T4B optical cells repair

[beatnik]

I have been wondering wether the T4B optical cells unit are easy to repair

From what I see there are not many components involved, just a couple of photo resistors and the electroluminescent panel

I know the photo resistors need to be matched to ensure the vu meter is displaying correct gain reduction level. In case one of the two resistors is broken, is it possible to find a matching replacement with standard equipment ?

Regarding the electroluminescent panel, I have read these can lose brightness over the years and need to be replaced for correct operation. Is this part still available or is some kind of obsolete technology ?

 

[outoftune]

pretty straightforward repair try this store for parts https://sites.google.com/site/diypartsstore/catalog/new-t4b-opto-el-panels

 

[gyraf]

"1 Set EL Lamp Electroluminescent Panel for Party House Craft Toys" - quite inexpensive..

https://www.aliexpress.com/item/4000270646067.html

/Jakob E.

 

[Bo Deadly]

Regarding the electroluminescent panel, I have read these can lose brightness over the years and need to be replaced for correct operation. Is this part still available or is some kind of obsolete technology ?

Notes on Clairex CL-505L photoresistors:

https://groupdiy.com/index.php?topic=64961.msg823488#msg823488

The photoresistors are relatively slow compared to modern parts. I used a Kenetek one in an LA3A circuit and it works great.

 

[saint gillis]

I'd like to repair an original T4B from an LA3A.
I've just read all Groupdiy threads about T4Bs.

In my T4B, the EL panel is dead.

The LDRs seem good, although I've read that : "LDRs can degrade and indeed fail. Symptoms of degradation can be significantly higher levels of distortion and occasionally less than the required Rmin for a given illumination."

My question is straightforward : is there any El Panel from a serious supplier that fits the original dimensions and is worth testing as a replacement ? (I'm ok to buy 10 pieces or so and test time response and compression ratio)

Otherwise I'll buy boards from here : T4b opto cell parts - Curious Audio

Thanks you !

 

[beatnik]

I have been using the replacement EL panels from Curious Audio and they work very well

 

[saint gillis]

Thanks, I didn't noticed they were drop in replacements..