[Amps] TL922 Filament Transformer (Was TL922 Fan)

[Jim]

This diagram shown below is *WRONG. DONT USE IT!* Its the exact same as 
a TL922.

I'll get the proper circuit drawn and send it out.


Thanks
73
Jim W7RY

On 5/8/2019 7:54 PM, Jim wrote:
> Because you say you want to ground the grids and do other updates.
> *This is what you said:*
>
> /*_Tomorrow I will detail the rest of the TL-922A makeover, new tube 
> sockets, new band switch, new tubes and a W8JI grid grounding party_*
>
> /Which means to me, that you are going to do other work? So what does 
> this mean to you?
>
>
> What I said is exactly what I mean. If a tube shorts, (filament to 
> grid which is the only way I have seen a 3-500 tube short, and they do 
> it often), it shorts the 120 volt DC bias and relay supply to ground, 
> and burns up the filament transformer, because it has no fuse (fuse 
> wont protest it anyway, putting a fuse in the primary does not keep it 
> from burning up). Every wonder why so many TL-922 filament 
> transformers go bad? This is why they do.
>
> Only fix is to re-wire the relay bias switching.
>
>
> *Bottom line...*
> if you wire it like this, (from an SB220 schemaic) it will save your 
> filament transformer.
>
>
> Thanks
> 73
> Jim W7RY
> On 5/8/2019 1:28 PM, Artek Manuals wrote:
>> Jim
>>
>> A perhaps important point but I am not sure what it has to do with 
>> the fan replacement?
>>
>> Maybe you would just like to point us at a solution to the mentioned 
>> problem rather than have us reinvent the wheel
>>
>> ?????????????????????
>>
>> Dave
>> NR1DX
>>
>> On 5/5/2019 9:29 PM, Jim wrote:
>>> You have not mentioned the most important part...
>>>
>>> Re-wiring the 120 volt cut off bias.� If a tube shorts, it takes out 
>>> the filament transformer.
>>>
>>> Study the schematic.
>>>
>>> Thanks
>>> 73
>>> Jim W7RY
>>>
>>> On 4/29/2019 7:52 PM, Artek Manuals wrote:
>>>> OK after a bit of sleuthing and help from the A/C repair guy next 
>>>> door who has a meter that measured the airflow I found two probable 
>>>> exact replacements for the fan in the TL-922A... Which suggested 
>>>> that this was an ~53CFM fan that originally was spec'd at 100V/7W 
>>>> probably 1700RPM. Size: 120mm x 120mm x 38mm
>>>>
>>>> The first from Mouser is a Sanyo Denki fan #109S006 a very quiet 
>>>> fan at 28dBa. Problem is that it is a non stocked item with a 
>>>> minimum order quantity 40pcs at $24.76 ( extended order price of 
>>>> $990 !) ... deal breaker for sure
>>>>
>>>> With the spec sheet for the Sanyo in hand I could now look for 
>>>> other equivalents ! . I found the following on Amazon.
>>>> "AC Infinity LS1238",� 62 CFM @32dba� 120V/8W (probably 7W at 
>>>> 100V). $14.99 free overnight delivery ...Bingo
>>>>
>>>> Easy replacement. The new fan though rated at 62CFM measured closer 
>>>> to 55CFM installed in the amp. The old fan would raise the noise 
>>>> level at the operating position when switched on by approximately 
>>>> 12dba as measured with two different phone apps. The new fan 
>>>> switched on raised the noise level by only 2db when switched on a 
>>>> big improvement over the old worn out one. Air exit temperature was 
>>>> identical to the old fan at around 30C at idle and 35C key down for 
>>>> 2 minutes.
>>>>
>>>> So TL-922 owners� print this info out and store it with your manual
>>>>
>>>> Tomorrow I will detail the rest of the TL-922A makeover, new tube 
>>>> sockets, new band switch, new tubes and a W8JI grid grounding party
>>>>
>>>>
>>>> Cheers
>>>> Dave
>>>> NR1DX
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
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>>
>