Search results

  1. Wayne Phillips

    What should I get for beginning electronics?

    Us oldies have been doing this so long and there is much to learn..even switch power supplys and let's not for get using test equipment such as scopes..hot air stations the list grows. Get the ohms law sorted and colour codes on those reistors now!
  2. Wayne Phillips

    Blowing fuses on 1980's Fisher CA-880

    The chap did say he was not that electronically minded..a bit of cation here is needed to not get zapped by the 60vdc or more!! These old fisher amps do have large flat packed power transistors say 16amp at about 200w.. it will have a speaker relay circuit to aid connection and de-connrction...
  3. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    This amplifier speaker protection relay ic circuit will act fast if there is any offset above 1v at the o/p. Your readings look normal volts and current wise..now with a mains 240v 60w bulb limiter in the primary side...does it stay bright at power on with speaker load removed? There will be...
  4. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    Remove the speaker untill the amp is working as you don't want to damage the speaker. Have you checked the speaker? A 8 ohm would read 6.8..
  5. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    3.15 amp fuse will be ok.. or tack a thin wire on the blown fuse.. tr122 is a npn device to92 transistor. Use your meter on diode test as your testing the base to collector and base to emitter pins.
  6. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    It's a transistor amp and will work with or with a load.. them small transistors can be tested in circuit. You may use a test speaker to save burning up the amps own speaker or a dummy load resistor. 10 ohm 10w and if it gets hot with no signal applied then pull the plug! Yes that transistor...
  7. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    Bias transistor can be mje340 npn or bd139 both can be mounted to the heatplate.. When powering the amplifier up are you doing so with unloaded. Looking at the circuit dig..them transistors just in front of the bias tr are parts of the amps short circuit limiters and have these been tested...
  8. Wayne Phillips

    Juke box repair..

    This one was imported from the states with step up transformer for 230 v ac operation. It's up to people in there choice of audio gear they wish to buy. And this fella wanted this unit! But did not expect some unskilled tech with baked beans for brains to charge him for messing up he's...
  9. Wayne Phillips

    Juke box repair..

    I was called out to check this huge juke box after a engineer sparked the main power supply board in front of the owner and left it humming and not much else! He left red faced and a juke box sitting there for 3 months. Mmm so let's get stuck in and power it up and all that could be heard was...
  10. Wayne Phillips

    Kam amp repair

    Hello thanks for your reply.. I've been in the electronics service and repair for many many years covering tv/video to pa system and valve audio design. Most moden cheap audio like you say is pop it in the bin and buy new or second units. Mmm even board changing can save time in order for...
  11. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    Cold checking the power output transistors if all is good there ie base to collector point and b to emitter leg.. A amplifier circuit has few stages input signal transistors (your amp has fet input pair) followed by vas stage then driver stage and power transistors.. Removing the outputs is...
  12. Wayne Phillips

    Help finding fault with old bass amp that blows fuses

    Lot's of helpful pointers made here to help solve this fault. More pointers..has the power amp stage been desconnected from the psu to check that it's psu is showing level voltage on each rail. Yes use the lamp limiter as it will give some time to check the circuit. No load or signal until...
  13. Wayne Phillips

    Kam amp repair

    Some folk's may not want to buy second hand units and instead want there equipment repaired. I always look over an item to see if it's been looked at before as it can be a real pain if you have to spent to much time doing to many faults.
  14. Wayne Phillips

    Kam amp repair

    I will look over my notes and post...think it was a ka karaoke type with built in effects circuit..some of the ic's had there numbers scraped off.. Kka300 the model of this karaoke amp
  15. Wayne Phillips

    Prosound 1600 amplifier repair

    Just to make folks buy more electronic items when it fails..
  16. Wayne Phillips

    Prosound 1600 amplifier repair

    Yes..the odd think is, why was it such a poor design in the first place?
  17. Wayne Phillips

    Kam amp repair

    Kam mixer type amplifier repair... Blown output stage on right channel due to shorted bass speaker. This amplifier was in a bit of a mess with protection relay holding off the left side channel, the owner over powered a 150w speaker at this years new years party and the smell off the bass...
  18. Wayne Phillips

    Prosound 1600 amplifier repair

    This branded amplifier from a well known electronics store came to me for repair. The fault trying to power up said the owner? Well on opening it for a quick look I noticed the inrush circuit was missing a inrush ntc to slow the mass inrush voltage. What they seem to of done here was to add...
  19. Wayne Phillips

    Repair newb - need help fixing sub amplifier

    The 2w 1k resistor next to the zener looks like it's tide to it. Have you checked the voltage at this point also the amplifier does not need any speaker load connected to it as it's being worked on. One tip is the use a 100w or 60w bulb limiter in the primary 240 ac side as this will act as...
  20. Wayne Phillips

    Repair newb - need help fixing sub amplifier

    Fixing any amplifier comes with a set of problems..not only can it be costly if you are just popping heaps of parts and watching them go pop! I'am a service tech for a living and I can say read plenty before jumping into it! You must be able to use ohms law plus use test gear ie...
Top