Haynes Jazz King II Output Board / Update Success!

[plexi50]

I sold the Haynes Jazz King II 3 months ago and just bought it back. The gremanium output finals went south. It burned and chared the trimmer pots internal windings. I found the DTG 2400 bipolars to be shorted (DOA)



I dont know the values of the trimmer pots since i have not had time to try and clean the lettering to determine there values
I have NOS DTG-2400 & RCA 2N2148 germanium transistors so thats one major obsticle out of the way
The person i sold it to replaced R16 & R17 resistors with new ones before checking the transistors and why both 3.3 r resistors burned open again

Now the damage to the trimmer pots is sever and need replaced with new ones
The schematic says all resistors are in ohms. So to clarify: Is this 3.3 ohms and not 3.3K ohms?
The 3.3 r resistors are not shown in the board pic and have already been removed
I loved this amp before selling it. It must work again. The power supply is not damaged
Haynes schematic posted below last pic

[PRR]

You are finding out why hi-power tranny amps from the mid-1960s are most-all in landfills.

That bias scheme begs to let the big Delcos run WIDE-open.

Yes, everything in OHMS. All HIGH-current stuff. Only 2 parts above a K. Exception is R1 R2 (and R1 is notated in Ohms).

Forget the bias trims; bad idea then and hard to find those parts.

The amp has overall NFB. We only need an approximate bias. But a SOLID bias that WON'T break and let the Delcos go crazy.

The 500+3.3 will give a usable bias. Not perfect and not trimmable. The main effect: with no load, the output may sit at several volts DC. This will reduce with load. If it is less than a volt or so, go ahead and hook up any speaker with a power-rating suitable for this amp. If several volts, try adding 100r 10W across the output.

[plexi50]

I was thinking of bypassing those trimmers all together but wasnt sure. I ordered the 50r & 100r 10W resistors this morning. Cant thank you enough for the diagram and your thoughts. I love the tone this old amp has and it's chorus vibrato and reverb. The best part is it acts as a piece of cool furniture. I think George Jetson would have used this amp. I want your Brain* 
Send To:
Dave
Clearwater,Floridah
33770

[plexi50]

PRR i got the Delco DTG 2400 transistors in this afternoon. I was measuring them on my Fluke DVM and notice a big difference between the pair of them. Is this a case of mis matched or one of them leaking. The SS tech terminology is still not my knowledge base

Here are pics of each transistor and there readings. I dont have the 3.3r resistors yet as they are still in transit. I dont want to smoke up new transistors without your opinion first. The trimmers are out and the wires bussed to link up with the 3.3r resistors to the output transformer and each DTG-2400

[PRR]

I don't know what that Fluke is telling you.

If you are paranoid, before smoke-test, lift the Collector wires and insert 10 ohm 10W resistors in each. If the thing tries to suck BIG current, the resistors will limit it to a few Amps and then smoke, saving the big transistors. No smoke? Reading voltage across the 10 ohms tells you the idle current. 1 Amp (10V) is way too high. 0.02A (0.2V) is excellent. Anything 2V to 0.1V is acceptable. The amp won't make big power in a speaker with these 10 ohm resistors obbling it, this is just for the smoke-test and light "does it play?" phase.

[plexi50]

Thanks PRR for your knowledge & wisdom. Im waiting on those parts still. I will report back with my findings after using the 10r 10 watt between the collector and transistor. I feel pretty confident with your help that all will be good again.

[plexi50]

Ok i have the 3.3r resistors in place and bussed which i believe is right. I have to double check the schematic

[plexi50]

Making some changes i had wrong. Are we eliminating R12 560r 2 watt circuit in place of 50ohm 10watt?

Also .47r 2 watt are not present on this board from 3.3 to transistor

[PRR]

> 0.47r 2 watt are not present on this board from 3.3 to transistor

You MUST have those! It's like the 500 ohm under a Champ's 6V6: it's essential to bias and bias self-regulation.

This may be why it hasn't been reliable.

> Are we eliminating R12 560r

No. You need that for smooth sound. Sorry that my image is not clear.

[plexi50]

> 0.47r 2 watt are not present on this board from 3.3 to transistor

You MUST have those! It's like the 500 ohm under a Champ's 6V6: it's essential to bias and bias self-regulation.

This may be why it hasn't been reliable.

> Are we eliminating R12 560r

No. You need that for smooth sound. Sorry that my image is not clear.

Ok thanks for that update. Your diagram is just fine. It gives me a place to start. I am really frustrated with this board. The 0.47r are AWOL and the jumper wiring is a bit more complex than i previously thought. The board wiring does not follow the schematic with the V+ right on the 3.3 / 0.47 junction. It was at the trimmer pot lead before the 3.3r. I have it wired now as the diagram V+.

V- rail is originally in place as the schematic and diagram show. Now to find and order 0.47 ohm resistors. I really like this mellow amp

This board pic is only for part value references.

[plexi50]

I have sorted out the mind twisting trimmer pot wiring and have the board wired complete as per the schematic bypassing the trimmer pots. In the schematic of course the trimmers look convienently next to one another. But they are actually at opposite ends of the board. So i had to go over the board and schematic 1 million times to understand the wiring schem throught the 500r 20 watt resistors. Again the schematic is straight forward but the board is a whole other story

NOW for the good news! On the right corner of the schematic i have it states that this schematic is for boards of serial number 30,101 to 31,500.

I have a serial number of 3407 whatever that comes out to. That would explain why my board shows no .047 & also the 560r resistor doesnt exhist either but is made up of (2) 270r 2 watt series resistors for a total of 540r in that part of the circuit

Now! I do have sound and is present but it is very minimal at full volume. Full volume is equal to #1 on the pot full CW

The pic below represents my voltages on each of the DTG2400 trannys EBC positive and negative voltage rails
Again i think i have it wired right but this SS stuff is driving me insaner

The pinout is also screwing with my head. The plug in board socket is labled BEC. The insulated shell is the collector right?

The right side DTG voltages have to be wrong all at 40VDC. I have tested the this tranny again and it is still good

[PRR]

> my board shows no .047

Surely 0.47? And yes, you need these; something they may have discovered between #3407 and #30000.

> The pinout


http://www.ese.upenn.edu/detkin/components/active/TO3.gif

Q3 can't have +40V on all three pins. There is a wire missing from collector to output and Q2's emitter resistor.

I agree the layout is mind-bending.

I re-drew the basic plan more "logically".

[plexi50]

Surely 0.47?

Yes 0.47. Sorry about that. I wish i had taken a picture of this before i sold it. I suspect a wire is out of place as well. I know it is on the output. Everytime i start working on this it puts me in a box spining in circles,traceing wires,reading schematic and trying to keep my awareness all at the same time. Im ever so close. I dont want to go back in today but i will. Pray for me*

[plexi50]

There is a wire missing from collector to output and Q2's emitter resistor.

It is here. I believe i have this wired right. I finally feel comfortable with the circuit and how it is working. It's those dam dual wires on the bottom of the 500r 20 watt resistors that make the connections for the Q2 emitter & output. The small red wire in the pic is from the Q3 collector,500r,560r circuit that connects to Q2 .047 resistor and to Q2 emitter

The voltages still dont look right but the collector of Q3 is not showing +40VDC today. Maybe my meter was acting up?
There are small germanium transistor mounted to the preamp boards. I hope they didnt get zapped

The EQ is totally functional but at very low volume. The chorus vibrato is working as is the reverb
Making sure the feed wires to the preamp (voltages) are going where they are suppose to as the square socket is wired is what i am looking at now in the preamp. That should have nothing to do though with the output board as it is stock regardless of the schematic

Get the voltages right on the output and it should come alive if the preamp didnt get zapped as well some where

I have thought about the output transformer being bad. Did a continuity check between all windings isolated from any other connections and beeps good. Voltage passing through all windings and 500r resistors.

[plexi50]

EDIT: Error wiring Q2 emitter and output. This is latest correction. This is MADNESSSSSSSSS  

[plexi50]

PRR, The board is wired right and im confident that it is finished. What would cause the voltages to be wacky? Maybe i got a bum transistor off ebay. They tested good but one of them had a very high reading compared to the other. I know it is almost impossable to know without having it in front of you 

[PRR]

Measure voltages with (*both*) transistors out. This should give you about the same as in my sketch. The transistor Cases at near-zero and at -40V. Emitters at +40V and near-zero. Bases a few tenths Volt negative of emitters.

[plexi50]

DTG-2400 Transistors Removed
The transistor Cases at near-zero and at -40V
Case Q3 at +.312VDC and Q2 at -40VDC

Emitters at +40V and near-zero
Emitter Q3 at +40VDC and Q2 at .299VDC

Bases a few tenths Volt negative of emitters
Base Q2 at .032VDC and Q3 at +40VDC<
I have not changed any of the transistor base leads or transformer leads around.

[plexi50]

Ok PRR i have the output voltages looking good. This is what i did. Re checked wiring and circuit trimmer bypass is 100% correct. Then i looked up into the preamp and there are (2) Motorola 2N554 PNP germaniums that are shorted as well. One is for the preamp driver and the other the reverb. The 2N554 are not shown on the preamp schematic lest i be blind which is possable. Thus the weak signal output and not the output board IMO. That has been fixed. By the time im finished with this i ought to be a Haynes Jazz King repair shop. Problem is im 48 years too late

I have found and ordered the (2) 2N554 TO3's. Im surprised latley that i have been finding these NA parts with little effort

I wish the guy that i sold this too had left it alone. If the DTG-2400 trans had been pulled and tested before just replaced the two burnt 3.3r resistors and whatever else was static zapped those trimmers and what else i have found could have been still good. I love the tone this amp has. I have a small fortune in all the preamp board caps that i had replaced before he got it. I have already been through all the preamp boards and all is good there thank GOD/ 

[PRR]

> into the preamp and there are (2) Motorola 2N554 PNP germaniums that are shorted as well

Preamp transistors don't die like POWER transistors. Often there is so much resistance in the circuit they "can't" over-current or over-power. WTF happened to this box? Plugged into 240V?

[plexi50]

I wish i knew exactly what happened. Id like to think that it got hit by a lightning bolt but thats not the case. No rain here for a while. High power company surge? Nay. I wont ever get the truth. This was the wrong amp for someone to practice on. How the hell do HD trimmers literally burst into flames and melt along with burnt smoke on the board? Look at these removed pots. The pics dont show the melt down very good. Totally disgusted. But! There is hope*

Will get back to this when the 2N554 arrive.

[sluckey]

Just something to keep in mind when you replace those transistors again...

In less time than it takes to flip the switch on, say one Mississippi, and flip the switch off, those new transistors will poop if there's still a wiring error or other problem.

[plexi50]

Just something to keep in mind when you replace those transistors again...

In less time than it takes to flip the switch on, say one Mississippi, and flip the switch off, those new transistors will poop if there's still a wiring error or other problem.

I have been checking all the voltages feeding the preamp board sockets from the power supply. I have -24VDC going to the reverb board. This is the only data i could find on the 2N554

[PRR]

> data i could find on the 2N554

You sure that's the right part?

Your data shows 40V breakdown. The amp idles with 40V across each transistor. When big signal happens, each drops down to few-Volts and up to 79V. These really need to be 80V parts.

Or is this the Driver parts?

[plexi50]

This is the driver part for the preamp and i assume the reverb as well. Information is delicate and thats why i am measuring the preamp voltage feeds. I have -40VDC / -28VDC / -3 volts VDC and -38VDC running up to the preamp section. Something else i noticed is the second channel will not work unless the reverb power transformer voltage is plugged onto the reverb transformer. Pic later. Friday night dance party/

[plexi50]

Got the 2N554's in yesterday. No change. My bias is still not up to par. It sounds like a weak bias or bad OT. I recapped the power supply and output board neg voltage cap. This is a bummer.  

[plexi50]

PRR it's been a few months since i last had time to tinker with the underwear amp. I was thinking about the bias and wondered if the 3.3r could be raised or lowered in value to get the bias up more. Not knowing the values of those toasted trimmer pots really leaves me with wondering. Man if i had only taken a pic of that board before the damage occured/

[plexi50]

Well it's been almost a full year now tinkering with the haynes jazz king II when i have had the time to dabble with it. I now understand this amp inside and out like any tube amp. Though it's still hard at times to block out tubeology thinking i have made good headway. A main preamp board that feeds the first and second channels signal had a blown 2N408 germanium power transistor. I have had the amps output board working all along but there was the preamp issue that i finally tracked down. Also i have just inherited another Haynes JK II amp. It's output and power supply board are a year earlier (1965) than my 1966 model and they are totally different in appearance but are 99% the same circuit wise. Luckily i have a source for the preamp RCA 2N408 and 2N2613 germanium transistor. I have also discovered i dont need to use these exact RCA part numbers as there are many germanium transistors that will do the job as well. I stuck an NOS AC128  on the board to get a tone check for gain. It sounds fine. I love the reverb and modulated vibrato that this amp has. Thats the main reason i didnt want to give up on it. More later/

[plexi50]

Well PRR & Steve it's finally finished and sounds wonderful again. I received the parts i needed (1) (2N408) & (2) DTG-2400 power transistors. Put them in this morning and fired it up. Plenty LOUD as it was before the troubles. Dead silent idle. Quieter than a dead church mouse. Great reverb and phase modulated vibrato. AMEN! X 100

[silverfox]

What a long strange trip that's been. Could the wrong impedance speaker or hot wiring an external cabinet have caused all those failures?

Silverfox.

[plexi50]

What a long strange trip that's been. Could the wrong impedance speaker or hot wiring an external cabinet have caused all those failures?

Silverfox.

Your question is an excellent one* Before i played the amp after the repairs i replaced both of the 12" speakers. As i looked at them they looked good. But then i checked the speaker voice coil movement and there was none. Both speakers were locked up tight and they had no flex or movement what so ever. I now suspect the speakers were the probable cause of the transistor damage.

One speaker reads 12 ohm and the other 14 ohm. The voice coils being virtually frozen were probably cooking and the shorting load burnt up the power transistors. Im glad you asked this question. Happy Thanksgiving*

[smackoj]

nice job Plexi. you win the Top Tech award this year! PR gets the Pit Boss award too!

 

revision: Sluckey is a gem too!

[plexi50]

you win the Top Tech award this year!

Thanks but that would be PRR & Steve. Im just a persistant lover of what knowledge i can aquire from the masters and other on this forum. I wish i had a good scope. But my listening device in Dougs library just about does it all.
Make it the Top Haynes JK II Fruit Of The Loom Award.   

[Willabe]

Make it the Top Haynes JK II Fruit Of The Loom Award.   

     

No you stuck with it and got her up and running, GOOD JOB!



             Brad     

[plexi50]

Thanks Willabee and all. Thats what it's about. I bought another one and now i have 3 of them. The second one already works but needs a complete recap. The third one i dont have yet. I have Haynes fever now*

The Lab series gibson amps L5-L7 are the only other solid state amps i know of that have a nice tube tone
Speaking of the Lab series,i just aqquired a Lab L5 212 that i need to go through

[plexi50]

Well i have (3) of them now. They all work and have been gone through and recapped. I need speakers for the one on the left.

[smackoj]

Are you thinking about selling one?  thanks, curious geo.

 

[plexi50]

Are you thinking about selling one?  thanks, curious geo.

 

Actually i have one (top pic center) listed on CL for $450.00. But nobody knows what it is or anything about them. I am in Floridah/

[smackoj]

just an idea, but maybe you could offer the one w/o speakers and save a few bucks on both ends to ship the beast?  just a sugg.

fyi " they don't know what it is" ... I posted 6 pedals F/S yesterday to try and raise some 'fun' money for more projects. I posted them at below half the price of what they are worth. One measly phone call from a guy on a fishing expedition. People are extremely cash POOR right now and who knows when that will change?

adios amigo,  

[plexi50]

Boy your not kidding on the cash poor thing these days. Used to be i would sell everything i listed within hours. I sold on Ebay from 1996 when they first came online up until 2001. It was over for Ebay by then as a seller for the most part. After ebay bought paypal everything changed. People still try selling on Ebay but Ebay is the one making all the money off of fee's along with paypal fee's. They get you coming and going. I still buy sometimes on Ebay,but i would not sell again if you gave me a fee Free paypal account/