dynacord amps 600/1000/1600 repair help.

[showlyshah]

Hello all, i am new to this forum.

I am basically an electronics enthusiast. and recently my friend bring me some dynacords.
1. dynacord 600
2. dynacord 1000 v3 digital
3. dynacord 1600 digital.
4. dyncord 600

so all of them are having problems. let me tell you one by one.

1. dynacord 600 analog.

this thing have problem with its mixer borad ( pannel board) . when i got it.. the pannel borad was dead.. and so i changed few resistors which are used to give power to opamps at output stage. and few NE5532 op amps were blown.. so i changed that too.. and now its on. ever section including inputs , and eq sectons are working. but the output only have hum. i think few more op amps in the output were blown too. but cant trace it. i have checked the power amp section with another pannel board i had.. and its perfectly working. so this problem completely resides on the pannel board itself.

2. dynacord powermate 1000 v3. this one is a class d amp. and one of its channels were blown. one is working. the symptom is.. the damaged channel just gives a clicking noise on speaker even if there is no input. i have checked the output MOSFETS and the power out resistor. both were blown. but the power diodes are ok.

3. dynacord powermate 1600 .. this one too is a class d amp. and it have a strange problem. its working at times.. but sometimes the protect light comes up and out put cuts off in one channel. again.. this problem happes with one channel only. and with anytime and any speakers. i am checking it with two yamaha 500w rms /1000 w peak speakers. and most time it plays.. but sometimes it stops. fans are working. and there seems no over heating.

4. again another 600 w dynacord. this ones power amp is blown in one channel. and its transistor output power stage. few components were burned. and power transistor in one stage is blown too. driver transistor is blown too.. ie. literally every thing on output of that channel is blown.

so.. these are my problems. if anyone here have experience in servicing dynacords.. i request some helps.. like ...

i want to know the possible components that can be blown , why are they blowing out, some quick check ideas, or anything and everything that have came across with ur service experience. i have circuit diagrams of these amps.. and it can be obtained from google search. and i know things.. so u just need to provide ideas. insted of looking into wild.. i can fix it quickly with any possible help. i am new to this amps.. but i had done numerous other amps. so i just need a rough idea and help.. so that i can quickly sort the problem.


thanks in advance

[Enzo]

Hi, and welcome to the forum.

It can be very confusing discussing several amps at the same time in the same thread. I suggest you pick one for this thread, then start separate threads for each other amp as we go.

So #1, hum in outputs of mixer? If all the ICs EACH have power at their power pins, then look at the output pins of each op amp for unwanted DC offset.

[showlyshah]

ya. ok. i have checked it already. all ics have power in its power pins (split supply) . its is not just a hum + signal, but its is like more hum and less signal. may be 80/20 ratio. so if its dc offset, then it should be corrected by changing the coupling capacitor?

ya. i fixed the 4th problematic amplifier, thanks to the dynacord's design.. changed a couple of resistors along with three normal transistors and two power transistor (npn + pnp) . and it is fixed. and a fact. looking at the circuit board itself will make you crazy. but its really simple straight forward circuit.( atlest for the power section). the reason why it make you crazy is the component layout. its like one brick in one corner and another brick in another corner. lol... anyway 1 out of 4 got fixed. 3 more to go...

[Enzo]

DC offset on an op amp pin is more likely a bad IC than a bad cap.

[showlyshah]

sorted out all analog dynacords.. thanks for your help.
now i need one more help. does anybody have dynacord powermate 600- v3 ( latest digital model with smps power supply) circuit diagram?
it got the chip damaged ( second picture) , i have replaced that ,along with a burned resistor and lm317 regulator ic, but its still not powering on.
so if any one have that circuit diagram, please share, so that i can find out the related components.

[paleeman]

Hope this helps.

Dyn_snpsht.pdf

[showlyshah]

Guys.. i encounter another strange problem with two Dynacords the other day..PM600 and PM1600. both are old AB amps with transformer power supply.

The problem is.. these dynacords will switch on normally if i use 110v power supply or even if i use a 60w series bulb with 220v supply ( i alwsys use series bulb power supply to check repaired amps) . but it i plug directly into 220v supply, the protect light will turn on and fan spins at highest speed (the same behaviour when any or both channels are burned) . and the relays ( both speaker relays and power relays continue to click repeatedly insted of staying on or off.. but after a while.. like 2-3 minutes, it just turns on.. and amp works properly. ( seems like some component needs to heat up and then it functions properly ... lol am i missing some vaccum tube in the circuit!) .

Btw, there is no short-circuit with any of the channels, nor any transistor on power amp section is burned ( because it just works fine once when it is turned on) . I checked the same with disconnecting dc dual supply lines to power amp section , for synacords use seperate power lines to power amp section and another power line for all contols, fans, preams, effects board, relays etc.. and then too the same problem happens.. so i belive it has nothing to do with power amp section.

every volatage diagnosis pins shows the correct volatges. with in .5 - 1v difference at maximum. i changed the 074 opamp which controls the temp and fan speed, but no use.

what would be a possible reason for this strange behaviour..?? btw . both amps use 220v transformers.

i cant even figure out ,why it works normally with a low voltage supply, but shows faults with the normal supply.
i have checked all Transistors and diodes with the delay and relay driver sections.. all are ok.. not even a single weak Transistor.

This is soo strange.. if some one had figured out similar problem , please share it.. its been a real headache for me for past few days.

[showlyshah]

This is the delay/fan speed control/relay driver sections of dynacord powermate 600.

i have attached the whole service diagram of the same.. please take a look if any one can figure out something.

[Mikale]

Dynacord cms1600-3

Hello

I am looking for the service manual for the Dynacord CMS1600-3.

I have one units with no audio output at all from the pre amplifier stage.

Any help is more than appreciated


Regards

[Jazz P Bass]

Here you go: CMS 1600.zip

[Mikale]

Wrong number provided

Here you go: [ATTACH]45842[/ATTACH]

Hello

Many thanks for your help, really appreciated.

I wrote the wrong part number

the correct model is PowerMate 1600-3, its shown already in post #5

Here https://factorysound.com/products/pm1600

Please help me with that schematic

[Jazz P Bass]

Try this: Dynacord PowerMate 1000_1600.zip

[Mikale]

Try this: [ATTACH]45845[/ATTACH]

hi

Its not the one.

the PM1600-3 has a SMPS and a Class-D amplifier, not like the one you sent.

[Jazz P Bass]

Unless the smps is this: 85287f.pdf, then I cannot help.

[Mikale]

Any updates on this mixer?

PM1600-3

Received one unit yesterday, it powers up, but the PROTECT LED is ON, and I hear some clicking noise near the power amplifiers,tick, tick, tick

Any one got the schematics?