Seems to be working and not blowing fuses etc on my bench. Once in the car and run hard it pops the main fuse which is on a 4 inch long wire so its not the wire etc. Thing still operates now BUT its showing some problems now so I can go get it fixed I suppose. Hard to fix an already working amp. Its 45 years old so I get that its way past its life... The POWER SOURCE works, creates 28 volts+/- amd 12 volts so theres that. I am not a tech so loading the power supply down to see what its doing is out of my skill set at this point.
I spent all day in TOIL.... My aching back. No end in sight. STILL no working amp on my rear speakers... Uggggggg... THANKS!!!!
I have a couple other amps like this one that I will try to see if i can piece something together. My goodness... I try. BDBD/2022
Just another thought: Are you sure that your car's charging system (alternator, regulator) is working properly, especially doesn't present unwanted voltage spikes? Is the car battery ok?
Maybe 45 years ago the designers didn't have too much care for that and knitted the circuitry with hot needles?
Addendum: I don't know where you live, nor do I know your car. Anyway, since more than 50 years German automotive supplier BOSCH designs their alternators and regulators for a nominal charging voltage of 14 V and allows for 14.4 V at 293 K, with a tempco of -20 mV/K. How does your amplifier behave if you turn your bench supply to that voltage?
Best regards!
Maybe 45 years ago the designers didn't have too much care for that and knitted the circuitry with hot needles?
Addendum: I don't know where you live, nor do I know your car. Anyway, since more than 50 years German automotive supplier BOSCH designs their alternators and regulators for a nominal charging voltage of 14 V and allows for 14.4 V at 293 K, with a tempco of -20 mV/K. How does your amplifier behave if you turn your bench supply to that voltage?
Best regards!
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It’s not “already working” if it’s blowing fuses. Something isn‘t behaving right. Eventually the transistors that you paid $22 each for will protect the fuse. You will eventually have to separately test the amp boards and the supply to see which one is acting up. The amplifier boards may have some sort of breakdown related failure, especially if suspect transistors were ever used. The power supply might limit the current such that it doesn’t just explode and send pieces of TIP142 flying. They might start oscillating and that brings on excessive current draw. There could be voltage spikes coming off the supply up to 2X the nominal voltage, that for whatever reason are not being filtered. The amp boards won’t like that. The supply itself may be too heavily loaded, or not operating at the correct frequency. Those self-oscillating converters drop their frequency as the main supply voltage goes down and as load increases. If the frequency drops too low it will saturate the transformer, and draw excessive battery current. 14.4 volts may not be a problem, but 10 might be. If you only replaced one transistor in the pair, there may be a DC imbalance that gets worse as load increases. This can also saturate the transformer, or cause the +/- supply to become unbalanced, which can cause the amp to misbehave.
Hi, thanks for your input. I actually own 3 of these amplifiers, 2 of them work fine in the car, this particular one for whatever reason has issues. It is fused at the speaker leads 5 amp fuse on the + leads. I checked again the car side and its all good. I can SWAP a amp into this space and it works fine so..... It's this amp. It has issues upon hard use. It runs for hours on end at low volumes and periodic LOUD volumes on my bench.... Uggggg...... I need to hunt down a tech here i understand can repair these old amplifiers. Thanks for your input. MERRY!!!! BDBD/2022
Hi again, MERRY!!!!!!....... Yeah working already for hours on end... on my bench. THEN ya pop it into the CAR and there went another 30 amp fuse, my goodness. I own 3 total and 2 are working fine in the car, only this one amp shows this issue. I found a couple more amps but they too are damaged goods BUT I can swap the powersource. Use the 2 amp modules that WORK and see if that makes a difference. If it works then I KNOW its the powersource causing the blown 30 amp fuse. I have 2 working amplifier modules I think so thats the next approach. I HOPE the swap results in a working amplifier. If i swap it and its still blowing fuses then I would gather its one or both amplifier modules. Hope to get this done before the end of the year. OH YEAH... TIP 140 and TIP 145 are the main Darlington amplifier output transistors. 2 per amp module. Wish me luck....LOL... Thank you for your time and input. Greatly appreciated MERRY!!!!!... BDBD/2022
I purchased 2 "SOLITRON 0602016" transistors to replace the one that went bad. I measured all three before installing and the readings on one were much closer to the original one that did not blow so I decided to go with the closer matching numbers. I have one now that I bought for 22 bucks that I can use in case. LOL. my goodness. I finally got Perry's amp repair tutorial so I need to READ..... a LOT it appears. Sadly I have yet to find much on my little Audiomobile amp but... ON to LEARNING. THANKS!!!!! BDBD/2022
another thing... the Power Source has 5 amp picofuses in line of each 28 volt + and -... inline to the amplifier modules. Only 5 amp fuses there so. More to chew on I suppose. MAHALO from HAWAII!!!! BDBD/2022
it appears a SPEAKER has blown... finally. Likely the problem child here, I was yet again SWAPPING an amp into that spot when I noticed bad readings on one of the amplifier outputs to the speakers. GREAT. FINALLY..... So yes this is a quite NEW Kenwood Excelon 6x9 speaker rated at 300 watt PEAKS and 130 RMS. Man, I run these amps hard BUT in a Mid/Highs aspect, I roll off the bass a LOT... Basically FULL RANGE mids and highs with some bass potential. WELL I am sad as the Kenwood speaker cost me a good 90 bucks each. These are 3 OHM load speakers so perhaps thats an issue with these older amps BUT the front amp is operating fine on a pair of the same Kenwood speakers along with a tweeter addition. No problems up front so I wonder if the speaker BASKET is getting grounded and possibly causing Lightning bolts in the voice coil gap. I opened the speaker area and reached in to see if the speaker was moving. I pushed on the cone from underneith and it popped loose... It was welded to the bottom of the excursion. Maybe a bad speaker from the start, bad alignment. GREAT..... WELL I REMOVED a pair of Pioneer coaxials I bought/installed in 1985... Perhaps I will put them back in there. NEVER had any problems with them, just swapped em out for the Kenwoods since I had a all Kenwood system. Well..... Nobody sells Kenwood here in Hilo. Ya try to do it RIGHT and what do ya get.... Expensive speakers made in Vietnam. Wish me luck... My aching BACK. BDBD/2022
Congrats to your findings. Anyway, this is in very contrast to what you said just four postings above. If the defective speaker actually were the cause, any of your three identical (as you said) amplifiers that you've swapped (as you said) would have failed, wouldn't it?
Btw, 300 watts for a 6x9? Hard to believe. I think that's just PMPO, purely mythical power output (capability), as Morgan Jones said... 🤔
Best regards!
Btw, 300 watts for a 6x9? Hard to believe. I think that's just PMPO, purely mythical power output (capability), as Morgan Jones said... 🤔
Best regards!
So the cone was frozen and the voice coil pinned? THAT sounds more like the magnet shifted. Quite possible for speakers made in 1985 and installed in a hot car. The glue can vibrate loose or melt. When that happens, quite often the voice coil shorts, or possibly shorts to the speaker frame (grounded, in a car). That can take out the amplifier for sure. Or at the very least cause it to draw too much current.
The practically new KENWOOD Excelon speaker was working up till the last "event" it appears. I swapped another amp into that spot and the main power fuse is ok BUT I discovered at this point that the speaker was fried. I suspect the speaker was causing the suspect amp a lot of grief at higher volumes thus BOOM. It seemed to work all day at low volumes... only acted up during hard use testing. Regardless, I think I discovered the "hard use" problem, a poorly constructed speaker that shorted at extremes and eventually got stuck in that position... Possible GROUNDED speaker basket.... SO I am doing everything I can to ISOLATE these speaker baskets..... no grounds on the speaker baskets, inadvertant or otherwise.
These amps ALL have a 5 amp FUSE on the + speaker wire. Useless?.... The Kenwood speaker coil is fried as well as the TWEETER..... Damn, Typically tweeters survive...
Oh well. I invested in an AMERICAN BRAND.... KICKER out of CHINA. I bet they will outlast them BRAND NEW Kenwoods. New set of KICKER 6x9's cost 90 bucks, half the price of them Kenwoods made in Vietnam.
I ALWAYS held KENWOOD in high regard since the 80's.... Well I wonder if they lost their way somewhere. The PRINTED specs say 300 watts PEAK thus the 130 RMS rating.... These are 50 watt amps so.... PERHAPS the amp is throwing DC into the mix.... 5 amp fuse survived.... Uggggg. I will REBUILD that suspect amp... every part. I purchased Kenwood "EXCELON" BUT what came in the MAIL was NOT BRANDED EXCELON.... So theres that too.... What a disappointment from my long time friend KENWOOD.... Oh well. I am SURE the AMP is the PROBLEM too.... Been here done this. Many a long day at a Stereo shop in the 80's.... MEMORIES....
Happy New Year!!!!! Thanks!!!! BDBD/2022
OK... the speaker that got fried is a KENWOOD "Excelon" 6x9 and is only a few months young. Recently replaced all my 6x9's (from 1985) to the KENWOOD brand as I was running a deck as well as amps from KENWOOD. System worked OK for months. Just OK, Thats about it though.
SO..... I decided to pull all my AUDIOMOBILE gear out of boxes one day recently and see about possibly swapping them into the amp section. I got all three amps to operate on the bench so in they went. SOUNDED pretty good for a while then POP went the rear set.
AMP popped a fuse and the amplifier main output transistor went bad SO.... install a new one and it came back to LIFE. Ran 24 hours at low volumes on the bench etc so back into the car it went. THIS TIME it only ran for a SONG then died. POWER SOURCE main transistor this time. That SOLITRON one.
SO.... hunt down and purchase another set of them SOLITRON POWER source transistors. Amp yet again came back to life, ran for hours. Tried to REINSTALL it and discovered the blown speaker problem at this point BEFORE I reinstalled that problem amp.
Well I THINK that problem amp is still a problem and caused that speaker to blow, perhaps, REGARDLESS of the inline 5 amp "protection" fuse. LOL. I been messing with speakers long enough to know they can be poorly aligned NEW from the factory. These KENWOOD speakers are completely GLUED together, no screws at all. As the Basket goes it MIGHT have been getting GROUND so these KICKERS I have done everything I can to ISOLATE the baskets from any possible GROUND sources... OLD CARS were made of STEEL... EVERYTHING... did yas know?.... LOL...
I in fact THOUGHT I felt it myself upon inspection of them KENWOOD SPEAKERS when brand new... Seemed a bit tight at extremes upon manual movement. These KICKERS 6x9 speakers I purchased appear to have PLENTY of air gap space throughout the excursion. Hope they last longer than the 4 months them KENWOODS lasted. Uggggggg FUN FUN FUN.... My aching back.
I have Perry's Amp Repair Tutorial now so I am reading a LOT and learning some. I will REBUILD that suspect amp top to bottom soon and perhaps them others too... Bring them back to LIFE after 35 years in a box. I dont quit. A GOAL. ONCE I get them AUDIOMOBILE amps all to operate properly THEN I will reassemble them all back into the RACKS they came from and be happy.
THEN on to the A/D/S/ 2001 amplifiers!!!!! NEXT!!!!!!! LOL..... More PAIN PLEASE..... BDBD/2022
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this reminds me of Zapco amps and anyone who remembers those can likely share their horror stories...
BDBD aside from supply/step up oscillator transistors and outputs devices what other semi testing have you done?
seems to me without confirming driver transistors and offset for symmetrical clipping it's a crap shoot to just run it and make your ACID test be running it REAL loud and crossing your fingers?
BDBD aside from supply/step up oscillator transistors and outputs devices what other semi testing have you done?
seems to me without confirming driver transistors and offset for symmetrical clipping it's a crap shoot to just run it and make your ACID test be running it REAL loud and crossing your fingers?
Yes, pretty useless. The power devices always blow more rapidly than even a fast acting fuse opens.
Best regards!
Hi folks. Sad to say I have ZERO electronics education. Spent a LIFETIME installing electrical gear into cars, boats, planes, limos, busses... Whatever needed installing is what I did. I have 2 College degrees... none electrical... History and Communication Arts. So it is with me. I own a lot of OLD gear as i am OLD... Gear I kept in a BOX or picked up somewhere along the way for nostalgia purposes. TODAY I am faced with living on an island where thus far nobody does repairs SO.... I have to do them myself. Thus far MUCH SUCCESS. I Just wrapped up my AM SP-300 EQ refurb. ALL ORIGINAL parts... 45 years young and still operating fine. POTS etc need cleaning so I did that and managed to get 2 of my 3 SP-300's to operate properly, fixed the BALANCE slider on one and now its fine and the Made in Mexico one I bought from Fred Vinson is back to fully operational as well. YAY.... Persistence pays off. I have a lead on even more AUDIOMOBILE gear and recently purchased a AM-3 RACK system from the later period about 1986 when the "HS" moniker was added to the SA-1000 HS name badge. HS branded system was the last incarnation of the AUDIOMOBILE product line and addressed the prevalence of PRE AMP OUTPUT decks that were hitting the streets at them times. The ORIGINAL SA amplifier lines were designed to accept a HIGH LEVEL speaker input scenario so the HS series of product was better engineered for the Pre Amp Level signals available, 500mv.... HISTORY... I seek AUDIOMOBILE gear in 2023, if anyone is wondering... ALOHA!!! BDBD/2023
One more thing... I took a nice drive in the ol Firebird today and was BLASTING Peter Frampton on 8 track SO LOUD I was in fear of blowing an amp.... BUT they decided to just work... LOUDLY... SPECTACULAR sound in comparison to them KENWOOD amps I decided to chuck cause in the end they sounded "DEAD"?.... I removed the Kenwood amps and installed some of my OLD GEAR just to see..... What a DIFFERENCE... I tell ya.... Gear is GEAR?... Nope. Theres SUPERIOR GEAR.... Yep. BDBD/2023