Spider27 Posted April 4, 2020 Author Share Posted April 4, 2020 13 minutes ago, aussievintage said: I am wondering if one or more transistors were damaged when you had them soldered incorrectly and powered the amp on. Thank you for the info and Very likely. Is there a way to check if the transistors are damaged before replacing all of them with new one? I have digital multimeter but not sure if I can use it to check if it works or not. Link to comment Share on other sites More sharing options...
aussievintage Posted April 4, 2020 Share Posted April 4, 2020 1 hour ago, Spider27 said: Thank you for the info and Very likely. Is there a way to check if the transistors are damaged before replacing all of them with new one? I have digital multimeter but not sure if I can use it to check if it works or not. Not with any equipment I own. I did read about "in-circuit" testers, but... Some digital multimeters can test transistors. Honestly though, they are cheap. If you desolder one (for the second time) I would replace it with a new one. 1 Link to comment Share on other sites More sharing options...
mbz Posted April 4, 2020 Share Posted April 4, 2020 (edited) 1 hour ago, Spider27 said: Is there a way to check if the transistors are damaged before replacing all of them with new one? I have digital multimeter but not sure if I can use it to check if it works or not. Generally the transistors don't conduct when incorrectly inserted so you might be lucky. You can try testing in circuit, looking for a short between b-e or c-e or.. using either resistance/ohms function but the diode test feature is better. Attached graphic shows the 6 combinations to be tested with expected results OL (open loop) or 650mV(or there abouts), red/black give meter probe orientation. Graphic curtesy markthefixer from audiokarma. EDIT: I should add that some faulty transistors need a few "amps" before they fail, bottom line, a transistor that passess diode test may still be faulty since your MM does not deliver the necessary mA. Conversely anything that fails diode test is certainly faulty. EDIT 2:If you find a suspect transistor then you need to remove and test out of circuit in which case you might as well replace as per aussievintage Edited April 4, 2020 by mbz update 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 4, 2020 Author Share Posted April 4, 2020 (edited) I actually watched this video to understand how transistor works and how to do diode test. Checked all of transistors that I could see and they seem all pass the test. TR807 and TR808 did not pass the initial test so I was excited that I found the defect ones. However, I found that those two are PNP type when all others are NPN so had to do opposite and they also passed the test. I got some extra brand new BC550 transitors and will replace all 4 of them later today to see if it helps. Edited April 4, 2020 by Spider27 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 4, 2020 Author Share Posted April 4, 2020 (edited) Just completed replacing BC550 transistors with new ones. And, sound output is now back to normal. The crackling noises are still there though. I guess that these crackling noises are coming from old caps. Hope it is not noisy transistors but caps because do not want to replace same transistors again.... Edited April 4, 2020 by Spider27 2 Link to comment Share on other sites More sharing options...
aussievintage Posted April 4, 2020 Share Posted April 4, 2020 45 minutes ago, Spider27 said: The crackling noises are still there though. I guess that these crackling noises are coming from old caps. Or a more thorough clean of every switch pot and socket/plug is necessary. 1 Link to comment Share on other sites More sharing options...
aussievintage Posted April 4, 2020 Share Posted April 4, 2020 46 minutes ago, Spider27 said: Just completed replacing BC550 transistors with new ones. And, sound output is now back to normal Glad my guess was right for a change 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 4, 2020 Author Share Posted April 4, 2020 1 minute ago, aussievintage said: Or a more thorough clean of every switch pot and socket/plug is necessary. I am not sure about the pots and switch because they are cleaned quite thoroughly. When I test turning every switch & knobs up and down, it does not affect crackling noise at all. Doesn't it affect crackling noise when switch/knobs are turned up and down if pots and switches are dirty? 4 minutes ago, aussievintage said: Glad my guess was right for a change YES.. Thank you. Link to comment Share on other sites More sharing options...
mbz Posted April 4, 2020 Share Posted April 4, 2020 22 hours ago, Spider27 said: I got the transistor from JayCar and here is the link for datasheet. Soory, I don't consider the car place as a reliable source of silicon. Also their Serv**ol "Clean and Lube" does very little cleaning, reasonable as a lube. Both Mouser and Digikey have free shipping to AU for orders over AUD60-, delivery in 3 days max(!) For small orders RS. I'm undecided about ele14 though did buy a power supply from them, seems to be of suitable quality. 1 Link to comment Share on other sites More sharing options...
aussievintage Posted April 4, 2020 Share Posted April 4, 2020 6 minutes ago, mbz said: Soory, I don't consider the car place as a reliable source of silicon. Then again, I have never gotten any fakes from them. The also sell Deoxit for which I am very grateful. Link to comment Share on other sites More sharing options...
PKay Posted April 5, 2020 Share Posted April 5, 2020 Given all the effort you are going to the deoxit may be worth the extra spend. https://www.storedj.com.au/deoxit-d-series-contact-cleaner-and-rejuvenator-5-solution-142g?gclid=CjwKCAjwg6b0BRBMEiwANd1_SDKfhuvnkZ0RjCikc_jiH2rdeBzcfYDN09Y82ea1iS6tesxkvfeNwhoC87cQAvD_BwE 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 6, 2020 Author Share Posted April 6, 2020 5 hours ago, PKay said: Given all the effort you are going to the deoxit may be worth the extra spend. https://www.storedj.com.au/deoxit-d-series-contact-cleaner-and-rejuvenator-5-solution-142g?gclid=CjwKCAjwg6b0BRBMEiwANd1_SDKfhuvnkZ0RjCikc_jiH2rdeBzcfYDN09Y82ea1iS6tesxkvfeNwhoC87cQAvD_BwE Thanks for the suggestion. I happen to have DeOxIt D100L which is brush type. I applied all of joints and gap inside pots but does not make any difference. However, it is not spray type so could not reach deep inside the pot so it may make a positive difference with spray can type. When I pass the city next time, will get one to try. However, I feel that it is more likely transistor or solder joint. The reason for this assumption is that the crackling noise is now on the left channel when it was on the right before replacing the signal transistors. Link to comment Share on other sites More sharing options...
Spider27 Posted April 15, 2020 Author Share Posted April 15, 2020 Been away from this project and just coming back and placing my order to element14 to purchase required capacitors. @pete_mac By any chance, would you be kindly spare just a few sec to have a look at below linked list look okay to you? First time ordering for capacitors and I think that I found them ok and just want to double check if possible. Link to comment Share on other sites More sharing options...
pete_mac Posted April 15, 2020 Share Posted April 15, 2020 (edited) Hi mate, I'll see if I can have a look tomorrow afternoon or evening... I'll be burning the midnight oil tonight on an urgent report. EDIT: I won't be able to comment on the suitability on capacitors from a physical sizing perspective, as I don't have any details regarding the dimensions of the original caps. I'll have to take your word for it. Edited April 15, 2020 by pete_mac 1 Link to comment Share on other sites More sharing options...
audiofeline Posted April 17, 2020 Share Posted April 17, 2020 On 04/04/2020 at 4:46 PM, Spider27 said: ...Maybe i am too novice after all and not cut out for this task (my self-confidence level is dropping down rapidly now)... I've been reading this thread and have a degree of admiration that you are tackling this - I feel it's one step beyond my novice skills! I'm pleased to see you have persisted through this challenge, as this is what develops competence and knowledge. Good luck with the rest of the restoration. 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 17, 2020 Author Share Posted April 17, 2020 1 minute ago, audiofeline said: I've been reading this thread and have a degree of admiration that you are tackling this - I feel it's one step beyond my novice skills! I'm pleased to see you have persisted through this challenge, as this is what develops competence and knowledge. Good luck with the rest of the restoration. Thank you for your kind word and encouragement. If COVID-19 lockdown was not in place, I would have been given up already. Since I have some spare time, I am doing this but it is still not progressing into positive way or improving from current status as yet 2 Link to comment Share on other sites More sharing options...
pete_mac Posted April 17, 2020 Share Posted April 17, 2020 Sorry @Spider27… still working on that darn report. Let me see what I can do later tonight. 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 17, 2020 Author Share Posted April 17, 2020 12 minutes ago, pete_mac said: Sorry @Spider27… still working on that darn report. Let me see what I can do later tonight. No worries. Take your time. Link to comment Share on other sites More sharing options...
Batty Posted April 17, 2020 Share Posted April 17, 2020 Will we see this in the classifieds soon Spider? Link to comment Share on other sites More sharing options...
Spider27 Posted April 17, 2020 Author Share Posted April 17, 2020 29 minutes ago, Batty said: Will we see this in the classifieds soon Spider? I am not evening thinking that far. My sole focus is making this work without crackling noise coming and going which is very annoying and unpleasant whenever I power it on and try to listen. 1 Link to comment Share on other sites More sharing options...
Batty Posted April 17, 2020 Share Posted April 17, 2020 Good, man, I hoped you wouldn't give up on this. 2 Link to comment Share on other sites More sharing options...
Spider27 Posted April 17, 2020 Author Share Posted April 17, 2020 2 minutes ago, Batty said: Good, man, I hoped you wouldn't give up on this. We will see the outcome either making it work and enjoy listening with it with big smile or fail miserably and wasting money and time on this and weeping at the corner of my room soon.... 1 Link to comment Share on other sites More sharing options...
Batty Posted April 17, 2020 Share Posted April 17, 2020 You will not fail, that is an order lol. 1 Link to comment Share on other sites More sharing options...
Spider27 Posted April 24, 2020 Author Share Posted April 24, 2020 On 17/04/2020 at 2:23 PM, pete_mac said: Sorry @Spider27… still working on that darn report. Let me see what I can do later tonight. Hi Peter. Have you had a chance to check those 9 capacitors by any chance? No urgency... It just has been 7 days waiting and not sure if I just should proceed placing an order to see how it goes or wait for your confirmation before proceeding. Link to comment Share on other sites More sharing options...
pete_mac Posted April 24, 2020 Share Posted April 24, 2020 9 minutes ago, Spider27 said: Hi Peter. Have you had a chance to check those 9 capacitors by any chance? No urgency... It just has been 7 days waiting and not sure if I just should proceed placing an order to see how it goes or wait for your confirmation before proceeding. No closer unfortunately - work has been consistently busy. Provided that you have double-checked your list against what is actually physically installed in your amp (there can be variations during production runs and improvements to the design over time) then you should be OK. This also gives you the opportunity to measure the diameter of the current caps and ensure there is space for the new caps that you've chosen, and to get a feel for the lead spacing of the original capacitors vs the ones you've chosen (I have no way of doing this remotely). I'd particularly check the 3.3uf film cap - is it a 5mm lead spacing? If not, it definitely won't fit. 1 Link to comment Share on other sites More sharing options...
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