, CE needs to be strobed. The datasheet
will tell the details...
Maurice
toggle quoted message
Show quoted text
On Mon, Mar 11, 2019 at 8:33 AM Adrian <Adrian@...> wrote: I'm happy to get a couple and mail them to you if that helps?
Adrian
On 3/11/2019 2:17 PM, Reginald Beardsley via Groups.Io wrote:
RS wouldn't allow me to enter any country except the UK when I tried to buy a couple.
Digikey says they'll have them in late May. I'm sure ST only makes a
small run, probably just once a year, because of the shelf life issue.
I asked a NA eBay seller about the origin and date code of their stock.
Came from a defunct distributor, but have a 2002 date code.
Unfortunately, with Farnell and their many names and websites, there is
no telling where their stock is. If shipment is by sea from the UK it
might still take until June :-(
so it looks as if I'm just going to have to wait.
|
Re: 2247A PSU Troubleshooting
To prevent that ground ring short, always practice safe probing; use a probe condom.? One of those plastic SMA connector caps works well, or just tape in a pinch.Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
toggle quoted message
Show quoted text
-------- Original message --------From: nielsentelecom@... Date: 3/14/19 7:16 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 2247A PSU Troubleshooting Nick,I have a 2246A that I had to get the ripple on the various DC busses knocked down. Replacing the ZS diodes was done, most of the secondary DC busses caps, a number of those were bad, I could not get all the voltages into spec with the single voltage adjuster. And I replaced those hot resistors near the HV section that scorch the board, they sit right in front of the air intake, and I replaced them with a higher wattage R and elevated them above the board. they were OK, but its a pain getting that power supply out! There is a HV cap in that section that will need constant discharging after powering up. It holds a lot of juice! I also blew the regulator chip in mine when I was probing around that tall heat sink, I forget which semi conductor, I had hit it with the ground ring on my scope probe on it. Pop, it went. I believe it has 150VDC on it. From your symptoms, it's similar to mine with the popped chip. Read about the delayed start feature, make sure it's doing what it's supposed to. There is also a crowbar circuit. I sourced that chip at DigiKey. I also created a resistive load to test the power supply voltages outside of the scope. I have lineman's gloves, and I put that HV CRT cable inside of that glove. I also elevated the board above a cardboard box with a box fan inside to cool those load resistors. It was a pain, but it worked very well. I have those resistor values if you need them. And I know all, doing it this way was not very safe! And I did use an isolation xformer.Nielsen TelecomTom Jobe helped me a few years ago get thru the repair. He has good advice. Search my handle and you will see what I did.
|
Re: 2247A PSU Troubleshooting
Nick,
I have a 2246A that I had to get the ripple on the various DC busses knocked down. Replacing the ZS diodes was done, most of the secondary DC busses caps, a number of those were bad, I could not get all the voltages into spec with the single voltage adjuster. And I replaced those hot resistors near the HV section that scorch the board, they sit right in front of the air intake, and I replaced them with a higher wattage R and elevated them above the board. they were OK, but its a pain getting that power supply out! There is a HV cap in that section that will need constant discharging after powering up. It holds a lot of juice! I also blew the regulator chip in mine when I was probing around that tall heat sink, I forget which semi conductor, I had hit it with the ground ring on my scope probe on it. Pop, it went. I believe it has 150VDC on it. From your symptoms, it's similar to mine with the popped chip. Read about the delayed start feature, make sure it's doing what it's supposed to. There is also a crowbar circuit. I sourced that chip at DigiKey. I also created a resistive load to test the power supply voltages outside of the scope. I have lineman's gloves, and I put that HV CRT cable inside of that glove. I also elevated the board above a cardboard box with a box fan inside to cool those load resistors. It was a pain, but it worked very well. I have those resistor values if you need them. And I know all, doing it this way was not very safe! And I did use an isolation xformer.
Nielsen Telecom
Tom Jobe helped me a few years ago get thru the repair. He has good advice. Search my handle and you will see what I did.
|
Re: Test input for an SD-32 sampling head
I have one of Leo's 100 pS impulse units as a source for initial experiments. If I can narrow that to 10 -20 pS with discrete SMD parts I may be able to get the idea to work. There's a close connection to the Hilbert operator hiding in there somewhere.
I've been reading an excellent book on FPGA implementation of DSP by Roger Woods et al most of the afternoon. So I've not started on the dissertation yet. I can't really say much else until I understand the mathematics and physics of using the reverse biased diodes as capacitors. That should keep me entertained for a few weeks at least.
In any case, failure doesn't matter. It's a hobby project, not a client deliverable. I've been fascinated by the problem of getting a fast rise time edge for a long time. It's a bit of circular logic. My excuse for doing it is I bought an 11801 and my excuse for buying the 11801 is so I could try to do it. If I can narrow the 100 pS pulse by 5x I'll have an excuse to buy an SD-32.
I spent 3 years studying sparse L1 pursuits using "A Mathematical Introduction to Compressive Sensing" by Foucart and Rauhut as a text followed by reading the original papers by Donoho, Candes et al. Beats the hell out of watching television. I just wish I could find someone else who was interested in the subject to discuss it with. It's quite amazing what you can do with sparse L1 pursuits and really easy to do in practice. Understanding the math is not easy, but most people use FFTs without really understanding them.
Have Fun!
Reg
|
Re: 2247A PSU Troubleshooting
On Thu, Mar 14, 2019 at 08:29 PM, Nicholas Keller wrote:
But you are correct that this is starting
to feel overwhelming and I am losing confidence :(
Nick, That is the way some of these threads go. You don't need a variac at this stage. A while ago you mentioned you had an isolation transformer, as I recommended and you asked whether to connect the safety ground through to the 'scope. I recommended to do that and Brian S. made some good remarks, which didn't contradict my advice. In your current situation they are not relevant. What *is* relevant is that you isolate the mains-connected part i.e. up to the primary side of T2204 from the mains, nothing more, which is exactly what you did with the isolation transformer. I am not confusing you with another user, no variac or even autotransformer in your situation. OTOH, I'm not sure at the moment what the symptoms with your 'scope were and I'll have to look that up again. Unfortunately, I'll be quite busy over the next few days (promised to repair a few scopes). As long as you realise all the time that *inside* the now isolated (primary) part of your 'scope there are still places carrying a dangerously high potential between them, no longer against your 'scope's case, ground, the floor underneath your feet nor safety earth after you installed the isolation transformer to feed the primary side of the 2247A and you're sure it is in good shape i.e. *if it is safe*, you may take measurements. If you want, let me know what you know about the status and symptoms and I'll be able to look into it within a few days. Three things: 1. Make sure you understand where the dangerous voltages are and between which points, now that you have an isolation transformer installed, and have utter respect for those 2. Make sure you act accordingly 3. Don't despair! Raymond
|
Re: TCP202 replacement body parts?
On Thu, Feb 28, 2019 at 4:57 PM Siggi via Groups.Io <siggi= [email protected]> wrote: I tried emailing buy@..., which acknowledged that the parts are
available, but instructed me to call 1-800-833-9200 ext 1 for sales. I
called this number, whereupon a very nice lady acknowledged the
availability and pricing, then proceeded to explain to me how she's unable
to process Canadian credit cards.
She then told me I could send a PO to the email above, and Tek would send
me an invoice, which I could pay by US check. She sincerely wished for me
to have a FedEx account or the like to arrange the shipping, as that's
going to be a problem otherwise also.
She could find no Tek representative in this here cold tundra that could
mediate this business either.
I'm happy to report that a kind gentleman member of this list had some parts he shared with me. I've transplanted the probe to a new housing and the patient looks to have survived. The little ball between the slide and the outer housing is feral, though. I don't know how many times it leaped for freedom, and I was sure I'd lost it several times. He also informed me that these probes are quite delicate and can fail in strange modes. In addition to the performance check in the service manual, he advised running my PG506 through the frequencies available for fast rise or high ampl, looking for "droop" on the measured waveform. Mine was pretty much ruler flat across all settings. In my performance testing this probe well exceeded spec. The rise seems to be on the order of 4.5ns and the 3dB bandwidth is closer to 100MHz than 50. DC accuracy was well inside 1% as received, and although the DC balance was totally out the window, it adjusted fine with the course balance trimmer on the probe.
|
Re: 2247A PSU Troubleshooting
In my experience, the main transformer either works, or it doesn't... and yours works. Having an internal short to ground is what killed the few T2204's I know about.
There are about 17 one amp ultra fast diodes that are used to rectify the low voltages on the secondary side of the transformer. About a dozen of them are in a row next to the transformer in the middle of the A18 board and they are known to fail especially if they are marked "ZS" or one other marking which I can't remember. Regardless of markings, follow theT2204 secondaries and see what you get for voltage and ripple as it all gets rectified and filtered.
The Tekscopes message archive will remember the details of this and lots of other problems the 224x family had over the years, and it's all in there for you to read when you search on 2246, etc.
toggle quoted message
Show quoted text
On 3/14/2019 3:20 PM, Nicholas Keller wrote: It was suggested earlier this this thread that I should find 160-170VDC
across C2202. I tested across R2256 as they appear to share the same
connections, and got 156VDC. Next I checked for ripple using my DMM set to
VAC and got about 2.5V.
I also tested across C2203 by using the same ¡°negative¡± joint of
C2202/R2256 for the black probe and pin 10 of T2204 for the red probe:
result = 40.5VDC
I also got 40.5V at T2204 pins 8 and 9 which should give +7.5V and -7.5V
.... and 38.4V at all DC power pins at J1204
Does this point to a bad T2204? Is C2202 allowing too much ripple?
Thanks for everyone¡¯s support!
Nick
On Thu, Mar 14, 2019 at 3:29 PM Nicholas Keller via Groups.Io <Nirokeforums=
[email protected]> wrote:
OP here. Variacs weren¡¯t mentioned until today so perhaps you are
confusing me with another user. But you are correct that this is starting
to feel overwhelming and I am losing confidence :(
This is the first HV device I have worked on so I am not familiar with all
the components in the 2247A PSU. Most of my experience has been with
analog synthesizers, drum machines, and effects, though often the problem
has been PSU related.
Nick
On Thu, Mar 14, 2019 at 12:56 PM Raymond Domp Frank <hewpatek@...>
wrote:
On Thu, Mar 14, 2019 at 05:03 PM, Brian Symons wrote:
I was only answering to the comment about isolation transformers.
Hi Brian,
I found your post very informative but wanted to keep things as simple and
clear as possible for the OP. I had recommended a Variac and he wasn't sure
what to do. In his case he can either connect safety earth or not.
Raymond
|
Maurice Smulders
Raymond Domp Frank