Another possible project in my 7K organizing and cleanup program is making a regular 7613 out of a rack version R7613. I've had this R unit for years. It works fine, but is a real pig, space-wise, and awkward. A rack style can be handy sometimes, depending on the situation, but I think overall I'd prefer to have it in the standard bench scope format. I have a carcass of a 7403N, which was similar to 7603 but lesser performance, and shot anyway. I've been pondering using it as the platform to transplant the guts into from the R7613, but am not sure if it's totally possible or practical. I think it should be OK electrically, but maybe not mechanically. Does anyone know if this is possible without too much grief? I don't know if certain boards and such are different for R-form, or even if the standard 7603/7403 cabinet is the right length for the storage versions. I'd appreciate any info/experience/wisdom on this matter. Ed

Please, has someone the 3D model for the foot used in 2465, 2430 etch? See the photo of the original part among the photos. Thanks Gianni

The following photos have been uploaded to the Reviving interest in Tektronix 500 and other Series Oscilloscopes ( https://groups.io/g/TekScopes/album?id=299466 ) photo album of the TekScopes@groups.io group. * IMG_1814.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3868099 ) *By:* John Williams <books4you4@...>

I recently purchased a 7A18 with Option 6. For cleaning purposes, I removed the knobs and faceplate. When I removed the VOLTS/DIV knobs, each had a washer against the frame with a spring which pushes against the back side of the knob. I've never seen this arrangement and the manual doesn't show those parts. Was this ever included from the factory? I doubt it and figure that someone decided to add those but I'm not sure so thought I'd ask the group. BTW, both VOLTS/DIV knobs and the small trigger selection knob are pretty badly broken. If anyone has some for sale, I'd be interested. Thanks, Barry - N4BUQ

I just got bit by "none of the above". Rather than Dallas, Maxim or ST NVRAM parts, U500 and U511 on the timebase board are NEC D43256C SRAM in a battery powered socket inserted into the PCB socket. Not having seen this before, I pulled the SRAM from the battery backup on U511, so whatever data might still have been there is now gone. Is there any documentation of what is stored in U500 and U511? My understanding is that factory "enhanced accuracy" data are stored in one or both. It's very frustrating not having component level service data as it's all TTL parts and *should* be easy to maintain indefinitely. Though now that I've seen the board, I doubt that the 1.4 ps jitter can be reduced with reasonable effort. It's likely a consequence of the variation in propagation time through a long chain of gates.

Has anyone had good results with any sort of treatment for old Tektronix covers? I have them for some of my "5" series scopes, but they have shrank and won't go on the scope without serious risk of tearing. Bruce Gentry, KA2IVY

Bonjour à tous! Just received a 7904A, little used in decades. So far fine CRT, all works but scratchy CRT controls and a few switches. Will CLA them. Seeking advice and tips on typical weak points, e.g. tantalum capacitors. Finally has anyone tried to reduce the fan speed? Many thanks, Have an absolutely fantastic day! Jon

My DSA602A shut off by itself and clicks with power light flashes / will not start. If I disconnect A24 from power the DSA shows signs of life and appears to boot normally. Before I go doing component level repair of A24. Does someone have a parts unit for sale or an A24 board they want to sell? I'm located in Michigan and someone local would be great but beggars can't be choosers. Besides being a huge power hungry boat anchor, I love my DSA602A. It has been a fixture in my lab for years and a reliable final answer to many questions when troubleshooting.

Hi everyone, I’m starting with oscilloscopes and electronics. I got a Tektronix 475 that I would like to repair for my lab. It turns on but unfortunately I have no trace...I tested the voltages. Everything seems to be ok (+15v, +8v , +115v) except for the 50v, I get +65v...all components in this sector tend to heat up after 10 minutes. For the rest, I do not know where to start? Thanks in advance for your help, PS

Having spent some time trying to fix a 2756P analyzer, I can contribute to the group some of my findings. The analyzer had so many problems that I was close to giving up. In many cases, troubleshooting had to be based on replacing suspicous components that behaved strange as well as replacing most supply bypass capacitors I could find without actually testing them for value or ESR. It was a matter of saving time and working my way board by board. After all, this analyzer is almost 35 years old so I guess it could have passed its "best before" date long ago. There were several Allen Bradley carbon resistors that had drifted far beyond their designated resistance value. Both low ohmic resistors used for supply bypass as well as high resistance types found elsewhere. A 4.7 MOhm was found to be 7M. A 10 MOhm was found to be 14M. These resistors are found on the YIG/PLL boards. Also the resistor locations given by John Miles, KE5FX was bad but in my case I replaced them with 1% metal film types. Note that there is one A-B resistor hidden underneath the large R1040 (25 Ohm) on the 1st LO driver board. C2072 (10nF) was replaced with 0.1uF. In general: All ceramic thru-hole capacitors Y5V was replaced with modern X7R or NP0 types (where applicable) Some tantalum axial capacitors was found to be a bit leaky and was replaced with aluminium types. I did replace some OPAmps in the YIG/PLL circuitry, replacing them with OP07 (and removing the 100pF frequency compensation capacitors) but used sockets after unsoldering and saving the removed OPAmps. If this contributed to the analyzer performance I do not know but it drifted out of lock before and together with the rest of the components that was replaced stayed stable afterwards. PSU was completely recapped but I remember a hint by a friend: Replacing suspicous older electrolythic capacitors in power supplys can result in shut-downs due to detected over current transients caused by the modern types lower ESR. In the case of the 2756, no such shut-down occurred however. The temperature of the air from the rear vents was +65 celsius or higher and the surface was getting hot to the touch. I had previously drilled extra holes in the large case close to and under the front panel. This time, I increased the number of holes considerably and the air temperature went down as well as the fan started running at a slower pace. I do not know if Tektronix designed the instrument and its case to run that hot as the original air vent intake area was even smaller but it seems strange to me if that was the intent. Ulf SM6GXV

John Williams <books4you4@...> added the photo album Reviving interest in 500 Series Oscilloscopes ( https://groups.io/g/TekScopes/album?id=299466 ) : I am posting some photos of my Tektronix oscilloscopes in the hope that this will stimulate interest in these fine scopes and bring some more discussion. --- The following photos have been uploaded to the Reviving interest in 500 Series Oscilloscopes ( https://groups.io/g/TekScopes/album?id=299466 ) photo album of the TekScopes@groups.io group. * IMG_1790.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866320 ) * IMG_1789.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866321 ) * IMG_1788.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866322 ) * IMG_1790.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866323 ) * IMG_1789.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866324 ) * IMG_1788.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866325 ) *By:* John Williams <books4you4@...> --- The following photos have been uploaded to the Reviving interest in 500 Series Oscilloscopes ( https://groups.io/g/TekScopes/album?id=299466 ) photo album of the TekScopes@groups.io group. * IMG_1741.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866326 ) * IMG_0667.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866327 ) * IMG_0600.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866328 ) * IMG_0598.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866329 ) * IMG_0597.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866330 ) * IMG_0596.jpeg ( https://groups.io/g/TekScopes/photofromactivity?id=3866331 ) *By:* John Williams <books4you4@...>

Hi folks, I'm new here. The NVRAM (Dallas DS1245YP) inside my TDS7104 just died and I found that someone had created an FRAM replacement for this. https://www.eevblog.com/forum/testgear/tek-csa7404-repair-project/msg1448143/#msg1448143 Gerbers for an updated version are available: https://www.pcbway.com/project/shareproject/DS1245YP_Replacement_Board.html Unfortunately, no further information is available, e.g. components used and the author won't answer... I find it very attractive to get away from the backup battery for good so I am tempted to go this way. Is there anyone here who has built version 2 of this? If so, what voltage regulator was used? Does the replacement work as expected? Thanks, Tom

Looking for schematics and manual for a United Systems Corp. Digitec Model 311 DC Calibrator. Any help greatly appreciated. Rick

Hi everyone, I have a 7L13 that seems to have a gain issue somewhere. A -30 dBm signal comes through as approx. -60 dBm. The input attenuator is set to 0 dB and the gain selector is fully ccw for a top screen reference level of -30 dBm. The front panel AMPL pot (R80) is not able to increase the gain enough for full-screen amplitude. The RF section appears to be intact since I can see the 50 MHz signal along with the harmonics when I use the calibrator signal as input. Only the amplitude displayed on the screen seems to be low; everything else seems to be working. I've also tested the input attenuator all the way to the output of the 3dB PAD. I've done the calibration for the Function IF and a 0 dBm 10 MHz signal does produce full screen deflection as indicated in the block diagram. I've been able to complete the full Function IF calibration with no issues. Block diagram: https://w140.com/tekwiki/images/3/38/070-1673-00.pdf#page=124 Function IF calibration: https://w140.com/tekwiki/images/3/38/070-1673-00.pdf#page=48 I am now trying to troubleshoot the Resolution Selector section since there are some amplifier stages in there. Here is where I'm a bit stuck. Waveforms: https://w140.com/tekwiki/images/3/38/070-1673-00.pdf#page=149 I'm looking at the waveforms that show the output of the 3rd mixer and the output of the pre-resolution amp. I am able to see a similar modulated waveform but what I don't understand is why those diagrams say "Input -10 dBm" and "Input -18 dBm". What do those input level refer to? According to the INPUT specifications, I don't think I can apply a -10 dBm or -18 dBm signal at the input. It says: "MAXIMUM INPUT POWER LEVEL: -30 dBm with the RF Attenuator at 0 dB, for linear operation, +30 dBm with the RF Attenuator at 60 dB. (+30 dBm is also the power rating of the RF Attenuator.)" QUESTION: Why did they insert ", for linear operation," in that sentence above? Are they implying that greater than -30 dBm will produce distortion (and not blow the input mixer) or does this have something to do with linear vs. logarithmic? Does this apply to the latter half of the sentence only? It also says: "NOTE: The maximum input power level to the RF attenuator is 1 watt average and 200 watts peak (SN B119999 and below); or 100 watts peak (SN B120000 and above). +13 dBm will destroy the first mixer." Isn't this saying the same thing? An average of 1 watt into 50 ohms gives an RMS voltage of sqrt(50) or about 30 dBm, which is the max input into the attenuator as stated above. QUESTION: Based on the specifications, am I allowed a signal in the -30dBm to +13 dBm range? I don't want to blow the first mixer or it's game over! Thanks in advance for any advice on how to proceed with this troubleshooting.

Does this look odd to anyone else? https://www.ebay.com/itm/375606603143 https://w140.com/tekwiki/wiki/T7510 Thanks, Barry - N4BUQ

I have been working on a 7844 dual beam scope that has a beam intensity problem. The scope was working, then the power supply quit with a rapid tick. Ok I had another 7844 that has a different problem but a good power supply. Swapped the power supply, now both beams are overpowered, even at minimum intensity, power supply voltages are all in tolerance. The intensity controls do increase intensity but can't reduce the intensity below what was close to maximum before. Focus controls can adjust the focus but not enough. Readout intensity is normal. Thoughts of where to start checking would be appreciated! Mark W7HPW

Interested in a TR502 and cable to pair with my functional 7L13 Also would like original manuals for both Marty KL7AM

Hi, is there any way to open and fix the 155-0064-00 ? Mine has one transistor input open Thanks Best regards

This is Michele from Italy. I' am a Tek lover too, I have two scopes a 465B and an old monster 556. Recently I added a S.A. 2715 to renew the ancient HP8558/182T. Now I am in auto-training phase, playing and reading the manuals. I would ask your help to understand the best way to make sure I have no risk that all normalizing parameter in the NVRAM will not get lost. I don't know the residual life of the backup battery (BT1) located in A11-Digital options board, so my intention is to change it asap. *1st question : If I change the soldered backup battery NVRAM will remain without power supply for several minutes. In the mean time data will be lost. There is any trick to avoid this situation? *2nd question : To upload normalizing settings I understood it is necessary a PC service application communicating via RS232. There is any other way to do this work? Data can be displayed on crt screen but is not clear if is possible to simply rewrite manually in same menu. I have an idea on how to do this work, but probably someone here is more experienced than me and I will wait your answers. Thanks in advance for your attention.

I powered up one of my 7704As which worked fine the last time I used it several months ago. This time it worked for about 30 seconds and stopped with the power supply going into a rapid tick mode which I presume the frequency of the relaxation oscillator. I opened it up and using an autotransformer to slowly take the voltage up, I observed DS3019 flashing in time with the ticks. At first, the ticking is much slower but as I increase the input voltage, the ticks get faster and are fastest at full input voltage. I checked across CR3015 and the voltage is getting up to what I remember as a normal level (don't remember what I measured but since that circuit develops peak-to-peak the line voltage value, it should be around 350vdc which I think is close). I know what "normal" tick mode sounds like but this seems to be something that's occurring before the startup circuits are at work causing the the "normal" ticks. Is it likely that the inverter is never getting to the point of trying to start? If so, then I presume the inverter controller chip isn't working or, at least, isn't seeing what it needs to work. Is that a reasonable assumption? Thanks, Barry - N4BUQ