Bench Power Supply Repair (TTi CPX400A)

Mark repairs a bench power supply that died whilst testing a 5kW amplifier (see previous video, for the demise of the power supply). Luckily, its a well built piece of kit, and not as damaged as feared. However, Mark does get bored of the calibration - especially when it looks too powerful for the other calibration gear!

[@VoeViking]

The attention to detail while filming is amazing. I can't imagine how many times you have to move between shots just to show a bolt being unscrewed. Excellent production value, guess you go 110% on everything you do. Congrats.

[@ovalwingnut]

VVman. You are a gentleman and a scholar Just saying :)

[@ewhibs]

I’d be dreading fooling with that chip and Mark is like whatever, let’s move em around for kicks. Dude is amazing. Love this channel.

[@twotone3070]

I was thinking the same, I wondered how many cameras were in use and what sort of mount to get in behind the equipment on the bench.

[@Tony-he8ze]

Hey Mark. I have a B&K 1550 bench supply I suspect got wacked by an inductive load. It's been sitting for years. I almost threw it away because I couldn't find a schematic for it. You inspired me, so today I dug into it and found a shorted FET that switches the output on and off. Replaced it with a similar part I had on hand, and it works perfectly. Love your show. Thank you!

[@nickloughrey9841]

72 year old ex repair guy from the 80,s . Only things I can add are use capton tape around before air gun desoldering and a drop of liquid flux on the pins to help desoldering . What amazes me most is your dogged patience . I would have thrown half the stuff out the window ........................... respect !

[@itsmecen50red70]

if there were more people like you, the world would be a much better place. While i am interested in what you're doing, who you are as a person is why i keep coming back. All the best from Australia mate

[@stephenmorrissey1254]

I really believe you'd get 250,000 subscribers easily if you keep posting. The editing of your videos is probably more of a hassle than fixing the equipment but I really see you getting a significant group of followers. Extra cash flow is always nice as well! Would like to see you try again fixing that unreleased Bose that stumped you!

[@hydorah]

Well done Mark. Excellent diagnostic skills! Handy to have lab equipment to help you check your lab equipment 🙂

[@hydorah]

I was thinking when I saw you hot air soldering, I made a foil shield with a rectangular hole for the IC I was after heating the legs on, last time I did some thing like that as not to melt adjacent components! That said my diagnostic skills and knowledge are zero compared to yours! Good to see you are still human 😛

[@qwertyFUBAR]

Sliding it back onto the shelf, and the moment when you push it back and forth a few times just for the joy of hearing the rubber feet squeak... small things like that make life worth living. You are my favorite Internet technician with your deep and useful skill set, the cheerful and dogged determination with which you attack any problem, and your respect for vintage electronics... even a few things we recognized as 'cheaply made' back in the day. You shrug with every new challenge, fix it right, repair the hinges and recast the knobs. You give it your all which exceeds 150%.

[@FunzieOne]

hell yeah! was hoping this would get a follow up. you are by far one of my favorite repair channels on here. keep it up

[@ekus6196]

Hi Mark , good to see an excellent engineer at work . Just to say that I designed the main power PCBs . The front panel circuit was a successful legacy design and used on many of the other TTi PSUs . I am not on the TTi staff , rather an external designer . The company is very helpful if you ever require schematics etc .

[@jaycee1980]

@ekus6196 out of interest, why was a magamp chosen for the design? It's not something you see very often!

[@ekus6196]

The magamp affords a very easy method of synchronous post regulation . The control of the reset current is very simple , the switching is very soft thus not causing EMI and it is virtually indestructable . A semiconductor implementstion is considerably more complicated and no-where as robust . Over the last 30 years , I have used magamps in various different TTI designs putting the quantitiy of magamps out in the field in the hundreds of thouthands .

[@jaycee1980]

@@ekus6196 Interesting :) When I first came across the schematic I started looking for info about how magamps work - and just couldnt find anything much other than them being "historic" components!

[@jaycee1980]

Of course now I've searched again, I've found a paper at TI called "Magnetic Amplifier Control for Simple Low-cost Secondary Regulation" :)

[@puciohenzap891]

Time to grab a cuppa and watch

[@Mr_Wh1]

Yes! A new video from Mark, just in time for some nighttime relaxation. Thank you Mark. 👍

[@ProfSimonHolland]

Mark....i held my breath....metal screwdriver tip! how about a plastic pot adjuster? great channel

[@DeadKoby]

I always enjoy watching your fixes. I'm a fixer myself, but with less experience in certain areas. I appreciate your attentiveness to diagnose the issue in an efficient manner. It keeps things in a watchable manner.

[@billwoods9302]

It's amazing to think that Mark's skills include the knowledge to diagnose and repair his own test equipment. Warranties on electronics mean nothing to this guy. :)

[@-Troll-]

I love this guy. His happy face shows how much he loves his job.

[@montygore1200]

Sir I have been a tech retired worked for 40 years. You are a natural. Very bright and the fastest I have seen at troubleshooting. You are still young I hope you get rich. W5DN

[@misterbonzoid5623]

Nobody gets rich repairing hardware like this. It's a vocation.

[@alien8r33d]

At 11:36 I shouted at the screen that the chip was round the wrong way, at 11:39 it was correctly orientated, so you heard me then.

[@thedevilinthecircuit1414]

Outstanding fix as usual. You have such a relaxed, deliberate and effective approach to troubleshooting. This is the South Main Auto version of electronics repair

[@andrewwturner]

My 'go to' is PHAD, got to clean those green crusties!

[@IanScottJohnston]

Nice repair Mark.......am thinking a voltage spike might have wiped out that ADC, and if it did you were lucky it didn't take out the PIC etc.

[@KarolosAthens]

Telequipment / Telemecanic .............. WHO KNOWS in the new Net Web !!!!!!!!

[@jimle22]

If this were me, I would probably get the chips mixed up and forget which one was good and which one was bad.

[@tony359]

amazing tool the TTI, I have two myself someone was throwing away! They're smaller and much older but amazing! Great video I enjoyed the cal process!

[@markfx12]

What level of tech schooling did you complete? And when/how did you become interested enough to pursue it? When I went to your website to see if you list those answers there, I noticed that you are currently not accepting equipment for repair due to being overwhelmed. A problem for only the very best in their respective fields!

[@kaiwenwu1947]

Brilliant. And entertaining. Well done. And let's have more videos. Lol

[@fluke196c]

Great to see you upload! I can't wait to see how you fixed the decapitated rocking horse.

[@UKDrew]

Awesome as Always... Great Update Loved this.

[@JCWise-sf9ww]

Wonderful electronics repair channel. Good thing you have other Lab testing equipment to re-calibrate the repaired dual power supply.

[@andrewwright1200]

what muppet broke that 🙂

[@CaptainKirk01]

Well, I have watched almost all your videos since finding you a short while ago. Besides having great videos, One thing that sticks out to me is, You seem to have everything (not hyperbole either) , tools/equipment/gadgets, even cast your own parts. I was amazed when you rebuilt a transformer. The more I watch the more you blow my mind with everything you have at hand for the repair. Amazing! Nice work Sir.

[@darrenmurphy6251]

great to see a uk repair channel ! love your optimism , if i see a pic micro i think bugger thats the end of that then! ive been haunted by pics suffering amnesia in arcam amps and tti psu,s keep up the good work , youd be a hero if you keep saying "esd protection ? dont need that nonsense here in the uk ! no one believes me, rain earths out esd

[@robertmeyer7664]

I love the fact you don't give up Excellent discipline and knowledge Good show for everyone

[@DominicClifton]

i was talking to the screen as you removed the adc saying "where's your kapton tape over the pots!", and chuckled when you said you'd melted it later! heheh. doh!

[@stumeek6825]

Mark. Another exceptional view, many thanks , pls keep them coming!! Your channel, is immense . Pure inspiration and joy!! Wonderment ⚡️⚡️

[@ianliston-smith7921]

Great work. But Jeez, does a power supply really need to be that complex?

[@kevinmothers904]

Nice bit of detective work and methodical analysis found the fault but you had me worried @26.36 with that, 'I can smell something getting hot' moment. Even though you are fully qualified do you have get an outside company to do the PAT tests now as there are several different categories and the sticker showed a company from Hertford?

[@tiromancino_tt]

Great job, very nice power supply , high-quality electronics

[@clivequinn8978]

Excellent video, thank you Mark.

[@audiodiwhy2195]

I would have been scared to swap the chips as Mark does in the video using just hot air. Very gutsy repair.

[@jampskan5690]

I wish everything came with available schematics

[@chilledoutpaul]

Hi Mark Just a small gift from one repair guy to another, I only started watching you a couple of weeks ago, Now I watch you all the time! I have a youtube channel but it has remained dormant for ages. Thanks for the great videos & the inspiration. Paul from Edmonton, UK

[@MendItMark]

Hi Paul, I just found this in the comments! Thankyou very much! A bit late, I know... Mark

[@JosevaldoSilva-p8c]

Muito bom parabéns 👍👍👍👍👏👏👏

[@fozzienz7616]

hi mark watching in new zealand just love watching your videos

[@Yorumcu63]

Best electronic repair channel also have so much smile too lol

[@marekg2303]

Super.Szanuję ludzi z pasją.A do tego taką, jaką sam posiadam. Uwielbiam elektronikę audio, zwłaszcza tą z duszą.Pozdrawiam z Polski.

[@JoopKomkommerShake]

It was not necessarily to swap both adc. Only move the working (left) adc to the right was enough to test your theory. Nice repair again.

[@Tokaisho1]

Your channel is going to grow huge in time Mark, amazing content.

[@pauldavies6037]

Wow those PSU are complicated I am going to tot up how much all your test gear will cost out of my league glad I am out of the trade now and dont have to use a microscope to repair things great job as usual Mark

[@John-we7jx]

Superb content and video quality- in awe of your microsurgery skills!

[@iyann3204]

Salam Hadir dari indonesia

[@stewstube70]

I picked up a dead one of the exact same power supply that was being thrown out at work. Haven't confirmed the fault symptom yet but this has inspired me to open it up and have a look :)

[@paulmcdonough9595]

Very satisfying watching you mend test equipment, nice one Mark

[@marczarattini946]

Hi Mark. Very good video again and I've had a few thoughts. The ADC has two ground pins. The digital ground which goes with the supplies to the chip, and an analogue ground (marked GA) which goes with the input voltage to be measured. Now, whilst the analogue input pin is probably fed via a buffer, the analogue ground may be connected directly to the negative PSU output terminal. If the negative terminal of the PSU was forced positive by an incorrect connection to another PSU then the analogue ground of the ADC could be reversed polarity and take it out. Just a thought. Cheers

[@ЁбрагимИпатенкоибнАдхарма]

forced positive relative what? If you rise PSUs neg terminal, you also rises its rest circuitry by same potential thus no destructive voltage can be created until you reach voltage strength limit of primary or ground insulation.

[@typedef_]

These are good power supplies. I've been using one for 10+ years and it's been used before me by others. I've dropped it, bumped it, overloaded it, operated it in below 0 degrees C 🤣... The thing just keeps on working.

[@turbokadett]

I saw the thumbnail and witout reading the caption I knew it was the supply under the knife. I don't think any engineer can face doing a job until their own kit is fixed and back up in its rightful place.

[@MrPnew1]

Very nice diagnostic tips and great videography as usual Mark. Thank you

[@neilbarnett3046]

That setup procedure reminds me of CDC band printers around 1980, 12 25-turn resistors to get it set up, and nearly all of them mutually dependent, even the +5 and +2.5 rails. Oh, what fun we had.

[@paulmccolgan8462]

Man truly knows his stuff absolute pleasure to watch thank you Mark

[@berndb.5097]

Nothing is more satisfying than having your own tools work. Good job , Mark 😎😎👍👍

[@voltare2amstereo]

that tds-754 scope, is that a sequential colour lcd filter over a mono crt? like the jvc tv technology connections showed?

[@xuanthuyvannguyenthuy4781]

Chào Shop rất hay tuyệt điện tử thiết kế điện áp hiệu quả đẹp Hello

[@ajitvasudeo6227]

Hi Mark....Is it possible to convert a 5.1 channel receiver to a 2.1 channel amp with internal circuit modifications ? Do reply.... just curious to know....

[@tomharris1457]

You have some great kit there.

[@JotaVe_45]

Hey mark! I really enjoy your repairs!! What is the spray that you often use to clean pcbs? Greetings from Brazil! And thaks for the videos!!!

[@hancecrawford]

very enjoyable repair much learning Merry christmas Happy Newyear for 2024

[@ashokmarwah3410]

Hi Mark, I have Ti EL651 Power supply. I didn't use it for a couple of months. When I switch it ON, with no any load connected, the output voltmeter shows 15 Volts even turning Course and Fine Voltage adjust Knobs to minimum (FULLY ANTICLOCKWISE). I measured output voltage it shows 15Volts. Current meter shows 0.9 Amp.. Can you please help me fixing the problem. Thanks Ashok Marwaha

[@Mikishots]

So...if you blow up another power supply while testing your power supply, then you'd have a... See, this is where black holes REALLY come from.

[@Choober65]

I HATE TTi PSU's with a vengeance, Ametek, and California Instruments too. Bought the latest and newest 100A PSU from TTi. So new this was serial No. 1. Turned it on and it blew up, and I MEAN BLEW UP. Oh, and Sorensen's are shite too.

[@fellpower]

You are the "Funny Electronic" - I laughed in all your videos ;)

[@سميرعجاج-س7ص]

شكرا لك عندي دك كينوود x_7J بدي اشغل دخول 14فلت AC كيف

[@gregreynolds5686]

Great video. I really like TTI kit, normally very high quality.

[@Piodor007]

Good job Mark. Do you know how to update firmware on TSX 3510P model? I`m trying to communicate TTi software TEST BRIDGE with my PSU but can`t connect so TTi advised me to update firmware to latest revision. The flash updater software TTi showing that my PSU is not in flash mode. I know in version with LAN (LXI) need to be pressed lan reset button with power on at the same time to enter into flash mode. I appreciate for any help.

[@ovalwingnut]

M.A.S.T.E.R.F.U.L :) Cheers from So.CA.USA 3rd house on the right. p.s. That is one sweet P/S. And it's build quality seems to be top-notch. You lucky !%&#$

[@miltonthecat2240]

I have a TTi power supply, model QPX600DP, that is broken. The factory was kind enough to send me a pdf of the service manual, but it is a scanned copy, and the schematic is unreadable. Where did you find your service manual? (Yes, I expect to pay for a service manual.)

[@radarmusen]

I like that power supply, we got one at work. Like it’s able to give full current out of the front connectors. It’s too expensive for me even as used so I bought me a RND.

[@jpdesroc]

How did you manage to put back the firmware in that new 16F72 chip ? The other one was readable so copyable ?

[@ttyR265]

I have to chuckle at using metal screwdriver bits that if dropped could potentially cause a short on a live circuit. Wouldn't plastic tools for adjustments be more prudent?

[@martsmiscmix]

Many people I know what "The Repair Shop" on TV and think it's great - I watch "Mend It Mark" on KZbin, and I think it is WAY better! 😂

[@jules4096]

Hello Mark. Very very good videos you have made. Interesting and educative, wish there were more like you. I'm talking from the position of a hobby "fixer", way less experienced than you. Only one thing intrigues me: are those chips soldered ok? I mean is there enough solder on the pins? I have to agree that no one pulls on them and the forces upon them should be quite small except the possible thermal stress which can lead to accidental de-soldering or cold joints. Love your videos, looking forward to seeing more.

[@mountain177]

Hi Mark! Have you ever had to repair a crown d45/75 amplifier? Im hoping to seek a little advise. I have one that the IOP indicators stay illuminated on, with no signal applied, and the output is muted. Any help is appreciated! Thanks

[@centontube]

Salve Mark. -- Domanda: ripara amplificatori a valvole della marca MESA? Grazie. Complimenti per i suoi video….grande!!! 🤗👏🏻👏🏻👏🏻👋👋👋💪🏻

[@YannickClolus]

Hey Mark, I have a power supply TTI QPX600D and I try to find the manual service to repair it. Do you have this manual or do you know where i can download it ?

[@paulm3079]

That power supply is actually a really nice piece of equipment; dual 1200 watt channels 60x20…definitely worth the effort to fix that. Nice unit

[@realistictruckers8208]

greetings @Mend It Mark Do you have the schematic of the Uni-t UT601 RC meter?

[@johnwilliamson467]

I have found that both Mouser and Digi-key the shipping because of low weight is about the same for 1 part as 200 USD worth of parts . Causes me to only order in 200 to 300 USD batches.

[@johnmarchington3146]

Mark, does that power supply not incorporate multi-turm pots? There is one other thing that puzzles me. When you suspect that one of two identical chips is faulty, why do you solder the suspected faulty one back in when you do the swap? If you just solder is the supposed good one into what was the 'faulty' channel and it works, surely you've proved that the other chip is faulty and you would still have a vacant set of pads ready for the new, replacement chip to be soldered in. Just a thought. Maybe I'm missing something.

[@ZiggyStardust-pk5wt]

I never cease to be absolutely amazed by your incredible skill, knowledge and talent Mark.

[@andremantovani]

oh you’re awesome! great videos, a lovely time to relax watching! congrats, keep it up!!

[@elsaarmstrong-zp6ng]

Mark! I thought all semiconductors were with built in anti static devices nowadays?

[@MrScubaduba1]

I have some old HP Logic Probes if you're interested. Looks like they would fit in with your scopes.

[@HammysHangout]

Good Power Supply, I had an issue with mine and the same chip, letting it stay turned off for a day fixed it.

[@SDS-1]

Wahoo!!! Good fix 😃

[@andrewsoldan6050]

man I have Chinese power supply 30V 15A and it won't start , only fan turns on and off along with blinking red led on the board - any tips how to tackle this?

[@absurdengineering]

The mechanical engineer in me cringes slightly at the location of all those calibration potentiometers. First thing in the layout they go on the edge of the board, right angle mounting so they all point up for easy access when the front panel is installed. Readout calibration pots can feed voltages to the ADC and be read by the MCU. Great alternative to doing pure digital calibration brouhaha: it’s still digital; just constants using pots instead of eeprom data. The MCU needs no alterable memory and can be OTP. Basically: pots for every section should output voltages proportional to the reference voltage. These voltages then are either captured by the ADC or buffered and put on the ends of the front panel control potentiometers and so on. As it is, some of pots act as dividers for dynamic signals or adjustable gains so they need to be close to the circuit that uses them. That’s the easy way out. It’s also much easier to filter out a scratchy pot in a voltage source than in a feedback loop voltage gain adjustment.

[@andydriscoll1903]

I enjoy your videos but is there any need for a bench power supply to be so complex! It’s like a modern car when it breaks down, never a mechanical fault but a faulty sensor, drives me mad!

[@BrianSmith-ow9gy]

I was too nervous to keep watching as you used that metal screwdriver bit to adjust the pots. For the sake of my heart, please find a plastic one. If it fell out of your fingers, for whatever reason, there would be an almighty blue flash; and a whole new video I suppose :)

[@dkoxperiakoziukov3808]

I wish you luck in a door phone repair. Precisely In replacing the new blank PIC microcontroller and geting nothing eventualy, because of the code lack

[@Mindsi]

Has anyone seen that episode of mr Carlsons lab, when they put an ociiliscope parts in a dishwasher😂😂😂😂😂😂😂😂😂🎉🎉🎉

[@PaulHigginbothamSr]

And the smiling Mark adjusts the outputs to read better than it did when first seen. Of course one side read nothing but was still operating. A good way to destroy expensive graphics chips.

[@Duracellmumus]

When you switch the power button off @2:08 the psu output going to 72V from 9V. It may do some fun if the controll section power is geting off before the main psu is halt.

[@alanreynolds5985]

What was the reason you put the bad chip back into circuit on the good side when it could have damaged something if it was faulty. I like your videos. You obviously are very good at what you do.