Pioneer X-HM21 repair . No display on front

[@PeakAtlas]

The DCA75 will identify the device as a "Darlington" if the Vbe is greater than 1.00V for devices with no internal shunt resistors or greater than 0.80V for devices with internal shunt resistors. I need to re-check that those thresholds are indeed correct as I see yours detected it as Darlington for just >0.9Vbe. In some signal transistors, when they go faulty, develop a very slopey B-E junction and so the Vbe rises more than you would normally expect, and so show as a Darlington. Also, if that happens, the current driving capability (through the collector-emitter) can be badly impaired. It may test ok at 5mA, but really struggle at higher currents, as you have seen. Cheers, Jeremy (Peak).

[@michaeldranfield7140]

Hi . Jeremy , many thanks for the explanation, I did also later try a B-E diode junction test with an analogue multimeter which did indeed show up as a higher than normal B-E resistance which incidentally seemed to change every time the transistor was tested .

[@pauldavies6037]

@@michaeldranfield7140 Yes I was thinking that was weird and do the old multimeter test

[@paulsanderson8804]

This is where your years of experience kicks in .. excellent video Michael ..Great fix

[@michaeldranfield7140]

Yes it does help somewhat, I have only been doing audio though for the last 9 years or so, I never had any time for audio with so much TV and sky boxes coming for repair but I started to take in audio stuff after we went digital and everyone was throwing there CRT sets away.

[@wigcheren61]

Hello Michael, old lady (87) has a Pioneer X-HM36 with the same display problem. Now I had bought another Pioneer X-HM36 and it did nothing at all. Now I have resoldered the transistor from the defective device according to your solution. I was very surprised! The display works again. I'm so happy with your solution, thanks Michael, from old lady Martha.

[@OaklynHall]

Another excellent video, thank you for sharing it with us. Its amazing that the service manual had no schematic or even a basic parts reference list. I think your videos are the best on the internet, I find it fascinating how you go about solving the problem even without a circuit diagram.

[@michaeldranfield7140]

I can not understand why you would put all that technical information in a service manual and then no diagram.

[@FulvioGa]

The best electronic repair channel for me!

[@michaeldranfield7140]

Many thanks for that , I do try to post material that is a bit different to others .

[@allen5976]

Brilliant result Michael, unfortunately I have experienced these useless manuals also all too often nowadays, it just adds to more waste on the pile unless you have the bank of knowledge that you have Michael, thanks for

[@michaeldranfield7140]

I hadn't realised audio stuff has gone the same way as televisions, disposable .

[@mistermikeanson]

I was getting withdrawal symptoms of no new videos from you - then this came along! Nice piece of work and nicely explained!!

[@michaeldranfield7140]

Im actually working on a lot of new mind blowing stuff which the viewers will really like , I have 6 different projects on the go at the moment but my problem not enough hours in a day to do everything so the best videos take time , for example the TV game took nearly 9 months to make , watch this space !

[@michaelwaite6725]

Good video once again Michael, A service manual without circuit diagram who would have thought that was a good idea ? Hope the customer appreciates your time and effort 👍

[@michaeldranfield7140]

You tend to find people with audio equipment appreciate your efforts much more and don't mind paying, unlike TV sets where people are happy to just throw them away and buy another.

[@daveg8htfadlibaudio250]

Magic Michael, yet another good one for the viewers. Regards Dave.

[@michaeldranfield7140]

Very time consuming though without a schematic, this would have taken just a few minutes with a circuit diagram.

[@robtitheridge9708]

An excelent video but i am glad i am retired and no longer have to deal with such things.

[@michaeldranfield7140]

Your not missing that much , every job is challenging now , even the simple ones !

[@allandenman9387]

Hi Michael. Just wanted to add that we ran a Pioneer ASC back then and everything was good. Then we had to give it up when they went over to centralised service. God alone knows how they work now. If ever you want a real challenge, you could try working on some of the Denon units that look similar. You may need a padded cell then!!!!!! Kind regards Allan.

[@michaeldranfield7140]

I get quite a few Denon units in for repair and manage to repair with quite a good successes rate , however a couple I have not managed as yet is the st/by transformer going open circuit and no longer available and more recently a couple with no DAB radio which I traced to software corruption in an EEPROM .

[@allandenman9387]

Hi Michael. A most excellent piece of deduction. I thought you might short the collector emitter junction to confirm that the display came on. Brilliant work to find a suitable substitute. I used to work on Pioneer products in the earlier years when data was some of the best. How times have changed! Keep up the good work. Kind regards Allan.

[@michaeldranfield7140]

Yes , just shorting the transistor would have bought the display back on but with a high on the base and no change at the collector only the transistor could be faulty.

[@Roundymooney]

Another experience driven solution-thanks Mr. Dranfield!

[@michaeldranfield7140]

Many thanks for that Roundy.

[@ralphj4012]

Well done. Many of the AUK 2SC semiconductor range had DAG markings, i.e. the 2SC5343S, but, of course, your equivalent / working substitute is fine.

[@michaeldranfield7140]

I would have preferred just to fit the correct transistor to save time but got a result in the end .

[@sieldemesmaeker1037]

Excellent! Also had displayproblems with mine. Just resoldered the current transistor, works fine again! A weak point in this circuitboard I think... Thank you for this very well explained video. Greetings from Belgium

[@angelosanagnostou5550]

Absolutely smashing Michael. Nice Video.

[@michaeldranfield7140]

Many thanks for that .

[@darrenmurphy6251]

Great display of logic, excellent video.with The sot23 and others I've learned recently the hard way that you ignore the last 2 markings if they are printed bellow the first 2 as they are just a batch or date code and always try to find the manufacturer as that 2 digit code is specific to the brand, that's why data books say random stuff like its a bjt or a mosfet or a diode ect

[@michaeldranfield7140]

It is a bit of a pain as so much time can be spent trying to track down a part, even worse with SMD integrated circuits that are so small they may only contain 3 letters , with a schematic this repair would have been a 5 minute job .

[@robertgreen4050]

It's a pleasure to watch you work

[@michaeldranfield7140]

Many thanks for watching .

[@walker55able]

Great work Micheal

[@michaeldranfield7140]

Many thanks for that .

[@samslots1234]

Great work again Michael.

[@michaeldranfield7140]

Many thanks for that .

[@PRDowding]

I've been frustrated several times recently by down loading service manuals only to discover there wasn't an actual circuit diagram. Manufacturers obviously don't want their products to be repaired down to component level.

[@michaeldranfield7140]

Same here but luckily this was available for free on the Internet, you would be very dissapointed if you paid money for a service manual and it contained no diagram.

[@gonzinigonz]

Pioneer had a change of policy on their service data maybe 5/6 years ago. I think what happened was a lot of it was getting leaked on the web which they didn't like. They started to split schematics away from the service data which always used to be present. Also parts have now become a problem so only official service centres can get hold of newer parts at great expense. When we had audio at our place used to do all the servicing which included all the DJ equipment like CDJ's and mixers. We mainly stocked Pioneer as that was the industry standard in that world. It was quite a sudden change as well, when new updated models in a current range at the time got released suddenly couldn't get hold of parts or service data from the usual channels.

[@michaeldranfield7140]

Yes I had a look on ASWO and there only seemed to be a remote control available for this unit, maybe then if I spent more time looking on the Internet I might have found a schematic?

[@lewiskelly14]

I'll ensure to avoid Shitoneer in future

[@Tegelane5]

Pioneer has tried to use proprietary parts long time, like those car radio output amplifiers with PAL005 chip which was basically TDA7385.

[@michaeldranfield7140]

@@lewiskelly14 Trouble is everything is going the same way these days .

[@michaeldranfield7140]

@@Tegelane5 I can imagine , its even worse when they make up there own numbers .

[@f.k.burnham8491]

Great job. Thanks for the video.

[@michaeldranfield7140]

Many thanks for that.

[@terryblackman6217]

Absolutely brilliant. Well done.

[@michaeldranfield7140]

Many thanks for that .

[@ianhuxstep211]

I’m presently repairing a NAD amplifier and found a 2SA1815 that was faulty and showed up as a good Darlington on the peak. Despite it showing leaky on the Huntron Tracker.

[@darrenmurphy6251]

So the peak atlas determines it is a darlington based on vbe being over 0.7v very unusual fail mode for a bjt but my experience of sot23 is they love to go noisy so maybe same thing going on

[@michaeldranfield7140]

Over 1 volt the peak assumes its a Darlington which is a bit odd as this was around 0.9v, I'm going to put this through Jeremy's letterbox tomorrow for evaluation as he's only down the road from me.

[@michaelshaw1827]

I diagnosed a similar fault with a newer Allen & Heath SQ-5 earlier in the week (no phantom supply) and I used a BC846 so I was shouting BC846 at the screen and you chose one! HAHAHAHAHAHAHAH!

[@michaeldranfield7140]

Got there in the end , would have been a 5 minute job with a schematic and a part number .

[@michaelshaw1827]

@@michaeldranfield7140 silly question (a Pioneer thing) on the first page of the service manual did it suggest referring to another service manual for the schematic as too often there are 1 or 2 similar related models.

[@aardvarksmith6852]

Hi MD I have the same problem I am trying to find a circuit diagram for a Panasonic Tx49fx 555b ,I can find all the service info except the circuit diagram. How are you suppose to repair without a diagram GRRR.

[@mynung7008]

I fear you are not supposed to repair it at all - you are supposed to buy a new one. Don't you love to boost somebody else's economy? /s

[@michaeldranfield7140]

@@mynung7008 Trouble is everything is going that way these days .

[@michaeldranfield7140]

I have noticed for a few years now Vestal have stopped updating there website with diagrams , what problem do you have ?

[@aardvarksmith6852]

@@michaeldranfield7140 I had not starting and please wait so I recapped the power supply and now it is dead ( I have killed other one story of my life ) so I need to find out what rails are missing and start again.

[@michaeldranfield7140]

@@aardvarksmith6852 is this the 17IPS72 power board , if so I have recently had some problems with these and just fitted new boards but kept the old ones for a more in-depth look at a later date . the two I had both had low output voltages

[@audioal8015]

Genius well done, I've a JVC with an identical problem.

[@reginaldigweike4002]

Hi Michael, i have a similar receiver X-HM50, when switched on it goes into protection mode with 3 single red blinks and 4 fast blinks. No display no sound and relays clicks anytime i press a function botton like play, tunner etc. Please can you help.

[@EngoDevyat]

hi, would you happen to know how to reconfigure the remote control. The remote is working, batteries tested and led flashes but the receiver doesn't seem to detect it. I cannot find a way to program it or even get to the main menu without the remote.

[@michaeldranfield7140]

best thing to do would be scope the IF signal coming out of the receiver first to make sure that's working correctly .

[@EngoDevyat]

@@michaeldranfield7140 thank you so much for getting back to me. I'll try it, hopefully that would do. Great video by the way

[@robertgreen4050]

I enjoyed that great job 👍

[@michaeldranfield7140]

Thank you for that.

[@adamdavies163]

How bizarre, a duff transistor with the same gain as a working one. I wonder how it would've tested with a standard multimeter (the usual two diode test)?

[@michaeldranfield7140]

Yes I tried that and it seems to have an unusually high resistance emitter terminal.

[@MacroMonetary]

I own the X-HM26 model and it was fine up until yesterday. It clonked out completely whilst playing a CD and now completely unresponsive. Nothing works. Help please :)

[@michaeldranfield7140]

you would have to get the service manual and start with some easy voltage checks first .

[@JohnSmith-pq7vn]

An excellent piece of logical fault finding. Years of knowledge paying off. Do you service all types of vintage and modern hi-fi electronics? Best regards

[@michaeldranfield7140]

I didn't use to , its only since we went digital and with the fall off of TV repairs I started taking in audio stuff for repair

[@matambale]

A service manual without a schematic is ... well it's not a service manual then, is it? And..Nice fix, Michael.

[@michaeldranfield7140]

Someone has suggested there is a diagram but it does not come with the service manual and it only available to authorised service agents .

[@kinklesstetrode]

as a test, just short the collector and emitter to see if the display came on. You could have fitted a nice 1940s Bakelite switch on the front of the amplifier and marked it "Manual lamps on". Would look good.

[@michaeldranfield7140]

a switch would have caused less trouble !

[@pauldavies6037]

A simple fault in the end but made difficult a lot of newer stuff have no circuit diagrams and unknown SMD IC and TRs

[@jimmacdonald9746]

🙏🏻

[@michaeldranfield7140]

Many thanks for watching .

[@RyanGonTV]

Hi Michael, I came across your video on converting an old Sky Digibox to a colour bar generator (kzbin.info/www/bejne/bXOcf5eMgsqaiJY) Is it possible to do this with a Pace? Thanks!

[@michaeldranfield7140]

this is an old video now and I cant remember but seem to think not , I know it can be done with Amstrad DRX300 and DRX400 .I think pace uses a different video chip .

[@RyanGonTV]

@@michaeldranfield7140 Thanks Michael, I might try it with my DRX400.

[@michaeldranfield7140]

@@RyanGonTV I have not tried it with the DRX400 but it uses the same video chip so it should work the same .

[@jamesvw769]

Get on with it. Boring.

[@coffdrops69]

Another great video Michael, thank you.

[@michaeldranfield7140]

Many thanks for watching .