D-lab recommends how to repair tube amps best oscilloscope Iwatsu SS-5702
Вставка
- Опубліковано 17 кві 2015
- I get e-mails here and there asking " what is a good scope for repairing tube amps/electronics. I say: buy an inexpensive Japanese type. Leader/ Iwatsu, etc. You can find these scope for well under $100.00 and they do the job well. Tektronix scopes are nice, but expensive and overkill for vintage electronic repair.
- Наука та технологія
Thanks d-lab. I got my enormous Tektronix valve scope for show-pony work, and to make my desk look great, or to warm up the workspace in winter, and then off the back of this video and your recommendation I got my Leader 524 scope for donkey work.
Thanks for the great advice D-lab, I'm an ongoing fan and learn so much from your vids. So far I've built a 5F1 and a 5E3, re-voiced and completely reworked all the grounding based off of Merlin Blencowe's tube book. You're videos helped quiet things down and find a few previous issues. Maybe my next build will be a jtm45, I can't wait.
I couldn't find any good deals on an Iwatzu but I found a Leader LBO-524 40Hz in great condition $74 out the Ebay door this is my first analog O-scope I was previously using a very simple cheap portable handheld digital scope/meter. Now I just need to find some decent probs.
Thanks for your practical advice Terry!
I love old Japanese scopes. Leader makes great gear. Iwatsu made scopes for other big label brands, as well.
Hey Mr. D. - Thanks so much for this and your other videos. I picked up a Circuit Test 25mHz O-Scope for $100.00 Cdn, and a Mercury 1100C tube tester for $65.00 Cdn and with my two previously purchased VOMs years ago, am quite pleased with my bench test gear at bargain basement prices. Still need a sig-gen but one will pop up on CL sooner than later. Your videos, as well as Uncle Doug's are appreciated. Have a Cabernet on me tonight! Kind regards from the west coast of Canada! - c / 1993 Fender Deluxe Reverb RI. PS - Keep reminding them about those Caps that can pack a punch and how to discharge them a couple of times before anything is attempted under the hood. Rgrds.
Brother, what a great video...thank you for the down to earth wisdom!! God bless!
Great Respect and Gratitude, to professor D-Lab from The University of UA-cam!
Thanks for being around, and Keep with the good Work!
Steve
:-)
Thanks for this great info! And helping us with your guidance.
Thanks for the public service announcement on appropriate oscilloscopes for guitar amps!
Hey guys, the scope will work on any tube amp.
Just make sure to use a dummy load
Do these sometimes need to be calibrated if so how about do you go about it?
how about a Leader LS 8022 for around 125 in great condition, would that be a good one?
that's 1000 times
Top channel keep it up i`m enjoying your videos!!! P.S love the tunes in the back ground rock on !
Thanks Terry! Great advice done well!! cheers man!!
***** Thanks, Good luck with your oscilloscope
Good information Terry; My scope is switchable from 100MHz down to 20MHz which I find is more than suitable for most applications, "nice demonstration"
Thanks for the recommendation. I picked up a Leader 1020 dual trace 20MHz scope from an eBay seller in practically new condition for less than $100. Great scope.
Cool deal man, The Leaders are great machines. Perfect choice for audio work. TD
hi there terry love your vids and really appreciate your time and effort that goes into making them. I was wondering if you could do a video on interpreting scope wave forms sometime .if time allows cheers from new zealand
I bought a Hitachi 35MHZ scope back in1990 and it still works great so if you can find a used one it's worth consideration.
I have a 5MHz scope. I did all my audio related problems on it. It is good enough. In my previous job, there were a few Tectronix 4 channels with digital storage costing S$60000 in the mid 80s. Only engineers were authorised to use it. I could only carass it. On one incident, we had some problems with a high band Sony U-matic recorder. The Japanese (attached to us on loan) engineer asked to me to hook up a scope. After powering up, he found that beams were out of focus no matter how he adjusted it. He then proceeded to remove the enclosure and began an inspection of the likely fault. I came by and have a look. After a while he asked me to get the service manuals from the storeroom. I told him no need to check the service manuals. Without a blink of my eye, I told him, xxx san please check the rows of resistors on the crt board, I was sure one of them was bad. He replied with disbelief. "SURE GA?". He took the multi meter and did some checkings. Sure enough, there was an open resistor. He was pleasantly surprised. How did I knew it? Because it was similiar to normal crt tv problems. I was repairing tv in my spare times. For those who do not know : high band Umatic recorders were used in broadcast recordings and editings. A single 60 minutes cassette cost S$60.00 back then. Hope you like my story.
Thank you so much for all the great videos. Would you recommend this scope over the new digital ones like from Rigol, Owon, UNI-T, Hantek etc. because they aren't that expensive either these days.
These were great scopes in their day but just like all vintage amplifiers the switch contacts and pots can get oxidized and their function becomes intermittent. You have to clean these with contact cleaner but If you can get one to work like when it was new you will be a happy camper ! ! ! !
Wow, right at the time I needed one. Thanks, man. Will it work the same on a 100 watt head, albeit much louder when connected to a 4x12 cab load?
I'm partial to Tektronix like many people, but they're famous for using custom parts, so some of them can be a real pig to service.
Hi D-lab, Great videos, thank you. Pro Gtr player here who is just getting into my own amp repair. Putting together my bench and learning the basics. I bought a huge load of stuff at an Estate sale , bunch of old tube radios, test gear etc ( what prompted me to make the leap) I have a Tektronix 434 Storage Ocilloscope and a Leader LBO-520A Dual Trace and a BK Precision 1403A. Which one of these ( provided they work ) would be the best for me to keep for my bench? Thanks for any info.
hi ! what is the brand and the model of your little audio generator ? thank's
The Hitachi scopes are a good choice also.
Yeah, thanks... ...I'm looking for some cheap scopes for audio use. I have two older Tek scopes, but they were cheap hamfest/ebay finds... ...one was given to me. They can be buggy due to age/use as you say. Even for a low end Rigol, Keysight it is expensive.
Hi nice info ....is the scope just for troubleshooting signals alone on the amp? or can it find voltage or component issues?
I wish I would of saw your video first before I watched Mr Carlson's Lab video where he working on Fender Deville where he recommends using a tube oscilloscope for tube amp repair. I bought a Bell & Howell Devry tube oscilloscope #34. Whatever I did to it caps ect it is still a POS. I bought a second one it has a bad tube in it. It was for parts though. Then I bought a sencore PS127 it was working fine until I tried to replace the input jack . It was the old RCA mic type. Now it won't trigger.
Hi D-Lab, I know this is an old video but this is a long shot! I recently inherited one of these Iwatsu scopes from my father who passed away. I've checked it over and it seems to work well except that I cannot get the Dual trace to work, Ch1, Ch2 and ADD are ok but I only get one trace on the Dual mode. I have managed to find the service manual and will probably have to get someone more knowledgeable than I to go through and troubleshoot it but do you happen to have any idea what the problem could be?
terry where do you get the leads for the ss5702 i picked one up but it didn't have them or do ya have some ya might want to sell
Great advice Terry, it is silly to see the beginner go out and pay $350 to $500 for New Digital storage scope when the scope you have will do fine. My first scope was a second hand Heathkit 10MHz scope that dig what I wanted it to for $25.00.
73 KG0MN
Good info Terry! I actually found a nice used Tektronix 2014 here in Austin on craigslist. So I'm ready to test my amps. It would be great if you did a follow up video on just what to look for on the scope display with regards to the amplifier signals we are seeing. i.e. what are the anomalies on the trace and what do they mean in terms of the amplifier problems. Also, exacty what do the connections between the amp and scope look like? I understand the need for the dummy load. But what does that look like and how do I make one or can I just buy something?
Thanks for all the great videos! and cheers to Robert Mondavi, a personal fav of mine.
ObeWanKobe in Austin
+obewankobe Hello, Yes Sir, I do need to make a video of the scope connections. Have been asked by others as well. Will get something out soon. Congrats on the Tek scope! They sure are cheaper than they were back in the day. I bought my first SS-5702 Iwatsu scope in CA at RAG electronics. Mostly did stereo repair back then. Now 70% tube amps. Glad you like my wine choice. Its part of the presentation. TD
Hello there Terry! Thanks for making this video and giving such a nice example of a fine scope for simple diagnosis. I decided to see if I could find any Iwatsu ones around where I live through mercadolivre (brazilian ebay), and all I found were out of order / part sources.
However I did find some scopes going from 80$ up to 180$, and I wanted to ask if maybe you knew if any of them were decent or not?
The models are (from lowest to highest price) :
- Pantec-5210 15 MHz (mint, no probes)
- Kikusui COS5020 20MHz (used, no probes)
- Minipa MO-1221 20MHz (mint, 2 probes)
- Goldstar OS-9020A 20MHz (mint, no probes)
- Hitachi V-650F 60MHz (well used, 2 probes)
- Instrutherm OA-202 20MHz (mint, 2 probes, gator clips, user manual, 2 spare fuses)
- Icel SC-6020 20MHz (mint, 2 probes)
I just would like to hear from a more experienced tech which would be the best choice out of those. Personally, I've used and heard good things about the Minipa brand but I'm not familiar with that particular scope model.
Thanks ahead for any information!
blackcorvo Hello, out of your list, The Hitachi and Kikusui are in my opinion great scopes. Also look for Leader and B&K. Some of the Heathkits were nice, but they were kits so you gamble with the quality of construction. Heathkit also made factory wired units.
blackcorvo I have 2 Hitachi's they are great scopes You should be able to find one on ebay for around $100, I got mine for $75 plus shipping. Make sure it powers on and shows a trace, sometimes I email the seller and ask questions.
Problem is very few of the sellers know how to test them so usually they are sold as is.
Is this the more gooder way?
Fairly new to tube amp repair. I have a WEM Dominator 45 guitar amp ( UK built, 1970s guitar amp) which uses 4xEL84s. The output on the scope at 1000hz is dancing about like in this video. I'd say it's worse with about 6 images of the sine wave overlapping and jigging about. Is it safe to assume this is power supply problems caused by bad smoothing caps? If so can you explain what the scope is seeing. Thanks, I think your videos are great.
Hello, do you have excess hum coming from the speaker? Thanks for your support
D-lab Electronics Hi Terry, the amp hums quite a bit, it's not a quiet amp when turned up without an instrument plugged in. The sine wave sounds a bit rough to my ears. Can other things besides bad filter caps cause the jiggling sine wave? I enjoyed your signal tracing video with a fender champ.
Have you looked at the input jacks. Corroded contacts/open shorting contact??
So hi Terry i must start by saying how much i enjoy you channel and videos. I have a question for you if you dont mind. So my grandfather was an electrical engineer and a teatcher in a university in sweden were im from. So when he passed away i saved all of his equipment and among his stuff was an oscilloscope. Now i buildt a couple of amps and pedals and stuff and after watching your videos i realy felt that i wanted to learn to use the oscilloscope.
And now finaly my qustion. How do you hook it upp to the amp and the oscilloscope? so i understand that it has to come from an dummy load or the speakers in to the thing but precisely were im not sure of. So were on the speakers or dummy load and what input in the oscilloscope.
Ok that was a long message for i pretty short question and i hope you understand my english.
Bye and thanks for a good channel
Jens Lindell
+Jens Lindell ua-cam.com/video/EpsUVc3lcMk/v-deo.html Hello, watch this video. I shows the oscope and audio generator in action. Hope this helps.
please what is the title of that song
Many scopes on ebay don't include probes. Which kind of probe or probes are needed to work on tube amps? High or low voltage, current... etc. I'm a noob with scopes so have to ask. Thanks for the great advice!
From what I understand Get the 1x-10x switchable scope probes. Most O scopes with a 10x reduction probe can suffer 400-600 volts for short time. A second or 3 enough time to see a wave form. Then get off the test point pronto, just to be safe.
So, from what little I understand, is'; a 10x reduction probe reduces the 400-600 volts down to 40 to 60 volts on the input, which could be over voltage for the O scope input circuit for more than just a few seconds. Most input circuits can tolerate higher voltages until the input IC internal heat rises and may cause damage. Then its a bummer to find and replace the chip. BWTFDIK.
For poking around high voltage audio circuits you can build your own probe like a signal tracer would use. It doesn't have to be in the probe body, but the signal from the probe tip goes through something like a 0.01uF 600V (or more) cap to block the DC and only let the signal through, then THAT is connected to the scope.
It's not so much that the probe will or won't work on a tube amp, but rather will it properly couple to your scope's vertical amplifier. There are a few things to consider for scope probes. One is the voltage rating as mentioned elsewhere, another is the connector on the vertical amp and probe and other very important things are the bandwidth of your scope and the compensation range of the probe.
You will need to see the capacitance of the input of your scope's vertical amp in picofarads and select a probe that has a compensation range that will adjust to that capacitance. If you don't, you may get a probe that will give you a round leading edge on a square wave (undershoot) or a spike on the leading edge of a square wave (overshoot) which means that the probe is not properly coupled to the vertical amplifier of your scope. It is OK to have a scope probe that has a little higher frequency bandwidth than your scope's vertical amp, but if you have a 10 or 20MHz bandwidth scope and you get a 100MHz probe, you aren't really doing yourself any favors and the compensation range of the probe will likely be outside of the pf coupling of your vertical amp.
I just ordered a set of four scope probes on eBay for a four channel 50MHz vertical amp for one of my scopes. The input capacitance for that one is 20 pF. My other scopes have a bandwidth of 20MHz with input capacitances of 47pF. I can not interchange probes between the two scopes because the compensation range of either types of the probes will not have enough adjustment to work well on either scope. This matters when using square waves (yes, square wave inputs are used in audio testing too) or other testing when looking for distortions in signal.
I bought a Hitachi v-212 ....it seems like it should be ok
the best analogic oscilloscope of all times!
Thanks for this video. I picked up a Leader 514-LBO oscilloscope last year. It's rated at 10 Mhz. Would this scope be suitable or should I be on the lookout for a 20 Mhz? Thanks!
That scope is perfect for audio work
Thanks!
Are you using a 10-1 probe? You say 50v but the knob is showing 5V? Can you give me a link to using your scope to check each filter cap?
Thanks
I got a Leader, 2 channel, 20MHz scope for about $100 that works well for audio and even most radio work.
+Rob T Hello, Yep, Leader test gear is top notch.
I wish I woulda seen this 4 years ago in 2011. I bought a Rigol 1050, 50 Mhz for $350 brand new. They make nice scopes for HP/Agilent low end and by SW it can be hacked to 100 Mhz. but I'll most likely never need 100 Mhz. $100 scope sounds good to me.
I agree, I had a OWON scope and hated the delay before waveforms updated. Sent it down the road. The old analog scopes are my 1st choice for tube audio work.
What do you think about the PC based Oscillicopes? like the Pico 2205A PicoScope 2 channel + AWG, 25MHz
I find that the display update rate is slow as compared to a CRT based scope.
I bought an Iwatsu SS-5711. But when I test the calibration point on the front that says its 1 kHz - 0.6V. My multimeter only reads 0.3V. Is that bad? Shouldn't it actually read 0.6V or close to it?
Also, can you recommend a solid newer digital Scope? Or at least what brands to stay away from or go after? Thanks
The signal at the calibration point is a 0.6V peak to peak square wave. Your multimeter reads AC r.m.s. voltages. If it reads 0.3V it's in the ball park.
Nice..
I have the same scope. Channel 2 just wont appear no matter what. I'm currently trying to diagnose the problem.
Check the vertical for that channel. When they fail, the trace goes off the screen. It may simply be bad solder connections
Thanks mate. I'll check that.
Don't overlook Heathkit scopes. They were well designed. Although every scope will vary on how well it was put together. The good part is that complete manuals are easily available and you can use the troubleshooting guides to help repair your own equipment. Also several Facebook groups for Heathkits in particular, and for vintage test equipment exist, and you can find a lot of help there too.
Who's that playing the blues?
Hp and trio are some others I’ve got both. Hps dead trio works fine I’m getting a 100 MHz myami from china one day and a few others 😊
1000x.
Textronix 465?
I have one with the DMM on top, got it for $50 on ebay... Seems to be a low time unit.
20mhz /20khz is 1000 times more frequency responsive that the audio you will be testing
on the tube amps 20,000,000 /20,000
. Most tube amps start to rolloff around 12khz and down quite a bit by 16khz and so does most guitar speakers..never mind old ears.
My $40 wShipping Toshiba dual trace 20 MHz works great and came with several probes and dozens of jumpers and every connection you can think of to BNC. My best eBay find ever I think, except maybe $39 and change for a signal generator and a frequency generator.
That's made in Japan. I have a Hitachi it's built like a battleship.
This Iwatsu scope is probably OK for audio work, but in a broader sense, it isn't much of a scope. I would recommend searching through ebay for a used Tektronix scope. You may well find a much better used scope that is in great shape for the same cost as the Iwatsu featured in this video.
Turn off background music bud ......
This guy does not show the viewer how to hook up the scope leads to the speaker outputs!! :(
+William Hill The scope leads go in parallel across the dummy load resistor. I have other vids showing the connection. This vid was to recommend a low cost scope for amp work.
+D-lab Electronics So you should also explain why you need a dummy load - because dummy loads are not needed on modern scopes if you use the test leads that come with the scope - they are minimum 300ohm loads.
Will do. I use a 8 ohm non-inductive load. You can buy them at Parts express, rated 10 watts. Simply strap is across the speaker leads and parallel your scope.
+William Hill For got to say, the dummy load takes place of the load that the speaker normally applies to the amp. I disconnect the speaker, 1. so it doesnt drive me nuts when troubleshooting. 2. Allow bench troubleshooting without the need for the speaker and cabinet in my way